high revs , and choke won't kill engine .. vacuum Leak ?

[Joshbus]

Hello everyone. I am having an issue with high revs after my engine warms up. I have replaced the intake manifold gasket , the carb. o ring , etc. I have a 66 cc china girl engine. I built it myself, and it runs great otherwise. plenty of power , plenty of acceleration, just screams when I come to a stop. I am starting to wonder if I could have a torn crankshaft seal. is this possible, and would that cause this? Thanks , Josh

 

[zippinaround]

most likely cause is either idle screw , binding throttle slide or an air leak .

in most cases i've come across it was either the intake gasket not sealing posibbly from stripped bolts ? or else the clamp holding the carb not tight enough .

 

[Joshbus]

Thanks I am leaning towards the idle screw. it feels sloppy , though it's a new carb , still made in China though

 

[crassius]

spray all around motor with water spray bottle

 

[Joshbus]

Thank you I'll try that .

 

[Joshbus]

I put an rse reed valve in today , but lost bottom end torque. It came with a thick rubber gasket , no more high revs , but it had plenty of power before. Does anyone know if you have to have a cylinder with the third port , or if the piston needs to have a hole bored into the piston ? Thanks , Josh

 

[zippinaround]

yes you need to drill holes in the piston.www.dragonfly75.com/motorbike , look around on there

 

[Joshbus]

Thanks a lot. That's Jaguar's site right ? I should have thought to check there. Before I tear it down I'll put my big mouth billet intake on with a thick gasket . I think the paper china gasket was my issue .

 

[skyash]

Or if you can find them not to common for a 66cc a... window piston

 

[Joshbus]

I can probably machine an extra piston to look like that . CR machine just bores one hole on the intake side I think , and Fred's bikes are insane . MZ parts Miami carves a square hole.