TOPIC:

I am in the process to rebuild a 80 750 4. I read somewhere about building the 750 up to an 810. What is involved in this process. And what kind of performance improvements can I expect. I don't want something totally wild......well......not yet anyway. So any info would be Greatly appreciated.


Steve Willis

you bore the cylinders 3mm over and use the Wiseco K810 piston kit. it puts compression ratio up to 10.25-1. Get an aftermarket performance exhaust system, individual pod air filters, jet the carbs accordingly, and you will see a big jump in power:evil: for more power (maybe later on)do some light porting, and get a set of bigger cams
Oh and welcome to KZR!

Post edited by: 77KZ650, at: 2006/10/08 18:03

the 650 750 head swap is still debateable i believe. the 650 has smaller combustion chambers 23.7cc and the 750 has combustion chamber volumes around 25cc. smaller chambers = higher compression(more power). but the 750 comes with slightly larger valves which allow more flow. more flow = more power. you see where somebody would relly need a dyno and be willing to try both heads on the same motor to see which combo makes more power

thanks for the quick reply. I am also curious about those who made statements about putting 650 heads on. What kind of horse power approx. will I be gaining. I read somewhere that stock is around 65hp I believe.

Thanks,

Steve

hp for a stock 750 is 74, a stock 650 is 64, with all the mods I listed(one more here, get a set of 26mm or 28mm carbs if you are using 24's) you would be in the 100 hp range I would think.
Colin Firth (reborn650) has a very nice 650/750 hybrid bike with an 810cc kit which is very similar to what I am currently building. do a search for some of his posts, lots of great info;)