Rebuilding Husaberg Motorcycle Engines

This information about stripping and rebuilding your engine is for the Husaberg 400/450, but should work for other Husaberg motorcycles. For your reference to incorporate into your Husaberg engine rebuild:

Husaberg 400/450

Plan of Action

If a complete engine stripdown is required, it can be as easy to remove the rocker cover and head in situ as well as all the left cover, etc. making the engine easier to lift out. Stick a shaft through the S/A and frame so the bike can be wheeled about.

When rebuilding it’s advisable that the entire engine is built and sealed (so spark plug in then!) because muck and grime among the electrics will find it’s way into the engine. Also the kickstart mechanism ONLY JUST fits on the crescent and the slightest knock and it’ll unwind necessitating removal of the clutch AND the possibility that it will happen (if the engine is upright in the frame and the frame upright on the bench) again and again. And if the left cover is closed, you don’t want that silly camchain falling right down the bottom now do you!!!!

Engine Stripping

Clutch Cover Removal

There are three lever tabs around the outside. Turn the cover over and file a gradient gently to allow a lever in and aid leverage.

Checking the Mains

Put here because you can’t check it when the engine is all stripped! Stand on the opposite side of the bike to the side you’re going to try. Lean over the frame and grab the end of the crank with both hands as best you can and then try to push and pull; feeling for the clonk of a main bearing thats gone.

Measure Crank Float – NOW!

Crank axial float is vital and many engines have too little. Measure the axial float now and you can then make a decision as to what to do. Axial clearance is in ‘blueprinting’. I have always whacked the end of my cranks left and right and measured using the heel of a vernier gauge what the float is. Tool of choice is a ‘dead weight’ hammer. Simply move the crank one way and mount the vernier heel on the crank and the tail on the bearing to measure. Move the crank the other way and measure again.

Breaking The Cases – OPEN!

Undo all the screws to the cases and then replace two cylinder studs in the right-hand half. Use a hammer initially to tap upwards on the heel at the back of the cases. Then tap back down the end of the crank and both gearbox shafts. Use a drift and hammer on the input shaft – be gentle. Tap upwards the base of the two studs lightly and look for other excesses on the right-hand case that will allow a tap.

A thin screwdriver shouldn’t be used unless as a last resort and go again to the swingarm boss area and the frame bolt holes on the front of the engine as the cases are very broad at these points. If the spigot area is difficult try to put a lever in halfway and tap down at the back to tilt the top – up! Remember that every little lift of the case must be accompanied by taps to the end of the three shafts….

Most people forget the screw in the middle of the cases at this point.

Bearing Removal

Gearbox Output: The best way is to slip another gearbox bearing in but from the outside while holding the inner race in the roller bearing. The inner race keeps the rollers OUT and the old gearbox bearing just presses through taking the old roller with it. Like A.B.C!

Input, Right-Hand Bearing: Easy

Right-Hand Crank Main: The gearbox bearing nearest to it should be pressed out first and then it presses straight through the seal housing onto the right-hand main. If it’s a roller you can hold the inner race in while pressing it out. Jobs a good un!

Left-Hand Crank Main: Press out with gearbox bearing through the seal housing.

Top End Rebuild Only

When doing this the one thing difficult to check is the cam chain condition. If the sidecover isn’t coming off then having removed the tensioner completely, feed another old chain on and remove the current chain. Measure the chain on a bench and then make your decision. The split link can be used without the sideplate or the spring clip. The link won’t come out.

Stuck Woodruffe Keys!

When stuck there are two ways out. Firstly, tap one end down exposing the other and with good purchase by mole grips they will come out. Secondly, try drilling several times with 1-2mm drill bits being careful to get the centre of the key and not the shaft. This will loosen the key as it loses it’s strength.

Diagnosis and Preparation

Cleaning Out the Crank Pin

It is known that the crank has just a small 0.5mm hole through which the oil feeds the big end. So blasting air the traditional way could be a bad move! Below is a system for reverse cleaning the crankshaft.

A piece of plastic tube runs across the end of the crank which is submerged in a bath of cleaning fluid
A piece of plastic tube runs across the end of the crank which is submerged in a bath of cleaning fluid
The air jet blasts along the tube and into the catch can. The run across the top of the crank sucks fluid up
The air jet blasts along the tube and into the catch can. The run across the top of the crank sucks fluid up.
A pin hole in crank. Block this with a Dentist's pick
A pin hole in crank. Block this with a Dentist’s pick.
With this squirting oil, balancer failures are a thing of the past
With this squirting oil, balancer failures are in the past!
To finish, bath the crank in oil!
To finish, bathe the crank in oil!

