ggggggggggrrrrrrrrrrrrrrrrrrrrr

right have spent the day tweeking
stock 650 motor with pod filters and a kerker system with baffle
timing is spot on and have tried variours differant set ups today ranging from 20 max advance to 50 max advance no set at40 max and seems very happy at that.
points and condensor are spot new and set right
compresion tested and there all even and good
coils are getting 12volts and are new as are the leads and plugs
carbs have been stripped and cleaned and rebuilt
started with 110 mains and have gone through my collection up to the biggest i have 125 and it still wont rev out
if you pin it to the stop it just bogs, you can get it to rev to baout 7500rpm but it wont go above.
only thing i have not checked is cam timing as the engine was ment to have had a top end overhaul before i brought it.
it is starting to wind me up now and its not fun to ride as when ever you crack the throttle hard you dont know if its going to rev or not.
any ideas?
cheers rob

I was working on a 750 Twin that did the Exact same thing.
It would run real good and then just suddenly hit a wall and
stop accelerating.

Turned out the problem was that the plug wires were all ate
up where they screwed into the caps. I cut it back about a 1/4"
and screwed the cap back on. Presto. Reved pretty good. But
still had jetting issues.

I had some similar problems on my 650. I would say it could either be your idle mixture circuit (choke) is plugged or your valve clearance could be off. If its the idle circuit it just needs cleaned out. If its the valve clearance you need to pull the cover and use feeler guages to check your clearance between the cam lobes and the valve tappets then find the right shims. An easy way to tell if its valve clearance is if there is any clacking sounds from the top end.

judgie wrote:

.
only thing i have not checked is cam timing as the engine was ment to have had a top end overhaul before i brought cheers rob

:blink:

that concerns me, can be off timing or no valve lash. check it!!
It should run pretty well with 125 mains. running almost the same set up with 130 mains.

did a bit more tweeking before i left work tonight, opened the points gap up to 16 thou an dits made it a bit better still not clean but loads better.
going to try some bigger jets before the weeks out and going to check the cam timing tomorrow night
i will get to the bottom of this