may be a big problem

[lowrider92]

when i put a passenger of substantial size, 100lbs to 140, and i engine brake the bike shakes, and makes an ugly noise, also if i hold in the clutch and roll down the streat after about 50 feat the bike starts to shake bad. this doenst happen with just me or if i put my little cousin on the bike, any ideas?

[Y2K]

Swingarm bushings may be bad (if so look at doing sta-bo),motormounts should be checked.
There was also an aftermarket part called a torque arm to stiffen up the trans to engine link on FXRs.

http://sta-bo.com/

http://www.carlinidesign.com/harley-...-arm/index.php

[jwh2573]

low pressure in the front tire will also cause it to shake. I'd check there first.