Crank Seal Out?? My Kettle is drinking transmission oil

[kettle750gt]

Hey Guys..
I have a 72 750.. Only had it about 6 months..
Was not much to get it running.. carbs, battery, fluids.. easy stuff
Then I added pod filters, Jemco chambers, and upped the jets
It ran great, but smoked heavily from the right pipe, so I thought the right crank seal was going out.
I kept a close watch on the transmission fluid/oil level and after 500 miles I had seen no drop in the level.
So I thought it would be safe to take it on a longer trip.. 400 miles round trip
I was wrong.
The bike ran great TO my destination, but the trip home was a different story.
Halfway back I lost a great deal of horsepower and really had to throttle it to even go 55mph
And the amount of smoke I was putting out was unbelievable.. like a crop duster(literally)
Additionally, when I stopped to change the plugs, I re-checked the transmission level.
It was almost empty. (Crank seal right?) I added fluid and continued to hobble it home..
No increase in horsepower after changing the plugs. still smoking like a steam engine..

I finally did make it home, and after it cooled I pulled the stator cover, expecting oil to be everywhere.. no oil splatter
The housing was bone dry.. so obviously the right crank seal is not out.. great! now what?

I tested compression on the:
right cylinder: approximately 94 lbs
left cylinder: approximately 91 lbs
center cylinder: no compression (obviously a hole in the center piston)

Thats all of the details so far.. any help will be greatly appreciated..

Thanks, Rian

[tz375]

Sounded like the inner seal on the right crank until you mentioned the lack of compression on the center pot. Now it sounds more like a holed piston or blown gasket as well.

Pop the head off first and take a peek inside. If the piston is holed, the motor has to be stripped to clean out the crank, so maybe a good time to get the crank seals replaced by Bill Bune or your favorite crank builder.

Before you strip it (or remove the head), you should do a leakdown test on all three cylinders. Don't worry about the actual leakdown percentages or PSI for so many minutes. Just use a hand pump and adapter onto the hose from your compression tester and listen for where the air is leaking. If you can get it to 10psi great but I suspect it will leak out faster than you can push air in.

90-94psi is also rather low if you tested a warm motor with the carbs wide open. I'd expect to see 120 ish on a good stock motor.