Counter shaft sprocket seal leak.

I've checked the search function but did not
find this question.

Is there an inherent flaw or weakness with the 610 (and family)
C/S sprocket seal or bore or?

I'm a under 2500 miles and now have a drip (overnight leak).

Check chain tension, too tight a chain will pull hard on the countershaft on hard hits to the rear suspension.

every brand bike i have owned has leaked oil from the countershaft seal.

There is a spacer behind the countershaft sprocket and the very inside has a groove that holds an o-ring. Replace the o-ring and you should be good although you could replace the spacer as well.

Thanks OldHuskyRider, I did adjust the chain as close as I could to the horrible directions in the owners manual. I guess it's like a KTM a little lose is better than a little tight.

Joedirt, do you mean every husky has leaked from the C/S seal or all makes?

Thanks Rancher1, I plane to lay the bike on it's side tonight and pull the C/S sprocket.

I've owned several hondas and yamahas. They all leaked.

I'll post something after I get the old seal out. Maybe someone will see something I don't.

I have a 310r and the only oil leak is in the grommet where the stator wires come out of the left side cover; and is a known issue (I haven't even fixed it yet). In fact, the only bike I had that I can remember leaking at the CS seal was my shovelhead; and which didn't leak too bad for a shovel... AND the counter shaft was inside the main shaft.

Actually, I gotta say: there is very little downside to running a chain too loose; but even a tiny bit tight puts tremendous forces on the case during suspension travel. Remember, all the delivered power goes through the counter shaft (and thus the bearing and case that supports it)- you do not wanna add to this load.

Compress the rear suspension (a ratcheting tie-down makes it easy) until the rear axle, swing arm pivot, and the counter shaft are all in line- this is the point of maximum chain tightness. Adjust the chain so it can be deflected a little (I dunno- maybe 3/4"). Your chain is now perfectly adjusted (mud riding? give it more slack). Measure the "at rest" chain tension and adjust to that point from here on out. It ain't rocket surgery. hell, your seal may even stop leaking.

KTM had a problem about 10-15 years ago (?) with the small 2-strokes. When the chain was tightened to factory specs, cases developed stress cracks and even failures IIRC- the leaking CS seal caused by this was just an annoyance by comparison. Keep your chain loose (IOW: adjusted correctly) and avoid seal failures. Factories can be wrong; you don't have to be.

What are the specs for the CTS bikes? (my kid has a 511, but I forget what the tension was. nothing unreasonable IIRC)- use that as a "compressed tension" guide.

Of course, none of this may have any bearing (hah) on the seal leak. It could be just a bad seal or rancher1's o-ring.

good luck.

Thanks for the procedure TC85.
Since I'm the second owner (1st only put 2400 miles on it), I am hoping that
the damage hasn't been done already.

I agree with loose being better than tight (except maybe some of the Japanese bikes I hear).

The countershaft seals on several of my bikes have all leaked ,after a good season if they lasted a season, of riding in the conditions we have for our off road competitions in the East Coast Enduro Association . That would be the Northeast area of the USA .The combination of mud/sand especially our clay mixed in with the any sand , will get behind that counter shaft sprocket and just slowly grind that spacer down to the point it won't seal as well . Some have even tried 2 O-rings instead of 1 in an attempt to stop the leak . Others have decided as long as the bike doesn't lay on the side they'll just check the trans/motor (2 &4st) oil more frequently and don't bother with fixing it. My personal experience change O-rings and spacer/bushing when the time comes , sometimes you can polish the grooves out if their not too bad (maybe once or twice before changing). I like to look at things like this , if oil is leaking out then water or worse can eventually make its way in the same way .

Joe,

I've only had one bike that leaked at the CS. Yamaha WR426

I changed all the seals and spacers and it still leaked.

I later found out that the crankcase breather hose was riding on top of my E-line skid plate and was clogging with mud and the crankcase pressure keep rising till it pushed out the countershaft seal.


Make sure your breathers are clear.

wow... that's a great idea for 4-strokes! And simple also- two of my favorite characteristics.