Perplexed................

[mjremington]

Ok, its an 82 GS750T. Carbs were cleaned three times and rebuilt. All internals checked to make sure they were the right size and factory specs. Inline fuel filter installed. Seals are replaced, as well as the carb boots. Sealed and checked for air leaks. New air filter, oil/filter as well. We completed the valve adjustment (only 5 were not with in tolerance). New gaskets and half moons. Plugs are new and I went with a hotter plug. Synced Carbs. Now my perplexing issue. Its still running rich. We used the "highest idle" method for the mixture screws which ended up being about 2 1/3 to 2 1/2 turns out for the best result. I thought this would take care of the richness but it didn't and I'm out of ideas. Any thoughts would be appreciated.

As a side question...........The knob underneath the carb that adjusts idle, does this need to be in any specific turned in or out before the "highest idle" method works?? Could this be part of the reason for my problem? Thanks for all the help along the way.

[Steve]

Most of it sounds OK, but there are a few things that caught my eye.

'Carbs were cleaned three times." Since you had to do it so many times, I can only assume it's because it was not done correctly. Still might not be clean.

"Inline filter." Ditch it.

"I went with a hotter plug." Why? You trying to hurt your engine?

2 1/3 to 2 1/2 turns sounds OK.

Idle speed for the adjustment should be, ... well, ... IDLE SPEED. About 1100 RPM.

.

[mjremington]

The three was because the mechanic I brought it to last year cleaned them when I bought them(the carbs), then when he put the rebuild kits in. Then I did it because it was a part of the flow of BassCliffs procedures. Using carb dip and following every detail of BC's site.

Fuel filter is in because the screen/filter on the petcock is gone. Tank was cleaned and relined but I thought better safe than sorry.

I assumed "hotter" would help with the richness. I haven't noticed a difference and the manual on BC's site said to use a hotter plug if they were prone to being wet. Well I made the assumption wet equalled rich.

While we were doing the hightest idle method. We started by turning all four mixture screws in then out to 2 as outlined. Fired the bike up, warmed it, but only got real results turning in. It almost died. It ran very choppy. Turning out barely made a dent but we got them at the 2 1/3 to 2 1/2 and set the knob until we reached 1100rpm.

Every part in the carbs are new and I'm %99.01 percent sure they're clean. I guess I'll start there again and re-sync.

Thank you for the repy. If I didn't love the bike so fricken much I probably wouldve sold her off or used her for target practice! But She's in really good shape and I'm sure its simple but these gremlins are there.

[mjremington]

And as for the adjusting knob. So I'm clear on this. It only adjusts final idle rpms?? It has no other bearing on the richness? So there is no benchmark on turns? Also, if the richness is in the mixture screws, should I turn them in a little at a time and adjust idle up with the knob? Other then the rich running the bike is basically perfect. I've replaced every thing that needed it. Including the carbs last year.

[MisterCinders]

The overall idle screw just adjusts the slides at the closed throttle position. It does nothing to the mixture. If the idle screw is is too far in, the idle will be high because the slides stay open with no throttle. Back it out too far, then you will not idle, because the slides will close entirely.

HTH

[Loki]

How does your spark look? May not be too rich at all, may have weak spark. Set your idle around 1100, then your mixture screws for highest idle one at a time, adjust idle via the knob in between.

[alke46]

I'm seeing a similar problem with my bike running too rich. I have been through a lot of different procedures to cure it and nothing has worked yet. However, I am having a problem of getting a full 12 volts at the coils and I am assuming that the plugs are not firing as hot as they should.

I just have not had the time to get the electricals all cleaned, but when I do, I am hoping this will help my situation.

Hope this helps you as well. Check to see if you have proper voltage at the coils. Good luck.

Larry

[Steve]

Fuel filter is in because the screen/filter on the petcock is gone.

That's OK, as long as you use a proper filter. Most automotive filters are designed to go in a system with a fuel pump, so are a bit restrictive. Use a filter designed for a lawn tractor.

Also, if your filter on the petcock is gone, you will have no RESERVE function.
When you run out of gas, you will be OUT OF GAS.

I assumed "hotter" would help with the richness.

No, "hotter" won't help with the richness.

It will only mask the richness. Fix the richness, don't apply a Band-Aid.

While we were doing the hightest idle method. We started by turning all four mixture screws in then out to 2 as outlined. Fired the bike up, warmed it, but only got real results turning in. It almost died. It ran very choppy. Turning out barely made a dent but we got them at the 2 1/3 to 2 1/2 and set the knob until we reached 1100rpm.

I usually recommend starting at three full turns out, because so many times I have had problems getting them to run on two. Trying to keep it running while turning the mixture screws out is too hard, so I just start at three now.

As you warm up the bike, set the idle to about 1100. Slowly turn each mixture screw, listening for any increase in speed. Keep going in, listen for a decrease in speed. When you hear the decrease, back up about 1/8 to 1/4 turn and go to the next carb. When you have done all four, go back and do them again, just to make sure.

If the engine speed gets much over 1100, use the idle speed knob to get it back to 1100.

And as for the adjusting knob. So I'm clear on this. It only adjusts final idle rpms?? It has no other bearing on the richness? So there is no benchmark on turns? Also, if the richness is in the mixture screws, should I turn them in a little at a time and adjust idle up with the knob?

You are correct, the idle speed adjuster is just that: the idle speed adjuster. It has NOTHING to do with the richness of the mixture.

As mentioned above, tweak the mixture for one carb until you hear the best speed. Adjust the idle. Adjust the next carb for highest idle. Adjust the idle. Repeat as necessary.

If you still feel that you have a rich mixture, I would suspect the rebuild kits that were installed. Too many times, they have inferior parts.

The overall idle screw just adjusts the slides at the closed throttle position. It does nothing to the mixture. If the idle screw is is too far in, the idle will be high because the slides stay open with no throttle. Back it out too far, then you will not idle, because the slides will close entirely.

Mister Cinders is talking about the idle screw controlling "slides". Please don't get confused. The "slides" in your carbs are NOT controlled by the idle speed adjuster screw. He has the older VM-series carbs, where the "slides" are the throttling mechanism. In our BS-series (CV-style) carbs, there is a butterfly valve that does the throttling. The slides are only variable venturis to ensure constand velocity (see? CV) over the jets to ensure somewhat proper carburation at any throttle opening.

.

[MisterCinders]

Oops. Hope I didn't confuse things by projecting my carbs onto your bike. My bad.

[mjremington]

Well I'll check the voltage and start there to make sure its not to little spark.

Steve, quick clarification. Set all four carbs to 3 turns out, warm bike up, if idle is high set it to 1100. Then turn screws out until rpm increase? Then back in until decrease? Then back out the fraction. Then reset the rpm to 1100? repeat for each carb? Just making sure. The "highest idle" method says set rpm to 900.

If it doesnt help I'll buy some new carb kits and go from there.

Thanks for the info and thoughts everyone

[mtlzrx]

I have the exact same issue on my 1980 750 et. I am still trying to resolve it. Let us know it you find the cure. I am going out to check the volts at the coil now just in care. Otherwise it runs and pulls great. She does hesitat a fraction however pulling from zero in first which is a clue I am sure. Probably need to back out the mixture screws 1/2 a turn as they currently sit at 1 and 1/2.