Funny sound???

With a new starter solenoid, new fuse box, new spark plugs, and a rebuilt starter, I am back on the road.

Many kudos to Chacal for the great parts service.

Now there is a funny noise and feel to my bike when cruising. I will try to explain but please forgive me in advance.
There is kind of a whum, whum, whum sound when I'm cruising. When excellerating it is not smooth, more like a specifically timed hesitation. When crusing it is fairly smooth but the whum, whum sound is there. When I let off, it is somewhat jerky but in an evenly timed sort of way. Almost like something oval instead of round, if that analogy makes any sense.

When I try to think it through, it seems too smooth to be carbs, plugs, or plug wires. Wondering if it might be cams, clutch, tranny, ???

Any help or opinion is greatly appreciated.

 

Have you checked your rear brake shoes for delamination? Don't ride again until you have, see links in my sig for why. Also check the drum for ovality.

To be honest it could be other things but I'd check that first & also being chain drive, that your chain is not pulling tight in certain spots when you spin the wheel (some cheap sprockets are out of round)

 

Replaced both front and rear brakes last summer. I don't think it is the chain as I spray a little lube on it every other day (commuting ~ 65 mi/day) and the chain seems to run smooth. When I engage the clutch, everything seems smooth.

 

does it change with the clutch in? cupping tires, tire air pressure, tight chain, speedometer cable.
try just touching the front brake then the back brake.
when did you first notice it?

 

I'm fairly sure the issue in the engine. As mentioned above, accelerating and deccelrating is where it is noticed the most. When at crusing speed and then let off, it is like someone that can't make a clutch work smoothly. But it has an even jerkiness to it. It feels like something internal vs. an external source.

 

look up under your fenders

 

Too funny Polock ...

 

Windlover, my first thought was chain related as well. I had a Suzuki 450 years ago with bad swing arm bearings that made the same sound. Put her on the center stand and see if the swing arm moves from side to side...

 

How about we start by checking the chain and sprockets for wear? That's the most likely place to start.

Have you adjusted the chain, or just kept it lubed? Lubed with what?

I suppose it could also be primary-related (it is a 550 after all, with a TRUE primary) but that's kind of unlikely, however---

What OIL are you running? Conventional motorcycle oil, 20W40 or 20W50? I ask because the primary tensioner is oil-pressure activated.

I'm still voting for the drive chain though.

 

I'd go for the drain chain too. It could look fine but be unevenly stretched.

Sprockets could be parts of the problem also, since they sometimes wear down unevenly (the rear one mostly) and become a bit oval as the chain eat them.

 

Guess I need to check the chain and sprockets. I just read through Chacals info on chains/sprockets and I'm probably due to change mine (~15,000 mi).

 

The Rear Axle Chain Tension Adjustments say a good bit about the need to replace the Chain and Drive Sprockets.

If you are beyond 75-Percent of the travel in the Adjusters; the Chain and very likely one or both Drive Sprockets may very well need renewing.

 

I vote for a stretched chain as well.

I had a feeling like my tires where oval shaped, a slight but constant jerking. of course the engine was making a "kind of a whum, whum, whum sound when I'm cruising" also.

I put the bike on the center stand and in neutral and sure enough the chain had a stretch in one spot where the links would ride up on the sprocket teeth....

Changed the chain and sprockets and it's all good.

 

This might help.

Put the bike on the centerstand, and grasp the pin of a chain link at the 3:00 position on the sprocket.

Pull it straight rearward. If it then reveals more than 1/2 of the adjacent sprocket teeth, you need a new chain and sprockets. Always replace all three items as a set.



If the bike has sat (and whose hasn't) the chain is likely rusted internally and will quickly stretch and could fail, even if kept lubed. Don't put it off. You can go with chacal's standard-grade everything and get way more than the original mileage if maintained properly.

TIP*** The factory spec for the chain (35mm~40mm) is a bit too tight for it to be "happy." Run it at 40~45mm or even 45~50mm and it will hold adjustment for much longer. I lube every 300~500 miles, and adjust every 800~1000 or so, running the chain a tad loose to begin with. Lube immediately if you get caught in the rain.

 

Seems to be the way with most chain driven bikes I've owned, ridiculously so with MZ's, which kill their output shaft bearing in short order when set to "factory" spec... Agreed it's better to keep it a *bit* looser. If nothing else it mentally conditions you to check it more often when you know you didn't set it "by the book".

And new non o-ring chains can be killed off after just one good soaking if you ignore that final bit of good advice, iron oxide mixed with lube makes a great abrasive...

 

I want to thank everyone for the great advice.

Put on new sprockets and chain and my bike is running smooth again. My chain was quite stretched. When I laid down next to the new one to check size, the old chain was 1 1/2 links longer. I'm amazed at how these three items affected the overall smoothness of the ride.

I also rebuilt my clutch and my shifting is much smoother too.

Props to Chacal for great advice and EXCELLENT parts service.

 

Good to know this is a happy ending!

 

Len's the man! Glad to hear of xj's getting fed properly

Happy Riding!