Skim the Barrel/Block

Raise compression or for warpage. Here’s the correct how to guide for skimming a Husaberg block. The spigot should be flush with the block or can be proud by up to .005″ (Lineaweaver). It may pay to have the spigot and crankcase machined separately.

Drill Funnel Type Hole

The right hand cases on the 2001-2003’s have a small drill hole for oil to drop down the back of the main. ‘Kiss’ with a 12.5mm drill bit to create a funnel effect to collect more oil. Clean BEFORE you fit the right-hand main.

Reusing Gaskets

In order to continually reuse gaskets (except cylinder head): try smearing them in copper grease before fitment, the rocker and WP gaskets will be re-usable many times but extreme caution should be taken with the sidecover gasket as half will stay ‘down’ on the dowels and half will try to come away with the cover!

Reusing the Headgasket

This is barely feasible with the blue-lined gasket. Don’t just leave the gasket on the head, remove and clean both surfaces as well as the gasket or they WILL leak. Renew if you’re not cheap! My experience is that it isn’t worth trying to re-use. 75% fail and whether they have been there a month or a year doesn’t seem to matter.

Case and Cylinder Head Screw Tightening

Tighten the case screws lightly, then the head lightly, then tighten the case screws, then torque the head down. The longest screw goes into the middle of the cases whilst the four shortest go each side of the top of the ‘block’. Two long screws go at the back of the cases and the rest go where the rest of the holes are!

When Fitting New Mains – At Home!

Tape the old pair together and lay on the workshop floor under the outside of the crankcase half. You’ll also need a small piece of wood for good support at the back of the cases-get this right before the crankcase comes out of the cooker!

Also put the cases in the oven and the bearings in the freezer for a long time before doing this. This allows full expansion or contraction of items.

Big-End Play

To check for big-end play fit a feeler gauge down the side of the con rod and THEN try pull/pushing the con rod.

Wear limits crank
Wear limits crank

Another good way is to hold the assembly by the little end in one hand and slap up the crank from below. This will produce a clonk if worn. A well oiled crank will disguise this.

Screw Jet on End of Crank

Although it looks like it is part of the crank, there is a screw in the left hand end of the crank that can come loose (up to 2004). It has two flat faces for a small 9mm spanner to tighten with thread running in the usual direction. Some will tell you that you get more oil to the crank if you drill it out. Wrong! There is a similar hole up through the crankpin and if there is a blockage here, the centrifugal force absolutely blocks the hole, at least on the axle you have a chance. If this screw has been drilled out – change it again for new.

Crankend screw
Crankend screw

Wash Crank Gallery

If just stripping engine to replace the big end bearing or for inspection always try to wash the oil feed gallery through the crank out using a pressure engine cleaner/degreaser. Work from both ends and be thorough. The restriction points are the above mentioned screw in the right-hand end as well as a fine hole into the big end. It’s likely that these two small holes have been blocked and been the ruin of many an engine…

From 2004, you’ll also find a very, very fine hole in the left-hand crank cheek on the opposite side to the big-end, this feeds the straight to the counter-balancer bearings.

Big-End Sidefloat

Impossible to measure as the big end bearing is recessed into the flywheels.

Pressing in the Gearbox Input Right Bearing

This is the bearing that can go right through the engine! traditionally you would press this bearing like all others in from the ‘inside’ but because the outside of the case has about three levels it is actually best to rest it on the inner face and press in the new bearing from the outside!

Pressing the Crank Together

Some info here. The clearance is in the book but here is another way to measure, Problem is IF IF it has a wider rod.

Measure across crank wheels (micrometer)
Measure across crank wheels (micrometer) (Neil_E)

Gearbox – Erratic Selection

The hardening can come off the teeth, dogs wear at the edges and gears are missed and jump out. It’s normally the gears on the secondary shaft that get it. Unfortunately, with their oval end profile they can’t be saved. Any shininess here on the corners and corners that are more reduced then you’ll see elsewhere mean that the selection is going to start breaking down.

Hardening gone off 5th gear.
Hardening gone off 5th gear. (Weed)

Little End / Wrist Pin Bush

The 450501/550/650 little end/wrist pin bush will spin in the rod-nothing will stop it . The little end bush can be delivered loose so order another and another until one arrives that’s ‘nice’ (Lineaweaver). Look for spreading. A worn little end will be wider at the bottom of the hole than the top and sticking out of the rod’s eye. In later years the little end is very prone to wear and often the only reason initially that you would strip the engine. rock the piston ACROSS the bike to check.

