carbs size

I recently bought a motor from a gentleman for my 1976 KZ 900 He tells me that this motor has a 1260 kit installed. My question is can I get by with jetting a set of 28mm carbs with this motor set up. I don't intend on racing the bike. Thought or comments

Should be fine. Maybe a little restricted but that depends on the head flow and cams, not only the displacement. Going small on the carbs is almost always better than too big unless top end power is the desired goal.

My answer would be "it depends". If the motor was done up with big valves, big cams, and big ports then the 28mm carbs will be a bit too small. By the time the motor reaches the RPM's where it wants to start working, it would be running out of breath due to the restrictive carbs. On the other hand, if it's a very mild motor, then you might get by with a rack of 28's and it might prove to be a very streetable combination.

Just wondering, too, if your motor is, indeed, a 1260. Does it still have a factory cylinder block? The rule of thumb used to be: stock KZ cylinder block and liners were good for 1100cc, stock cyl block w/aftermarket liners good for 1200cc, and anything larger required an aftermarket big block.

I'm sure that other forum members will be by to offer more advice. Good luck with your project.

Mike

Thanks Ed I had some else tell me that it might tame down that motor a little bit.

Thanks Mike.

Dragbike_Mike wrote:
Just wondering, too, if your motor is, indeed, a 1260. Does it still have a factory cylinder block? The rule of thumb used to be: stock KZ cylinder block and liners were good for 1100cc, stock cyl block w/aftermarket liners good for 1200cc, and anything larger required an aftermarket big block.

Mike

Have to correct myself here - you can go to 1260cc using the factory cylinder block and aftermarket sleeves. My bad...

Mike