bs38's, 700cc input

[gunch]

Looking for some input on how to set my carbs for a 700cc build I'm working on.

700cc kit from Hoos
Shell 1 cam
Mild head porting, basically a clean up
Stock BS38's

What size jets and needle position should I start with? I am not opposed to getting a few different sets of needles, just looking for a starting point.

Thanks

 

[blackbetty]

I wasn't able to get my 700 shell cam motor to run very well with my stock 76-77 BS38s, kept having issues with pop stall. I had to run as high as a 37.5 pilot just to get it to idle smoothly without randomly stalling @ 1200 rpm. (Stock is 4M1 needle, Z8 needle jet, 122.5 mj, 25 pj)

I had JBM manifolds and diaphragms. New butterfly shaft seals and needle jet orings, all genuine Mikuni. Before I took them off in favor of roundslides, I had the needle dropped one notch, 132.5 main and a 32.5 PJ. Mix screws I think at a little less than 1.5. Ran pretty well and plugs looked good, but again, the inconsistent idle bugged me and I was not able to isolate any air leaks.

My motor is a 700 with shell 1, boyer, pma, but I opted for around 9.5:1 compression with copper gaskets for better reliability.

 

[XSLeo]

When I swapped the second over 650 cylinders to Mike's 750 kit with no other changes the carbs tuning was exactly the same. So if your carbs worked before then they shgould work now.
With the Shell cam then they might need some work but I doubt it. Intake and exhaust will have stronger effect on carb tuning.
Leo

 

[blackbetty]

I should degree my camshaft and make sure it's not off a few degrees. I remember XSjohn saying that even a camshaft off by 2* can throw a motor into a perpetually "fake" lean state.

 

[gunch]

Thanks guys. I guess I'll see how it runs before changing anything. Ran really good before so I'll keep my fingers crossed... I'll post what I figure out and end up doing.