Piston Scoring

If you find signs of piston scoring on the thrust faces-don’t touch but leave-as this will reduce the diameter of the piston.


The rings are Chrome in a niksail bore which isn’t ideal and makes it two VERY hard materials. The rings should be replaced not because they wear – they don’t! but because they lose their strength and flutter in the bore (on some pistons), this shows up as waves at the top and a lip at the bottom and if the linar has this it MUST be replaced. The factories end ring gap is certainly a minimum. Change them each season if racing.

Clear oil ring marks. So how will YOU! hone this out Mr DIY man?
Clear oil ring marks. How will YOU! hone this out?

Spigot Ovality

Not as rare as you think and bad on all the 100mm pistons that have seized. It really might be that the barrel has lost it’s shape so check with a bore gauge and if more than .002″ (.05mm) out then they can’t be saved.

Wear limits piston
Wear limits piston

An internal bore gauge is strongly recommended. Husabergs, 6-years old, etc. have been through the mill and the cases can squeeze up the linar.

If you lack an internal micrometer a simple check is to fit the piston complete with rings and then turn the piston in the barrel. Easy, hard, easy, hard means oval. You judge…

Honing the Spigot

This can be done with alacrity as the bore is well safe. It will show up low spots and remove a lot of rubbish. Spigots can be saved if mildly chipped but welding on the bore is a no-no except for the 400 which has a bit more ‘meat’ on it. A professional engine reconditioner should be used to hone the spigot because it’s at the bottom, around the cutaway that the professional equipment can do a better job than a ‘home-hone’. Worth the money. Also you can now go to the ‘B’ piston or ‘II’ as Husaberg call it!

Rocker Pads – Concave

The pads must be checked for ‘cupping’. Cupping will ensure odd valve opening as they move about – especially if the arms have too much float! View by looking at the reflection of light in them. They’re relatively cheap to replace.

Badly cupped tappet pads
Badly cupped tappet pads

Cam Follower Bearing Check

The inlet bearing can be checked in situ but the exhaust rocker arm MUST be removed for a proper check. Play can be detected in the plane that the arm moves and the wear is actually at 6 o’clock. The most important area to check is in line with the valve stem as the underside of the pin wears that faces the tip of the valve. Any looseness detected, knock the pin out 3/4-way using a perfectly sized punch so that the needles stay put and check the condition. When they go dull grey, they have just a few hours left so replace them NOW. Those who are cheap have been known to turn the pin over 180 degrees… disgusting! (LOL!!)

Worn pins go a dull gray and are about to fail, you only have a few hours left. Failed pins are through the hardening and ‘picking up’. The walls of the rocker fork get ‘scored’ and ‘ditched’ but can be filed flat. If you replace a CFB, always keep the little blue plastic spacer to help do this check the next time – it’ll keep the needles in place. If the pins are partly out, they must be pressed back in and the shoulders (not the pins) punched to secure. Another usefull item is a single roller pin out of an old gearbox bearing ground down.

Tuliped Valves

Always check the Inlets, they’re usually tuliped if any high revs have been used, they can be cleaned up and their total width reduces as little as 0.2mm with careful machining. Make sure that you keep some radius on the tip/edge but on average around 0.2mm is ‘lost’. Have the tip of the stem machined at the same time. The 37s are more prone to it and also the most expensive! Exhausts are usually fine.

Rocker Shaft Wear

With the 2001-2003 heads the pins can be turned over if money is short. Wear is on the underside of the shafts. Best to make a note when removing of course! The bushings in the rocker arms are very hard and last better than the shafts.

With the 2001-2003 heads the pins can be turned over if money is short. Wear is on the underside of the shafts. Best to make a note when removing of course! The bushings in the rocker arms are very hard and last better than the shafts.
Wear limits head


Bearings in the Cases

Remove the two small dowels from the left coverside of the left case to allow a nice flat face on the bearing press. Note that there is a boss sticking out from the CCT area and this will need to be avoided. The main bearing must go in before the intermediate shaft as the gear on this just overlaps the left-hand main housing by a mere 1mm!

Case Seals

The left-hand seal and the gearbox seal are both slightly wider than the case, so the usual trick of tapping them in flush will lead to the seals jamming into the bearings. You have a choice of pressing the bearings in first and the seals second or vice-versa! However, DON’T fit them after the crank and gearbox are in because if they are pressed in too far and can’t be drawn back!

