Chain de-rail question??

[duffy924]

Hey, I've had this virtually stock '86 r for about 7 years now and never had a problem with it. It is my first and only four-wheeler which replaced my Tecate 250-3.

But recently my chain has come off three times, always when landing a jump. The slack is perfect and the sprockets are flat and unworn, also the chain seems straight when I it take it off and look at it on a flat surface. (all three have maybe 25hrs). Could my tensioner be slipping, and if so how? I'm not quite sure (other than the cam shape) how it works as I've never had it apart.

I planned on replacing the rear bearings before my next ride, but I would like to be sure that I have solved the problem before I hit and trail and risk my case any further.

Also could it be a result of not having my axle jam nuts tight enough?

Any insight would help give me peace of mind next time I go out.

Thanks.

Aaron.

[racerx573]

I had this problem when I was running stock frames.

Are you running a stock swingarm?
If so, and if it is the steel ones, go buy a stock Banshee chain guide and have some mounts welded on. This will help keep the chain in line.

Als it could be that your swingarm pivot bolt is bent or twisted. That is what was wrong with mine. And the swingarm pivot holes were a little ovalled out on mine...

You may also want to check your axle bearings..

And as you suggested about the locknut not being tight enough, this could be it as well.

Do you run a skid plate? I used to have an OMF skid with the teflon chain slider on the bottom, and as soon as I took it off my problems begain, because nothing was keeping the chain tight with the rear sprocket.

Put your bike up on a stand and check and see if there is any play in your pivot bearings, and axle bearings (with the locknut tightened). Also try pulling out your pivot bolt and see how easily it slides it. If it does not pop right out, it's probly bent.

[csr250r]

I had my chain come off yesterday when i was goin up a jump, i cracked the throttle to make it over the double and i had nothing, it caused my 250 to nosedive into the landing and i went flying over the bars... got my air back and flipped it upright just to see all the oil pour out of the case. ends up that it wrapped around my front sprocket and took a chunk out of the case under the shifter, 3-4 hundred bucks of damage...plus labor getting my case in right. it ruined my left side of case, buper and chain. I got a new bumper and the other parts are soon to come...this cuts into my budget for new plastics and tires lol...

but yea my sprokets seem good and the slack was bout right. I have laeger swinger.

[deathman53]

everytime I had chain jump off was because of the bad axle carrier, loose axle lock nut, and worn swingarm bearings. My friend had the chain come off, several times, he blamed it on not using a skid plate, it was a bent rear sprocket and bad carrier bearings. Fix your problems and get a case saver, before you even think about riding your bike. A smart person would replace the carrier bearings, swingarm bearings, get a case saver and anti-fade lock nut. You could have bought those for about 1/3 of what it costs just to buy a new left case and rebuild the motor.

[duffy924]

Great advise all, Thanks for your help.


I've got a stock frame and swing arm. I had the same problem with the chain feeding up in between the frame and front sprocket, I managed to get it out on the trail with a stick, and go home. I wonder if there is a good product that would stop that.


I'm going to pick up new swing arm and carrier bearings, anti fade, and chain slides. I've got a good case saver. And I will check the swing arm bolt for straightness, holes for roundness, and hope for the best.:devil:

[C-LEIGH RACING]

Installing a chain guide like racerx just said is the best thing you can do on a stock 250R swingarm.
If Honda failed on anything on the TRX250R it was not designing a guide into the swingarms on them.
I have chain guides on both my 250Rs & my daughters, all the balls came out of the sprocket side bearing in the carrier & the chain never jumped off the sprocket.
Those guides are worth their weight in gold.
Neil

[86 Quad R]

Originally posted by C-LEIGH RACING
Installing a chain guide like racerx just said is the best thing you can do on a stock 250R swingarm.
If Honda failed on anything on the TRX250R it was not designing a guide into the swingarms on them.
I have chain guides on both my 250Rs & my daughters, all the balls came out of the sprocket side bearing in the carrier & the chain never jumped off the sprocket.
Those guides are worth their weight in gold.
Neil

what neil says holds true. just this past weekend i TOTALLY shattered my rear bearings while in the revs in a creek bed and the chain didnt even think of jumping track.

[duffy924]

Sounds like a good idea, that works. I have done a little looking around and noticed that a lot of after market swing arms seem to come with the mount already welded on.

Thanks for the advise, it can't wait to try this out.

[Meat]

uhhh i just went through my first 250r chain derail fiasco. Finally got it all fixed up and I didnt pop off once today. About a two weeks ago was the first time the chain popped, the chain jammed around the front of the swingarm\front sprocket so damn tight I couldnt un-jam it. And I didnt have a 10mm to take the front sprocket off. So I walked about 2 miles to get home, in riding boots no less :( I got the quad home and found my stock POS axle nut was loose and my axle was wigglin' around throwing the chain, so I tighten everything up and head back out the following weekend and didnt get 2 miles out and the chain pops. This time the chain BROKE MY CASE SAVER and the boss on the case where the upper case saver bolt is located. Doesn't leak oil thank god. I couldnt beleive it broke my case saver. So I limp it back home and find out the swingarm bearings are loose as all hell. So I start the greasy job of replacing the swingarm bearings and I find... my swingarm is cracked right at the pivot tube. So... I bolted up a sweet Laeger swingarm I had waiting for this occassion and now everything works great. the Laegers swingarm has the Banshee style chain guide and the whole new swingarm seutp worked flawless today. I really got on the throttle hard and pitched the rear end around, and the chain stayed on all day long.

So get your jackstand out and plop the quad on it, and if something is a wigglin', then start a fixin'