Engine Vibration Problem

Hey guys, I need some help. I checked the archives, but didn't find anything on this. I have a Y2K WR4 with about 700 miles on it. The problem I'm having is a very noticeable vibration at a certain rpm. I haven't checked with a tach, but I'm guessing it's occurring somewhere in the range of 4000 to 5000 rpms. The vibration goes away with any minor change in engine rpm, so it is occuring at a very specific rpm (doesn't matter if bike is moving or not). The vibration is very noticeable in the handlebars, and will even cause minor numbness in my hands if I keep it at the specific rpm. I don't think this is normal, and wondered if anyone else has experienced this. Rode my buddy's '99 WR, and noticed nothing like this. Thanks for any help.


2000 WR4, Stock Exhaust with Vortip, Airbox Lid Removed, No Throttle Restrictor (CAN Bike), 170 MJ/45 PJ/#4 Clip/1.75 Turns/ Elev. 500' to 6000'


I have not experienced this on my '99 WR. However, on other machines I have had vibration problems due to loose fasteners. I suggest a thorough torque check of the fasteners on the Engine mounts to start with.

If that doesn't bear fruit, then try to isolate the source of the vibration/noise by using a stethoscope. For a ‘stethoscope’, I use a metal or wooden rod and place one end against the engine cases, engine running, machine secure and stable. I place my ear to the other end of the rod. Then you move the ‘stethoscope’ around on the ‘patient’ to locate the ‘ailment’. You may need to run it in gear to get the noise/vibration.

CAUTION: Be very careful to have the machine well secured and do not get caught in rotating machinery. It can be ugly, even deadly. I know a number of people with missing bodyparts resulting from encounters with power rotating machinery.

Let us know what you find.

Eric in WA

Check your motor mounts and Steering Head. If either are loose you will feel the kind of symptoms you describe.


I had a similar problem with my 99 Yamaha SRX700 snowmobile. Turned out the crank was out of balance or phase as they called it. Had to be welded and rebalanced. I dont know how it could be tested easily on a bike but on a sled its real easy...just start it and watch the clutch wobble.

Eric, I checked the torque on all bolts/fasteners when I first got the bike, but I guess it's now time to re-check. Fershy, I thought about the steering head because of the nasty vibration in the handlebars, but didn't know if that could cause the problem at one specific rpm. I'll check it anyway though. And Scotty, let's hope I don't have to go there! Thanks for the ideas guys.


Could this vibration be from the HUGE crash you had at Lake Wenatchee? The one after the ride at the campground. From a reliable source. :)



Now you know why during my single years one of my female friends gave me a compass. I've had the extreme pleasure of getting a fair number of riders "really" lost. Lets just say that several of my former riding buddies have had the thrill of pushing their machines after they ran out of gas. Are you sure you want to go for a ride in September? hehe. :)

Very funny Rockster..... Seems I remember hearing about someone having a little "orienteering problem" early in the ride!!!??? :)

And as for your reliable source, remember, he stepped back down to the union ranks, so what does that do for his credibility??? :D

UPDATE: Hey Fershy, I checked the steering head for play, and found some. When I grab the lower forks and push front to back, I'm getting about 1/8" of freeplay! I ASSUME THIS IS NOT NORMAL? The manual really doesn't discuss this much, but just gives torque settings for the steering head nut. I was going to wait until winter to take the steering head and swingarm apart to re-grease everythng, but I guess I'll be doing it now. How big of job is it to take apart and grease the steering head?


[This message has been edited by Tim in WA (edited 08-16-2000).]

An 1/8 inch of play is way tooo much!

I had the same symptoms once on a RM125 so I am glad my past experince was able to help out.

It is not a very big job really. remove bars, top triple, a 27 mm nut if I recall then a lock ring,couple of washers, 1 hour at best in and out. Because the WR carries its oil sump close to the steering head the heat tends to melt out the grease like butter. It is wise to add this to your periodic maintenance shedule Use a good waterproof lithium grease while you are in there. Bearings are tapered rollers so everything stays intact. You should be able to fine tune the play by hand tightening the lock until there is no play and no drag. You will be able to intuatively feel this point. Keep tightening until you feel a definate drag and then back off little by little from there.



Tim, just finished putting the steering head and swing arms back together. Yamaha is not real keen on using much grease at the factory. On my 98 I needed a 1 3/16 socket to remove the upper triple clamp BEFORE I could get to the 27mm nut on the upper steering head.

Taber recommended Silkolene grease, which I have tried. Also raised my forks 5mm in the triple clamps to improve steering response.

After this and the other work I did, including installing a Scotts Steering stabilizer, rode the bike, and amazingly, nothing fell off (YET). :)

Removing the swing arm is fairly straight forward, no unexpected problems. Again, don't expect to see much evidence of factory installed grease.

It is time well worth spending.


Fershy & Rock, thanks for all the info. I am just getting ready to go out to the garage and start into it. Hope I have enough of the large sockets, etc. I just happened to have a brand new can of the Silkolen RG2. Bought it awhile back knowing I would be doing the big grease job soon. FYI: The dealer I bought my WR from in Canada said their service mech. goes through and thoroughly greases each bike during setup. And I remember seeing some grease coming from the steering head and swingarm bushings/bearings when I bought it. I guess we'll see just how "thorough" they were!

Isn't the steering head nut a 30mm?

Originally posted by Dougie:

Isn't the steering head nut a 30mm?

Yeah I think you're right Dougie.


I just used a pipe wrench on that funny shaped stem nut and tightened it until I could feel resistance when I rotated the triple clamps.

You should probably inspect your bearings closely to make sure the cages or rollers didn't get buggered while you were riding around with your stem all loose.

Personally, I would be ticked at your dealer because even though its great that he was kind enough to grease your bike (my dealer didn't even give me a friggin' triangle/stand :) ) I don't think the stem should come loose on its own like that. Maybe he undertightened it.

[This message has been edited by Hick (edited 08-17-2000).]

Well it looks like I might have jumped the gun on the amount of play in the steering head. The play I originally felt was when I was grabbing the bottom of the forks and pushing forward and back. I checked for play AFTER removing the forks, and the steering head felt fairly firm (I realize there's less leverage) :). I hope there was some play in the steering head, because if I put everything back together and still have the vibration problem, I don't know what to check next. Checked all the engine mount bolts, and everything's tight.

By the way, there was hardly any grease on the steering head bearings, so I think the dealer was giving me a bunch of crap about greasing everything. There was grease, just not much. The bearings look good, and I'll be putting everything back together today. Had a few beers last night after taking everything apart, so I wanted to wait to finish today so I had a clear head when I put everything back together!

By the way Dougie, the steering head nut is 30mm. I ended up making a trip to Sears to get the socket. I don't have a pipe wrench.

[This message has been edited by Tim in WA (edited 08-17-2000).]

Originally posted by Tim in WA:

By the way, there was hardly any grease on the steering head bearings, so I think the dealer was giving me a bunch of crap about greasing everything.

I don't have a pipe wrench.


There was literally NO grease on my bearings ('00 426) when I inspected them a few months after purchase so maybe your dealer did grease them.

I meant for you to use the pipe wrench on the notched nut under the top clamp. Mine took a decent yank to free it up. If your's came off w/out a wrench I would consider that way too loose. How did you get it off?

Hopefully you'll diagnose the vibration problem after your next couple of beers :)


I removed the slotted not with a punch and a hammer. I have a spanner wrench somewhere, but couldn't find it. The nut was snug, but the first whack with the punch loosened it right up.

AS FOR THE ORIGINAL VIBRATION PROBLEM, I just got back from an 80 mi. trail/road ride. The vibration is still the same. All engine mounts are tight, and I don't notice any strange noises coming from the engine. Maybe it's just an inherent problem within the high-strung thoroughbred motor! :)

Also, I don't really notice the vibration when trail riding. Only feel it when on hardpack roads (dirt/asphalt). I figure this is because I'm using the powerband differently, and don't stay at one particular rpm very long for trail work.

Thanks for all the suggestions and information guys!!!


If you only notice the vibration on the roads running a constant speed, I would guess your wheel is out of balance, just like your car gets.

Tim in WA

This just occurred to me...

I had some problems with my counterbalancer gear on my 426 a few months ago. Specifically, the straight key was toast and nut was loose. So I was wondering then, if your counterbalancer were not "timed" correctly, i.e. the gear is off one tooth from the main shaft in one direction or another then that would be a small enough variance to make counterbalancer be out of phase with engine "wavelength" at certain rpms, creating some vibration.

The problems I had with my straight key getting squished allowed the counterbalancer gear to move a substantial amount independently of the shaft. The main effect of all this was a weird noise.

BUT, I also noticed that my bike vibrated less once I replaced the key and retorqued the nuts on the main shaft and counterbalancer shaft.

So maybe you should yank your right cover and check your counterbalancer gear for alignment (the gears are marked), and for play. The nut on mine was pretty loose (and that is not good).

It makes some sense, to me anyway, that a loose connection between your counterbalancer and crank could cause vibration, and I did experience this to a noticeable extent.

It is revealing that for '01 Yamaha no longer uses a key on counterbalancer shaft, the gear is held in place w/ splines.


Just cause I feel lazy right now, I'll go ahead and ask before opening my owner's manual: How big of job is it to check this condition out. Is it as simple as draining the oil, pulling off the rt. cover, and just visually looking at the timing, etc., without pulling anything else apart. I'm assuming I'd have to pull the counterbalancer gear to check the conditon of the key. How difficult is it to pull the counterbalancer gear?


In answer to your reply, the vibration is still noticeable even with the bike sitting still and reving the engine to just the right rpm. Thanks for the suggestion though!

[This message has been edited by Tim in WA (edited 08-22-2000).]

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