Hitchcocks Forum

Hi. Just brought a 2nd hand Bullet and have the following problem. Bike starts OK but after a few minutes if I rev it up or blip the throttle it only slowly returns to tickover. Gradually gets worse until revs won't die down at all. Fitted a new throttle cable but still the same. Suspected the Slide so brought a brand new Mikcarb VM28 (They are so cheap it is not worth fiddling about with them) and fitted it with the new cable but still the same. I have tried running with the Tank off incase the cable was getting trapped or bent.

Has anyone experienced this problem and found like me that the obvious reasons are not the cause, but found a different reason for the problem.

Cheers.
Mick.

Is the twist grip returning, my old Gilera did this and it turned out it was all gummed up, I cleaned it up and put it all back together with some grease, problem solved..

My Bullet classic behaved a bit like this when I first got it. It was rather fun trying to change gear as the revs stayed uo for quite a while after I closed the throttle. The bike only had a very low mileage (600kms) despite being some years old. I then had a brainwave and thought that perhaps it needed a service! The points gap was almost non existent, and when I reset to the right gap the tickover went through the roof as the carb had been set totally wrong to compensate for the ignition defect. I weakened the mixture and reset the tickover and the problem was immediately solved.
So your problem may well be a combination of similar factors and a good service may well help. Good luck.

What is the position of the throttle cable at the carb top?

Hi All.
The Twistgrip is definitely returning OK. The Ignition Timing is worth investigating. If I set the carb at suggested start point (Mixture Screw 1.5 turns out) it will not tickover. It wants to be fully in (Rich?) and then sounds much better but the Plug is black. I will make this the first job after Christmas.

I have to work outside so will need to wait for a warm(ish) dry day so may be some time in reporting back. Keep the ideas coming though. I will come back eventually.
Thanks. Mick.

If that carb slide is returning to the tickover screw with a click then i suspect you have some highly volatile additive in with the fuel.

NF, You mat wish to take a look at the possiblity of an air leak between the carb and head also whether or not the cold start system is shutting off properly.

Air leak twixt carb and head?

Surely, if I have an Air leak anywhere, the engine would be weak, wheras the plug indicates it is running rich?

hi N.F ANOTHER ANGLE although this was more prevelent on 2 strokes maybe an air leak between the primary chaincase and the crankcase burning primary oil? making richness and reving just a thought as i,ve never encountered the mystery reving although i know a bloke who has 4 carbs and still has no solution to his problem ,atb paul.