Crazy Idle when hot

[Guest]

Hi,

The idle on My GS750 78´ rises very rapidly after a very short drive (200 meters) - when the engine is gets hot. I have made a video of it, so you guys can hear how much it rises.

I sprayed some start fluids on the intake boots before it ran hot to see if there are any leaks, but it don't seem like it.

Any ideas?

Thanks,
Bo

[roeme]

Doesn't seem outlandish to me; assuming the starting point is a cold engine. On mine, I always have to adjust the idle screw a little bit when switching from highway to city traffic, by about 500 rpm, roughly.

[Downs]

I'd guess a vacuum leak. Have the carb boot orings ever been replaced? Seems like something is leaking after warmup and when cool its sealed.

[mmattockx]

On mine, I always have to adjust the idle screw a little bit when switching from highway to city traffic, by about 500 rpm, roughly.

There is something wrong with it then. You shouldn't have to touch the idle screw once it is set.

I'd guess a vacuum leak. Have the carb boot orings ever been replaced? Seems like something is leaking after warmup and when cool its sealed.

+1. The idle shouldn't jump that much just from warming up. It's running lean somehow, whether a leak or stuffed up pilot jets. My 1100E idles around 850-900rpm when it is dead cold and 1100rpm when warm.


Mark

[Bosteen]

I'd guess a vacuum leak. Have the carb boot orings ever been replaced? Seems like something is leaking after warmup and when cool its sealed.

No, they have never been replaced. Is it these you are referring to? I have new boots from the airbox to the carbs though.

[05Astro]

Yes, those are the o rings, look the boots over as well when you have them off.

[Downs]

Yup those are them. If they aren't cracked they're probably flat as a pancake and rock hard. They're easy to replace you might need an impact screw driver to get them off though.