paul45
paul45
Anybody got a pair of pistons and rings for an overbore you want to part with? or does anyone know where I could order some.
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sherwin
XS650 Addict
Try Mikesxs.com, I think it's about 50 bucks per piston then another 30 bucks per set of rings.
The 707 is a 6 over, right? Since Mike's started selling the 750 kit's he doesn't sell the 6 overs any more.
Nope. 6 over is 76.5 mm. 77.5 mm. gets you 700 cc's. To figure what displacement 76.5 would yield, apply the formula for volume of a cylinder, using the 74 mm. stroke as the height.
paul45
paul45
Ya I see mikes 4th piston is 1mil over not a cc increase, more of a honing or piston slop fix. Punkskalar told me he had used wiseco ck194 pistons but they are not produced anymore. Now whether they are 6mil over I dont know but I beleive that 707 is about as far as you would want to bore a stock sleeve.
Punkskalar
Hugh's HandBuilt
The pistons I have are 3MM overbore. I've run this thing pretty hard, overheated it a few times, and the cylinders are still in great shape. I don't think I'd bore the stock liners any more than that though...
6 over would be 679cc's. Right? The 78 mm is 707 cc's and 10 over?
member3480
RICH
Have you tried MTC or JE
JE will make you a piston. I use them both for RACE motors but never asked if they had anything for XS. Will ask next time i call. MTC may make them too never asked. WISCO use to carry alot of pistons but in the last couple years there dealer book got thinner but they still may have some. I have used MIKES XS pistons and the only complaint is i don't like the clips. Someone should make buttons they last longer with heat.
MIKESXS 750 kit who makes that??? Here in US or overseas. I tripped over a JAPAN company that makes pistons and kits about 6 months ago have to look them back up see what they have.
I am looking for a kit for a CB550 and they use to be out there and so far only pistons found. Getting hard to find stuff.
JE will make you a piston. I use them both for RACE motors but never asked if they had anything for XS. Will ask next time i call. MTC may make them too never asked. WISCO use to carry alot of pistons but in the last couple years there dealer book got thinner but they still may have some. I have used MIKES XS pistons and the only complaint is i don't like the clips. Someone should make buttons they last longer with heat.
MIKESXS 750 kit who makes that??? Here in US or overseas. I tripped over a JAPAN company that makes pistons and kits about 6 months ago have to look them back up see what they have.
I am looking for a kit for a CB550 and they use to be out there and so far only pistons found. Getting hard to find stuff.
paul45
paul45
I guess the question is what is the maximum overbore on stock sleeves rather then the cc.
I thought punkskalar had 707 cc with his 3mm overbore but by your calcs it would have to be 6 over. Regardless what is that maximum overbore?
I thought punkskalar had 707 cc with his 3mm overbore but by your calcs it would have to be 6 over. Regardless what is that maximum overbore?
78mm is max bore and risky to some degree,if you're gonna push liner limits that thin might wanna opt for a ductile iron sleeve to reduce chances of liner distortion .
paul45
paul45
Your right about it being risky I dont want to get too crazy just want to bump it up a bit 6 - 7 mm over would be enough as long as I can find the right pistons
Punkskalar
Hugh's HandBuilt
6-7mm over ain't happenin' You wont even have liners left
3MM over is as far as you should go and still be on the safe side...
paul45
paul45
Ok I guess i was confused with xsleo sayin 707cc was 10 over. I suppose that can be done by changing the sleeves but what it boils down to is that 78mm or 3 over is the max for stock sleeves Ill let you guys debate the cc's
Paul45, in these pistons 1 oversize=0.25 mm.=0.010". In shop talk when someone says "It's bored 10 over" that doesn't mean 10 oversize steps, it means ten thousandths of an inch. The 10th oversize would be 77.5 mm.--an increase of 2.5 mm., or "100 over."
paul45
paul45
That is what I love about this forum guys like you clear up issues that dummys like me dont understand thanks a bunch!
Grizld1, you may be right on the shop talk. I did mean 10 over size steps. Each over size is .25 mm. 3 mm over size would be 3mm devided by .25 mm = 12 over. I think I miscalculated before. 77.5 would be 10 over.
My calculations were just the amount over size by .25 mm steps. I have no idea just how big you can go in stock sleeves.
Sorry if I caused any confusion. I was just trying to get things straight in my head.
I think Jack said it right. Both he and Grizld1 have much more knowledge on this than I.
My calculations were just the amount over size by .25 mm steps. I have no idea just how big you can go in stock sleeves.
Sorry if I caused any confusion. I was just trying to get things straight in my head.
I think Jack said it right. Both he and Grizld1 have much more knowledge on this than I.
wiseco have made them in the past, I've got a set in mine, from memory they are 78mm making 710cc, they also make the head gasket to suit the pistons, not sure what everybody is using for head gaskets with their kits, as I've seen lots of pistons for sale but very few head gaskets.
dwyatt
XS650 Addict
I like the JE 77.5 pistons. Well made and no problem with the overbore. Wouldn't want to go much bigger without new sleeves. Hoos Racing carries them. The ones I run bump the CR to 10-1/2:1, I added a thinner copper head gasket to get close to 11:1.
