stupid bike won't idle (83 750 Maxim)

Can keep an idle with choke, but would rather not. Turned in the center knurled pretty far til it would hold idle, but when I rode it, it would rev on it's own to 4k. I haven't looked too hard, but I don't think this is just an idle screw.

You think it might just be a matter of the throttle shaft seals (2 each carb)?

It runs superb, and I don't want to start pulling these apart (not to mention all the cost of all the gaskets/seals and such) and risk ruining how it runs now.

Anyone run into this prob before? I had to turn the center screw all the way back to it's original position so it would run well, but then of course no idle.

Also, what are the adjusting screws on the levers between the carbs for? Is that so they all actuate at the same time/throttle position?

I'm really more used to the sliding throttle bore with the attached needle found on dirt bikes and stuff. Not too familiar with these vacuum ones.

Thanks

 

you don't want to do it, but you have to.

 

Could be a vacuum leak.

 

Do you also have a sputtering issue at 3500-4000 RPM?

 

FIRST;
have the carbs been synced, prob not b/c those screws you speak of are the sync screws.
This NEEDS to be done, so heres a link to the How-To
http://www.xjbikes.com/Forums/viewtopic/t=2132.html
When the syncs are incorrect funny things happen.

If you do suspect a vacuum leak AFTER you sync...

Get a propane torch

and run the unlit torch over the suspect leak spots. If idle increases you have found a vacuum leak.
EDITOr your mixtures are too lean...

 

Wouldnt brake cleaner do the same thing?

 

I have never heard of the propane torch trick. I like it.

 

WD 40 does just as well to find Vacuum leaks and it doesn't explode in a confined area.

 

propane is actually very stable.

 

But isn't it ill advised to try and sync with a known prob (likely vac leak). Maybe I should try the propane - great tip BTW. As far as I know, it's never been synced (33k) and I'm sure it needs it, just wondering if it's worth it knowing how much I ride (but it is so fun I may put serious miles on it). Also, I have no sputtering anywhere in the rev band, which is why I'm hesitant to pull them apart.

Anyone know if the knurled screw facing rearward from the center of the carbs is strictly for idle? Is the idle controlled by vacuum too, and not just a lever stop?

Thanks

 

obviously you want to get any vacuum leaks or mechanical issues sorted before you try to tune it.


if there is no vacuum leak you likely need to pull the rack and clean the carbs.