Z650 capacity increase?

[coldsummer]

I've just started the baby zed resto (sr650) and even though it will be fairly standard, I'd like to increase the performance with a bit more mid range grunt. I think the easiest way would be to fit a big bore kit or swap the barels with 750 ones. Has anyone any experience of either and are there any pros and cons to consider, eg changes to carbs, cam chain tensioner mechanism etc? Would it be best to swap the complete top end from a 750, and if so which model? Or would it be better to bore out the original 650, but what is the maximum capacity? I know an 810 kit is available but is that only suitable for 750 blocks?

These are the kind of things I'm pondering and not made any definite decisions yet so any advice or pointers would be very welcome indeed.

Thanks guys.

[Big John]

I had aZ650 with a 710 big bore kit and Pops Yoshimura cams back in the late eighties early nineties, was a very rapid bike but it out performed the brakes by quite a margin.

[Padders]

Here you go Simon fill your boots.

http://japan.webike.net/categories/1000 ... 45032.html

[Crofty]

Simon, I am building my second 650. The first one I put together standard, this one is going to be improved a bit. It has a late 650 set of cases (advantage they will accept the 750 liners through the crankcase mouths without machinework). Just about ready to build the bottom end up, new bearings, cam chain, primary chain, starter clutch and bearings, shot peened and balanced rods, Wiseco 810 pistons, rebuilt clutch housing (the standard baskets are now suffering from age and the rubber pucks inside the housing perish and give play). GPZ750 sump with oil cooler take offs.
Then I just need to save up to get Debbens to do the head, I already have a set of GPZ cams to go in and a set of 26mm Mikuns (24mm is std). i will try to get a set of 29mm CRs later when pennies allow.
I actually have a whole stack of articles re Moriwaki and overseas tuning to these motors, so I will pm you with the links, the German article is bonkers.

[coldsummer]

Thanks guys for the replies and pm's. I'm really looking forward to this one having cut my teeth on the Z1b

[GUYZED]

Simon...my Z650 has a 720 Wiseco kit with Z750 cams and 28mm Z1000 carbs.

[coldsummer]

I'm starting to think the easiest/cheapest option is to do a straight swap with 750 barrels? Wiseco kits are a lot of money for less cubes, unless I'm missing something. I'm not after a huge top end rush as I don't think the SR chassis is up to it, especially with the 16 inch rear wheel, but a bit more mid range grunt would be very nice.