Anyone Else?

[Alan_nc]

Does anyone else have this problem - and have a suggestion on how to fix it.

Bike is running great.  But it has always had (for the 3 years I've had it) a strange problem at 5,000 RPM.  Right at 5,000 it seems to hunt for the right speed.  It will  seem to slow down for a bit then speed back up.  If I raise the rpm just 300 it will run smooth as silk and if I lower the rpm 300 it runs smooth as silk.  Just this one spot in the rpm range that it can't seem to settle down.

Any thoughts?  (besides:  Don't run the bike at 5,000 rpm)

Bike is a 92 with 22,000 miles, V&H exhaust.  Garage kept.

[Big Rich]

Stock intake & jetting? And when riding at 5k rpm, does it matter what gear / speed your at?

At such a specific rpm, I'd guess it has something to do with the needles, carb slides, or maybe even a funky main jet. But I'm curious now....

[Alan_nc]

Jetting is set for the exhaust.  It is most noticeable in 5th....but I think it does it at 5,000 no matter what gear you are in.

It may be a flat spot in the needle at that rpm.  If it were the jet I don't think it would be rpm specific.

[The Buddha]

If its 5k in all gears - well is it 5k at idle in your driveway ?
Then its almost certainly not carburetion. 5k under no load is probably just north of 1/8 th throttle. In 6th 5k may be 1/2 throttle.

If its 5k no matter what, it could be electrical (as odd as that sounds) - you're at full spark advance and have been since 4k so its not that ... I cant imagine 5k under any circumstances = no idea.

Maybe its vibration related. Though with a rider it wont vibrate the same as without.

Cool.
Buddha.

[DoktoroKiu]

So you are not able to hold it at 5k, then?  If the speed is varying then your RPM must be as well.  Does it do it in neutral when not moving?

I notice that at some RPMs/speeds I get some harmonic action going on and have a slow rhythmic pulsing/humming, kind of like a detuned synthesizer sound (like the "beat frequencies" you hear when two instruments are out of tune).  I always figured it was due to the two cylinders being slightly "out of tune" with each other at that frequency/speed.  I could understand this sounding like a variation in speed/RPM even though it is not.

[RedMark]

Mine was doing this before I changed the battery.

[Alan_nc]

Have not checked to see if it does the same thing when sitting still.  Yes the rpm does very - feels like you have run into a slight gust of wind.  Usually only happens for a few seconds then runs normal for several minutes before doing it again.

It really isn't a problem...but I always wonder if it is telling me that I have some problem that is going to get worse or leave me stranded at some point.

[Janx101]

Mine has a very slight hesitation when accelerating thru 5k +- a tad. .. but it's kinda like "wegonnacruise? Nope!"

[bombsquad83]

I have a very very slight hesitation when accelerating through ~5,500 RPM, especially in the lower gears.  I think it has to do with the motion of the slide in the carb.