arrrgh! help! motor won't start

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brethren22

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i'm hoping someone has some advice on this one for me. i pulled down the head and cylinder last weekend on my lifan 140. it was starting like a pig (taking 5-10mins of kicking the thing) but running fine once going so i figured there might be some issues with the valves not sitting completely closed when cold(?!) there was a bit of carbon build up on the valve seats that i cleaned up being careful not to scratch the buggers

anyway i chucked in a a2 akunar cam, valve springs, a new piston and a copper head gasket when i was there and put her back together with new gaskets got her ready to run. now when i go to kick it it doesn't have the compression it should. it's squeaking air out of somewhere and there's no way it's starting. i've checked the valve clearances but they seem fine or at least they definitely aren't keeping a valve sticking open, the springs aren't binding. i'm stumped! i'm thinking that i might just have the valve seats machined to ensure they are sitting super flush with the new valves but i'm not sure if that's the problem.

anyone got some advice for me??

:(:(:(
 

pbk

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not to sound like a wanker but did you take the spark plug out and if so did you put it back in?
 

brethren22

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haha, nah it's a fair question. i had it all back together. carb gaskets glued, spark plug screwed back in leads on. something's leaking from somewhere but i'm not sure where. i can't imagine having a thin copper gasket on would make any diff but can't say not having used one before
 

pbk

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is the motor all in correct time and i woould try the orginal gasket and see if it works i havent heard of people using copper gaskets before
 

headsmess

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ok, copper gaskets are good... heat it up, til its dull red(be careful...i usualy use just a blowtorch, but you can melt it if youre not careful) then quench it...you dont have to quench it really, copper anneals just after heating it up... annealing is softening, makes it squish and produce a better seal:) then you have to clean the "oxide layer" off... steel wool:)

um... lower oil gallery, the "return" to the crankcase(the hole at the bottom of the cylinder)...usually has an o-ring AND a washer....take the washer out, cause it may be thicker than the head gasket? if it had one...some do, some dont...

get the valves lapped in. can buy the paste and lil suction caps at repco etc... its the only way to make sure they seal up properly... cleaning them doesnt get the valve seated in onto the seat very well... grinding/lapping them does.... either do it yourself or pay a fortune for a half hour job at a shop...
 

brethren22

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is the motor all in correct time and i woould try the orginal gasket and see if it works i havent heard of people using copper gaskets before
yeah i think i'll have to give a standard gasket a go. i wouldn't think you'd get air leaking out from around the gasket given that the head is cinched up pretty tight but it's gotta be worth a shot!
 

brethren22

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ok, copper gaskets are good... heat it up, til its dull red(be careful...i usualy use just a blowtorch, but you can melt it if youre not careful) then quench it...you dont have to quench it really, copper anneals just after heating it up... annealing is softening, makes it squish and produce a better seal:) then you have to clean the "oxide layer" off... steel wool:)

um... lower oil gallery, the "return" to the crankcase(the hole at the bottom of the cylinder)...usually has an o-ring AND a washer....take the washer out, cause it may be thicker than the head gasket? if it had one...some do, some dont...

get the valves lapped in. can buy the paste and lil suction caps at repco etc... its the only way to make sure they seal up properly... cleaning them doesnt get the valve seated in onto the seat very well... grinding/lapping them does.... either do it yourself or pay a fortune for a half hour job at a shop...
thanks headsmess so is that the only way to get a good seal with the copper gaskets?

i have heard of the lapping kits so i'll check repco out for one of those. regardless of whether it solves my problems or not it's probably a worthwhile investment in ensuring a solid seat for the valves
 
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