26mm to 28mm carbs

I run the stock 26mm carbs on my 900 right now. I have a line on a set of 28mm carbs for a reasonable price. My question is will there be any noticeable diffference in going from the 26's to the 28's? Is it even worth messing with?

Did you ever get a reply to this question?

I got a great response to this question from Jeff at Z1 Enterprises. I don't think that he'd mind if I posted it here:


"Much better top-end. The 26’s are really too small. In the scheme of things, on a scale of 1-10, the 26’s are a 5 or 6, the 28’s are a 7 or 8, and the 29’s a 9+
The 26’s have good throttle response around town, but the engine dies about 7,000 rpm. The 28’s liven a 900 motor up as they pull to 8,000+, the 29’s are a better carb overall, a little crisper responding and allow you to pull to the redline."

Humm.... interesting.

I have a '77 KZ650 bored to 66mm with some real healthy cams. I'm thinking about putting a KZ750 head on for the larger ports and valves.

She currently has a set of 26mm carbs that were "tuned" by some place out west in the early '80s.

A friend has a set of 28mm that he'd sell me for a reasonable price.

In your opinion, do you think that the 28mm carbs would be a good upgrade?

stock kz 650 carbs are 24 mm going up to those 28's should work well it all depends on how big those cams are and what exhaust and how much head work you done. it definitly improve the top end of the engine.

Thanks for the reply.

You know, once I typed that I thought to myself, "you dummy, you just asked the same thing again".

I guess that the question should have been "what's too much carb for a built 750"?

On the old set-up with the stock 650 head and the 26s, she did seem to flatten out a little on top. I suspect that the guy that originally built her ran 29s when he raced her, and the he put the 26s on when he sold her to me.

Anyway, I know a guy that has a set of 28s that he's willing to let go of for a decent price. Think I'll give them a shot next year.

Sorry for the newbie questions!!