Engine Stumbles when I open throttle

[Guest]

This problem seems to be worse when the bike is warm. It will idle for a very long time. If I just twitch the throttle a little, the engine will respond. But when I hit about 3000 RPM, it stumbles and wants to stall out. Eventually it'll work its way through then go as high as I want it to.

I had the bike running and it was going fine, then this problem slowly crept in over the last week until it's not really useable on the road.

It's an 1981 GS550 T

Any ideas? Thanks!

Jonathan

[60ratrod]

Look at the cv tuning tutorial up at the top of this section and follow the link. Sounds as thought it's running rich. What do the plugs look like? When was the last time you properly cleaned the carbs?

[tom203]

Make sure your mechanical advancer moves freely.

[60ratrod]

Also, is it fine all the way to 3k and then stumble or does the stumble happen until you pass 3k?

[JBro]

mmm...depends on how much I open the throttle. If I just crack it, it'll creep up okay. But if I yank it open, it stumbles right away.

[JBro]

I believe my carbs are the BS model. Does that tutorial apply? I am a total newbie at this!

Thanks!

Jonathan

[Steve]

Stock intake/exhaust or aftermarket stuff?

.

[JBro]

It's all stock...

[60ratrod]

Mikuni bs series carbs are cv carbs, or constant velocity carbs. Look into the link that's in the sticky at the top of this section. Sounds like improper floats or too big of main jet. The other possibility is a weak igniton system/bad spark plugs/plug caps unable to burn all of the fuel when you crack it wide open.