I know alot of you are doing 720's that consist of using a sleeve. My question is, can the stock cylinder handle a larger bore and re-niked and if so how large of a piston can I get to fit this application.

JMiller

 

102 seems to work ok

 

I think you can go up to a 103.

I have a 102mm bore (stock is 100mm). It is a strong bike (especially with a race head (similar to Ron Wood stage III).

The 720 with the same head work is stronger on the hill. But, I think it becomes more of a weight issue at that point. If you weigh 175 and you're on a 680 and you go up against a 225 lb. guy on a 720 you will take him up a hill (Nothing positive or negative about either engine just that weight is an issue. . . )

Things to consider before doing this modification - head gasket / head seal - the 680 has had NO issues, the 720's seem to have their issues worked out - just talk with the right people before doing the job.)
How much extra power do I want - again, the 720 (105mm bore) is more powerful (I would guess about 3-4 HP???)

What kind of cams are you looking to put on?

 

Thanks for the info. After talking with both TheBom and Mr.Horsepower I've decided to go with Mr.Horsepower's newly designed 16:1 piston and A1/A2 cams on alky. Porting and larger valves will have to wait until I get a raise or I win the lottery. The 16:1 piston will support .450 lift cams as will the newly designed 14:1.

JMiller

 

I have the A1/A2 cams and LOVE THEM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

i would love more then the 11.5 piston but I have to run pump gas still...

 

Jay dude, YOU SUCK!...LOL

Gotta beat me to the punch dont ya???

Should have come out to the atv rodeo bro...great time there. About 51 bikes showed up and I ended up taking second again..[img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img]

 

I'm tired of getting sand thrown all over me. I think thats why I'm going bald....to many people are sand blasting my hair folicles right off my head. It's time for a change...and no I'm not talking about a wig.

I bet the rodeo was a good time. Good job on 2nd place. What/who took first? Next year I'm going to attend more events around the country.

JMiller

 

hEY JAY, ARE YOU GOIN TO ST JOE YTHIS WEEKEND? EMAIL ME AND LET ME KNOW