Decompression spring

Hi guys!
Can anyone tell me how much does an auto decomp spirng cost on my 2004 Husaberg 650, and also where can I get one from?

I sell them for 6gbp. they are modified versions of the original to get the strength right.

regards

Taffy

http://taffmeisters.co.uk/product_info. ... cts_id=276

yes that is the standard one which you don't want.

this is the one that should be bought:

http://taffmeisters.co.uk/product_info. ... cts_id=922

regards

Taffy

A friend of mine has a 2003 model 650, can u fit the strengthened version to that as well?

yes mate

as long as they have the later auto decomp (and he does) fitted it goes like this:
all bikes and models up to and including 2002 ran the '01' code (400), '53' (470, 550, 650), or '55' (501) cams. they all had the earlier decomp arm and spring = no good.

in 2003 the 650 got the '08' cam and the later decomp with it. so the decomp arm is correct - the spring is still no good though.
the 400, 470, 501 and 550 continued as above with the '01', '53', '55' cams and bad ADCs.

in 2004 we have the new engine and 450, 550 and 650 as well as some 501s. they all run the '08' cam and just need the modified spring.

the important thing to know is that the later ADC has a shorter reach arm to work with the steel sprockets which are thinner than the alloy ones. thinner by 2mm. so they also made the cams with 2mm off.

now some more info about which bikes this affects:
all bikes up until 2002 had a thick alloy cam sprocket and a thick cam location boss poking through. the ADC was therefore a long arm at the time.

the cure: you should really get the steel sprocket and have the cam boss ground down by 2mm.

in 2002, the early examples for Australia and some of the other countries like the UK still had this set up. then later in the SAME PRODUCTION year they went to a steel cam sprocket but still have the thicker and wider cam location boss. so the boss must have 2mm removed. then the later ADC and spring.

in 2003 the cam shoulder was thin along with the thin steel sprocket so the later decomp and spring can be fitted straight into all 2003s

if you have a 1997-2000 treat them like a 2001 (do the cam shoulder and get a steel sprocket) but also as a good spruce up idea why don't you buy a KTM cam assembly complete? you get
a cam
a pair of sealed bearings
an auto decomp and useless spring
the waterpump seal carrier all nice and fresh
2 waterpump seals
a cam sprocket that is no good to you

if you have a pre 1997 there is some luck! the later auto decomp fits straight in. this is the cam with the narrow sprocket bolts OK?

one other thing to look for. if you ever get a Husaberg cam that has 1-2mm space between the cam and the cam cap at ther end ALWAYS PUSH THE CAM IN AS FAR AS IT GOES. this allows the rocker arm to tun on the middle of the lobe.

regards

Taffy

Thank you for the information mate!

Taffy said:

if you have a 1997-2000 treat them like a 2001 (do the cam shoulder and get a steel sprocket) but also as a good spruce up idea why don't you buy a KTM cam assembly complete? you get
a cam
a pair of sealed bearings
an auto decomp and useless spring
the waterpump seal carrier all nice and fresh
2 waterpump seals
a cam sprocket that is no good to you


Taffy

Click to expand...

Hi Taffy:

The KTM cam I received is 2mm longer from inside of the sprocket carrier to inside of the cam lobe but you have stated that the steel sprocket is 2mm thinner that the aluminum one.

If I use the steel sprocket 80036011100 with this 07 KTM 525 RFS cam do you think that I should have fairly good sprocket alignment?

husabutt said:

Hi Taffy:

The KTM cam I received is 2mm longer from inside of the sprocket carrier to inside of the cam lobe but you have stated that the steel sprocket is 2mm thinner that the aluminum one.

If I use the steel sprocket 80036011100 with this 07 KTM 525 RFS cam do you think that I should have fairly good sprocket alignment?

Click to expand...

Hello Eric

good to know warm blood still courses those veins!

"2mm longer from inside of the sprocket carrier to inside of the cam lobe"
lay the cam in the rocker cover. your first task is to make sure the followers roll 100% on the cam lobes.

the sprocket alignment can then be done by measuring the old one first. this is always good.

finally the cam bearing to cam bearing can be 1mm under the old length so you have 1mm to use up. nearly certain that you always push the cam towards the spark plug everytime.

I use the washer off the 2002 drain bung to keep it pinned back.

regards

Taffy

Total length is exactly the same: 109mm

Cam bearing to cam bearing length is the same: 82mm

Lobes are spaced exactly. Everything is the same. Except for 2mm extra length from the inside of the sprocket carrier to the inside of the lobe and 2mm taken off the boss.

