750 cylinders, 650 cases

i know we hit on this before but i am still confused on the proper answer.
i got a 784 kit off e-bay and the sleeves are in 750 jugs.
i know i can put the 750 sleeves in 650 jugs
i am still unsure if the sleeves will fit my 77 650 motor without boring the cases.
if they will fit without cracking the cases, i'm up and running with the 650 this weekend.
if i need to bore them, i'm screwed again.
anyone got a yes or no answer for me?

The 7550 cylinders will fir the 6540 bottom end, you just have to make sure thathte cam chains are the same style, earlier 650's were simplex chains and the later ones and most of the 750s were hyvo type cains that have a different tensioner set up.

Hey Steve - My guess is you will have to open up the cases as I did with my 810. My bottom end is a 1977 Kz 650 and the 750 cylinders were from a 1980 Kz750 which was really just a resleeved 650 block. The larger outside diameter sleeves prevent the 750 block from just sliding onto the 650. The cam chains were both the early roller type.

Opening up the cases sounds more complicated than it really is. In fact it is not that big of a job which is made a lot easier if the motor is out of the bike and you remove the top half of the cases. I wouldn't suggest trying to do this job with the motor in the bike as you would have to manouver around the studs, pistons, rods and frame downtubes. It would be a hassle.

Start with some trial fitting of the cylinders to see where the metal has to be removed from the 650's bottom end. Keep a red Sharpie marker handy to mark the metal to be removed.

I went to the local tool supply shop and picked up 2 aluminum cutting/boring bits for my variable speed cordless drill. One of the bits was cylindrical with a flat end and the other had more of a concave end. They are designed for trimming aluminum.

I found myself switching back and forth between the two bits depending on which area of the cases I was working on.

The engine studs tend to get in the way and sometimes it is best to work from the underside of the cases. Take off just a little bit at a time, test fit, mark and continue removing the metal until the cylinders slide into the top half of the cases.

Once you get started the whole job shouldn't take longer than an hour per cylinder. Remember to take your time and do lots of test fittings as you can't add metal once you have removed too much.

If you have any questions fire me off a u2u and I will try to answer any questions you may have.

Cheers-Colin Firth-Ontario Canada

If you have any questions

thanks for your help again reborn.
i kind of knew i had to but was hoping for the best.
oh well, now i'm cracking the cases.
all in fun right?

Colin has you covered, I pretty much did the same thing;)
now if i could just stop spending money on the drag bike i could get my cases glass beaded and put it all together:pinch:

Post edited by: 77KZ650, at: 2007/04/21 00:13