Got a new KLX 250 S 2 month ago. Since the first day I noticed a kind of whining noise from the front sprocket. After having had a look at the front sprocket cover which does not deserve the name cover I thought no surprised I can hear that noise. Additionally this poorly designed cover allows the chain lube to fly onto the gear lever and part of the engine underneath the gear lever.
Are there any proper aftermarkets covers available??

Got another question. There are 2 chain guards near the rear sprocket. Tried to move the chain by hand into all directions but I couldn't get it to touch any of these guards. Guess the chain needs to have an extreme amount of slack to do so. What is the purpose then? These things are to small to protect the chain against dirt/rain so what are they for??

 

I believe the reason for the thing jokingly called a chainguard is a legal one...probably even DOT for anything with a street certification. There is some of the same going on with the countershaft cover. I'm getting the impression that you're coming from street motorcycles...or maybe not. If you have a full enclosure countershaft sprocket cover like many road bikes have, you will clog up that enclosure with just a little bit of mud. They have to be highly vented and minimal for off road use. This bike was originally designed as more of a dirt bike, so even the SF models have to live with some of those concessions. If you want a "Mr. Clean" bike, dual sports are generally not in that category.

Upon a second look at your post, I think you're referring to the guide and rubbing blocks back there on the swingarm. They do protect the chain to a degree...from excessive grinding on the swingarm...but they're mainly to guide the chain and protect the swingarm from being "chainsawed" by the chain. Bikes with more travel than conventional pavement bikes need these due to the broad range of chain slack and tightness as the suspension moves through its arc. The "whine" you hear is probably from these rub/guide blocks and not the sprocket as much.

 

If you have oversized tires, they can rub on the chain guard causing a whine.... no, i'm not going there!
I had to cut part of the guard off to cut down on the noise, went to the next smaller tire next time.

 

Does your chain have enough slack? Better to have it at the loose end of the spec.

 

Is it properly lubricated?

 

Tight link screech. Lube or replace chain perhaps?

 

Chain guards aren't really to guard the chain, they're to guard against stuff like your pant leg getting into the chain. The ones on the swing arm will help keep sticks out of the chain at the rear sprocket and to cut down on mud dumped on the chain by the tire in heavy mud.

If you had a true chain case set up to protect the chain it would look like this Bultaco Matador set up from around 1968:



The gaiters attach to the cases which have matching openings. It would be hard to do for LTR suspension and adds weight and complexity, but the chain lasts a whole lot longer.

By the way, are your sprockets worn out and hooked due to the chain pins wearing causing the chain to "stretch"? That could make a fair amount of noise if bad enough.




Both of these are worn far beyond what I'd run.

 

[/PHP]Yes TNC, used to drive street bikes and this is my first dual sport bike. Thanks for all the explanations.

Would like to mention that the bike is just 2 month old, using the OEM tires, sprockets and chain are like new and chain is regularly lubricated.

Still using the stock exhaust which is pretty quite (but ****ty sounding)
Recently a heard the sound of a KLX 250S with FMF Q4 and mega bomb. This thing was so damn loud it would cover the sprocket noise. Believe most of you use after market exhausts and T4 do not hear that whining noise.

The cover is made from plastic. Will try to buy a sheet of black plastic and modify
the cover

 

I have a 2010 KLX250s and ride every Sunday off road. I come home filthy dirty and covered in mud as well as the bike. It's not hard to keep them clean it just takes a bit of elbow grease. I clean my bikes after every ride for two reasons. 1 I'm **** and like a clean bike, I'm my opinion a dirty bike tells me it could be neglected and not looked after properly. 2 the most important one, if you clean and wash your bike after a ride you have a much greater chance of picking up on problems before they become failures ( usually fail in the bush a long way from help). I found a big tear and hole on a brand new tire after the first ride. Fat tube saved me from a flat but I'm sure luck would have run out with a flat in the middle of no where.
I have found a product called SC1 high gloss clear coat. I re apply it after every wash to everything but the tires brake rotors and seat. Engine cases hoses body panels lights the works. It makes cleanup easy dirt and mud wash off easily. I never have trouble selling my used bikes ( most of the time multiple buyers) jut because I look after them. With the exception of a few scrapes and rub marks on the frame from my boots my bike still looks showroom. Can't figure how to add pic sorry. I've also found my chain lasts longer by cleaning it really well then a ride to warm it up expelling the water then a fresh coat of chain lube.

 

If a new chain is making noise odds are it is too tight. I recommend the following to KNOW how your chain is adjusted:

1. Loosen things up to adjust the chain
2. Use a tie down or the like to pull the swing arm up until the countershaft center, the swing arm pivot center and the axle center are lined up. This is the tightest point for the chain, anywhere above and below will be looser
3. Adjust the chain until you have 1/2-1" play up and down (12-25mm for you metric people)
4. Let off on the tie holding the swing arm
5. Check your play to see how much is there.
6. Now you know how much play is requred to have correct adjustment at full rear suspension extension.
7. Much like cam drives it is better to be a bit loose than too tight. Your chain will not fall off.

Now for cleaning - do NOT use a high pressure washer or even a garden hose blast on the chain directly. You can blow water past the O-rings into the pins on the chain where it can rust. Chain lube does not penetrate past O-rings easily if at all. Fact is what most chain lube manufacturers recommend is to lightly brush off chunks of mud and such, then spray the lube on generously to allow it to wash off dirt and lube, then wipe off excess. There are chain washing setups that can clean the chain, but key is you don['t want to blow the lube sealed in the pins.

I rarely clean my O-ring chain, just lubing it well. With the 650 I don't get in much heavy mud, but moisture and dirt a whole lot. I run about 15,000 miles before I'm seeing sufficient wear causing hooking to start with the sprockets and a tight link or two. When I see that I order chain/sprockets to replace them when I do the next tire change. I hate to take wheels off twice, so I plan ahead.

I could run a chain longer than I do, but the hooking and tight links tell me it's time. I usually notice a bit of snatching noise when pushing or backing the bike out, not running.