QuestionQUESTION: Hi Mike -
Thanks for reading my question. I have a '96 FXDWG with 105k miles on it and over time I've had an increase in drive train vibrations under certain conditions. It is acting like the primary chain is loose... jerky on deceleration, seems to have very slight surges while cruising with even throttle. Coming to a stop sign for instance, 2nd gear, clutch out, as I slow it gets jerky and when I pull the clutch in and the motor spins down to idle, there are increased vibrations until she levels out. I feel I need surgical precision with the throttle to ride the bike smoothly.
Descending grades off throttle there's more vibrations, ascending them it's not bad when I'm giving her juice, but if at even throttle and the grade increases, as she bogs a little the vibes increase and I feel them from my feet first. I noticed today when my feet vibrate, my right knee that's pressed against the air cleaner does not. I did some tests lifting my right foot off the peg... while my left foot is dancing around, there is no vibration in my knee with my foot elevated from the peg.
What I've done to date. About 4k miles ago I had the front and rear motor mounts replaced, top isolator too. Engine is smooth as glass at speed. I also had the primary chain replaced.
I've got a Hayden M6 in the primary and yesterday I checked the adjustment and added a plate to get the required 5/8" space between the plate and shoe. This is how the instructions say to adjust it so I feel the primary chain is done correctly. This unit has been in my bike for approximately 70k miles and I have not replaced the springs or shoe. The shoe has minor channels worn into it, not deep ruts. Springs seemed OK when I inspected them.
While in there I also checked the torque on the compensating sprocket nut by installing the Jims tool between the two sprockets, then using my torque wrench to turn the front sprocket to get a click at 155 lb-ft. The FSM states 150-167 lb-ft for that nut. Having never done this before, I'm not sure what I should have seen, so I'll tell you how it went. The sliding cam turned right until it met the compensating sprocket, then I was able to get a click out of the torque wrench. I attempted to turn the cover assembly with springs by hand and could not. Visual inspection didn't expose anything out of sorts with this assembly.
After adjusting the M6 and checking the torque on that nut yesterday I have put about 270 miles on the bike and things have definitely improved, but it's still not Cadillac smooth as it once was. I've owned the bike since new in Feb 1996.
I cannot find any concrete information about compensating sprocket failures or wear characteristics. I also don't know if the M6's get tired over time. It seems to me it has to be one of these two things given that increased tension on the primary chain did improve things.
Any ideas?
ANSWER: While you were checking things did you check the rear drive belt for proper tension and wear?
Mike
---------- FOLLOW-UP ----------
QUESTION: I have not, but I have had it to two different shops in the last 8k miles and asked both to do it... and I assumed so, well, you know how that goes.
Is my issue a symptom of being too tight? Loose? I'd bet it's on the tight side. I feel it's mostly normal when I leave the house in the morning, seems to get worse as the day goes on.
I visually inspected the rear belt for wear/cracks 8k miles ago and I didn't notice anything out of sorts. I'm pretty sure this belt has 50k miles on it, maybe more. Maybe it should be replaced?
I work alone, is there a way to check the belt tension on my bike without it being upright with weight of the rider on? I am due for a new rear tire so it's a perfect time for a lesson in working solo.
Thanks!
AnswerIf it gets worse after you ride a while I would say, might be to loose. It will stretch a little as it get hot. I dont know of a way to check it without a rider ont he bike. When I check them I get my wife to sit ont he bike! lol 50,000 is alot of miles on the belt. They can last up to 80,000, but I have never seen this.
Another thing to check is your tires. They can cause a vibration. Run your hand around them and see if feel any bumps or if they feel rough.
Good luck and happy riding
Mike
