dual 44s on 701

fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
ive got a full 62t engine with dual 38s. a friend has a set of 44s to trade. its a stock 62t/62t engine for now with a c4 chamber bpipe. what carb settings should i start with on the 44s? i believe they are stock 44s off a 760
 
Quinc

Quinc

Buy a Superjet
Location
California
If the c4 pipe is your only mod keep the 38's. The 44's will make more power, but not worth the headache of tuning for the minimal gain you will see unless you are racing. However, once you upgrade to a zeel, porting, and reeds you should go with the 44's or 46's.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
yeah i have the 760 electronics just no zeel at the moment and the plan is for port job maybe in the fall. and more pression. an old friend had a jetworks ported 61x/62t engine with a bpipe and head with dual 44s and it ripped pretty hard. im aware the 38s will give a little better throttle response on the bottom. the only reason for doing this would be a free upgrade to 44s from the 38s
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
well i would be doing a trade for the complete setup. i do have another set of gold 38s that ive had for a few years i could put on if i dont like the 44s. i was gonna run the gold carbs to begin with but the mounting holes are not threaded like the oem 38s are and when i put it together i didnt have time to make the gold 38s work cause i was trying to get the ski together for daytona in jan. a friend is trying to get a raider running to sell and thats why he wants my 38s to trade for the 44s
 
S

Storbeck

Location
Minnesota
Just to throw this out there, the intake manifold is different between the two carb sizes if you're using oem Yamaha intake manifold.

So trade the whole setup if you're going to do the trade.
 
kevbo

kevbo

Location
dfw
Get the pump worked out first. Stock or standard SBN44s will make the pipe hit a little harder. Not difficult to tune but will require a little richer pilot/popoff setting than 38s.
 
S

Storbeck

Location
Minnesota
kevbo said:
Get the pump worked out first. Stock or standard SBN44s will make the pipe hit a little harder. Not difficult to tune but will require a little richer pilot/popoff setting than 38s.
Click to expand...

Not sure what you mean about the pilot/popoff...everything about the jetting will be completely different than the 38's, this is an obvious thing, no?
 
headshock

headshock

still doin it
Location
Norcal
Heres what I ran with Dual 44s on a 701 with a B Pipe.
H 145 - Start with 1.5 turns out and work from there
L 125 - 3/8 Turns
N/S 2.0 (Gold Spring) 19 PSI
 
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S

Storbeck

Location
Minnesota
headshock said:
Heres what I ran with Dual 44s on a 701 with a B Pipe.
H 145 - Start with 1.5 turns out and work from there
L 125 - 1/3/8 Turns
N/S 2.0 (Gold Spring) 19 PSI
Click to expand...

Are you sure? That seems way rich on the high speed, up in the neighborhood of what people run with single carbs.

I have not personally run these on a 701 but I'd be surprised if a 701 needs jetting that much richer than the 760ish motors that all seem to be in the 115high 125 low neighborhood.
 
kevbo

kevbo

Location
dfw
The specs above would be a good starting point. I used 140 mains and the top screw ended up a turn out with a stock F/A. Make sure you engine can get close to 7000rpm. Flame arresters can alter the main circuit greatly.
 
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W

waxhead

wannabe backflipper
Location
gold coast
Storbeck said:
A mikuni speed plate can make a 38mm hole in a 38mm manifold increase in diameter to 44mm???
Click to expand...
I have seen those and while they work as a cheap alternative, You are leaving horsepower on the table in my mind. My jetting spec listed above is for 760 44s.
Bear in mind there is 1000 different ways to skin a cat and other people have different tunes, my is just based on what works for me
 
kevbo

kevbo

Location
dfw
Power tune the main circuit and you will never burn a piston, unless you get too much air in the fuel line.
 
Quinc

Quinc

Buy a Superjet
Location
California
waxhead said:
125 low
115 high
2.3 needle and seat
115 gram spring
b-pipe with top two closed and bottom open 3/4
When you put the zeel in then move to a 130 low
Happy days
Click to expand...
waxhead said:
I have seen those and while they work as a cheap alternative, You are leaving horsepower on the table in my mind. My jetting spec listed above is for 760 44s.
Bear in mind there is 1000 different ways to skin a cat and other people have different tunes, my is just based on what works for me
Click to expand...


If you are lucky enough to get jetting/tuning advice from this ^ man you should follow it.

Also get one of these:
https://www.waxracingproducts.com/collections/yamaha-parts?page=2
 
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