Replacing trans crankcase seal

[BrandonH]

So you guys were right, that's why I come here for advice. You guys are pro's.

A month ago I made a post about a blaster I just bought with a Toomey B1 exhaust, and with a 310 jet it wouldn't run for crap, and ran much better with a 280. Haven't rode it but around the yard a few times. You guys said probably a leaky trans seal.

Today after messing with it, I fired it up, went to put it in gear and it grabs hard and stalls out. So you guys are correct.

My question is can I replace the seal with the engine still in the bike? I replaced the one on my other blaster but the engine was out of it. I really don't want to pull it unles I have to.

 

[speedyslyder]

grabbing hard and stalling is either it is not warmed up enough/needs oil change or clutch adjustment and or clutch.
you dont need to split cases to install seal/but take clutch apart

 

[BrandonH]

Reason I think it's the seal leaking is because of having to run a smaller jet. Last time I ran the bike it shifted fine. Clutch adjustment never changed. Now when I went to ride it if u pull up on the shifter to grab first you can feel the gears catching. I bet the fluid got low enough and the clutch is dragging. Plus it's been hard to start cold

 

[BrandonH]

I know i should throw my leak down tester on it but if I have to pull this carb one my time.... I feel better knowing its rich and not lean.

 

[speedyslyder]

okay
drain the gear oil and measure it
alot of quads bikes slam into first gear once in awhile===even on pro tv races lol
you got 66 post read buddy everything has been written

 

[jus_me]

Pull carb and leak test or possibly do a rebuild. << don't mean to be harsh but it is what it is. If you think its a bad seal trans side than fix it now before it gets real expensive and/or leaves you stranded.. Not hard to do with motor on the bike. Leak test will tell.

Also an air leak would require a larger main jet and not smaller in most circumstances. A larger main jet to compensate for the xtra air the engine is sucking in. It may seam that a smaller main jet lets it run better because of the trans oil it is sucking in and the motor is trying to burn it off. It would be hard for a properly jetted bike pulling in trans oil/not yet air to run properly sucking in trans oil thus wanting xtra air/smaller main to compensate for the added fluid so to speak.. Use up all the trans oil and it would be pulling xtra air, then creating an xtra lean condition because you dropped the main jet size already. All in all pull the carb and leak test already.

Is it smoking allot?

Remember the smaller the jet the leaner it is, the larger the jet the richer it is.

 

[Larry's Shee]

In all reality, anyone who doesn't know how old the crank seals are should just replace them. It costs about $20 for both. Simple, easy, cheap peice of mind = priceless.
Once it finishes drinking up all the trans fluid it will easily go into auto ignition/runaway. When that happens, you will soil your shorts, and the only way to kill it is smother the carb, rip carb off, slam in gear with brakes on to stall, or hope it runs out of gas before it melts (highly unlikely).
The key or kill switch WILL NOT work. The spark plug has heated to the point it is just like a glo plug on an RC car.

When I first read "trans seal" I thought of the output shaft/sprocket seal.
Opinions vary on leaktesting. I settle for less than half pound loss in 10 minutes, much happier if I detect no loss at all.

Now to answer your Q, all seals can be replaced while engine is in frame. When doing right side clean crank and collar oil free and seal to crank with 3Bond, Yammabond, or simular. Smear a little bit inside collar, then install.

As mentioned, do a leak test again, don't settle for "It only lost two pounds in six minutes" WTF? That's 30% !!

Another thing, warm the bike till the cylinder feels warm to touch, no matter the weather. While it's warming, work the clutch lever several times, helps to get oil between plates, easier to put in gear, less wear on trans and clutch.

 

[BrandonH]

thanks for the advice, at least I know it can be done with it in the quad now. I have done them before but the motor was out. I will throw my leak down tester on it. I have never had any bike grab into gear hard enough to stall on any of the bikes I have ever owned. In this case I had the engine warming up for at least 3 minutes before I got on it

I have Yamabond and a spare seal already sitting around, just need the case cover gasket and I will give it a shot. The sealant on that collar is a good tip everyone needs to know, on my last rebuild I did a leak down before starting and the leak was between the collar and crank. A little Yamabond cleared that up.