Really enjoyed your post Farmr123!!! Very good detailed information. I have already printed it out and put it with my repair manual. I am considering doing the same thing with my 350L only maybe I would add some port work and head machining.
Can anybody out there tell me if a 400 cylinder and head will bolt up to a 350 engine?
350's are rare and top end parts are becoming much harder to find, and performance heads etc. are not available for the 350.
I think most of the lower end is the same; is'nt it???
I know the 400 heads won't bolt onto the 350 cylinder without extensive machine work.
Does anyone have any experience or thoughts on the Swaintech coatings put on the piston face and skirt?????

Thank you
Doug

 

Talonhawk:
Yes I checked the torque. All was OK. I did it after the gas tank, but before the fenders were on. I was able to loosen the rear tank mounting bolts, and the fuel lines gave me just (barely) enough room to get at the bolts. I figured since they all stayed tight, I didn't need to mention re-torquing, but it is never a bad idea.

 

Well, I got the required 4 hours on the thing now. There is definately more 'oomph' than there was. Not a lot, but just enough to tell. I can't tell if I gained or lost any top speed yet, but time will tell. My brother has a 400 Xpress, and our machines run about as close to exactly the same top speed as possible, without being the same machine. That way I don't have to try to adjust for if I was going uphill or downhill, or the temperature, etc. Besides, I want to get another couple hours on it before I do any sustained full throttle runs with it.
Farmr

 

Waylon's motor specs before machine work :
Piston 3.256"
Cylinder 3.271"

I measured Farmer123's piston it measures 3.261"

Clearance on a freshly bored stock (without port work) cylinder is .003"

Standard bore on a new cylinder should be 3.268" although polaris cylinders can run a little bigger .

 

Thanks, Rick, for taking the time out to measure that for me. I didn't have anything here precise enough to do the measure myself.
Correct me if I am wrong, but by my calculations, there was at minumum .007 clearance, assuming that the cylinder had NO wear on it. Allowing for a little wear, I could assume I had .010 or more clearance, correct?
Thanks again for checking that out for me, and for helping me out with a few tips on what to watch for. Like I had mentioned on the phone, I had done some work on air-cooled 2 cycles (chain saws) and on 4 cycle engines of all types, but this was my first foray into the world of water-cooled 2 cycles. Your pointers helped me out, and my machine is running like a top.
Thanks again

Farmr

 

That is correct . Even on a perfect bore your clearance would have been at .007". I would suspect your cylinder was in the same condition as Waylons.