Counterbalancer Retention

This is a major decision as they can fly to bits. If removing, simply knock the centers out of the ball races and refit the inners to space the crank. There are many early threads on the subject on UHE and the jury is still out but more likely to say ‘keep them’ than not. Machining down 61906s makes it possible to keep them.

Present Only the Crank Initially

Below is a description of how to press in the crank but do try to only fit the crank initially and check side (axial) float as well as the fit of the bearings both in the cases and on the crankshaft. Husaberg motorcycle’s main bearings are far too tight a fit both into the cases and the crank’s fit into them. If they are a really tight fit the mains feel notched. Check “Blue printing” for correct tolerances and how to achieve them.

Now Present Only the Linar

The linars can be crushed oval and has caused many problems so fit it alone WITHOUT the ‘O’ rings. You need to remove any high points until it does! Some measure the run out in the linar with the cases tightened up. Secondly, look for a factory mark at the rear of the linar which should be placed on the crankcase split. If the linar doesn’t have one, you must mark one – it’s very important because if you don’t you will be blind as to wether the linar has turned, if it turns and one edge of the cutaway rests on a squared edge: you’ll have a warped linar and another expensive rebuild. Convinced now?

First Fit The…

Not the most obvious choice but, after pressing in all the case bearings in you should fit the intermediate gear shaft in the left case. The main bearing must go in before the shaft. The reason for this is that the shaft has no circlip to keep it staying right out so you need to lay the gear on something solid and then start to fit the sprocket and gear. Fit the small woodruffe key, sprocket, second (thicker) woodruffe key, the gear: before adding the nut – locked up or otherwise. Its vital that you ‘DRAW’ the WP shaft back out again as it will have moved into the engine. If working with the engine rolling about on the bench, the shaft will need one more ‘pull up’ before fitting the sidecover.

When Fitting the Lower Timing Sprocket and the Intermediate Gear

You’ll note that you have a choice of two slots for the woodruffe key. You can tell their old positions upon reassembly by the ‘stain’ on the shaft created by the ‘dummy’ groove. If struggling with the woodruffe key in front of the lower timing chain sprocket-just grind the end off slightly. Tightening the nut on the countershaft will draw the shaft right through eventually. You’ll have a shorter key but it’ll be fine.

Fitting and Timing the Balancer: >2004

The timing mark on the W/P shaft gear is a very large and clear punch mark, on the balancer it is in the bottom of a tooth and if still covered in oil will be invisible! Mark the end of the balancer plate with a felt-tip pen, firstly on the end and then behind the balancer. Thats right – behind! Having fitted the crank into the left cover you can look through the crank’s drilled holes to view the balancer and the gear. It is possible to make last-minute adjustments through here. You can even tap the balancer down to engage and then tap the crank to catch up!

Fitting and Timing the Balancer: 2004>

With the 2004>, you need to place the shim(s) then the balancer on the bearing and place the crank through them all. a little grease can keep them all from being mischievous. Afterwards, if you care too, you can fit the clutch basket and the timing gears, turn the engine and a dot on the bottom of the balancer will come up and touch a dot on the intermediate gear. they will be 2mm apart but on separate gears crossing paths at 90 degrees.

Dot on drive gear to balancer
Dot on drive gear to balancer
Dot on the balancer gear close-up. Now mark the end face and then carry the mark on around the back!
Dot on the balancer gear close-up. Now mark the end face and then carry the mark on around the back!
Balancer drive gears meshed. Note the felt-tip mark on the end.
Balancer drive gears meshed. Note the felt-tip mark on the end.

Piston Circlip Fitment

Place the piston circlips in with the ‘C’ facing down.

Fitting the Rings in the Spigot/Linar

No ring compressor – no problem! Get all the ring gaps to the same side as the cutaway in the spigot. Then as you feed in the rings around the back (easy) you can tuck them in around the front as you go. I use the flat face of a flat bladed screwdriver and just crush the rings down/in to the groove.

Watch out for the oil rings (note: plural!), as the spring must not overlap at the joint and the various parts do like to pop out.

Spigot ‘O’ Rings

The three huge spigot ‘O’ rings in place and to seal by putting a smear of silicon around them whilst in their grooves ready for fitment. If you ran the bike without coolant and cooked the engine you must purchase new ones as they will have overheated and lost their rubberiness!
Working around the engine without the gearbox flopping out.

A simple zip-tie will keep the gearbox in place, while you work around the left cover, crank, etc.

