TOPIC:

Hi, Folks.

Hoping some one can point me in the right direction. Recently I have noticed a "clunking" sound and feel when starting up from for example a red light. It only occurs in lower gears (1st & 2nd) and only under load (acceleration). It seems to come from left side just inside the shifter. The bike clutches and shifts fine, accelerates fine, but clunks and jerks a little. It is quite audible and I definitely can feel it.

The bike has only 12K miles on her, engine runs great, valve clearance exactly at nominal, carbs synched with Morgan Carbtune, fresh oil (Valvoline 20W50 for motorcycles), everything works great. It doesn't pop out of gear, there's plenty of power, no slippage, I haven't done a compression check, but everything checks out.

But before I park the bike (my only bike) and start tearing it down and splitting the case, etc., I thought I'd ask you folks what you think and what you would do in this situation. If there are things I can do or check before I shut down my riding season, I would really appreciate it!!!

Post edited by: Norseman, at: 2007/07/11 16:08

Post edited by: Norseman, at: 2007/07/11 16:10

For some reason a few guys here have had the nut come loose in the front sprocket. I'd check that and chain slack. But, then I don't know if you have chain or shaft drive.
Ride safe

I will definitely check the front sprocket nut, and yes, I do have the chain drive. I checked the chain slack by pushing the bottom center - chain travel is roughly 1.5 inches from gently pushed-down to lifting up. I don't know exactly how to correctly check slack.

Check your front and back sprocket bolts.I set my chain
slack at 3/4 to 1" movement max while I am sitting on
the bike.On the center stand,motor off,put the trans in low and rock the wheel back and forth listening for
noises.Also check the rear hub for movement.Sometimes
the rubber dampers deteriorate over time.

I agree With the foregoing check the chain first.


I had this on my newly rebuilt J and feared the worst; particularily as I had been having some clutch lifter issues. However all it was was maladjusted drive chain.

Thanks, Guys. I did check the chain, which had a generous 1.5" travel. I adjusted to 30mm (roughly 1&3/16". That helped significantly, but I still feel a slight "clunking" feeling through the footpegs. I really don't think it's my imagination, so I will tighten the chain just a tad more to 1".

What's bothering me a little is the "clunking" does not go away when I pull in the clutch and just coast in any gear. I did check the front sprocket and everything was nice and tight (I did take off the locking collar and checked the bolt). Teeth look fine on rear and front with what I assume is normal wear for 12K miles.

If anyone else has any suggestions beyond what I already have done, I'd appreciate it. Thanks!

When you adjusted the chain, did you use the little "lines" on the adjuster brackets to line it up?
They aren't always exact, even when set on the same "line" on both sides.

I always use a tape measure to measure the distance the ends of the bolts are from the brackets once I get the chain at the proper tension, and have never had any probs with proper wheel alignment.

If they arent set the same when measured, then what you might be hearing is the master link as it rolls over the smaller teeth on the front sprocket.
It will obviously be more pronounced sounding at lower speeds, since higher speeds (and a 4-into-1 exhaust if so equipped) will usually drown out anything below a dull roar.

Perhaps overlooked, but see nothing about having actually lubed the chain. Am guessing original chain, which probably requires regular lubing as routine maintenance. Without lube, the chain will kink. Would lube the heck out of it and do another test run.

Perhaps overlooked, but see nothing about having actually lubed the chain. Am guessing original chain, which probably requires regular lubing as routine maintenance. Without lube, the chain will kink. Would lube the heck out of it and do another test run.

Thanks for taking time to respond, Retro and Patton. I did use the "lines" on the swingarm when adjusting, and it did seem to me to be a rather inaccurate reference. I will definitely use a calibrated measure to check and re-adjust if necessary - so thanks.

Patton, I did lube the chain with a product called Maxima Chain Wax (recommended by dealership that mounted my new Dunlop tires). However, after just a few miles (less than 50 miles) the wax was flung off and the chain and sprockets look bone dry again. I'm not sure what the best chain lube is, so if you have any suggestions, I'm all ears.

Now, the clunking doesn't seem to correspond with chain speed/links, but it definitely got better after tightening the chain. So my plan of action is to fine-adjust using an accurate measurement as recommended, and then lube the heck out of it, then take a test ride. Will report back. Thanks again, all who responded!

Is it a CLUNK or could it be somewhat "softer"? could it be a badly balanced or just a bad tire?

FWIW, I "align" my back wheel by checking the measuremnet (spelling?) between the sidewall of the tire and the inside edge of the swingarm, at the front of the rear tire and making sure both sides are the same.

Well, I measured the distance between the very rear of the swingarm and the inside of the adjustment bracket, and I was .5mm off. I lifted the bike off the rear tire and adjusted to exact distance and tightened everything back down and took it for a test ride. What do you know - clunking disappeared. However, my alignment slackened the chain a bit, so now I get to tighten it again:lol:

This time, though, I will tape down my own lines on swingarm and bracket on each side before loosening wheel and adjust 1mm on each side, maintaining alignment.

My conclusion is that even 0.5mm difference at rear of swingarm translates to enough misalignment at front of rear sprocket to cause noise/feel issue. If that's the case, the crude lines on the bike are useless in really truing the rear wheel. Also, the factory minimum spec on chain slack of 30mm seems to generous as I'm currently at exactly 30mm now and I have noticeable "slop" when shifting (sorry about my highly technical terms of clunking and slop, but it seems to accurately describe my perceptions LOL). It seems that tjettim's method of 1", or 25.5mm, may be more effective, although that might be because the chain is somewhat worn?