It seems like this should be a perfect drop in once I get the steel sprocket which is 2mm thinner.

How critical is the sprocket alignment?

How can you truly align the sprockets? It seems to me that the best you could hope for is to try to mimic the placement (distance from side to side) of the old sprocket in the head.

I had read in an older post that a cam sprocket was 1.5mm out of alignment from the factory on a particular bike with no adverse effect. How much wiggle room is there and what would be the result of sprocket misalignment.

Since the steel sprocket is going to be 2mm thinner does this have an adverse affect on the chain?

Sorry for all of the redundant questions, but I am a bit out of my comfort zone right now.

Thanks

husabutt said:

Total length is exactly the same: 109mm

Cam bearing to cam bearing length is the same: 82mm

Lobes are spaced exactly. Everything is the same. Except for 2mm extra length from the inside if the sprocket carrier to the inside of the lobe and 2mm taken off the boss.

It seems like this should be a perfect drop in once I get the steel sprocket which is 2mm thinner.

How critical is the sprocket alignment?

How can you truly align the sprockets? It seems to me that the best you could hope for is to try to mimic the placement (distance from side to side) of the old sprocket in the head.

I had read in an older post that a cam sprocket was 1.5mm out of alignment from the factory on a particular bike with no adverse effect. How much wiggle room is there and what would be the result of sprocket misalignment.

Since the steel sprocket is going to be 2mm thinner does this have an adverse affect on the chain?

Sorry for all of the redundant questions, but I am a bit out of my comfort zone right now.

Thanks

Click to expand...

can use a straight edge

i have some hi carb steel 5mm diam chrome plated rods out of a flatbed scanner, use as a straight edge. spin the rod 180 deg and check twice to allow for any slight bend in the rod

I put the whole LHS of my 08 engine on the bed of the mill with the head hanging over the side of the table and used the DRO to measure the height of the 2 sprockets.

was out as new from the factory, original berg cam so you can't always rely on the original setup as being correct

bottom line is its a chain so perfect alignment isn't crucial ... just desirable and entirely possible if you are able to check it.

the cam bearing tunnel in my 02 engine wasn't even parallel to anything, 0.2mm out at one end so its obviously not that important.

you can also modify the lower sprocket, the main reason you would choose this end over the cam end is that the tensioner foot does not push in the middle of the guide so if you are able to move the chain and guide over a bit without it hitting the cases you also correct this issue.

moving the bottom sprocket also allows you to leave the decomp on the top sprocket.

this is what i did to make mine work

bushmechanic said:

the older KTM one is stiffer wire (same diam just better wire) it works better and has 1 less turn than the berg one.

the spring on the right is the spring out of my 08 650. I preloaded it more but the end nearly broke off

to make it stiffer I cut off some coils from the lower end and bent the coil out until it worked properly you can see the end makes it more preloaded than the oem and less turns means its stiffer.

if you wind more preload on the spring it gets too small in diam and bottoms out on the shaft then the ends get deformed and eventually break like mine did it needs to be a stiffer spring not just preloaded more.

cutting coils off the end is easy the wire handles being bent just try not to have any sharp bends, wind the coil out straight untill you have what you want then snip off the end mine now has 13.25 coils total, the KTM spring has 14.5 coils and mine originally had about 15.5

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Thanks BushMechanic and Taffy. The steel cam chain sprocket and a new chain is now on order.

It still bothers me that the steel sprocket will be 2mm thinner and what effect it will have on the cam chain with 2mm of play. Any thoughts?

see here regarding widths

http://husaberg.org/mechanical/18078-07-ktm-rfs-cam-97-600-a.html#post150651

How do you get to the auto decompression spring on a 2004 fe450? Do I have to remove the head. I know it sounds like a dumb question but I am not familiar with this. Thanks

You have to take the rocker cover off. Split the timing chain. Lift out the camshaft assembly. Then you have access to the decomp and spring on the cam / cam gear.

Thanks Husabutt. Does any of that require any special tools and is it worth doing. I adjusted my valves and still have the same starting issues. That just seems like a lot of work.

It is a lot of work. The only special tool is a cam chain breaker and riveter.

https://www.youtube.com/watch?v=G6lFFXk_btY

https://www.youtube.com/watch?v=yzGQxtirfrE

Bonus video:

https://www.youtube.com/watch?v=BTxSNosJrDo

Thanks for the info. and videos. I will give it a try but may need to take it in after I make junk out of it.