The Bullet Board

I see that S&S is coming out with a big bore kit for the 650's. They are talking about re-sleeving the cylinder. Is that really necessary? All I have ever done is send the cylinder and the piston I intend to use to the machine shop and done. No sleeve swap required. I got a couple thousand miles out of my G5 with zero issues, my cylinder was bored at Napa Auto Parts. $20 LOL No special gig no blah blah blah.

It really makes me wonder how much of this stuff is big flashy lights. I mean it's one thing if you're building a bike you run every weekend. But will the average or even above average rider know the difference between the sleeves?

I hear ya.... very few people will do it and spend the money I figure. But to bore something THAT much over stock, you would have to put in in larger sleeves . There would be nothing left of the stock sleeves after it's machined. To do what they are doing, they have to press out the stock sleeves. Machine the sleeves openings MUCH larger, then press in wider sleeves for the bigger pistons. You can only re-bore and re-hone stock sleeves so much.... you have to leave some wall thickness on the stock sleeves. For instance, with the UCE's 500's.... you only have enough sleeve thickness to over bore to a 535-540 cc sized piston.

That would just be the beginning with those massive slugs. ... the compression ratio would likely sky rocket , with the stock sized combustion chamber . So that might mean head work... or Cams with MUCH longer duration or both and etc and etc..

I get it, the number didn't really register when I typed it, 865 does seem like a lot.

This is probably a Pandora's box but how does HMC get to 612 with there 612 kit?

The change the stroke length and the bore a bit I Imagine. A longer stroke inside the piston bore will give more swept volume. To do that though, one would need a new or modified crank shaft. And a piston and a cylinder and etc. And it would rev slow.

I came pretty close to buying a new "Int" last Spring. I had a deposit on a chrome one, then chrome got delayed until August...

If I had gotten it, I wanted to get the 865 kit ASAP. The funny thing is, I already have an 865 Bonnie that's pretty well sorted, so I just couldn't see the sense of it, with cost of bike, 865 kit, maybe cams, throttle body, and time put in... I'd still like to do it, but can't sell Bonnie and I can't see having both:(

I also found that there is a sweet "904 cc big bore kit" for my Bonnie which was about $1,000.00. Gives a little more hp and a lot more torque. I think the main ingredient of the kit was increased compression pistons.

The testimonies I read were all very positive. I wanted that for Christmas, but it didn't happen. Btw, to go over 904 cc with Hinkley (air cooled) engine required stroking the crank. I bet that got 'Ol Bilford's attention, lol!

Now, maybe if I had both bikes and "big bored" them... I should probably get a better helmet first, ha ha!

Be cool project Narada .... Just sayin'. Did you price the kit with machining ? Might be worth it down the road if you can score a used bike at a good price?

Narada wrote: ↑Tue Jan 28, 2020 7:55 pm I also found that there is a sweet "904 cc big bore kit" for my Bonnie which was about $1,000.00. Gives a little more hp and a lot more torque. I think the main ingredient of the kit was increased compression pistons.

The testimonies I read were all very positive. I wanted that for Christmas, but it didn't happen. Btw, to go over 904 cc with Hinkley (air cooled) engine required stroking the crank. I bet that got 'Ol Bilford's attention, lol!

Now, maybe if I had both bikes and "big bored" them... I should probably get a better helmet first, ha ha!

It did in more ways than one!!

Hi there,
New to the board.
I too have been drooling over the S&S 865 bore kit.
I'm sure it'd require a remap of the ECU, bigger injectors, the cam upgrade (maybe port the head) and a beefier clutch.....already have upgraded exhaust and DNA air filter.
Then, upgrade the suspension with the Ohlins kit and regear it for better top end......
Sigh, can't pour that much money into it, have too many bikes and 4x4s and I'm sure the Mrs wouldn't be happy
Hans

Oatmeal wrote: ↑Sun Mar 01, 2020 4:52 am Hi there,
New to the board.
I too have been drooling over the S&S 865 bore kit.
I'm sure it'd require a remap of the ECU, bigger injectors, the cam upgrade (maybe port the head) and a beefier clutch.....already have upgraded exhaust and DNA air filter.
Then, upgrade the suspension with the Ohlins kit and regear it for better top end......
Sigh, can't pour that much money into it, have too many bikes and 4x4s and I'm sure the Mrs wouldn't be happy
Hans

To me Ohlins is synonymous with BMW and Hagon with British bikes. I am sure they both have their pros and cons, what does one do better than the other?