Tranny Skipping

[turbo j]

I recently bought an 09 Apex MX90 Pro with very low hours on it. On our first ride it is bucking like the chain is skipping a tooth or something.

I took the tranny apart last night and all of the gears look perfect.

The previous owner replaced the stock slipper sprocket with a solid one that had been machined down to fit into the case saver.

All of the sprockets and chain look to be in really good condition and the chain tension is right.

It seemed like there was a little bit of wiggle in the whole rear clutch assembly so I pulled the cover off of my DRR70 and it has the same amount of play.

Any ideas here?

[RichC]

The gears that are pressed on the shaft are probably slipping. You can weld them, if your a good welder, or have them welded. Mainly it the output one(one the sprocket goes on). If you want to make sure, use a sharpie and mark it to see if it slips.

[selbygirl]

one of the teeth on your tranny gear my be bent , we had one do that years ago , and the gear with the shaft going to the sproket may be bent had that happen also . and check your chain you may have a few stiff links .

[fomospede]

are the sprockets lined up from front to rear maybe its climbing on the sprockets?
ther would be wear on the sprocket face possibly
do i know you? :D

Take the chain off and remove all the cvt cover bolt's. Leave the cvt cover on and have some one hold the rear and front, and then start it up. Remove the cvt cover very carefully. Then take a look at the unit working listen and maybe you can identifie were the culprit is. Hope it help I've had success in the past.:cool:

[selbygirl]

THE WAY I FIGURED OUT THE PROBLEM WITH THE TRANNY GEARS . I TOOK THE TRANNY COVER OFF AND THE CHAIN TURNED THE GEARS BY HAND THERE WAS A STIFF SPOT SO I MARKED IT WITH A MARKER DID IT A COUPLE OF TIMES WITH COVER ON AND OFF IT HIT THE SAME SPOT EVER TIME THAT I MARKED WITH A MARKER, TO BE ON THE SAVE SIDE I WOULD DO A TRANNY REBUILD , IT MAY SAVE YOU MONEY IN THE LONG RUN .PLUS THE NEEDLE BEARINGS GO BAD IN THER ALSO , A BLOWN TRANNY CAN MESS UP A ENGINE CASE$$$$$$$$$$$

[turbo j]

Thanks for the replies. I will try these things tomorrow. This motor has very little run time so I really don't think its a tranny issue. The previous owner replaced the front sprocket with a different used one prior to me picking it up. He did not run it all prior to me picking it up that night. this issue did not show up during the kids test ride around the guy's yard.

I'll report what I find...:cool:

[turbo j]

So I got it all back together and then started looking at the chain drive more.

The issue is that the chain was too loose. I thought that would not be an issue with the STR chain tensioner that is on it but it was. The thing is the rear suspension geometry allows the chain to go real loose in the last 30% of downward travel. There are slight grooves warn into the frame above the chain near the front sprocket so I will have to rig some sort of guard for that.

So now with the chain tightened it does not skip anymore!!!

[fomospede]

Turbo
this is why we dropped the engine in the rear on carters Drr
im not sure if the apex's are the same but it really helped out keeping the tension correct when putting more power to the ground
also ive noticed small sprockets promote the chain sliding

see you guys soon!

[rd2005]

Do what Rich C said all mine are welded and yes the chain can cause it to seem like there is an issue been there done that also when you take the trani gears out always replace them all if you have one not wearing correct and you replace one it will not wear correct and could break a tooth or even break the case hope this helps.

[TTracer#22]

Is it slipping with you on it or with your son riding it? The reason I ask is with the weight of an adult on one of these mini's the chain will jump teeth.

[turbo j]

That's exactly what it was. the rear suspension geometry makes the chain go pretty loose at full compression. I am going to be looking at making the aftermarket chain tensioner work even better for next season.

[tyler70t]

Pick up a ZTR frame saver, the chain won't hit the frame anymore. They don't last forever but they do work

[tyler70t]

Pick up a ZTR frame saver, the chain won't hit the frame anymore. They don't last forever but they do work