Engine overspeeding.

[DerekNC]

Today I get my mirrors on as well as the idle adjustment screw. The bike starts up instantly and idles pretty good. I turn off the choke and go to ride around the yard a little. After a couple of minutes the idle starts to overspeed if I rev the engine and then let off it. It also started to rev up by itself without any throttle intervention. If I back off the idle adjustment screw it instantly starts to settle back down to a normal idle. But as soon as I rev it again it does the overspeed thing again and doesn't settle back down to an idle. I also noticed that if you give it some choke while it's overspeeding it speeds up even more.

The throttle cable and choke doesn't seem to be hanging up. The engine didn't speed up after spraying WD40 near the carburetors.

The funny thing is after a few more minutes the throttle control became almost perfect and settled down very nicely. When I give it some choke it starts to die like it normally should.  I'm thinking of doing a complete carb overhaul so if you have any info on obtaining the right jets and stuff for the job that would be great too. The bike is pretty much stock except the exhaust has some holes drilled around the baffle. It appears someone has already been in the carbs so who knows what I'll find.

Other people seem to have this problem as well but there don't seem to be any consistant answers. Thanks.

Derek

[The Buddha]

Holes in exhaust, otherwise all stock?? ... OK 40/125 1washer/3 turns.
Cool.
Srinath.

[Susuki_Jah]

are you mirrors bar ends?

if so it probly is your throttle sticking to the bar ends. I cut that rubber lip on the outside so mine wouldnt stick. dont like having cruise controle lol

[DerekNC]

Thanks Srinath. I could have found it on here I guess but was too lazy last night. My mirrors are the stock style Emgo mirrors. The throttle cable doesn't seem to be sticking as I've watched the control on the carb and it doesn't move when it suddenly decides to idle up. Everyone seems to have this exact same problem but noone has reported fixing it.  

Derek

[Anonymous]

When were the valve last checked.  Mine did all kinds of weird things and it was the valves being WAY too tight.  There are kits going around.  All it will cost you is shipping and some time. Easy to do.

[Daniely]

Does it do it when you are turning? I had my throttle cable to tight (didnt like freeplay) and it caused it to jump every time i turne dleft or right, i fixed that REAL quick.

[DerekNC]

I'm not sure how the valve adjustment is. I was hoping to put off doing one for a little while but I might need to pull the valve cover and just have a look. My first thought was that the throttle or choke cable was too tight. When I turn to the left or right it does affect the throttle slightly but not as great as the other time.

The funny thing is if I turn the idle adjustment screw out about 2 turns while it's at 4000 the rpm drops immediately to where it should be. If I give it a little choke it idles even faster. But after it fully warmed up yesterday it ran close to perfect.

I'll do some more checking this weekend. I may go ahead and rebuild and rejet the carbs as I'm sure they're leaking a tiny amount and are dirty. Any more thoughts to consider. Thanks.

Derek