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you may want to replace your valves if they have done alot of work (bent on sealing edge)
 
I've got a fmf 4.1 and its sick, nice deep note and reckon it gives ya a bit more top end I had to re-jet up after installing it. The quality is second to none.
A lot of guys like them but a lot of guys also like the yoshi. Personal preference really.


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Good build so far mate, keep the piccies rolling :)

Oh and I merged the threads and moved them into the China builds section so people can find it easier mate.
 
nice,
Hi Comp piston ?
and what size gudgeon pin does it take ?
 
Hey everyone. finally kicked it over and it fired second kicked :coolthumb:
It seems to be running rich? i have the 26mm OKO on it (with 36 pilot and 100 main jets) it blows a bit of smoke and back fires.. the valve clearances werent 100% im sure but dont have my feeler gauges at home. It wont idle and sometimes when it dies puffs smoke out of the air filter. where should i start with tuning?? it has hc piston, race cam and uni filter.

CHEERS :D
 
the puffing out the air filter most likely would be caused by the valves not sealing properly.
grab a cheap set from a $2 shop if you have to.
then adjust them to .003" inlet and .004" ex

turn the idle speed up a bit (approx 1800rpm) and adjust the mixture screw to get the best idle, then drop the speed back down a bit
 
mate i had a 125 with a oko26mm carby and it ran sweet and went like a machine , ur just gunna have to play around with the jets mate untile you get it right and good luck with the build , i also am now running a oko 28mm on my 128 and runs good aswell but the 26mm is much better
 
I lapped the valves before I put them back in. Could the timing be out? The flywheel had a T mark but the housing didnt have a notch?? Ill take my feelers home from work today to check them.
Would it put out smoke from being to rich or lean?
 
smoke out the air filter, is just unburnt fuel being blown back through the carby, if the valve to rocker clearance is a bit too tight/close.

smoke out the exhaust, would be from the rings not bedding in properly yet.

timing may be out, but it would have been pretty hard to get it started
 
Ok cheers man. What about with the timing. It didn't have a mark on the engine case to line up with the flywheel? It's a CDI motor does that mean it dosnt need to be spot on like similar motors?
 
as long as the T mark on the flywheel was at 12 o'clock, and the mark on the cam sprocket was at 9 0'clock, it should be fine.
if it was a tooth out on the cam sprocket it wouldn't rev or start too easy.
also the marking on the cam would be closer to either 8 or 10 o'clock with the flywheel sitting at TDC

CDI just means Capacitive Discharge Ignition,
so inside the CDI unit, a capacitor will store the peak electricity/energy made from the source coil on the stator.
then when the crank pickup tab on the flywheel passes the pickup coil , it tells the CDI to fire the power through to the Ignition Coil.
 
ok rechecked the timing when its at TDC its at F not T but the T is at about 1oclock ?? and the valve clearances were at about .006" intake and same for exhaust so got them sorted. i got it running a bit better with the valves set right but still wont idle 100% and when i give it a twist on the throttle she dies in the arse and back fires like a ***** :/
 
sass34 said:
ok rechecked the timing when its at TDC its at F not T but the T is at about 1oclock ?? and the valve clearances were at about .006" intake and same for exhaust so got them sorted. i got it running a bit better with the valves set right but still wont idle 100% and when i give it a twist on the throttle she dies in the arse and back fires like a ***** :/
Click to expand...
you positive there are no cold air leaks?
it has to be at the t not the f and the cam should line up with the mark and you should be able to move it a little bit with little resistance (so its not opening the valves and ensuring its not 180 deg out)
 
the way that you describe it running sounds like it is 1-2 teeth too advanced?
put up a pic of the flywheel/case, and we can tell you where to set up the tdc mark on the flywheel to.


i would definately be setting up the timing marks correctly first, before worrying about tuning it.



take the stator/ignition and cam covers off.
rotate the crank to get the flywheel mark and the case marking at TDC,
take the cam cover off the head, check the alignment .

if it's out then, undo the cam chain tensioner, drain the oil., don't lose any of the bits.
undo the cam gear, 3 bolts
then rotate the cam gear to set it up correctly so the marks are lined up.
then reassemble it.
 
Ok well ill put the T at 12oclock and that would put it out by a few teeth so that might help. What does the F stand for??
 
the F marking is for when it tells the CDI to fire and sends power to the ignition coil
 
Ok so that would be part of my problem? It's firing to early because the F is before the T on the flywheel? Ill fix it tomorrow and see how it goes.
 
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