[Monkee]

I tried the same carb on a C5 Classic, but was never able to get rid of a midrange lean patch, so on the end I got rid of it and fitted a Mikuni VM, which worked great straight out of the box.


I had a similar lean patch in the mid range. i managed to get around it by using a slightly bigger main jet and shimming the needle by about 0.8mm




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[Onurag Chatterjee]

Thanks for your response!

Which size main jet did you use to cure the problem?

[Monkee]

my current set up is:

PJ 37.5 - 2 1/4 turns out
MJ 135
Needle shimmed 0.8mm.

I'm still tweaking the needle height to get best mid range response but with CV carbs they'll always be kinda sluggish. I could also probably go down a couple more sizes on the MJ probably down to a 130 or 125 but i'll keep it at 135 since its going to get a bit cold in the following months probably drop down to 125 in the summer

[TSTM]

I tried the same carb on a C5 Classic, but was never able to get rid of a midrange lean patch, so on the end I got rid of it and fitted a Mikuni VM, which worked great straight out of the box.

No you didn't.
You just copied this post.

I tried the same carb on a C5 Classic, but was never able to get rid of a midrange lean patch, so on the end I got rid of it and fitted a Mikuni VM, which worked great straight out of the box.
On the Ucal carb, I found  the 130 main too big (stock air box and Hitchcocks silencer) and ended up with a 115.
I was told that the Ucal works well on India but was unable to get good performance with it over here.

[Onurag Chatterjee]

Thanks, again!

my current set up is:

PJ 37.5 - 2 1/4 turns out
MJ 135
Needle shimmed 0.8mm.

I'm still tweaking the needle height to get best mid range response but with CV carbs they'll always be kinda sluggish. I could also probably go down a couple more sizes on the MJ probably down to a 130 or 125 but i'll keep it at 135 since its going to get a bit cold in the following months probably drop down to 125 in the summer

[mcplorer]

@Onurag did you figure out the carb? If you are sticking with UCD33 start with 20 pilot. For a bit crisper throttle response you can think of porting the carb slide(I did this on my 350 CV BS29 carb and there was much quicker response to wrist twist). Main jet you can keep stock 130

Else for a spirited throttle response go for Mikuni VM32 or VM34

[mcplorer]

my current set up is:

PJ 37.5 - 2 1/4 turns out
MJ 135
Needle shimmed 0.8mm.

I'm still tweaking the needle height to get best mid range response but with CV carbs they'll always be kinda sluggish. I could also probably go down a couple more sizes on the MJ probably down to a 130 or 125 but i'll keep it at 135 since its going to get a bit cold in the following months probably drop down to 125 in the summer

Try with different needle position or port the carb slide for crisper throttle response. Been there, done that on BS29 CV carb