Carb sync and tune guide

[peanut]

Exhaust is .004 and intake is .002

ok ....current thinking is thats too tight ...

there is not one good reason I am aware of to run such tight valve clearances and several reasons why its not good to.

Have a read of Howard Smedleys research and conclusions under 'XS650 Cams' section about half way down the page and make your own mind up .
Yamaha used to recommend 0.012" and 0.006" for early XS650 engines which had better performance and compression .
http://www.smedspeed.co.uk/tech.html

 

[Ccanady]

Just going with Clymers

 

[peanut]

Just going with Clymers

I understand ...most owners do just follow Clymers or Chiltons or haynes or whatever but if you are building your own engine surely its worth doing a bit of research and checking on current ,thinking, mods, adaptations, substitutions etc to get the best out of all that hard work and expense.
Now you have the frustrating situation of not knowing what is wrong with your build and having to ask others for advice. I hate being there myself I can tell you .

I'm not pecking your head... but you do seem to have the attitude ' I've already checked everything so none of our suggestions have any value or interest

Work with us and between all of us we'll get to the bottom of the problem .. we nearly always do .

 

[Ccanady]

 

[peanut]

the reason i normally suggest setting the valve lash to a looser lash is so that even the most ham fisted amongst us are more likely to end up with all the valves seating properly. Yamaha recommendations for the later models are so tight that it is very easy to end up with valve lash that is too tight, especially as lots of folk don't seem to understand that each cylinder need the valves to be set on its compression stroke . You can always tighten them later once you resolve the issue you have with low compression and flames in the inlet etc.

Have you told us what year your bike is and what ignition system you have ?