jetski9010

My friend and I are swaping a tigershark 770 motor into a kawasaki 650sx. The stock exhaust is not going to be able to fit into the hull so we are going to have to make a custom set up. I am going to get an adapter plate made to let us bolt on an exhaust from a stand up jet ski. Here is my question. He had a westcoast exhaust will all the rings still on the pipe on his 650sx motor. We are thinking of saving some money and making that pipe fit the 770 motor. Would that pipe work as far as the expansion chamber not being to small and over heating the motor. The other option is we fit a factory B pipe with a limited chamber on there. I know the superjet guys are running these pipes all the way up to 1000cc engines. What do you guys think?

dank

I would use the pipe for the factory B pipe over the westcoast 650.

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jetski9010

I am going to go with the factory B pipe off a superjet. Thanks

Krispy

I am just subscribing to this thread.

Here is a computer program used for pipe design, These 2 strokes are black magic, I don't think I have the balls to try a custom pipe setup

Best of luck!

Attached Files

pipe_dsn.zip (1.44 MB, 2 views)

jetski9010

What RPM do the 770's pull stock? Where is the rev limiter set at?

Krispy

mine usually runs about 6600, with my shaved head and tuned carbs I am hoping to bump the 7100 rpm limiter

jetski9010

What compression are you running at with your shaved head. I am trying to get around 180psi with a squish of around .045-.050 did you just shave the head down or did you have to recut the domes?

Krispy

I just removed .025, but you must be careful, all 770 heads are not created equal, the older ones (pre 97) can be shaved more than the newer ones. I targeted combustion chamber volumes of around 35cc's. Once again my head shave was mild, I just brought my older head up to the newer spec.

Also, 180 psi on your engine might not be 180 psi on my engine. The condtion of the top end will cause those readings to change.

My uncorrected compression ratio started about 6.8:1 after milling the head I increased it to 7.1:1. Keep in mind the uncorrected compression ratio doesn't take into effect any gas dynamics that makes a 2 stroke work. I would guess that the pressure pulses would make for an actual compression ratio that is 15-20% higher than what is calculated geometrically.

I will be making a thread on shaved heads in the next couple of weeks. I have just finished my rebuild and only have about .5 hours on the engine, still havn't gotten the carbs tweaked in yet either.