750 kawi engine advice

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Coreyf983

Location
Minneapolis, MN
Here's what I have...

I have a 750 big pin, it threw a rod.

As best as I can tell from looking/feeling, the crank is still good. The top crank case is also unharmed, and all mating surfaces good. The bottom tabs on one of the cylinders were messed up, but again, only the cylinders. One piston and one rod is fine, the other rod obviously snapped and the piston where it mounts is bad. The head is fine.

Basically, I need new cylinders and bottom crank case half (assuming the crank is balanced, I WILL be doing that).

No, onto the question...

I do not like the port timing on the big pin, and would like to not use the big pin cylinders if all possible. I read up a bit on putting small pin cylinders on it, and also SXR cylinders...

Whats the way to go? and whats the least expensive (not saying im going that rout)? What about just modding the ports on a big pin cylinder? Thanks a ton.
-Corey
 
MTRHEAD

MTRHEAD

Location
MotorCity
SXR cylinder is a like a modified SX cylinder...lower exhaust port timing like a 93' with better boost and rear transfers than any Kawasaki twin cylinder.
But when in search of more power the exhaust port is way too low....

You Big Pin, assuming its an SXI, cylinder is a great start if you widen the exhaust port...you can also run a .010 base gasket to pick up a touch of low end and reduce the squish.

Beware, the best setup SXR limited's use the Sxi bigpin cylinder with a spacer to LIFT them even more...and they hit hard and get the boat to 60mph.

Be careful not to get rid of something you'll regret.

Also all pre 03' cylinders cant go much beyond 83mm where the SXR cylinder 'can' go to 85.5mm
 
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Coreyf983

Location
Minneapolis, MN
ok, so I just pulled one of the biggest "duh" moments in my life.... Yeah the crank is good, but it now has one 'half rod'...

now.... does anyone put rods on? or do I have to pay for a full rebuild?
 
MTRHEAD

MTRHEAD

Location
MotorCity
Crankworks can put a rod on it if thats all it needs...crankworks.com
I would do the front and rear bearings while I was at it and replace the other rod bearing.

Also lots of sled shops in your area will do watercraft cranks.



Rebuild isn't that expensive
 
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Coreyf983

Location
Minneapolis, MN
I will get it all inspected professionally, but I am fairly sure that this engine has less than a few tanks run through it, and woman owned. the bearings look immaculate. I will get them all checked out during the rebuild. Thanks for the help!
 
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