Engine dies at idle - help?

[pkat696]

I have a 1997 Monster 750 and lately the engine has been dying on me quite a bit.  When I come to a stop, and the engine is idling, it dies just about every time. 

Not sure if it matters, but no modifications have been done on the intake.  I do have a set of Two Brothers pipes though.

Any help would be greatly appreciated.

Thanks,
Peter

[Speeddog]

Increase the idle speed with the idle screw.....

[Latinbalar]

check to make sure that all the plumbing after the carbs are intact. an air leak usually causes dying at idle.

[pkat696]

Thanks for the replies!!

Speeddog...really?  That's it?  Cool!!  I have yet to really dive into the mechanics of the engine, so I apologize in advance for my ignorance.  Where is the idle screw?

Latinbalar...good tip.  I'll check the plumbing.

Thanks,
Peter

[Speeddog]

It's rather hard to get at, between the carburetors below the airbox.

I'll try to take a picture later...

[pkat696]

Speeddog,

I found a picture from one of your previous posts.  Thanks!! 

I finally got around to taking the bike out today, after all of that rain.  I warmed it up good, and adjusted the idle.  I remember reading somewhere that idle should be set at around 1200 rpm.  I set it as close as I could, and it idled much better.  It didn't seem like it was going to die.  But then, I encountered another problem.  When I revved the engine, it didn't return to idle quickly.  It was a slow reduction in revs back down to idle.  So, I reduced the idle speed down to about 1000 rpm, and it was much better.  The idle sounded good too.  But then I took it out for a ride, and it died a few times.

Any ideas?

Your help is greatly appreciated!!

Thanks,
Peter

[koko64]

Speeddog,

I found a picture from one of your previous posts.  Thanks!! 

I finally got around to taking the bike out today, after all of that rain.  I warmed it up good, and adjusted the idle.  I remember reading somewhere that idle should be set at around 1200 rpm.  I set it as close as I could, and it idled much better.  It didn't seem like it was going to die.  But then, I encountered another problem.  When I revved the engine, it didn't return to idle quickly.  It was a slow reduction in revs back down to idle.  So, I reduced the idle speed down to about 1000 rpm, and it was much better.  The idle sounded good too.  But then I took it out for a ride, and it died a few times.

Any ideas?

That symptom of the idle hanging up can be that your idle mixture is too lean. You can put the idle back to 1200rpm and turn the idle mixture screws out 1/2 a turn to richen things up a little.
Or
There is an air leak from a manifold rubber as has been suggested and this causes the idle to hang up also. You can spray the manifolds with WD 40 and see if the bikes idle changes.

Try the former first to see if that works, then do the second test if it still hangs up before settling.

Your help is greatly appreciated!!

Thanks,
Peter

[pkat696]

Thanks koko64, I'll give that a try.

Also, thanks to Latinbalar for the suggestion on the plumbing.

[pkat696]

Thanks again for everyones help.

I tried increasing the idle speed and richening the mixture by backing out the idle mixture screws, but it didn't help.  It still dies and the throttle still hangs up.  I first backed out the misture screws half a turn, and then another half. 

I also visually inspected the manifold rubber and didn't see any potential leaks. 

Any other suggestions?  Any additional help would be greatly apprecited.

Thanks,
Peter

[Speeddog]

Carbs may need a cleanout, especially the idle jets.

Replace the O-rings on the float valves while you're in there.

[pkat696]

Thanks Speeddog.  Sounds like I need to do a good once-over of the carbs then huh?  I guess I should buy a manual then.

[ducpainter]

All the advice is good...but...humor the humorless one.

Before you go tearing everything apart....

drop the idle to 1100 rpms and see if that stops the hanging.

It may be that you're idling just high enough to kick in the advance which raises the idle even more.

If it still stalls you probably have dirty pilot jets like Speeddog said.

[pkat696]

Thanks Humorless.  I did that the first time I adjusted the idle speed.  I had it at around 1000 or so to eliminate the hanging, but it still kept dying at idle.  Then, I tried it at around 1200, with the throttle hanging, but it still died at idle.

So what's the best way to clean teh pilot jets?  Do I need to tear apart the carbs?  Or can I just spray some carb cleaner in there?

Thanks again for everyones help!!

Peter

[ducpainter]

If it were me, I'd try some Techron carburetor cleaner mixed in the fuel for a tank before I tore into things.

If that doesn't do it you'll have to take them apart.

Have you looked at the plugs?

[pkat696]

One of my buddies mentioned adding some fuel injector cleaner to my gas.  I guess I'll give that a try.  I'll also take a look at the plugs.  What am I looking for?