CB450K with VM32 carbs - stuttering at 5.000 rpm

[Jan84]

Got some trouble with my VM32 carbs on my '68 CB450K. It throttles really slow and doesn't runs over 5.000 rpm, than there is only stuttering.
Setup is:

MJ = #185
JN = #6DH7
NJ = P-5
PJ = #35
AJ = #2.0

Clip on leanest position. Carbs are clean and synced. Run Pamco ignition.

Who can help?

 

[regal7point5]

Are these the out of the box Dime City carbs? I have the same carbs, same jetting on a KZ400 with the SAME exact issue. I started at 185 went all the way down to 140 main with really no change. Raised the needle all the way and it got worse....lowered it all the way got better but still stuttered at anything over 5k. I am beginning to think it is ignition related...

 

[Sonreir]

What needle jet series are you running?

The VMs come stock with a 159 series, but you should be using a 176 on a four stroke.

 

[regal7point5]

What needle jet series are you running?

The VMs come stock with a 159 series, but you should be using a 176 on a four stroke.

Not to second guess you, but are you sure? I got jetting recommendations from Sudco and they said a 159 P-5 would be ideal. What is the difference in the 159 and the 176 bleed type? Thanks in advance

 

[Sonreir]

159 needle jets are richer at the top end and leaner at the bottom to help account for that way two stroke bikes operate (reversion and all that).

Futhermore, bleed type needle jets (like the 176) provide better atomization of fuel, which is less important on a two stroke (which has the crank beating the heck out of the mixture before it enters the cylinder).

Bleed type needle jets also flow less well than the primary types, so you'll want to increase the size a bit, too.

I'd be willing to be a 176 P-8 with 150 mains will get you a lot closer to where you need to be.

 

[regal7point5]

Awesome...I will have to give that a shot. I have the mains already, will get the NJ's ordered. Thanks!