400EX vibrations

[OZ-T]

A couple weeks ago, I faintly started noticing small vibrations in the engine. But, today during a long ride, I noticed the vibrating steadily getting worse and worse. It is most noticeable in 1st and 2nd gear about half throttle. When I let off the throttle it does not do it as bad but is still noticeable. When I pull in the clutch and let it coast, it pretty much disappears, but there is still a slight shimmer.

Now, on a side note, my axle got bent a couple months ago and has a pretty good wobble. Is there any chance that could have caused the bad vibrations to come about? I ordered a new axle and it came in earlier this week and I plan on installing it Tuesday, do you think that will help? I put a new bearing carrier in it not long before the axle got bent and perhaps the bend caused the bearings to blow out, but the quad still rolls and coasts nicely so I pretty much have written the bearings off. Any suggestions, anyone? I sure hope it's nothing serious, going camping labor day weekend and would be really bummed if I couldn't take the quad.

[OZ-T]

The vibrating is bad to the point where I can feel it come through the handlebars and jar my hands and even through the footpegs. It is bad enough that on a long ride it would numb my appendixes to sleep most likely.

[Mtndew99]

It cld just be that a bolt it loose somewhere make sure everything it tight where metal contacts metal I forgot to tighten a bolt on my skid plate and when I started the quad it vibrated rlly bad I loctite or put a lock nut on most of my stuff and also idk if its just my 400 but even after I complete engine rebuild I still get vibrations past half throttle

[OZ-T]

Checked all the bolts I could think that would come loose, motormounts, skid plates, swingarm and the a-arms and all were tight. Then I rode it around the driveway a bit and noticed the vibration was substantially decreased, but was still there from time to time. This has me baffled big time.

[CJM]

I had a similar issue, everything was good, tight and whatnot. Finally dawned on me I had countless hours on my 400 and chances are the crank bearing was finally on its way out.

[2001400exrida]

this sounds like motor vibrations not axle vibrations. get a new axle either way though. I'm guessing the reason it isn't as bad when you pull the clutch in, is because you're lowering the revs. If i had to guess i would say your crank is going bad.

[buck440]

I always thought it was normal lol, I call it the sweet spot. all vehicles I've been in did it including my 400ex, crank never went out. if it's a quad shaking vibration it should be your axle but if it's more high intense hand numbing I would say motor. if i'm correct you can check without tearing your whole motor apart.

[OZ-T]

Dang, I hope it's not the engine, but wouldn't be surprised considering it is 12 years old. New axle is going in Tuesday so will see if that helps, going to see if I can adjust the valves that day as well. I read somewhere else that unadjusted valves cause vibrations also, really hoping that's the case!

[DragonGunner]

Oil change, and maybe some different brand of gas with higher octane.

[OZ-T]

Oil change, and maybe some different brand of gas with higher octane.

I changed the oil here a couple weeks ago and used synthetic for the first time. I run premium 91 octane all the time which is the highest I can get at the pump, where would I get higher octane gas do you know?

[Exrider911]

I changed the oil here a couple weeks ago and used synthetic for the first time. I run premium 91 octane all the time which is the highest I can get at the pump, where would I get higher octane gas do you know?

Your local race shop or the air port

[DragonGunner]

If your running 11:1 compression you want at least 93 octane otherwise you should be ok.

[OZ-T]

http://i981.photobucket.com/albums/ae299/1980JeepCJ5/946374_217853825039653_877743883_n_zps21710956.jpg (http://s981.photobucket.com/user/1980JeepCJ5/media/946374_217853825039653_877743883_n_zps21710956.jpg .html)
Well, threw the new axle in there today. It seemed to help a lot, but the vibration isn't completely gone and I started to notice it after a short time riding it. Sure is much more pleasant to ride considering I don't need to see a chiropractor after each ride! Man that wobbling axle was exhausting.

[OZ-T]

Well, had a couple of reputable people check it out and ride it, they all agree that it is likely the clutches on their way out. being that it only really vibrates when the RPMs are low or you downshift you can feel it also. That makes me feel better, a clutch kit is a relatively cheap repair. What should I go with? OEM clutches lasted 11 years so am leaning toward going that route again but want to know if there are any better options. My quad is stock and I really have no plans to modify it so probably don't need heavier duty clutches than what it had, right?

[DragonGunner]

Well, had a couple of reputable people check it out and ride it, they all agree that it is likely the clutches on their way out. being that it only really vibrates when the RPMs are low or you downshift you can feel it also. That makes me feel better, a clutch kit is a relatively cheap repair. What should I go with? OEM clutches lasted 11 years so am leaning toward going that route again but want to know if there are any better options. My quad is stock and I really have no plans to modify it so probably don't need heavier duty clutches than what it had, right?


Ya I just posted that I think the OEM cluthes are still the best out there by Honda......did you check your rims to see if they were bent or flat spotted? If you bent your axle good chance your rims are not right either.

Don't forget to scrub the plates clean and soak the new clutch in oil before installing.