Vibration problem...ideas needed on what it is

[sporty16001]

Wanted to mention, low RPMs not high. Vibration isn't bad at speed.

[72_Ironhead]

hmmm

[Buster]

Sounds similar to the problem I had on my 04 Low Rider. Can't remember exactly what RPM range it occured in but it did it in every gear in that same RPM range. It was smooth as silk under and over that certain RPM. Since it was still under warranty, I took it to the dealer and had them check it out too. They couldn't find any thing wrong. Even pulled the tank and checked the top brace. I sold the bike because of that reason.

I have read of people having the same problem on their Dynas but not on the Sportster. Some have said they cured the problem or helped it by reshiming the front motor mounts.

[sporty16001]

So Buster, by reshimming the front motor mounts the idea was that the motor wasn't in the frame square? I'm willing to try anything. I even pulled the bolts front and rear to make sure they weren't broken or stressed. All were ok. Thanks, I'll check the motor mounts to see if the engine is square, not sure how but I'll try to figure out a way.

[Buster]

Here is what I gathered from what I read. One guy put a jack under the engine and took out the bolts in the motor mounts. When he did, there was a gap inbetween the frame and the mounts. He measured the gap, cut some shims and installed them in the gap using longer bolts than stock. Then he made sure the belt was still in proper tension and alignment. Said it took his vibration problems away. Others stated it didn't stop theirs but did help considerably.

[Sirrrom]

Here is a site with ton's of info on "everything", including "Vibration"
http://www.chuckhawks.com/index5.motorcycles.htm

Here is his article on pre-rubber mounted engines (2003 & earlier)
http://www.chuckhawks.com/sportster_vibration.htm

One of the things discussed is a change in gearing to move the vibration out of cruise speed. He suggests changing the rear pulley to a 55 tooth, front 29. I was never able to find the 55 pulley. The final ratio with a 29 front and a 55 rear is 1.9:1. There is a 32 tooth front pulley now available for Sportsters. The 32 with the original 61 offers the same final ratio, 1.9:1. These pulleys are available on Ebay. Doesn't get rid of vibration, just puts it where you don't "see it".

Hope this helps someone else.