38mm SBN questions (NOT OEM's)
- Thread starter MTRHEAD
- Start date
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
I remember them from old Protec catalog, they had a setup for dual 38's.....
Having a hard time believing you have not messed with any.
Having a hard time believing you have not messed with any.
I know. Lol.
No mikuni sells and makes sbn 38’s. With shafts. They are not the shafts like Yamaha twins. They are almost identical to 44’s but 38’s
bored&stroked
Urban redneck
- Location
- AZ
Its not 38mm inside the bore everywhere, just like it sounds.
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
OEM 38s from a SJ (Yamaha 701) has a ridge on one side, this is a design of Mikuni with Yamaha. True Bore, is going to look more like how an 44mm carb looks.
- Location
- mobile alabama
i have some on a 61x manifold
For sale?
Hope I'm not beating a dead horse here but i'm most curious to aftermarket 38's vs. OEM 38's
OEM 38's on a typical b-pipe boat offer nice crisp performance and good fuel range. Many on this site complain about hard to tune with bored OEM 38's. Maybe there is a reason that is only appicable to OEM bored 38's because Mikuni sells clean throat 38's without obstructions or chokes. Are the obstructions due to the chokes?
What about:
1 -Real Mikuni 38's from Mikuni with no throat obstructions - they look like a mini 44 SBN (do these have different low speed holes? do they have 12 degree plates?)
2 - Speedysprockets bored 38's
3 - Group K bored 38's - tapered? straight like speedys?
4 - Jetworks 38's - tube in place of booster
I'm curious to a lake boat and/or a decent 550 that could use dual 38's
FYI: By the way I used 50mm Novi's on my 701 Limited superjet. All my experience since mid 90's has been Novi carbs on every boat I own except for my stock spec superjet
OEM 38's on a typical b-pipe boat offer nice crisp performance and good fuel range. Many on this site complain about hard to tune with bored OEM 38's. Maybe there is a reason that is only appicable to OEM bored 38's because Mikuni sells clean throat 38's without obstructions or chokes. Are the obstructions due to the chokes?
What about:
1 -Real Mikuni 38's from Mikuni with no throat obstructions - they look like a mini 44 SBN (do these have different low speed holes? do they have 12 degree plates?)
2 - Speedysprockets bored 38's
3 - Group K bored 38's - tapered? straight like speedys?
4 - Jetworks 38's - tube in place of booster
I'm curious to a lake boat and/or a decent 550 that could use dual 38's
FYI: By the way I used 50mm Novi's on my 701 Limited superjet. All my experience since mid 90's has been Novi carbs on every boat I own except for my stock spec superjet
Last edited:
- Location
- mobile alabama
everything is for sale , send me your # ill pop you a pic
Update:
I bought a set of 38mm Mikuni SBN carbs. There are many differences from the Yamaha 38’s
#1. No casting boss or ribs internal above the throttle plate
#2. Press in 90 fittings like 44 & 46 SBN’s
#3. 15 degree throttle plates. (superjets/raiders are 19)
#4. 3 hole low transition holes. (superjet/raiders are 2)
#5. Bottom is not threaded uses through stud
#6. primer fitting installed
I’ve tested 44 Yamaha 760 3 holes carbs versus 44mm Mikuni 4 SBN’s and the Mikuni 4 holes win in overall feel
im going to now setup these 38’s and compare the RPM, speed, and subjective metering. I believe they will be a little stronger Just like the 4 hole 12 degree plate 44sbn’s are compared to the 760 3 hole carbs
I bought a set of 38mm Mikuni SBN carbs. There are many differences from the Yamaha 38’s
#1. No casting boss or ribs internal above the throttle plate
#2. Press in 90 fittings like 44 & 46 SBN’s
#3. 15 degree throttle plates. (superjets/raiders are 19)
#4. 3 hole low transition holes. (superjet/raiders are 2)
#5. Bottom is not threaded uses through stud
#6. primer fitting installed
I’ve tested 44 Yamaha 760 3 holes carbs versus 44mm Mikuni 4 SBN’s and the Mikuni 4 holes win in overall feel
im going to now setup these 38’s and compare the RPM, speed, and subjective metering. I believe they will be a little stronger Just like the 4 hole 12 degree plate 44sbn’s are compared to the 760 3 hole carbs
I’m assuming the replacement is 15.0. The 44’ and 46’ replacements are 12’s. Most aftermarket 44-50mm carbs are 12
- Location
- Alaska
MTRHEAD
What was your final verdict on oem vs 8113 sbn38’s?
Trying to decide on which version for a 550 reed motor. I would rather have the quick acceleration than the ultimate top end.
Thanks,
What was your final verdict on oem vs 8113 sbn38’s?
Trying to decide on which version for a 550 reed motor. I would rather have the quick acceleration than the ultimate top end.
Thanks,
I haven’t made a manifold/speed plate yet.