 Just a simple zip-tie will keep the gearbox in place while you work around the left cover or crank etc
Zip tied gearbox

Gearbox Schematic Diagram Error

The schematic diagram of the countershaft/output shaft is wrong. The gearbox SPROCKET is shown at the wrong end of the gears, and the shaft the wrong way round if one considers the gears to be correct. As laid on your bench with the shaft assembled you should see: 1, 5, 3, 4, 6, 2 and then the gearbox sprocket

Gearbox Noise/Whine

It could be you can hear a noise coming from a ‘whining’ gearbox. This is noticeable at any speed, any gear, any time. If there is too much endfloat in the output shaft gears will rub inside. It’s not dangerous but is avoidable at a rebuild. By using thicker shims the float can be reduced from a noise inducing.020″ (0.5mm) to .008″ (0.2mm). Here’s the answer to gear shaft end float!

Parts including custom stop disc
Parts including custom stop disc (JoeUSA)
OEM & custom stop disc, shaft
OEM & custom stop disc, shaft (JoeUSA)
OEM & custom stop disc
OEM & custom stop disc (JoeUSA)
Stack assembled with custom stop disc. Perfect clearance for retaining ring.
Stack assembled with custom stop disc. Perfect clearance for retaining ring. (JoeUSA)

When Fitting the Gearbox

When fitting the gearbox in the L/H case, this is the order; output shaft half in at a slight angle, input shaft straight in, bring left shaft upright and press both down and in. Selector forks fitted, selector rods through forks but not located in cases but separate them as wide as they’ll go apart from each other. The single fork needs to rest on the case half. Fit hollow washers on forks, move over into the selector drum which has the drilled hole in the end placed at 1.30pm. This is virtually neutral. Push the fork selector rods home into their recess.

The order of the gears (a ‘box from 2001- to date) on the bench should be (as if sat above them):

1st 5th 3rd 4th 6th 2nd
14 24 19 23 27 or 25 (CR) 17
33 22 26 25 20 or 21 (CR) 30

Both 19 and 23 are on one gear and appear to be fittable either way around so be careful. The gear in the parts manual (2001/2002) coded #31 is shown as the wrong way around to the correct fitment direction.

Inserting the Crank Assembly

One need’s to have a true crank to start with, install a chisel between the flywheel cheeks with big end pin at bottom, insert crankshaft assembly into left-hand side with crank seal greased.

Then press the crankshaft assembly till lightly seated! keeping a good eye on your timing marks on the water pump shaft and balancer, does the left-hand side spin freely? Piston is now ready to install so a circlip must be installed on the left-side of the piston, slide down on rod as an assembly insert piston pin and other clip. Now fit the spigot and then the right side cover should now fit smoothly or some heat must be used on bearing! (Brother Boss!)

Second version: Place the counter-balance down, meshed with the WP shaft gear. This should lay upon any previously agreed shim. The crank assembly should consist of the crank, rod, fitted piston c/w rings and already inside the spigot and on the spigot should be the 3 spigot rings covered in a light silicon film. Drop the crank in whilst trying to see the felt-tip mark etc as the crank goes through the balancer assembly etc. DON’T let the linar ride up and down as you check the balancer dots and roll the assembly around on the bench! The ‘O’ rings will ride out of their grooves and warp the linar when pressed up causing failure in minutes.

Tiny Crankcase ‘O’ Ring

The ‘O’ ring for the cases and also for the head to rocker interface is often missing from gasket packs. In the absence of the correct parts simply coil up some 1mm solder into the correct shape. Sometimes there isn’t a machined recess for it either. The 2004> don’t have this, they have a dowel.

Fit the R/H cover and as it is gently ‘closed-up’ tap the top of the linar down that last fraction (no more than say 2mm). Any more and the rings roll out of their grooves and crush the linar out of shape.

Crank Seal

Fit crank seal after you’re happy that the cases are now closed-for good!

Working in the Left Cover-Side of Engine

When working in the outside left of the engine, fit the reed valve first so that anything dropped won’t go through and in to the centre cases (Simon).

Gear Selector

When trying to find neutral, remember the selector drum is clockwise to 6th and anti-clockwise to 1st gear. Turn ACW from 1st a little for neutral, check by holding one shaft and turning the other. Sometimes you can change gear simply with a 10mm socket on a speedbrace. Do this till you are perfectly satisfied that neutral was one gear and a fraction from the end of travel. Then fit the star with the odd part ready to fit the sprung wheel. Position: The short pin should face the front of the engine for neutral. (Simon). Why not mark a pin when disassembling so that the star goes in the right place and you have the bike in neutral.

