Higher rpm

Hey guys i know there are other threads on this. Have an 82 550 maxim. My rpms will not go below 3000 without stalling. Ive cleaned and rebuilt the carbs. Ive replaced the carb boots. From what i can tell there is no vacuum leak. Ive tried adjusting the air/fuel mixture screws 2 1/2 turns out and adjusted while engine running. Adjusted idle screw and thrittle adjustment. The floats are set at 21.5mm dry. The idle seems to stay around 3000-3500 when sitting. Goes up to 5000 when riding and using throttle. Its not shifting hard, except when first putting in 1st gear at take off from starting engine and warm up. Rest of gear shifying is smooth. Only noticeable thing happening from the rpm level is fuel consumption. Im at a loss on what to do. Also, the manuel says not to use the attached tachometer for idle adjustment as it is not accurate. I need to get a portable tachometer to try. Any suggestions welcome.

 

Did you vacuum sync the carbs ?? Pull fuel tank get a good book and 1 # hook up a temp fuel supply 2 and go over it again. You're close

 

Yes, carbs out of sync can cause exactly the issue you describe.

 

I did use carb calibration gauges. At the time that was before i replaced the carb boots and they were in sync but still high rpm. I can do another check now that they've been changed out.

 

I can definitely do it again.

 

What happens if you back-off the idle adjustment knob?
Is the throttle cable sticking at all?

 

If i turn the idle screw counterclock wise it will drop from 3000 to engine stopping unless i mainrain some throttle. The throttle cable is not sticking at all.

 

It doesn't take much knob rotation to affect the idle. Maybe too much?

 

Could be part of it. I dont turn it much. Kinda go back and fkrth trying to find that sweet spot.

 

Maybe not the issue then.

 

Likely not the issue.
I need to have a think.

 

Sync again, mixture again, sync again. One, or maybe two of the carbs are shutting off.

 

WAG, but maybe not carbs? Something in the alternator/coil system not passing enough juice at low RPM?

 

The alternator doesn't kick in until 2000rpm.

 

Will try that as soon as i get my sync guages in. Thanks

 

Rectifyer?

 

Can you expand on that please?

 

I read that on the forum somewhere l will try and find it.

 

http://web.archive.org/web/20071214...m/MotorCity/Speedway/7795/xjfaqbig.html#alter

Voltage goes from 1.8 volts at 2000 rpm up to 9-11 volts when you rev the engine, as the regulator does its thing.

 

That does not sound right, you need at least 13v to get a charge worth having going.

 

Yes good point. I think when l checked my alternator it was about 14.4 volts.

 

I think it refers to the regulator box heading, perhaps l have misunderstood this .

 

Indeed, I took it to mean the regulator voltage feeding the rotor fluctuates thusly to maintain the correct output voltage at a given RPM and load:

“This "electromagnet" rotor is fed a current which is adjusted to keep the output of the alternator between 14.2 and 14.8 volts (with no load).”

 

Yes must be that the regulator voltage feeding the rotor.

 

Update!!:

After many headaches, i finally found that the pilot jets that came with my carb rebuild kit were non-bleed type. I replaced, instant changed the way the bike ran and was able to get the idle rpm down to the appropriate reading. Thanks guys for your help.