Any ideas on what might be causing a growling noise from the front of my KLX250?

The noise is a low level, but definitely audible, growling noise that is on and off at frequencies that are shorter and quicker as the bike increases speed. The grrr noise seems to correspond to what you might expect if something was rubbing on the knobby tires, but nothing is touching the tires.

I thought it might be related to the speedometer or speedo drive, so I checked it out, regreased and even tried the bike with the speedo cable disconnected, but the noise persisted.

I've looked at the wheel bearings but they turn smoothly and seem to have adequate grease.

I then thought the noise might be coming from the tire itself, contacting the pavement, figuring the frequency of the noise should correspond to the rpm of the tire. Doing some quick math, this didn't pan out either. Given the front tire is about 27" in diameter and the frequency of the noise is about 3 growls per second at about 30 mph, it just doesn't add up. At 30 mph the front wheel should be spinning at about twice that rpm.

I've also tried to pin point the noise by jacking the bike off the ground and spinning the front wheel by hand, and the noise does not happen, but I can't get it to spin much more than 10 mph either.

Oh, and one more thing. The noise occurs on non-paved surfaces too, so that supports the idea that it's not tire tread related.

And, it's the same sound whether I'm accelerating, decelerating or coasting with the clutch engaged or not.

I'm beginning to wonder if it might be coming from the chain/sprocket area or even the transmission, but it sure sounds like it's coming from the front wheel area.

Has anyone had a similar experience? Or, better yet, can someone tell me what's going one with my bike?

 

This noise, or at least some form of it, has been around for awhile. I don't think anyone has totally figured it out, and probably it's not one thing on every bike. Mine used to do it in an infrequent manner both on and off road, and there never really seemed to be an identical set of circumstances in every case. For some reason, mine hasn't done it in a year or two. Why it started and why it quit is still a mystery to me.

 

Could be the speedo sender. Or just the hum of the tires.

 

Is something blocking your brake line from moving up and down with the front suspension? I had this issue with my GPS blocking the brake line movement and it would rub against the front tire.

 

I am experiencing the same noise. Sounds like something rubbing against the front knobby. I am hearing it when riding in the dirt but not all the time. I can associate it with coming off of a high rev in 2nd or 3rd gear.

 

I may have noticed this yesterday as well. I suspect that it's some sort of resonance in a taught structure or cable or something.

 

Could this sound be generated by side-of-tire ***** kissing ground, with greater spacing? Tire pressure related?

 

I'm not sure, but I may have found the source of my growl this weekend.

I need to double check but I believe it is coming from the speedometer and is amplified by the headlight shroud. When I grabbed the top of the shroud the noise stopped.

I suspect a repositioning of the shroud and re-tightening of the mounting bolts, or insertion of some plastic foam to dampen the vibration will do the trick.

I'll report back once I'm sure, but you may want to look at this possibility.

 

Any update?

 

It hasn't happened again since I wiggled the headlight shroud around, but I'd be reluctant to say it's fixed.

I'll post back if there's a change.