Timing Gears

Try and retry to get the single upper dot between the two lower dots as per manual. It’s worth pursuing. It may appear ‘nearly correct several times. Try using a ruler and closing one-eye! When fitting the two timing gears, the 2-dot gear fits the crankshaft and the 1-dot gear the intermediate shaft. The important thing will be later and the cam timing though…

Here is a diagram of the timing.
Here is a diagram of the timing.

Often though the single dot will appear to be over one dot or the other but NOT in between! I have found it best to usually opt for the single dot over the left of the two dots representing a capital ‘L’ if the dots were joined. If later, the cam timing cannot be made ‘symmetrical’, it may be necessary to put the single dot over the ‘other’ double-dot and try again.

Crank and Intermediate Shaft Nuts – Recess Face-In

Be warned, the nuts have a recess on them. this should face the gears because the ends of the woodruffe keys are proud of the gears. Fit them the wrong way round and they can’t be tightened correctly. 10 hours and the engine will fail!

When you have both nuts tightened, use a pair of gemmy bars behind the sprocket to prize the shaft out (up) as far as it will come. There is nothing to stop the shaft falling into the crankcases so you’ll have fun soon when you try to fit the pin through the w/p shaft ready for the impellor!

Kickstart Crescent Screws and Gear Selector Central Screw/Post

Vital that these are carefully removed, oil cleaned off and a bonding agent used to keep them in place. They are physically hit from the side which isn’t their usual task and are therefore susceptible to loosening. Torque screws are now available at the dealers so a greater tension can be used.

Kickstart Fitment

Remove the outer gear and bearing for now so that you have just the splined shaft complete with ‘keyhole’ ratchet (sledge key) and it’s tiny spring fitted. The diagram in the parts manual shows the kickstart spring the wrong way around! So you need the straight pointed end to face away from the bike at your face!

Fit the straight part of the spring into the tiny hole in the kickstart mechanism and then fit the hooked end into the engine case feeding it all in as one. Leave the body of the splined shaft OUTSIDE the crescent and re-fit the kickstart arm at 11 o’clock. Start winding the unit clockwise until the ‘keyhole’ shaped ratchet piece goes past the ‘stop’ of the crescent plate. Now, holding the sledge key ‘closed’, press the unit down into the case using the kickstart lever to ‘wobble’ it down. Release both the keyhole and the kickstart lever. The unit will turn itself counter-clockwise and rest against the shoulder of the crescent. Now hold the gear down while you remove the kickstart arm and you’re ready to fit the bearing and gear on. Because the keyhole is ‘closed up’, the gear will drop on!

Clutch Basket

The reason the clutch basket won’t drop in its place is because the plastic oil pump gear needs a ‘flick’ around! It can be reached through one of the back holes in the clutch basket. Use the wooden tail of a small hammer within the basket around it’s circumference to just agitate the basket down into position.

Clutch Plates

Change the outside plates into the middle and vice-versa so as to spread the wear throughout the pack. Split the pack in the middle and simply turn the middles to the outsides and then arrange the friction and steels…

Wear limits clutch
Wear limits clutch

Later Tensioner Blade

If you find a yellow one you must replace with black and remove alloy stump off the tensioner. The blade will also need a small amount of chamfering on the top 2″ otherwise all the pressure is at the sprocket end.

Rocker Arm Float

This can be found by fitting the rocker cover and screwing down then undo just the two screws over the end of the shafts. By tapping in with a light hammer the float can be adjusted.

Removing the Decompression Cables and Lever

With the latest decompression fitted, there is no need for the:

  • Kickstart decompression assembly
  • Manual decompression assembly
  • Bracket on head
  • Decompression lever

The hole can be filled by tapering gently a 6mm allen head screw and leaving inside the head with the nut on the outside. Exactly the same goes for the kickstart decompression, taper a screw head, add some silicon, pull into the case and nut on the outside. a rubber ‘O’ ring can be placed on the bolt shaft and squeezed in the hole for added reassurance.

Inverted Screw Up into Cylinder Head

The only upward facing screw is not removable with left sidecover on if you have a 400/470. Change from Allen head to a normal hexagonal head bolt when you next have the cover off. This will allow work on the head without removing the cover.

Decompression Stopper Bolt

The decompression weight hits this one. Peen over the threaded bit of the bolt to secure. (Ausberg) Better still, with the later auto decompression (dutch clog 2004>) – remove it completely and leave the decompression to hit the far bigger and sturdier cam bolts.

Rocker Cover Breather Tube

These can be loose and be the cause of the front left corner oil dribble! Remove spigot, clean both threads and use a gasket fluid before tightening back in.

