Question about stroker kit for a 77 KZ 650...

First off this is my first post here, Hello to all.

I have read about a 738 kit for a KZ 650 in an article else where. My question is, is there such a thing as an 831 kit and also what other variations did they have available in 77? Thanks!

810 kit using 750 cylinder seems to be a common build,im not sure about stroker kits.i wonder if once you get to a certain point if you wouldnt be better off just finding a 900/1000 as a starting point

Welcome to KZR. Back in 77 there were a few piston kits available for the 650's. Someone did make a 738 kit but are long gone. Yoshimura and Wiseco made kits too 716 and 720. The only kits now are Wiseco 700 and if you can find it a 710 or a 810 with 81 750 barrels like PLUMMEN said. You can get any size piston made and custom sleeves but no stroker kits that I know of.

Mark

Thanks guys, Here is why I ask. My first cousin bought a 77 KZ 650 from a second owner that became public enemy number one in a small town in SC, and his father made him get rid of the bike, so that is when my cousin bought the bike. Unfortunately my cousin was tragically killed at the age of 17 in 1981. The bike was kept by a brother until today. Again, unfortunatley the bike has been left out doors a good bit. My cousin that died did know the orignal owner and some info on what had been done to the bike. So here recently my nephew has gotten a Kaw 600 with some goodies and he brought up the idea of me getting the old KZ650 from my cousin. I'm not really into bikes anymore but the idea of getting that bike and fixing it up peaks my interest.

Back to the bike, as it sits right now it has less than 10,000 miles on it. It hasn't even been started or ridden since 86-87. I was 15 when my cousin passed and let me tell you it was a bad, bad bike in it's day. I know that the bike was bought brand new, and before it was ever brought home the guys at the shop did a lot of work to it. 4 into 1 header, the carbs were off a 900 it had a kit of some kind I can't remember. I know this, the guys at the shop said that a stock KZ 900 wouldn't touch it. It had velocity stacks on the carbs drag handle bars a square head light and a small tale light custom paint, and on the gas tank, of the metallic blue paint was the emblem of the Blue Max off Raymond Beatles old funny car. I was told by the cousin who now has the bike that it got less than 30 MPG.

So after this idea came up about getting it I ended up here. I read an article about the bonniville salt flat KZ 650 in Big Bike magizine from 77 and that is where I saw 738. and I was reading here where someone was inquiring about 750 cylinder jugs on the 650. So again I called and asked my cousin about the bike and he said He really didn't know but through the years the number 831 has stuck with him. So who knows without tearing it down. I know that in its day it would fly. My cousin who passed was about 145lbs. I would have loved to have known some 1/8 and 1/4 times on the bike back then. My cousin did run some 1/8 mile but we don't have any time sheets.

Sorry for rambling, just brings back some good old memories that I haven't talked about in a long time.

Actually, a 4mm "overbore" out to 66mm was a common "hop-up" for KZ650 "built" in the late '70s. In fact it was so popular, that the factory started offering it in 1980 as the KZ750 (ha, ha).

(66mm X 54mm X 4 actually calculates out to about 738cc and change. But since the original Honda 750 was actually a 736cc, I guess Kaw figured it was OK to call their new offering a 750).

Now if I'm not mistaken (and I could be), a 4mm overbore allowed the KZ650 to retain the stock jug and sleeves. Where as going out to a 810 would require a 750 jug (barrel) which wasn’t offered until the early ’80. And you said the bike was built late ‘70s.

Does the cylinder on the bike say 652cc on the side? If so, stock 650 and the 810 plus overbore is rather doubtful. Unless the original owner had the jug over bored and bigger sleeve fitted. Which wouldn’t have been unheard off……….

Welcome Max.
The bike sure has an interesting history.
Do you have any pictures of it to share?

Blue Max, not to say it couldn't be done, but after owning a 77 KZ 650 and having it built with 717 pistons, Andrews cams, 4 into 1 exhaust, bigger carbs,15 tooth countershaft sproket, I could not keep up with my dads Stock 76 KZ900. Not off the line, thru the 1/8, 1/4 or anywhere near top end. Before all the work I had seen 125 indicated, after all the money was spent I saw 130 indicated. My dads 900 would show me its tail light all the time. Switching riders didn't change anything, the 900 was always faster.

70mm pistons using 900 liners in the 650 (or 750) block would make it 831cc.

And my little 810 will outrun most 900s

yes it will lorcan but your motor has a bit of extra help doesn't it.

I have no problem showing 900, 1000, 1100's my tail light. When I was 716cc I would smoke my buddies 1000 by 1/2 second every time we went down the 1/4. He had a Yoshumura pipe a 28mm carbs.

Mark

ron768 wrote:

Blue Max, not to say it couldn't be done, but after owning a 77 KZ 650 and having it built with 717 pistons, Andrews cams, 4 into 1 exhaust, bigger carbs,15 tooth countershaft sproket, I could not keep up with my dads Stock 76 KZ900. Not off the line, thru the 1/8, 1/4 or anywhere near top end. Before all the work I had seen 125 indicated, after all the money was spent I saw 130 indicated. My dads 900 would show me its tail light all the time. Switching riders didn't change anything, the 900 was always faster.

Hey Ron, thanks for your response. Like I said above, my info was second handed so you know how that goes. I've always been one to say, numbers don't lie and people can sit down behind a keyboard and say anything. I try not to do that.

I am a newbie to this board, and in the last week I have read an awful lot. Like today me and my nephew looked up some specs on his bike 2000 ZX6 and it rated I believe 112HP while the stock 77KZ650 was just 64. man was my feelings hurt. But getting to my point.

The 77 KZ 900 had 82HP 54ft.lbs of torque at 7,000 and weighed 506 lbs.

The 77 KZ 650 was 64HP and 42 and weighed 483. So if my numbers are correct The 900 has 18 more HP and 12 more torque and is giving up 21 lbs. So like I said I'm not sure how much it would take to build up a 650 to be able to run with or out run a 900.

But I know weight means alot in any form of racing. so with a 21 lb. advantage and the additional weight reduction from stock to a 4 into 1 exhaust would also set you well on your way.

I'm not trying to be smart but asking a serious question? based on the numbers above if a person went from a stock 650 to 717 pistons, bigger lift cam, 4 into 1, bigger carbs and gear how much hp would one hope to gain by these up grades. thanks!

Lorcan wrote:

70mm pistons using 900 liners in the 650 (or 750) block would make it 831cc.

And my little 810 will outrun most 900s

most 1428s would have a hard time keeping up with your little ol 810! :woohoo: