no top end power

[pepsbro]

I have a 1974 TX idles perfect runs up to mid perfect will not come on past 40 mph. I suspect a timing advance problem but I'm not sure. If someone could point me in the right direction before I rip everything apart that would be great.
thanks
pete

 

[5twins]

Check the diaphragms for holes. If the timing was stuck in the retarded position, you'd be hard pressed to get much above 3K RPM. Timing would be the easiest to check 1st, though. Just put a timing light on it and make sure it advances to the full advance slash mark when you rev it up.

 

[pepsbro]

I'm and Idiot. From all the screwing around i have done with air/fuel mix I fouled out a plug.
It idled really good on 1 cylinder.