650 tweaking stroking destroking fun

my goal in this thread is just to THEORIZE some 650 building, I want it to entertain stroking de-stroking boring honing..... the works. I am building a 650 and am trying to solidify some more work for the future. I have ready for this season but am doing some more work when I head to wyotech for motorcycle tech and will have access to a dyno, I'm thinking of either a 710 with really high compression (11.5-1) or an 810 with some port work and such.
Anyway I would love to here you guy's ideas and experiences. here is what I have done so far it's not mych but it's a start right?

Mac 4-1 (it was free don't really like it)
jetted the carbs
gpz cams
dyna s
dyna coils

like I said not much but I'm planning alot more...

Has anyone here built a 650 stroker? or destroker (sounds like fun)
also has anyone pushed the compression limit?

I understand alot of the of the problems associated with high performance building (especialy on OLD bikes) but I enjoy building things for education and just plain street fun.

Lets here your ideas

I have done a lot of research on the 650 this last winter. First off there are virtually no crank options and no one really knows what rods can be used aside form factory parts, I am sure there are rods that could be used but it is not a well known subject. So as far as changing the stroke, though possible, it won't be easy. The Wiseco piston sets are top notch, the 700cc kit for the 650 is very simple to upgrade. The 810 besides a 750 cylinder bank requires some serious porting of the heads and larger carbs to take best advantage of the increased displacement which means more time and money but more HP. Because of that I have decided on the 700cc kit. The biggest advantage is not the extra 50cc but the increased compression ratio. If you shave the head or use a slim gasket you can easily bump that up even higher. Couple that with an electronic ignition and hot coils and there should be some good gains to be had. The gpz cams are really the only option you have and help squease out more revs at WOT. Stock these motors are around 60HP, which by any standars is pretty freakin amazing. 39.7 cubic inches means they make better than 1.5 HP per cube, that is crazy. I don't think 80 HP is hard taget to shoot for hell I bet 90 is possible.

There are a host of crank options for this engine, ranging from lightening and balancing to strokers. You could do a 4 mm stroker using a 2 mm plate under the block.

www.aperaceparts.com/crankwork.html

Jay

There's a similar thread on kz650.info here: 90 horse outa a 79 650?? .

Well I stand corrected on the crank issuses :blush:
I just assumed the stroking service wasn't common place on the 650's.

I have riden an 810 conversion with a turbo, crazy little bike. Went like mad and sounded like the world was going to end. It met a cruel end in an accident some years ago the owner was lucky, lucky and stupid.

You may want to look up some of the turbo mods done on this site. If your running a 750 top end with a big bore kit there are some options for adding a turbo.

On the subject I wonder if any one has fit even larger pistons in a 750 block? If larger sleeves could be fit and bored to fit say 900cc pistons or something like that.

Holly crap what do you know... some has aparently put 1100 sleves in a 750, with a turbo too. Shit thats gotta be fast!

kzrider.com/index.php?option=com_kunena&...ew&catid=2&id=266907

There used to be a number of fast 650s. A guy and his wife used to street race one in So. Cal. He wrenched, she rode. They made a lot of money with that little bike.

John Norad from Ankra Mn. has a laydown turbo that ran 8.60s. Both of these bikes had hard chromed cranks that we did. The stock rod journals are just too soft for the power they were making.

Now days we don't chrome them as we have a killer nitride process that we do to all of our strokers that makes the journals almost bullet proof.

Jay

so how high can we raise the compression ratio on our little 650/710? I know the kit is 10.25-1...but with a little off the deck could we go up to 11.5 or higher? I have heard of over heating problems with the 810 kits with higher compression (though I don't know the numbers) I'm just wondering if you could squeeze a little more with the less displacement, without to many reliability issues...

I'm thinking I'll do the 710 kit though I think if I was to want more than that I'll start with a different bike.

now don't chew me out for asking but has anyone run water injection on any of these little guys? I know it's primarily a turbo application but I could really see the use in a high compression air cooled motor. seems like you could get away with even more compression. again I'm just theorizing...

Well if you want to run alcohol...