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thouk

680 kit and Stage II cam

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Hey All,

I am going to go to the 680 kit on my 650R. I want to use the weisco piston 11 to 1 with the stage II cam. Will the piston and cam work? Can I use pump gas with this combo? I have my bike dual sported and I need gas on the road. Thanks for the advice. Tony

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I have a 680 kit with a weisco 11:1 piston. I can't use 91 octane gas if it old at all. I haven't used it with pump gas lately, I was planning on trying it again but, it pinged, bad. Weisco makes a 10.25:1 102.4mm (680cc) piston. The difference in Horsepower between the two pistons is almost nill. It's more how the bike come's on that makes the difference. If I do another 680cc BRP it won't be with the steel sleeve. I will go with the thicker Nikasil cylinder. I mix 20% Vp 110 with pump gas or 50/50 aviation fuel/pump gas.

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I just finished riding a week in Baja with the exact setup you're talking about. The piston and stage II cam bolted right in with no clearance issues- but you should clay-check your piston-to-valve clearances~ they were pretty close to the specs. I ran premium pump gas all week, even Pemex. No pinging, overheating or anything. This motor is awesome. No dyno numbers, but it feels MUCH faster than my buddy's 650 with an 11:1 J&E piston and stage I cam. We both have Barnum's exhaust , Edelbrock carbs (not over-bored), and cut side-panels.

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