Plane the Rocker Cover and Upper Side of Head

The rocker cover can be cleaned up and plained flat by simply mounting a sheet of P600 wet ‘n dry on a pain of glass and with the use of soapy water rub the cover 6 strokes before turning 90 degrees and continuing. Do as little as possible as the cover still has to press on the cam bearings. The Head can carefully be done either the same way while the valves are out or chasing around the outside with a small but straight piece of flat and plained wood wrapped in wet ‘n dry again. This should only be done once in it’s lifetime: after this you will have new leaks but now because the cam bearing is making the cover sit too proud!

Sealing the Rocker Cover

Particular attention must be paid to the use of a good bonding agent between the rocker cover and the head. Run it around the cover not the head and then let the agent cure and fit. Best results come by leaving overnight. About the only stuff that works is called WURTH RTV super silicon sealant.

Left Cover Crank Oil Seal

The seals can be nudged deeper into their housing when fitting the left sidecover. Use a later oil seal with steel circumferential backing. These need to be nearly driven in and are unlikely to move accidentally.

Crankshaft oil seal, metal vs. OEM rubber.
Crankshaft oil seal, metal vs. OEM rubber. (Bergoroadracer)

Clutch Cover Fitment Over Waterpump Shaft

590 29 005 010 is a plastic sleeve that is slipped over the water pump shaft, so as you install the clutch cover, the water pump seal is protected. (Fryguy) Another way to do it safely is to fit the sidecover and THEN add the oil seal afterwards.

The secret is not to look at the kickstart or gear lever shafts but to solely look at the water pump seal. Entirely focus on steering the cover so that the end of the shaft is exiting through the middle of the seal and not rubbing hard on one side. Use the cover like a steering wheel!

Losing Coolant

If using same head gasket again… May try torquing down to 60Nm. This is 15Nm above factory numbers on pre ’04 bikes which became the standard torque setting from 2004 onwards.

Oil Leak from Weephole

Don’t forget to clear this out of dirt and filth. Oil leaks from the engine past the bearing in the sidecover. The shaft has an ‘O’ ring on it and oil passes this.

When fitting a new bearing in the cover make sure the rubber seal hasn’t come adrift from the bearing. Also make sure the ditch created for the oil or water to vacate the engine is clear or deepened manually so that it is effective. The Rubber face on the bearing can tend to block the path.

Water Leak from Weephole

Drips coming from hole. Not too bad. Trick is to replace with two thinner oil seals. Also newer seals are available with a hardened metal backed shoulder. Easy to fit, they also seem to last well. Remember also that there is a factory tool to aid fitting new seals without damaging the lip. Read this dicussion about weep hole leaking..

Check the Back of Waterpump Cover

Many an impellor has come adrift and owners haven’t machined flat/renewed the back of the cover. The cover surface should be perfectly smooth.

Waterpump Seal

Check that it is located correctly relative to the weep hole. On some models it may be necessary to epoxy the original hole and drill again. The oil seal in the sidecover should have the part numbers facing you.

The coolant ‘O’ ring in the left cover overlaps with the cover gasket. Cut the cover gasket around the ‘O’ ring. Recent gaskets have this cutaway already. To keep reusing the same gasket: smear it in copper slip.

Wrecked the gearbox seal? In a panic? Fit the old countershaft bearing and then an ‘O’ ring as a get-you-out-of-trouble-for-the-day fix.

Engine Oil

When fitting the inlet stub, the tiny (molding) nipple in the middle should be underneath. It looks symmetrical, but it isn’t!

You’ll need 1200ML of oil to re-fill from a complete rebuild. But an oil change alone needs just 900cc to bring it to the lower oil window lower level. It’s very important that the oil stays at the bottom of the window ass, oddly enough, they are prone to overheating… Oil pressure 15psi @ 3,000 RPM (Lineaweaver).

Refitting the Engine

Drop the engine into the frame and very loosely fit the front mounting bolts, then the swing arm pivot pin and tighten, THEN tighten the engine mounting plates.

If however you have a linkless final drive chain you will need to fit the front sprocket, remove the chain from the rear sprocket and before you push the swingarm onto the back of the engine, feed all the spare chain you have past the gearbox shaft and onto the sprocket. SM engines with 15T+ make it very difficult to fit as there is a recess in the rubber protector at the front of the swingarm.

Fitting Carb and Airboot

It is best to fit the carb into the inlet manifold, then into the boot and then the boot onto the frame. Now screw the inlet manifold to the head and then adjust all joints for shape and comfort before tightening both clips and the manifold bolts.

