Bushmechanic Mongrel 628 Trailbike

Hey Rens I think I will call the new bike Helga, big boned and strong

hopefully Sandra doesn't take her new broomstick and move out

Goose was after some pictures of engine breather setups,

one is a heater hose elbow into a garden hose .. the 628 engine has no blowby so i don't run a filter on it, the 700 uses a piece of the original husaberg breather 3 ended wobbygong and a poly elbow feeding down to a car fuel filter

I block the rear rocker cover vent and just use the front one

also made some pics of the carb breather filters I use , 2 of the upper carb vents are blocked, one from each side goes up under the tank into fuel filters

the overflow hose has a bit of 3/4" poly pipe with air filter foam in it, it hangs down under the swingarm.

my internetz is slowed for another week have managed to upload to flickr though

https://www.flickr.com/photos/89798644@N07/

internets is fast again

breather pipe on the 700 ... the black hose is cut off the original berg wobygong thing.



filter



carb vent filters

Checking valve lash with Dial Guage

its always a pleasure to amuse Goose!

this is how I check the valve lash









it does take a bit of practice to get a reading that makes sense, the oil in the rocker arms, elephants feet and CFBs needs to move out of the way to get the real result, steady upward pressure on the arm and wait 5 seconds or so then push it back down.

Ive measured the "turns" method and find its very inconsistent .

some crappy video to compare the sound 700/628

https://www.youtube.com/watch?v=_UNhF320dqg

funny its been raining a lot this spring/summer but the sand is still dry as, it would take 100mm overnight to make any difference now.

yes the 700 is way faster all round, you can see in the vids ive buttoned it off a fair bit sooner than the 628 ... too blooday fast

just been ringing its 105mm neck all afternoon I can ride my whole track in 5th average speed 35ks

the 628 wants 3 different gears to do the same job

this vid is better IMHO https://www.youtube.com/watch?v=QeBY2JfpNBo

nah tourist you'd tire of that solution ive tried it when injured and its like watching ****; all you want is the real thing

low rpm load yes probably .. i don't know what the number is, i don't slip the clutch so if the bike stalls when i crack the throttle the rpm was obviously too low.

been playing forks

did these travel increase mods years ago but i don't think i put up any pics

these ones increase the length of the cartridge rod then you modify the bottoming system to let the forks compress further







this one shortens the top out stopper so the wheel starts further out



about 8mm travel increase from these, every 6mm equates to 1 spring rate increase in bottoming resistance without loosing any initial plushness

on my WPs I was able to increase the travel 35mm .. fantastic forks

just moved some shims around this time .. boring

today Im fitting a 1 1/2 piston 2010 KTM 450 SX shock instead of the OEM clown tube

bit of a surprise the KTM shock also had 2 pistons but its a much better design so i swapped the lower clevis's over.

removing berg shock I undo lower bolt first then push down on the swingarm with my foot to get the shock out of there then undo the top bolt later



the 2 lower clevis' and bottoming rubbers I used the big new KTM one can always cut it down later





tool to undo the locknut, rebound adjuster mechanism in background cover it in anti seize when installing



interesting shimstacks in the 2000 model shock .. preloaded rebound ringshim with a bleed hole in the primary piston



2000 model primary on left, 2010 on right, im a fan of bleed holes so i added one to the new piston 1.3mm



main difference is in the size of the bypass holes between the 2 pistons the little collar with tiny holes is from the old berg shock



KTM shock body and needle. it has a longer more tapered needle and bigger oil passage exiting to the res



berg shock body and needle



converting to schrader valve, these cost 3.50 at the ag supply shop, 1/8npt 28 tpi tap and a 8.3mm hole, if you don't have the gear to tap a thread you can use a presta valve and a schrader to presta conversion collar. the presta valve just screws straight into the shock.





to reinstall the shock i put a block of steel in the swingarm and knock the steel plug over to the rhs of the bike just a light tap is all it takes



2010 PDS 450 sx shock



went for a quick blast in the dark couldn't tell much

got a 2 hr force ride before breakfast tomorrow to dial it in. mainly looking forward to the adjustability the HS compression adjuster offers

the KTM shock with stock shims works good, still a tad stiff but im only 65kgs

if you are about 75 kgs and have a pds 7 just bolting the 2010 shock in with no valving changes should be a major improvement over the early berg shocks

to change the clevis all you need to do is let the res pressure out first and try to make sure the rebound needle assy stays in the shaft if it doesn't just push it in with some pliers as soon as possible and remove the clevis with it pointing up (oil stays in)

then just regas it, attached service manual and a different method of filling that does work OK with the PDS if you finish it off with a bleed bottle

the res is close to the upper mud guard and there is some contact as with my ttx, I just put a hose clamp around the res

got into a real good rhythm with this bike today, nice when things all work at once, dodgy knees and backs included

disconnected the TPS .. on my 700 its better to have it connected, on this one disconnecting it improved off idle response and made it smoother all round.

the selector plate has been sticking a bit, usually i just keep riding and it eventually frees up from the vibrations

took the clutch out for some keyhole surgery, everything seemed ok so i got a bigger spring for the plate out of grandads old collection.

the original spring didn't want to come out, had to use MMV Mixed Mechanical Violence





i tested it on the paddock stand vroom vroom shift times are down 2/100ths

spanner said:

10000rpm
I see you have finished the running in period

Click to expand...

approx 120 hrs Prox piston cracked through the middle conked out in a puff of smoke maybe 10 000rpm is asking a bit much

trying a wossner 570 piston instead from F1moto, orangeberg expressed posted me his last headgasket , thanks john

whats left of the seal area in the RHS case cracked slightly from axial fatigue loading, only 0.1mm crank axial play, it doesn't affect anything since i'm not running a seal on the ign side

I've removed the superfluous alumnium completely and will be running 0.25mm axial playnext time. the steel sleeve is undamaged although i would beef them up in thickness of the areas taking the axial loads next time

rest of the engine is minty fresh, crank pin welds are intact crank has no runout or spread, the spreading forces are minimized by reduced mass crank but mainly there is no spread because the low axial play allows the cases to help keep the crank from spreading and the 22206 bearings and the steel sleeves can take the axial loads.

I put the 02 case and the 06 case back into the mill and clocked all the clutch cover references to get to the bottom of the differences in shaft placements

there is barely 0.1 -0.15mm difference between most things but the countershaft is out by enough to be an issue so ill be moving the water pump bearing in the cover.

apologies for lack of visual aids the bigpond nazi internet is slowed will post pics when its back up