Loncin A/C 250cc motor in Quad bike

[Lethalleigh29]

Please Help..

I am having trouble with my loncin 250cc OHC aircooled motor.

it wont start.

the motor has just been rebuilt and rings replaced..


i have checked the valve clearances and set them at .003 inlet and .004 exhaust..

i have put a brand new replacement carb on the quad same carb as what came with the bike as i havent been able to afford a OKO yet its a jingke PZ30A

and we have fuel i have checked that there is good and strong spark..

now i have a lot of white vapour coming out the crankcase breather pipe.. on crank over.. so that has me scratching my head..

Spark plug has alot of blackish soot over the plug after crank over and a grey ish electrode..

If bike does start it only runs for a few seconds and then dies motor gets rather hot..

please help


:autogun: my QUAD

 

[sean01]

sounds like cam timing mate.. double check it and let us know..
if it is out then no doubt your valve clearances will also be out..

 

[Lethalleigh29]

judging by this noob the cam timing is correct the mark on the magneto is at 12 0clock and the cam sprocket mark is at 12 0clock is this correct..

 

[sean01]

for the cam sprocket mark, they usually line up to a notch or something. if they dont just make sure none of the valves are opened..
might actually be easier to set it up with the cam on the rock (1 lobe just closed a valve another is about to open) again both valves with be shut.. then spin the engine around a full turn (or 180degree's on the cam) and set the rockers..

 

[Lethalleigh29]

thanks thats good advice

 

[Lethalleigh29]

turned out to be a cracked piston..

 

[Carlts]

Good to hear its sorted mate!!

 

[MiniFighter]

Could it be due to your timing being out once you reasembled it?

 

[Lethalleigh29]

Could it be due to your timing being out once you reasembled it?

that could be a possibility i did notice a small hairline crack in my piston when i replaced the rings but my so called motorbike expert mate told me that it wouldnt make much of a difference and what happens it just blows by the rings Hmmmm new piston on the way for take three..

 

[Lethalleigh29]

and when your a noob to bikes i foolishly listened to him..