Stator Wiring

Is as follows; yellow into a double red, second yellow into the regulator (second from the right), light blue into a brown (or earth carousel), black into black and green into green, pink to pink.
Spark plug fitment

Apply a light coating of copper grease to the threads EVERY time you remove the plug.

Ignition Timing

Firstly, you need to know that the timing mark on the ’01-’03s is always scribed wrongly. The real TDC can be found in ‘tuning’. Use a strobe with a timing adjustment knob. Set the timing so that the line on the flywheel meets the mark in the spy-hole with the revs high enough that the advance of the flywheel marks have stopped, you are now at full advance. Using the adjustment knob look for 64 to 72 degrees of advance. Half this figure is your real advance. I.e. you have 72° which means it is 36° advanced. (Lineaweaver) You want 32-36°.

This also means that when making adjustments to the timing, a one degree turn of the stator will actually change the timing two degrees at the crank.

Cam Timing

Perfect Cam Timing

Assemble the cam without the decompression and also remember that the camwheel will pull straight over the top of the cam bearing.

To perfectly time the cam you need the engine at exactly TDC, then lay a ruler across the two lobes as they both sit up at 11 and 1 o clock. The ruler should be parallel to the cylinder head and can indeed tilt forwards ever so slightly to allow for future camchain wear. To change the timing you need to remove the camwheel completely and rotary file the slots to elongate them.

When finished, remove the end cam bearing and retro fit the decompression and go again for real…

At the Cylinder Head

Fit the tensioner and release it to let the camchain tighten. The cam will rotate backwards slightly. Rotate engine to exactly TDC (check elsewhere about how the flywheel marks are WRONG as standard on all bikes prior to 2004) which is equidistant from the left to right line but again to the right of them), and have the cam lobes pointing up at 11 and 1 o’ clock – they must look absolutely symmetrical. Is it level? Use a ruler diagonally flat across the lobes.

It doesn’t hurt for the ruler to tilt slightly towards the front wheel. The wear in the camchain is worth 2mm of turn at the outer edge of the camwheel by the end of it’s life. This will tell you that the cam timing will ‘come right!’. A really good way to check the ruler level, is to look across the top edges of the valve spring caps and gauge the gap up to the ruler.

Cam Timing Adjustment

Minor changes: Possible to file the camwheel bolt holes oval. In the above, allow the cam lobes to tilt down ever so slightly from level with the head. As the chain wears the cam timing will go from ‘leading/advanced’ by 2-3 degrees to ‘spot-on’. If the camchain link isn’t where you want it, turn the engine over 3/4 times until it is. It moves on a bit every time. Remember, you won’t hit the piston if you are as much as a whole tooth out, Husaberg built a generous valve to piston gap into the engines (bar the 470).

Major Timing Changes

Turn the straight cut gear on intermediate (single dot) shaft one tooth in a direction that will see the single dot over the ‘other’ dot of the pair on the crank. See timing diagram above. This will change the valve timing by 11.6 crankshaft degrees. One tooth via the camshaft driven sprocket is worth ~ 24 crankshaft degrees. (Lineaweaver). The 501 can be difficult and so it is possible to place the single dot over the ‘other’ of the twin crank dots and then go for the symmetrical look again at the cam.

Engine Cutaway

Husaberg Engine Cutaway
Husaberg Engine Cutaway (Grok)

Husaberg 470/501

Complete Counterbalancer Removal

Since the counterbalancer can be a potential source of engine failure, the counter balancer is sometimes removed completely to eliminate the hazard. This results in more vibration at idle and at very low RPM. In place of the counterbalancer a 7.4mm spacer-ring should be used. The balancer drive shaft gear teeth can be ground off. The crankshaft can be rebalanced if desired.

Since the counterbalancer can be a potential source of engine failure, the counter balancer is sometimes removed completely to eliminate the hazard. This results in more vibration at idle and at very low RPM. In place of the counterbalancer a 7.4mm spacer-ring should be used. The balancer drive shaft gear teeth can be ground off. The crankshaft can be rebalanced if desired.


The transmission was modified with a different tooth profile between 2001 and 2002. The easiest way to determine how the engine was built is to look at the counter balancers’ drive shaft. The early shaft has a straight surface and the later one has a diameter change between the position for the timing sprocket and the drive gear (tapered).

The following gears are not interchangeable between 2001 and 2002/2003: Counter balancer, balance drive shaft, drive gears on balancer drive shaft and crank shaft and also the outer clutch basket.