boring cases 650

Does anybody object to me grinding the cases of my 650 by hand. I Need to remove some material to fit the 750 block. The machine shop wants $130 to bore the case. I read somewhere on here that a dremel was used to bore the case out.

I guess i am wondering how exact the boring needs to be and if it is necessary to have a machine shop do the job.

thank you in advance for any help

Read this story about fitting the 750 cylinders to 650 case. Might answer your questionns..

grinding cases

that will take an awefull lot of grinding with a dremel make sure you get the depth right as well as the bore, give your self about .010" clearance all the way round and down in the cases as well to allow for heat expansion my self. i think 130.00 is cheap for sombody to do it right i would not attempt it by hand myself, even if you get a machine shop to doit you will find the cases to be very thin at the gasket surface so take care and do lots of trial fitting remember that you will need a min. of .010" clearance i can't stress that enough.

I'm rebuilting my seized engine but I noticed the picture of your bike. My questions are what kind of handle bar and mirrors do you have on yours? Is that a after market seat? Did you do the fender eliminator as well? I like to do something like your bike.




pburnhamb wrote:

Does anybody object to me grinding the cases of my 650 by hand. I Need to remove some material to fit the 750 block. The machine shop wants $130 to bore the case. I read somewhere on here that a dremel was used to bore the case out.

I guess i am wondering how exact the boring needs to be and if it is necessary to have a machine shop do the job.

thank you in advance for any help

timebomb33 wrote:

that will take an awefull lot of grinding with a dremel make sure you get the depth right as well as the bore, give your self about .010" clearance all the way round and down in the cases as well to allow for heat expansion my self. i think 130.00 is cheap for sombody to do it right i would not attempt it by hand myself, even if you get a machine shop to doit you will find the cases to be very thin at the gasket surface so take care and do lots of trial fitting remember that you will need a min. of .010" clearance i can't stress that enough.

I agree, mine will be going on a milling machine in May, no substitute for the right tools.

pburnhamb wrote:

Does anybody object to me grinding the cases of my 650 by hand. I Need to remove some material to fit the 750 block. The machine shop wants $130 to bore the case. I read somewhere on here that a dremel was used to bore the case out.

I guess i am wondering how exact the boring needs to be and if it is necessary to have a machine shop do the job.

thank you in advance for any help

You will be spending a lot of money on this project, from start to finish. Find some place else in the project to save money, not the boring of the cases. If you get it wrong, you will be filling it up with silicone, to stop your oil leaks. If you want to build a big dog motor, open your wallet and do it right.........Good Luck!

Yeah you're right kzz1p, i realized this the other day im going to have the guy machine the case when he does the cyls. where were you a few weeks ago when i talked myself into the 810 over the 700?!!! I think i will be glad in another week or two.

got the frame in tip top shape stripped and primer, paint tomorrow if the humidity stays down. pistons and valve cover for 750 head in the mail (or so i'm told) then the fun assembly part.

Eaglecrash: Im going for a bit of cafe. Ill have to figure out how to get all my pictures on here (tons and tons). handlebar is a dragbar, no mirror yet, probably a bar end type though. the seat is from Glass From The Past (great seatwork, but the sanding and painting was not so hot.

pburnhamb wrote:

Yeah you're right kzz1p, i realized this the other day im going to have the guy machine the case when he does the cyls. where were you a few weeks ago when i talked myself into the 810 over the 700?!!! I think i will be glad in another week or two.

got the frame in tip top shape stripped and primer, paint tomorrow if the humidity stays down. pistons and valve cover for 750 head in the mail (or so i'm told) then the fun assembly part.

Eaglecrash: Im going for a bit of cafe. Ill have to figure out how to get all my pictures on here (tons and tons). handlebar is a dragbar, no mirror yet, probably a bar end type though. the seat is from Glass From The Past (great seatwork, but the sanding and painting was not so hot.

After watching some modern sportbikes the other day. I have come to the concludion that KZ650's and 750's are a better choice, for a streetfighter against the mid size sportbikes. The smaller KZ's have better frames, handling and a short stroke for quicker rpm's. Myself I perfer the 700cc or 717cc kits for a kz650. I learned the hard way about overcamming the kz650. These motors respond to mods far better then Z1's do. A little bite goes along ways! I would suggest a good 700cc build to see how you like it. Once you bore the cases, theres no coming home. I would also suggest a cam with no more then 288* of duration, if you are a good rider. Bigger cams turn the throttle into, just a on/off switch. They will shoot your bottom end, all to hell! This is my opinion and my experience, take some time and think about it, for awhile.........John

Sorry to hijack, but its not too far off topic. I plan on doing an 810 kit soon as well, but I don't have the KZ750 parts yet. How much power can I expect with the 700cc's versus 810cc? I'm thinking on a 700 kit the BS34's I have bought will be overkill, and I'd only gain 10-15hp anyways. I'm hoping for at least 90hp with the 810, 750 head, pods, pipes, bs34's and GPz750 cams. Is it your opinion that this will be too much for the bike, or it'll be too rough? I can't see why, theres only 10.25:1 CR and stock GPz cams.

T_Dub wrote:

Sorry to hijack, but its not too far off topic. I plan on doing an 810 kit soon as well, but I don't have the KZ750 parts yet. How much power can I expect with the 700cc's versus 810cc? I'm thinking on a 700 kit the BS34's I have bought will be overkill, and I'd only gain 10-15hp anyways. I'm hoping for at least 90hp with the 810, 750 head, pods, pipes, bs34's and GPz750 cams. Is it your opinion that this will be too much for the bike, or it'll be too rough? I can't see why, theres only 10.25:1 CR and stock GPz cams.

I don't know about the power diff, I would say not much. To me it's all about building something that will last for years. Believe it when they say, bigger isn't always better.
I do not think your going to get 90 hp with just GPZ cams??
What are the GPZ (cams) opening and closing points compared to the 650's. When does the intake valve (open & close) how many degrees? To me the most important thing is the cranking compression. Even with 10:1's you can have to much cylinder pressure for pump gas. Your total compression ratio + intake valve closing, will tell the whole story.
When you hit 180psi or more, it gets real hard, to run on pump gas.

I doubt you're gonna get that kind of pressure. Sportbikes run pump gas with much higher compression, and much more agressive cam profiles. The GPz750 made around 90hp, I dont see it as a problem to do if I'm bored to 810 with the same carbs and cams, with aftermarket pods and exhaust. 810cc with pods and exhaust on the same cams will net a greater air flow rate, generating more hp with a good tune. I never looked up the GPz's numbers before, now I'm way more confident the 810 will make 90+ hp.

T_Dub wrote:

I doubt you're gonna get that kind of pressure. Sportbikes run pump gas with much higher compression, and much more agressive cam profiles. The GPz750 made around 90hp, I dont see it as a problem to do if I'm bored to 810 with the same carbs and cams, with aftermarket pods and exhaust. 810cc with pods and exhaust on the same cams will net a greater air flow rate, generating more hp with a good tune. I never looked up the GPz's numbers before, now I'm way more confident the 810 will make 90+ hp.

Good luck with your project.