Changed head now won't stay running By capncrunch (Read 407 times)

[capncrunch]

Hey there peeps! I haven't been posting on the board for quite sometime, but a need has arisen.

Somewhat recently as a result of changing exhaust on my 150cc gy6 the exhaust bolt stripped the threading on the head...I took this as an opportunity to bump up to a performance cylinder head and a14 camshaft.

Everything went extremely well until it came time to crank it up...it basically laughed at me initially and then i realized i hadn't tightened the nuts on the rocker arm assembly to specified torque...all good. Valves adjusted to .004 and .005. She started up with a hedonistic raucous sound! Beautiful!

But, she wouldn't stay running...Now its been extremely difficult to keep her running without giving her some juice...I adjusted the a/f ratio and saw some improvements...but getting her to crank on the first go round and keeping her running has been a chore...

My thoughts are that it may be that I simply need to upjet the main and slow jet on the carb...any thoughts or ideas?

[justbuggin2]

i would double check all vac hoses and all electrical connections to make sure everthing is where it suppose to be then i would double check the timing as the marks on the flywheel are not true top dead center easy way to check if the piston is at top dead center is to pull the plug and use a straw thought the plug hole turn the crank slowly until the straw stops coming out of the plug hole make a note of the timing marks on the flywheel so you can use it and check to see if the 2 small holes line up with the valve cover surface of the head with the big hole up

[imnts2]

Agree with just bugging to check everything. Remember the AF adjustment has most of its effect at Idle only. Yes, I would expect you will need to adjust the jetting. It is very important not to run it lean at WOT. Particularly with a big lift cam and a big valve head. 150cc are not overly cooled to begin with.

[alleyoop]

Start it up and let it die and pull the plug and see if it is wet or dry. I think you need to re-jet the carb.
Alleyoop