I've got a 2010 FLHX w/ 103 stage 4 that developed a shudder under aceleration yesterday. I can feel it most at about 3000 RPM. Thought it was rough pavement the first time, but it kept happening so it's something with the bike. It's very subtle, not a huge shake or anything, and it speeds up as RPMs increase. Any thoughts?

 

Could be the clutch disks..

 

I agree. Check your clutch.

Some help might be to use a non-synthetic primary oil like the HD formula+ and if you don't already have it put in the SE clutch spring. This is what FM did to my bike when they put in the thier 107 kit to help out the clutch.

Teardrop - You have a good looking scoot there.

 

+2 on clutch

 

isolate the vibrations from motor rpm/ road speed.

IF you have a vibration at 3000 rpm, does it happen at 3000 in each gear incl. neutral ?

clutch engaged or disengaged ?

or is it road speed related ? ( tires/wheel- balance/bearings/ belt wear/alignment etc)

do you have new motor mounts, which are stiff and "break in" softening with use.

do you have pipes or shields contacting the frame ( muffler bushings?)

the entire drivetrain "floats" on mounts there are only a few places where the drivetrain connects to the frame.

there are many possible causes/solutions.

detailed observation will show which direction to look.

mike

 

If you haven't at least added the heavy duty spring plate to your clutch, I would recommend you do so. It's easy to install without pulling the whole clutch apart. I think you may be able to do it through the derby cover. You can tell if it is stock because it will have a pink rectangle stamped on it.

 

Thanks for the feedback guys! in reply:

As background, I ride pretty hard and accelerate fast. Also I spend waayyyy too much time in Chicago area rush hour traffic (O'Hare can bite me!) so I'm on and off the clutch probably more than your average rider.
- I had the SE spring installed when I did the engine build at 2000 miles
- this happens in all gears up to 4 (didn't get on the highway to see about 5 and 6) and is a light shudder below 3000, but becomes most pronounced at 3000 rpm (where torque peaks) and continues through the range until torque drops off
- does not happen in neutral or in gear with clutch in
- does not happen when coasting (clutch in)
- original motor mounts (about 6000 miles on the bike)
- pipes are clear and mounts are solid

Thanks again!
Jeff

 

Who did the build on the bike. Do you have gear drive cams or chain drive? How long has the engine had this build?

 

I'm a little late to the party but I have to agree with most of the posts - My first thought was the clutch slipping/chattering.