YZ426F having problems

[cheese]

I thought you should borrow the head of Adams 426 that is sitting in bit and try it out.

[barty5]

How did ya get on ?? i probaby have more info if you need it and also access to online workshop manual if that helps

already got the manual ill try the 14 tooth appart thing 1st

[barty5]

I thought you should borrow the head of Adams 426 that is sitting in bit and try it out.

had thought of that think he have most of it back together by now but might be a plan.

[4stroke]

the 14 tooth thing sounds about right, ive come accross a few motors with that sort of a timing set up, i think the drz400 are timed a simular way.

[barty5]

the 14 tooth thing sounds about right, ive come accross a few motors with that sort of a timing set up, i think the drz400 are timed a simular way.

yeh strange cause my 426 had a 450 cam and was set up as per book line up the dots so fuck know could explain the real cool flames its spittin out if the exhuast is being held open.

Another thing i found and as far as im aware every bike ive worked on the flywheel keyway point up at TDC i found this bike to be set up the opposite pointin down which would put it at BDC with the cams in TDC and this was a bike shop that set it up???????????????? WTF

[flyingcr250]

yeh strange cause my 426 had a 450 cam and was set up as per book line up the dots so fuck know could explain the real cool flames its spittin out if the exhuast is being held open.

Another thing i found and as far as im aware every bike ive worked on the flywheel keyway point up at TDC i found this bike to be set up the opposite pointin down which would put it at BDC with the cams in TDC and this was a bike shop that set it up???????????????? WTF

some hairys probabbly been at it

[4stroke]

to me that sounds like they've had the crank apart, with the keyway down is the piston at tdc? hmmm strange its sounds all up the fuk aye.

[Buddy L]

adams bikes still in bits, im sure he'll let you use it, and he might even let you put it back together for him as well.

[barty5]

adams bikes still in bits, im sure he'll let you use it, and he might even let you put it back together for him as well.

yeh i was ment to catch up with him yesterday he is after a flywheel puller think he was kinda hinting i could then rebuild it hahaha

[barty5]

to me that sounds like they've had the crank apart, with the keyway down is the piston at tdc? hmmm strange its sounds all up the fuk aye.

Well the way they set it up it was pulled the chain of and spun it 180 deg all good now. Now set so keyway is vertical 0deg and piston is at TDC somy thinking is has to come down to valve set up or some bent ones.

[Boosted]

yeh its still off lol.. you can borrow it if needed and if you want can help put it on my bike mahaha :P

[barty5]

well heads off and all looks good valves seal no leakage timing was correct even doin the set up i was given re have 14 links between cam center didnt help ???????????

[4stroke]

rooted spark plug causing a pre ignition or hows the pickup setup for the igniton system, ie if its got a "air gap" the gaps not set up right? used to have a few issues with the john deere lawn mowers and incorect air gaps causing problems.
does the piston look ok, no marks on it from a hitting somthing.

[camchain]

Hmm bugga. Would've put money on bent valve/s (been there done that with dropped valve). You'll know a heap more about engines than me but maybe pull all valves out while head off to be thorough. Bearing blue the seats/valves, smooth operation in guides, correct springs, decomp funtioning properly, ie not jamming or even (unlikely) lifting valve all the time - basically rule out every possible prob with head.

If teeth were broken on cam sprockets, maybe some damage lower sprocket? Poke a torch down there and turn engine over? Chain Tensioner/Guides functioning right and look OK? Maybe lack of tension issue that caused broken teeth after rebuild?

Re that thumpertalk post/info - maybe that inlet cam is a 450 one and throwing things out timing wise?

Just fyi and comparison, I've had cam timed one tooth out before (doh), bike started fine and ran smooth but was very down on power.

[xen]

I thought 4 strokes were easy to rebuild