I will be rebuilding my 01 mxz 700, the intake and exhaust were ported with race logic templates. I may shave the head 10. The ring gap has opened up a bit and compression is about 135 warm. This is my main trail sled riden around central Minnesota and western U.P. Here are my options for pistons and I was looking for some feed back.

A. Replace them with stock pistons

B. replace them with Wiseco's.

C. Replace them with a stock 670 H.O. piston/rings (cheapest so far).

D. Replace them with 670 H.O. Wiseco's.

I was also wondering if anyone has used the 670's with good luck? And do you use both rings? What did you gain or loose?

What is the differance between the 670 ho's/summit and the standard 670?

Thanks.

may I ask why cudneys piston kit is not an option?they are cheaper than doo's replacements also.I went with the stock pistons last year ,but only because I couldn't afford to wait,or should Isay I would not wait on them to get here as the dealer had them on the shelf.if I was to do it now I would buy bills stuff.I am thinking they were around $200-250 u.s. with pins and rings.

I have run Cudneys pistons for two seasons on a 00700. I have about 7k on them and I couldnt be happier. With his head and shim kit and some minor clutching it puts away f7s and runs with or walks most 800s.

The Ho piston is a flatop, the reg 670 has a domed piston. When doo made the HO it was supposed to be the ultimate 670, they switched to a flat top piston squeezing into a small chamber head. The regular 670 has a more open chamber and uses a domed piston. Ever since the HO, doo has chosen the HO style piston/ head on their twins. ( a whole new topic)

If your planning on using your stock head I would stay with flatops, either 700 pistons or HO's. At sealevel try to the squish at .070, .065 is flirting with trouble

I would not use the domed reg 670's with the stock head, the cudney/polar/jaws/mcb head is of a reg 670 design and is a better "match". You must shim the cyls when doing this and leave the squish quite big, the running compression is raised ALOT and the squish velocity is touchy.

How many miles on your stock pistons? what do the skirts measure? skirt wear?, do the knock when warmed up? did the rings pit

Another tip: if you don't want to fumble with the needles bearings, use '99 670 formulaZ bearings

135psi is not bad, don't freak when your ported cyl's show less when you get it back together.

I'd sure like to see a pic of what the 700 racelogic templates do? just to compare what I've been doing.