Suzuki 2 Strokes

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

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.