Just picked up 96 RK. Bike runs rides great, only showing 15k miles and the condition looks it. It has a noise while under power in 4th gear, sounds like a supercharger spooling up, gets higher pitched as I speed up. The guy riding next to me can't hear it, but I can hear it over my non baffled full length pipes at full song. No other noises in any other gears.

I've owned one other EVO, a 98 RK and it didn't make this noise. I'm going to pull the inner outer primary and look for a loose transmission shaft indicating a bad bearing.

This could a noisy 4th gear and nothing to worry about, but it's hard to tell if it's a problem.

​​​​​​​How many of you have had a noisy 4th gear?

Those of you who have had a noisy 4th gear, what did it sound like?

 

Hi, I have 96 ultra and it has some untypical slight noise in 4th gear. Noise sounds like slight whirring noise. It's hard to describe the sound for me, but it is so slight that I dont pay much attention to it. The sound doesn't depend on load of acceleration. But other gears are driven without any strange noises. I live with it for 4 years and sound doesn't give any progress

 

You need to take the top off the tranny and look inside, something is about to blow.


You can get this at low miles if the bike has been pressure washed and that sprays water down the breather into the tranny.

 

Mine made a gear whine sound but it only made it under power in 4th like yours.
I had mine taken apart and the only thing that was found was a transmission main bearing starting to go out.
It still made the noise after the new main bearing but it was much quieter than before.
I ran it like that for the next 8 years then the transmission developed other problems and I switched it for a Baker that I had gotten cheap.

 

I had an EVO softail that had a 4th gear whine, I put Redline heavy Shockproof gear oil in it (the pink stuff) It took almost all the noise away.

 

red line or bel ray 85 / 140 will take almost all of it away

 

Thanks for the replies. I'm going to check the main trans shaft runout while I have the primary off. If it looks ok, I'll slap it all back together and try some Redline trans oil and see how it does. If it's still loud I guess I'm pulling the trans out and disassembling.

 

I checked trans output shaft while I had the primary off. No excessive endplay or slop in the shaft. I buttoned it all up, changed the trans oil to Redline pink stuff. Still has the 4th gear only supercharger whine noise. I'll run it and see if the Redline makes any difference after some miles. If it's still the same, hopefully it's not worse by winter, I'll look deeper into the trans. Thanks for the info.