Carburetor main jet size.

I have posted this before about fit a performance exhaust for my Suzuki CS50 1982 50cc, well today I had a new performance with large Expansion exhaust from Honda PX50 something like that and it was modified by a welding to fit my engine gasket head, the top speed has increase from 31.4mph to 33.5mph I was disappointment with the result. The scooter it have a performance air filter, it has lost 3.2kg of kerb weight. Before the original performance from my 50cc it was 28.8mph so I have gain 4.7mph more. I am try to get other 5mph more if it is possible.

I can someone tell me if I can swap my Mikuni VM14SH carburetor to a large carburetor? if is not possible would my current Mikuni VM14SH the main jet it has 85 size jet, would it work to get more mph if I swap for jet number 92?

Kind Regards
Fab.

 

Swap the motor for a CS80 3 speed...

 

Yes I was think of swap, but it is rare as a hen tooth to find one!

 

Yeah...
Your main jet will need changing as you have an open airbox and performance exhaust.
You may have damaged your engine by not using a bigger main jet...

 

Oh dear! sound quite serious for not change jet, which would you recommend the size 90 or 92?

 

I always buy a box of jets and fit one slightly too large and then work down from there.

its a lot safer than running with a jet thats too small and potentially putting a hole in a piston (yes ive holed a piston, but thats another story)

 

Thank you for your great info. Have a good day.