off-idle hesitation

[Guest]

Hello everyone, my 850 is hesitating just off idle again. I have readjusted the mixture screws, they are 3 turns out. It seems that the warmer the engine is, the worse it hesitates. If I change the pilot air jet to a 180, would that help? Mine has the factory 170. Thanks for the advice, Mark

[Steve]

A little bit of history, please.

Have you done a full "strip-and-dip" rebuild any time recently?

Spark plugs?

Ignition timing?

Carb sync?

Your problem sounds fuel-related, probably just a bit lean. Changing to larger air jets will only lean it further.

Don't be afraid to add more to the mixture screws. I have had one bike that required just over 4 turns on one carb (the others were about 2.5) before it ran right.

.

[hoppy1]

A little bit of history, please.

Have you done a full "strip-and-dip" rebuild any time recently?

Spark plugs?

Ignition timing?

Carb sync?

Your problem sounds fuel-related, probably just a bit lean. Changing to larger air jets will only lean it further.

Don't be afraid to add more to the mixture screws. I have had one bike that required just over 4 turns on one carb (the others were about 2.5) before it ran right.


.

I have done the strip-and-dip, plugs, valve adjustment, carb sync about 6 months ago. But, the temp around here was 99 degrees. Now that it's cooled off, it may be different. I am also running pure gas (no ethenol) and have reset the mixture screws. I didn't know you could adjust the ignition timing with electronic ignition. Maybe I need to richen the screws a little more??

[Steve]

I didn't know you could adjust the ignition timing with electronic ignition.

Yes, it's possible, but generally not needed.

Once it is set (at the factory), there is nothing to wear and change the settings. However, the mounting plate does have some adjustment built into it, so at least check your timing to be sure. You never know what a previous owner might have done to the bike (in spite of what they might have promised when they sold the bike). If the signal generators have ever been replaced, timing would have to be set. Yet another occasion when the timing might have been changed.

.

[hoppy1]

Well Steve, you done it again. I warmed up the bike, set the mixture screws to highest idle, turned them another 1/4 turn, NO stumble!!! They are all 4 1/4 turns out. I will check my timing just to make sure. Thanks a bunch, Mark

[tkent02]

I have done the strip-and-dip, plugs, valve adjustment, carb sync about 6 months ago. But, the temp around here was 99 degrees. Now that it's cooled off, it may be different.

Cold air is more dense than warm air, what was perfect then is now lean.

[850 Combat]

I would guess that you developed air leaks from old intake O Rings, carb O rings, and air box
seals.

[bwringer]

I would guess that you developed air leaks from old intake O Rings, carb O rings, and air box
seals.

What I'm thinking as well. Once an 850 is set up properly, temperature makes little to no difference. You should NOT need to adjust anything seasonally.

Something has changed, and it sounds a lot like an intake air leak somewhere.

[Steve]

Well Steve, you done it again.

. . . .

.

[hoppy1]

I would guess that you developed air leaks from old intake O Rings, carb O rings, and air box
seals.

I have changed the intake orings,all carb orings, and have resealed the airbox. I still have the original intake boots and airbox boots. The airbox boots are Ok, the intake boots are pretty stiff. I'm thinking about changing all of them in the near future.