660 carb mods?

[I Know Something]

As my moding season is approaching in a few months. I'm gathering information or ideas for what else I can/should do to my 660. A new jet? Thinning out crossing stuff for more air flow? Can/should you increase the bore size by buying a new one or by other means? Fuel meter mod of some kind? Sorry if some of this is me thinking out loud. I'm not trying to reinvent the wheel as of yet. Just looking for ideas or guidance.

Thank you.

 

[MustangMike]

I've been able to use the Asian 660 carbs as is (unlike the 440 carbs), but admittedly, some are on the edge of needing to be a bit richer.

One 660 carb needed the fuel lever to be re set.

I like the carb that came on my Blue Kit that has a metal part that locks the Hi Idle in place. Wish they were all like that.

 

[MG porting]

Mods I've done on some 660 carbs is polish the bore and give the choke butterfly a knife edge but you need to be careful doing so don't get crazy and I always recommend having a set of different sizes of jets.

 

[huskyboy]

There are small gains in thinning the shafts like this for example. Not easy to do and easy to mess up the carb if you don’t know what your doing.

 

[I Know Something]

That picture right there is exactly what I was thinking.

Can you increase the bore size?

 

[MustangMike]

Got to be very careful with that … I would not attempt it, messing with the relationship of the bore and the venturi can play havoc with things. They were "engineered".

 

[Lightning Performance]

That picture right there is exactly what I was thinking.

Can you increase the bore size?

Yes you can but, the big but is.....stay away from any and all port holes in the throat area. You will not end up with a concentric bore but IMO it won't matter in the grand scheme of air flow through that oblong hole.

If you take out the step that helps create low pressure....you will wish you didn't. Don't get metal chippies in anything or the carb will fail miserably in use. Most people destroy carbs attempting these mods.

You have been warned, you have been warned twice. Don't do it.

 

[I Know Something]

Yes you can but, the big but is.....stay away from any and all port holes in the throat area. You will not end up with a concentric bore but IMO it won't matter in the grand scheme of air flow through that oblong hole.

If you take out the step that helps create low pressure....you will wish you didn't. Don't get metal chippies in anything or the carb will fail miserably in use. Most people destroy carbs attempting these mods.

You have been warned, you have been warned twice. Don't do it.

Lol. Yes sir!