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Discussion Starter #1
Ok. I have a 2002 zr800efi. Recent top end rebuild with oem (spi) pistons. Factory cylinders and uncut heads. Cases have never been touched. I did a squish test with two pieces of solder along the wrist pin and came out with .105" in both cylinders. Thought i screwed up so i had my father in law check it. Came out the same. Factory spec is .063 min. Ive heard they can come from the factory with .080, but .105 seems like an aweful lot. Anyone else have one of these that are way out of spec? How can this be? Is it possible that Cat screwed the pooch when they machined the cases? I can whack .035 off the heads and thatll get me down to .070 dont really want to go that route though.....just dont know what else to do! Any help would be greatly appreciated! Thanks!
 

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The problem may very well be its because you don't have Cat pistons in it. If you cut the heads and someone runs the Cat pistons the next time around they will have problems most likely.
 

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Discussion Starter #6
Dont know the size of the solder. I actually had to take two pieces and twist them together to get a measurement. Factory base gasket.
 

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My buddy has the same sled with an extra set of cat pistons and they are the exact same!
The distance from the wrist pin to the top of the piston is different between the Cat and the SPI pistons on some models is what I am saying. Sounds like yours may be one of them. Especially if you have factory base gaskets. There was a thread on building a 1004 and this was mentioned.
 

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The distance from the wrist pin to the top of the piston is different between the Cat and the SPI pistons on some models is what I am saying. Sounds like yours may be one of them. Especially if you have factory base gaskets. There was a thread on building a 1004 and this was mentioned.
Your thinking is right but not lol your thinking if using the zr 700 pistons in a tcat cylinder which, which qouldnt really apply here. Using a piston made for a longer stroke in a shorter stroke that is kinda normal. I think u might be thinking of the dome shape being slightly different. By the way I'm making a 1004 with wiseco pistons they should be in tomorrow ill let u know how it goes, gonna pick up some tcat pipes next week.
 

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Seems to me I remember reading on here somewhere that the domes are different from manufacturer to manufacturer. Yes, I am thinking of the 1004 pistons too, but the domes do vary and depending on where -center or edge- of the piston its being measured may make a difference.

What kind of pipes you getting?
 

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Just stock pipes and can for now, its cheap enough 150 for everything. and I'm sure will be better than the stock 800 pipes. Yeah dome shapes do differ from each manufacturer. Like with wiseco I probably have to run premium. But gonna check squish and see where its at, might double base gaskets and check again, and see what port timing is at. Done it on bikes with gains and no problems
 

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800 and 1000 pipes are the same aren't they? What year is it?
 
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