Big Bore Kit
 

Hi,

New to the group and am planning a "project" bike. I'd like a bit more grunt that standard but don't want to go the inline 4 route. Ducs are OK but exorbitant where I live and a bit down on power at smaller capacities.

Has anyone out there bored their motor to 700cc? :idea: Anyone fitted cams? I'm thinking Yoishimura. Then a high mount exhaust. Yoshi or Akropovic? but I'm open to suggestions.

The rest of the stuff. Supension etc. I think I can get help locally as others modify their track bikes.

I'm looking forward to it. Oh have to find the donor bike first.

NSR Mike

http://www.jhsracing.co.uk/
These guys sell big bore kits, high compression kits, cams, new con rods the lot. If your that way inclined to modify your engine :)

Dan

Re: Big Bore Kit
 

sv1000 ?
http://forums.sv650.org/viewtopic.php?t=24078 :wink:

Cheers,

That's a bit more than I was thinking but good site for ideas. I was thinking Wisco 694cc Kit, reboring easy, and replace cams while motor is apart. All more or less bolt on stuff. I don't really have facilities for non bolt on modifications as I do it in the spare bedroom!! It's too hot outside.

Mike

you dont need to go for expensive cams if you want an upgrade, use the intake cam from a K3 bike on the intake and the intake cam from the curvy model on the exhaust side, this is good for more power (as the intakes have more lift and duration than the exhaust cam)

you can buy yoshi cams, but when oe suzuki ones cost a third of the price why not use them?

How about getting a SV 1000 and put 650 stickers on it... :?: :lol:

That'd be the cheapest option yet I think... :lol:

Welcome to the site BTW :wink:

My mate and I have done a bit of tuning, his bike has the JHS 700cc kit. There isn't a lot of difference top end, I have the dyno sheet but need to upload it, so will do this over the weekend and post it here next week. Mine has full Akro system, ignition advancer, K&N/DJ kit with dyno setup, his also has JHS 700cc kit and stage II cams on top. Top end of his is about 80bhp but wait till you see the torque curve.

For cams, I did the K3 intake swap, with the old intake going into the exhaust, as Weegaz mentioned. £200 including all gaskets and you can do it yourself if you're at all competent. You get no easy adjustability, though. JHS, Yoshi and Megacycle all do stage 2 cam sets and all are better options from a performance point of view, from what I've seen, but the difference in price is out of proportion to the difference in performance, so to me none of those options makes much sense.

Personally- and this is personally, not facts or proven experience- I don't think the 700cc kit on an SV is a very sound move if you want the engine to last. The bottom end's perfectly capable of dealing with some tuning but with the big-bore you're adding both a bigger bang and more moving weight. Puts a fair amount of stress on the 650's weak spot, the crank. I looked at doing it for a long time since if you've got the neccesary supporting mods to get the best out of it- intake and exhaust mods- it can give excellent results. But right now I'm looking elsewhere, since the engine gets enough abuse as it is.

I'd really like to hear from someone who's done the 13:1 or 13.5:1 JE high comp pistons mod- seems ideal for our purposes (though apparently the pistons are again heavier than stock) but it's not a widely tested option from what I can tell. Sv Rider guys seem very against it, but that seems to be kneejerk, since none of them have actually tried it. There's just an assumption that 13:1 is too high.

Another option, and a lot tamer, is to use Hayabusa pistons. You need to get the barrels honed since there's marginal differences in spec but for this you get lighter pistons, and you can deck the heads/use thinner gaskets in order to boost the compression a little too. But it's just as much work for less results, albeit with an excellent long-term prognosis.

Ooops sorry,took a wrong turn somewhere! Normally I associate bike leathers with speed hump as a "big bore's kit" ok ok I'm on me way! :lol: :lol: 8)