WR250R transmission rattle

[DirtPilot12]

Hello all,

 

I'm new to the forum and I have a 2008 WR250R that I recently purchased with about 5000 miles, completely stock. I only have about 500 miles on the bike and recently noticed a rattling noise coming from what sounds like the transmission. It is usually only when in a taller gear at lower RPMs (very noticable going around 25mph in 4th). I just put a new rear tire on and lubed up the chain and checked the sprockets, and everything looks ok. The bike pulls through all the gears and shifts perfectly, it just has an annoying rattle. Just wondered if anybody else has run into the same issue before I drop a couple hundred at the dealer to have them check it out. Any help is appreciated!

[Gath3r]

Hey Dirt Pilot,

 

If you don't get the answer your looking for here, you can try the wr forum.

 

http://wr250rforum.forumotion.com/

 

Between TT, and that other forum, and advrider, I get answers by the members fairly quickly on anything I inquire about.

 

 

 

 

[maim]

mine did not rattle or knock until I put the skid/bash plate on it.  try it with it removed if it has one.

[DirtPilot12]

mine did not rattle or knock until I put the skid/bash plate on it. try it with it removed if it has one.

It does not have a skid plate on it. It really sounds like an internal rattle to me but I'm not 100% sure. Also it seems to be more noticeable when the engine is still getting warmed up.

[YZEtc]

My guess is the drive chain making a racket from being at such a low RPM in a tall gear.

[mikeylikesit]

Mine also JUST started doing this. I also just put on a new back tire.

The new tire is very grippy and hard to spin, unlike the other 2 I've had on.

Mine does it when in too tall of a gear with heavy throttle.

My impression is the same as YZEtc. Seems like chain noise.

[DirtPilot12]

I have narrowed it down to chain slap/rattle. After hearing the noise while riding I was able to look down and notice the chain slapping around. I assumed the chain was a bit too loose and tightened it up to the smaller end of the slack tolerance. It seemed to help slightly, but the rattle is still there. I'm thinking I will just replace the chain and sprockets and see if that does the trick!

[YZEtc]

Be careful not to adjust the chain too tightly, something that even long-time motorcycle mechanics can do.

 

While in the middle of your next off-road ride, stop the engine, get off the bike, and feel how much slack is in the chain.

If there seems to be none or way too little of it, you know you need to loosen it a bit due to dirt inevitably getting caught between the chain rollers and sprocket teeth, something a street bike doesn't see.

[gomerkfx700]

mine also does it if the chain gets to much slack in it i have a cheap non o-ring chain on it were im trying to fine tune my gearing i didn't want to junk a good o-ring chain swapping gears and cutting the chain and stuff it makes a bad racket at times if it gets to much slack in it.

[Yamaguy55]

Check the stock chain guide rollers, one is above the chain run just below the left side panel retaining bolt, the other inboard of the kickstand mount. The stock ones are just nylon rollers spinning dry on a shouldered bolt. I replaced both of mine early on with similar sized sealed-ball bearing equipped versions from Moose. It cut quite a bit of the noise. The danger of too tight an adjustment is there will be likely transmission bearing damage.

 

Another thing to check is the swingarm chain slider, right under the front of the swingarm. The bottom part gets notched, and with the stock countershaft cover in place, you can't see this. If it gets too notched, then the chain starts sawing through the swingarm itself. Easy to see with the plastic countershaft cover removed. I have a Zeta Racing cover on mine, as sticks and debris got trapped in there and made a racket. Very snug fit so anything in there makes noise, and can't get out. I prefer the Zeta Racing one, as I can see the state of all of the important stuff at a glance, and all of the foreign matter just falls out the bottom.

 

There was a factory tech bulletin about this: See M2008-020, of 12/15/08. The gist of this is: With bike on sidestand, you should have about 8-13 mm clearance between the top of the chain on the lower run and the swingarm. The approximate measure point is roughly 165mm forward of the front bolt of the chain guide back by the sprocket. They tell you to use 36 lb of force to push up, but the goal is all of the slack removed for a good measurement.  I also suggest that you measure this several times for and rotate the wheel each time for a used chain, which often have tight and loose spots. When tightening chain, don't believe the factory marks. You can sight down the chain or use a laser and see if the wheel alignment is really straight. I then wrap a rag around the chain, put my foot on it and push down hard on the lower run of the chain while tightening up the axle nut. Otherwise, you torque off the adjuster blocks and the adjustment walks from where you had it set.

 

If the sprockets aren't obviously worn, and you can't pull the chain off the rear sprocket by a half tooth (exposed) plus there is little side play, then maybe your sprockets/chain are still usable. Maybe not. 

 

I have a Yamalink and 13/47 sprockets on mine, and run it on the snug side (about 8mm, measured roughly just behind the boss for the linkage on the bottom of the swingarm: see the bulletin, it has a picture). I also suggest that you measure this several times and rotate the wheel each time for a used chain. Due to my mostly-dirt-only use of my WRR, the stock chain had completely had it by 5K miles, and was replaced with an x-ring. (new sprockets as well, obviously)

 

Don't use an air wrench or impact driver on the countershaft nut, it will mess up the bearings.  Do it the hard way with a sprocket grabbing tool and a breaker bar. The nut is staked in two places, but a breaker bar will iron that out while you remove the nut. I restaked the original nut and then used a paint stick to mark the shaft/nut relationship, so at a glance you can see if it is still tight. I use a paint stick and mark all critical fasteners so I can just do a walk around and see if they are where I left them. Beats the pre-ride socket routine anyday.

 

Last, I'd say it is time to pull and check the swingarm pivot and linkage bolts/bearings/seals. I pulled mine at about 4500 miles and found enough water had gotten in between the swingarm pivot bolt and the inner bearing races to cause it to (just about, but not quite) rust in place. The bearings and seals were OK, so I just cleaned up everything and regreased/reassembled and didn't need to replace anything. Beats letting it grow together and then need all new parts, and a sawzall/cutting torch to pull the bolt.

Edited July 2, 2014 by Yamaguy55