Thickover

[monkeyboy]

Yes, that's not a spelling mistake.

My BBS's do not have any disernable effect on tickover. They never have. I have fecked about with the bike a lot over the last few years and it's always been the same.

I've changed a cylinder head this morning and I've had to adjust everything again - I had to wind back the stop on the right throttle body too.

Point is though, I can wind the BBSs virtually right out (I've had them out and cleaned them, and their orifices) and the tickover stays almost the same. It's stuck at about 1k. I've adjusted the TPS up from .31 to .36 to see if that makes a difference - no it doesn't. If I wind them right in it does start to die (as it should) but winding them out does not significantly raise the revs.

The only way I can raise the tickover is through the throttle slack adjuster and that is obviously not the way to go.

So....what am I missing?

 

[cookie]

the throttle stops are out of adjustment maybe?

 

[AdrianS]

Have you checked you have the correct amount of free play in all the cables where you should have free play?
I had a similar scenario but when I put a bit more free play in all the cables I was able to adjust the tickover better.

 

[Greg Masters]

Air leak between the throttle bodies and the cylinder head?

 

[monkeyboy]

I've zero'd the setup quite a few times over the years - everything seems to be sync'd properly. My Twinmax says its balanced on tickover and through the range. I've done it with the throttle cables slack (all the cables have been replaced) so set it even on the stops. I've sprayed the joints - no difference so no big leeks. I replaced the rubbers (they're not cheap!) to the cylinders in the past so they should be fine too.

The bike rides reasonably well - revs ok too. Just tickover seems to be the problem. I just expect the revs to rise as more air is introduced. Maybe I'll get some new o-rings for the BBSs in case they have swollen. The bike has had a hard life!