kz650 810cc big bore kit !!!

Ok i have a 1978 kz650 SR and it has the 810cc big bore kit installed. 650 head ,stock cams,and im going to run 28mm z1900 carbs with k&n pods, vance & hines 4 into 1 exhaust system. I also installed dyna 3ohm coils and dyna s electronic system. My question is on the carbs. What size piolet jets and main jets would be best for this setup???? Any info will be very helpful..........thanks everyone in advance.....:blink:

Can you list the specs on your big bore kit?? Like who the pistons are made by and all. I have only seen the 720 kit for the 650. The 810 is usually made for the 750.

He would be using the 750 jugs, as they will be a bolt on for the later yrs (I think), or can be made to fit the earlier yrs by enlarging the holes in the top case to accept the larger sleaves, or he had the 650 sleaves presed out, block bored to accept 750 sleaves, then those bored to the 810 kit. probly the wiseco k810 kit, 69mm, 10.25-1 comp (although it should be higher with the smaller combustion chamber of the 650 head)
Read about my project in my sig
Scott

Post edited by: 77KZ650, at: 2006/02/24 22:53

galaxian wrote:

Can you list the specs on your big bore kit?? Like who the pistons are made by and all. I have only seen the 720 kit for the 650. The 810 is usually made for the 750.

I've got a 784cc big bore kit for my 650. Old kit that MTC used to make. :thumbup:

I think I am running 120 main jets in my motor. It's a 700CC with lots more cam than yours and 29mm smoothbore carbs. Since you have lots more displacement but less cam this may be a decent starting point for you. The two might equal out to some degree. Needles are in the second position from the bottom I think as well.

Are 650 sleeves thick enough to be bored out to 66mm for 750cc ?

No.


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Quick answer haha.
Nowbwhen modifying an earlier kz650 motor with roller chain, besides having to bore out the cases a bit. Can you use the roller chain wheels in the kz750 cylinders (hyvo chain) or must you use hyvo sliders ?

Can't use the hyvo (later style) chain on the earlier crank so you need to keep the older style chain set up...... like said a 1980 or possibly a 81 block for the 750 is the only one that has the cut outs for the old rollers. 700cc kit is the only size that will fit the 650 block unless like said you have liners installed which would be pretty pricey. They did away with the 720 and 740 kit probably cause things were getting too thin. Search for 810 kit in 650 lots of info on here and else where.

Yea definitely not going the double bore route, boring cylinder block then cylinder sleeves. I know you can't use the hyvo chain on the a roller style crank, but if I use a newer style block can I use the sliders that block would normally use, keeping the roller chain, or does the block have the slots for the older style rollers ?

I want to be clear cause I plan on using a 700 block bored to 65mm and that block uses sliders not rollers. If I can use the rollers I will, but if I can't I'll use the sliders which would probably amount to less wear of the cam chain, although it's in constant lubrication, so wear probably isn't a factor