[Seipgam]

Ace has helped me out with a suggestion for a main jet and the bike is running well on the road, but the idle is erratic and won't hold a decent low tick over. Have adjusted the idle and air screws to be as good as I can get it but still not happy with it.
Would this suggest a larger that the standard idle jet may be required?
It's a '95 500, standard Micarb and air filter, with the short muffler (I had previously suggested the exhaust was standard, but I think I am a little better educated now).

Cheers, Geoff.

[Unlucky_soul]

Does the rpm increase with time on it's own?

On revving does it take a while to come Down to normal idle?

[Seipgam]

No, settles quickly - just wont hold a steady idle, up and down.  Not too bad if I kick the idle speed up, but then it's too high for a normal idle.

Geoff.

[mrunderhill1975a]

Have you checked for a vacuum leak?

[ace.cafe]

Air leak in intake tract or exhaust head joint.

 Could also be worn slide in carb.

[RE350]

Also make sure valve clearance is not too tight. A leaky valve could cause problems.

[Bilgemaster]

The most likely culprit in such cases is an air leak somewhere between the carb and the head...though this is often accompanied by "run-on", where the engine in neutral will take noticeably longer than normal to drop its rpm speed when the throttle is revved and released. To locate such leaks, while it idles spray a bit of WD-40 or carb cleaner spray sparingly here and there between the carb and motor. If the engine speed increases, an air leak is nearby. Loose carb or manifold bolts, split or cracked or poorly-seated rubber or hoses or gaskets are often the cause and easy to cure.

If it is such an air leak, you really want to get that squared away as quickly as possible, since it'll run much hotter than it should, very possibly damaging your piston. A quick look at your sparkplug for telltale signs of overheating is also advised. If you cannot locate such an air leak, then the other possible causes already described here should certainly be investigated.

Good luck, bro!

[Keepnmy65alive.]

I'm a first-timer on this forum so welcome to me. I have a 2006 500cc 5-speed with points. I have a new heavy-duty point spring I haven't used yet which I got from custom motorworks. The guy I bought it from had up and down idle and so do I. No amount of carburetor fiddling will fix it. I believe the stock spring is soft enough where it allows the advance to retard at a low idle. I believe the advance is used to facilitate starting by being retarded while starting and centrifugally ADVANCED to normal timing anytime the engine is running Stiffer springs allow adjustment of the advance curve to any engine speed desired; good for high r.p.m. shenanigans with old big bore engines whilst avoiding " pinging ". A slightly stiffer/ softer spring will allow many hours of fiddly entertainment.

[Seipgam]

Mine has a Boyer electronic ignition, so points points issue.
I have checked for vac leaks.

Geoff.