TOPIC:

Hello guys, I have a spare set of vm24 carbs and I'm running vm22s currently on my 78 650 sr

I'm curious the 24s have accelerator pumps which I want to swap for non acell bowls

Is there any "performance" to be gained over the vm22 with correct tuning?


Or simply not worth the fuss?


Thanks in advance!

The stock 1978 KZ650-C2 and B2 used the Mikuni VM24 carbs and made 64 hp.

The stock 1978 KZ650-D1 (SR) used the Mikuni VM24 carbs and made 62 hp.

The stock 1978 KZ650-B2A used the Mikuni VM22 carbs and made 60 HP.

The stock 1978 D1A (SR) used the Mikuni VM22 carbs and made 58 HP.

The VM22 carbs cost the bike 2 HP compared to the VM24 carbs, and the reason each of the KZ650-D (SR) models made 2 HP less than their KZ650 B and C cousins was because the D models had the criss-crossed exhaust system which made a little less power than the B or C models which had the normal exhaust systems. Ed

Your chart means the diff between the 22s and 24s are 4 hp isn't it Ed? (B2 64Hp and the B2A 60Hp) Maybe I will get the 29s back on.

Yes, I think the difference in the carbs amounts to 4 HP. Ed

If I have done the math correctly, that would be almost a7% (6.666) increase. If so, that would be pretty good bang for the buck.

I agree Texas a little more than I would a thought.

Wow the quick responses, you guys are awesome.
I measured the inlet and outlet of the 22s and 24s and they're identical, however the slide bore is larger. Still a boost in power with only a larger slide?

Well hell if I got them sitting here I'll use em.


My last question is can I swap the non accel bowls from my vm22 to put on the vm24? (Not a fan of acell pumps)


Thanks guys!

I don't know about the swap, but the VM24 carbs on the 1977 KZ650 models did not have the accelerator pump, so if the bowls are the only thing different maybe it will work. Ed

I don't think there would be a problem with non-pump bowls on pumper carbs. Putting pumper bowls on non-pumper carbs could create a serious fuel leak if the pumps make enough pressure to blow out the gasket. If the pumps are disabled, then it might work.

EDIT: If the non-pumper bowls are cast so that they block the passageway, it should work. Otherwise, the fuel mixture may be stupid lean as the pump orifice sucks air from the fuel bowl.

Compare the slide cutaways. One may be leaner than the other.
Steve

Here's some info that shows specs for the KZ650 VM24 and VM22 carbs. Ed

I swear I have read about people using non pumper bowls on pumper carbs. I'll have to try to find those post.

The slide cut aways on my vm22 are 1.5

The vm24 have 2.0 slides.

I like free hp but not at the expensive of a tuning nightmare lol.