Thank you OPT, I drained the oil and it came out clean, I think I only ran it for about 3 hours the since it was changed before I tore it all down. I put in a quart of the engine cleaner and sloshed it around the bottom end pretty vigorously dumped it and poured oil on the cam, crank and rods and sloshed it around a little more and cleaned out what I could reach with a rag around the inside of the block and the rods too.


I got a call from the machine shop and they said the bores looked perfect nothing was twisted or out of spec however the bore size is a thousandth over 80mm so it came to 3.1505 so I was trying to do the math to figure out what size pistons to order from Namura and after my calculations the piston kits are too big for the bore unless my math is wrong. I subtracted the piston clearance and it comes to 79.0067 plus or minus .015 so at most the size would be 79.3877. The Namura A, B, & C kits are larger than that? Am I doing adding this wrong?

 

Order the A kit. Ktm did the same thing for wear on the Nikasil plated cylinders. Very little difference on the A piston versus stock dimensions and clearances. Must not have had a really hard life or really low miles. Stock piston is 79.954 +/ .003mm so the A piston shown at 79.95 mm should be just fine.

 

Thanks OPT, I don't think it had a hard life at all! I bought it off a farmer in 2011 a few miles northwest of Milwaukee out in the country, never mentioned that it ate coolant though until I noticed it and started doing my research with the head bolt issue from the factory. It only has 700 some odd miles on it. I was just thinking if the A is the same as stock and the bore is a thousandth over without being honed yet wouldn't that put me at 79.97mm? I thought a thousandth is .025mm? Won't the honing process take off a couple more ten-thousandths off? I remember seeing the thread but I haven't been able to find it again


Definitely noticed the carb must have been rebuilt before since some of the screws holding the top plate and the bowl were somewhat stripped on the phillips head. Do you happen to know what I can soak the parts in for a few days? It seems like it would take me 5 cans of carb cleaner to get all the crap out of it. I'm assuming new screws for the outside of the carb don't come with the kit

 

In honing a Nikasil cylinder all you're doing is just breaking the old glaze so the new rings are able to seat easily. As far as taking any "meat" away from the cylinders,no you're not.

 

If in doubt you can go with the "B" Namura as it's only half a thousandths larger than the A. 79.96. Either one will work. The B may take an easier break in period and be sure to check ring end gap.

 

Thanks OPT, I ended up ordering the B kit after seeing your post. I was able to get the new oil and water seals installed on the magneto side of the machine along with the new pump impeller and gasket. Are there any tricks to figure out the proper ring gap while using a feeler gauge besides top, middle, and bottom of the cylinder? I did notice a bit of play on the u-joint under the rear of the tranny while working on it last night. Is it the same 338 part number that some of the side by sides use? I can't seem to find the thread that has all of the auto part conversions for this machine.

 

No tricks,just look at the manual on checking ring end gap and in the specs for the clearances allowed. Napa 338 is the same u-joint crossover on most of Polaris prop shafts. Here's the list you might be looking for on cross over parts.

 

Awesome great thanks OPT! I have a thing of gunk radiator cleaner too. I don't know if anything was caked on the inside of the radiator but since I'm at it would it be okay to use that with new gaskets and seals at the same time of starting up the engine for the first time?


I'm going to rebuild my carb today too however there was a lot of carbon built up on the pistons and the cylinder head when I took it all apart so would it be appropriate to move up the e-clip one notch to a leaner setting?

 

I wouldn't use any radiator cleaner additive to the coolant. Carbon build up on piston crowns is normal,I would mess with the clip position as this doesn't have that much to do with that. Worn need valves and seats,float level off are the biggest culprits on running rich. That should be taken care of with a good carb kit.
Shindy in Japan makes the best carbs kits. Wouldn't trust any of the Chinese stuff out there.Shindy Carburetor Repair Rebuild Kit-Sportsman 700 2002 2003 2004 2005 2006 Carb | eBay

 

Ok great, that's the kit I have