Ducati Monster Forum

Moto Board => Tech => Topic started by: pkat696 on December 13, 2010, 03:43:01 PM



Title: Engine dies at idle - help?
Post by: pkat696 on December 13, 2010, 03:43:01 PM
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


Title: Re: Engine dies at idle - help?
Post by: Speeddog on December 13, 2010, 04:01:46 PM
Increase the idle speed with the idle screw.....


Title: Re: Engine dies at idle - help?
Post by: Latinbalar on December 14, 2010, 07:21:02 AM
check to make sure that all the plumbing after the carbs are intact. an air leak usually causes dying at idle.


Title: Re: Engine dies at idle - help?
Post by: pkat696 on December 14, 2010, 10:05:30 AM
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


Title: Re: Engine dies at idle - help?
Post by: Speeddog on December 14, 2010, 10:12:21 AM
It's rather hard to get at, between the carburetors below the airbox.

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


Title: Re: Engine dies at idle - help?
Post by: pkat696 on December 24, 2010, 07:24:37 PM
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


Title: Re: Engine dies at idle - help?
Post by: koko64 on December 25, 2010, 01:56:31 AM
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


Title: Re: Engine dies at idle - help?
Post by: pkat696 on December 28, 2010, 08:50:54 AM
Thanks koko64, I'll give that a try.

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


Title: Re: Engine dies at idle - help?
Post by: pkat696 on December 31, 2010, 03:46:54 PM
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


Title: Re: Engine dies at idle - help?
Post by: Speeddog on January 01, 2011, 10:31:48 AM
Carbs may need a cleanout, especially the idle jets.

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


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 03, 2011, 07:40:36 AM
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.


Title: Re: Engine dies at idle - help?
Post by: ducpainter on January 03, 2011, 03:39:32 PM
All the advice is good...but...humor the humorless one. ;D

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.



Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 04, 2011, 07:41:28 AM
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


Title: Re: Engine dies at idle - help?
Post by: ducpainter on January 04, 2011, 08:36:05 AM
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?


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 04, 2011, 12:35:13 PM
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?


Title: Re: Engine dies at idle - help?
Post by: ducpainter on January 04, 2011, 01:47:30 PM
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?
We're assuming you have a fuel delivery problem causing lean running and stalling.

If the plugs are black and nasty that might not be the case.

How does the bike go down the road aside from stalling at idle?


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 05, 2011, 09:05:53 AM
It runs pretty good during normal riding.  I get periodic blips or hiccups.  Not sure how else to describe them. 


Title: Re: Engine dies at idle - help?
Post by: ducpainter on January 06, 2011, 07:08:16 PM
It runs pretty good during normal riding.  I get periodic blips or hiccups.  Not sure how else to describe them. 
I guess I'd try some cleaner in the gas first.

I hate to say this, but if that doesn't do it you may have to fork out some dough for a basic carb set-up...

synch...CO...idle speed.

If you have tools it is possible as a DIY but few of us have an exhaust analyzer.

I'd bet you can fix the stalling without one.


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 07, 2011, 09:38:57 AM
Thanks again humorless dp.  I'll try the cleaner and see what happens.  It will probably take a while to see the results though since I don't ride much at all. 


Title: Re: Engine dies at idle - help?
Post by: ducpainter on January 07, 2011, 09:41:32 AM
Thanks again humorless dp.  I'll try the cleaner and see what happens.  It will probably take a while to see the results though since I don't ride much at all. 
Keep in mind that with today's ethanol fuel lack of use can also be an issue.

If the fuel in the tank is more than a month old you may be suffering from ethanol separation.

Some Star-Tron or Sta-Bil might be a good idea too.


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 10, 2011, 09:12:49 AM
I definitely notice that the more I ride it, the better it runs.  Unfortunately, as much as I try, I only get out on it about once a month.  I'll try the cleaner first, and then the stabilizer.  Thanks again!!


Title: Re: Engine dies at idle - help?
Post by: WetDuc on January 10, 2011, 06:28:21 PM
I second the Stabil/StarTron advice from HDP.
I was reading through this thread waiting to suggest Stabil or Startron because it makes my 2000 Ford F150, 2000 Mercury 50HP outboard and both my 2007/2008 ducs run so much better.  Each and every motor runs better, but the outboard will only idle with the Stabil or else, forget it.


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 11, 2011, 09:46:16 AM
Hmm...maybe I'll try the stabilizer first.  Thanks!!


Title: Re: Engine dies at idle - help?
Post by: pkat696 on January 17, 2011, 12:48:35 PM
Just a quick update...

So I tried some fuel injector cleaner on Friday since I had some laying around.  It didn't seem to do much, but then I only went for a 15 minute ride. 

On Saturday, I got the Sta-bil and reset the mixture screws to 3 turns out.  The throttle hanging issue was definitely worse at that setting.  I adjusted it out and tested it using half turn increments.  It got a little better at 3.5 turns, but then started getting worse beyond that.  I stopped at 5 turns out as it was not getting better.  I put it back to about 3.5 turns out.  I then reduced the idle to about 1000 rpm, and the hanging went away.  Unfortunately, the engine still periodically dies.  However, it is better.  I figure that I will let the fuel in the tank run its course and see what happens.  Hopefully things continue to get better.

I also went to look at the plugs, but I don't have the right socket.  I will need to get the right socket and then I'll see what the plugs look like.  Hopefully I can get to that next weekend.

So also, I just wanted to note that the engine does not die right away at idle.  It will idle well for about 5 or so seconds, and then it starts to slow down and sputter a bit before it dies.  I don't know if that helps or not.

Thanks again to all for your help.



Title: Re: Engine dies at idle - help?
Post by: Howie on January 17, 2011, 03:27:20 PM
Drain the fuel tank and change the fuel filter.  Then attack the carbs. 


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