OEM SBN 44's and AM SBN 44's what's the difference?

[cycojon]

like the title says,

how do you tell them apart, any advantages to haveing one over the other?

 

[Matt_E]

The am's supposedly have better internal fuel circuitry.

Looking at model # is one way to tell. Another is to look at the fittings on the pump block. Removable brass fittings = am; while non-removable tubing fittings = OEM.

 

[Waste Land]

The am's supposedly have better internal fuel circuitry.

Looking at model # is one way to tell. Another is to look at the fittings on the pump block. Removable brass fittings = am; while non-removable tubing fittings = OEM.

I have AM dual 44 mikunis on my SJ with non removable fittings

 

[Matt_E]

What are the model #?

 

[Waste Land]

What are the model #?

.......Dunno, not at home to check.

 

[cycojon]

where are the model #'s located? i didn't see any #'s on mine at all
they do have non removable fittings (tube kind)

 

[Matt_E]

They are stamped on the carb body.

 

[cycojon]

ok i looked at my carbs again last night, they dont have the tube type fittings, they have the brass fittings with the square head, they look like they can be unscrewed. i must have been thinking about the 44 on my B1.

also i took off the fuel pump and looked at the fuel return line and the restrictor has been drilled out.

so at this point i am gonna guess they are AM carbs, which brings me to my next question

how important is it that i run a fuel restrictor in the return line? how does not running one affect performance and where do i get one?

thanks

 

[Matt_E]

You really should run a restrictor - it is essential to proper fuel pressure in the carb.
Yes, you can run without it, but the jetting will be drastically different and performance will not be what it could be.
Besides, restrictors cost about 3 bucks. :biggthumpup:

Btw, both OEM and AM Mikunis come with restrictors internally. Someone drilled yours out.

What was the model # on the carb?

 

[cycojon]

well i looked over the carbs last night and i didn't see any stampings at all, only the castings that say mikuni. maybe there is too much paint? how did you install your restrictor? i was thinking of turning a piece of alum on the lathe and tapping the ID to hold a pilot jet and installing it inline after the T. i read an older thread where you were tuneing your carbs, and one of the other guys was using a 70 pilot jet. so i was thinking about going that route.

 

[Matt_E]

I use a 60 main jet (because the body is bigger). You can put it inside the return line and clamp down on the outside with a hose clamp.

 

[cycojon]

I use a 60 main jet (because the body is bigger). You can put it inside the return line and clamp down on the outside with a hose clamp.

sweet and simple, i like it!

hopefully i can get the jets i think i might need for tuning, i just installed a limited B pipe, so sunday is gonna be tuning for me!

are you runing a flow control valve and restrictor to the stinger as well? i installed mine and set it at 3.5 psi with my pump.

i am on a mission for the best bottom end i can get with the parts i already have,

stock motor, no porting,
duel 44's protec intake
boysen dual stage reeds
lim B pipe
msd enhancer
13-15 cut back concord


do you have experiance with boysen dual stage reeds? any better for bottom end? i have a set of reeds that have a carbon fible look to them, they are single stage but i have no idea what brand or anything. i wonder if i would be better off with them?

thanks for your input matt

 

[Matt_E]

I run a Jetworks valve with 3 washers, no restrictor. Chamber gets sizzling hot at lower RPMs....I call it good.

I ran Boyesen dual stage for a short while, not long enough to really evaluate.

Get your stock flywheel lightened...that's cheap and a good improvement.