Super Jet Carb pop off suggestion

[jeremy chambon]

I have a 61x/61x stock port current set up is a single 44 with a 1.5 needle. At the end of the year last year I was having pop of issues and end setting the carb up for 12psiif I recall correctly. Everyone is saying that was really low for a motor with just a b pipe. So I took the fly wheel cover off and I could smell gas. I'm putting new crank seals in this week and don't know where to set my carb back to. So what's your set up?

 

[Westcoaster]

12 psi is low. You typically want to keep pop off around 25-35psi. That coupled with the below info should get you close.

Stock 701, single carb settings:
115 Pilot jet
135 Main jet
Low speed screw 1 7/8 +/- 1/4 turn
High speed screw 1 5/8 +/- 1/4 turn
Needle 1.5mm (90 gram spring?)

701, sing carb with Factory pipe (see page 3) http://www.factorypipe.com/media/instructions/yamaha/701SJ01.pdf
120 Pilot jet
140 Main jet

 

[Vumad]

Think of the popoff as a mind range jet and tune accordingly. My Superjet with dual 38s runs amazing at 18psi. We were tuning ryans x2 and gained power increasing from 18 to 24.

Popoff is too low if you...
Drip from the Venturi at idle
Have rich bog around 1/3
Leaks when the tank is pressurized.

Try various pop-off from 18-35 with various low speed jets. From what I read, the bn carbs had weaker fuel pumps than sbn carbs and 12 is too low for a sbn.

 

[jeremy chambon]

Well I'm running 12 and it ran crisp since my stator side was leaking I didn't have as much crank case pressure to work with I had to be low and when I got a run away I knew I had a seal going bad.

 

[Vumad]

Well I'm running 12 and it ran crisp since my stator side was leaking I didn't have as much crank case pressure to work with I had to be low and when I got a run away I knew I had a seal going bad.

If you were running a single carb, and one side of your engine was failing while the other was not, you could not have had "crisp". You may have had something that seemed acceptable to you, but the potential was likely not achieved. One cylinder had to be very rich to make up for the other being lean.

How did you obtain a pop-off of 12? How did you check it? You can not get a pop-off of 12 with a 1.5 n&s. a 1.5 with a 65 only gets you to 32. A 2.5 with a 65 would get you 12. Maybe you should recheck your seat and see what size you actually have.

 

[jeremy chambon]

I'm sure it's a 1.5. I went through the whole box of springs of the dude that run wave rave last year and only one spring got me that low and looking at the chart it says it wasn't possible. But it got checked many of times and got a lot of springs the same color put in it and we could get a diffent pressure every time. Not sure what's up but it ran good but I'm headed to MC in two weeks and need to get it close enough I can mess with it on the beach.

 

[fatboyktm]

Set it up with a 125 pilot 130 main 95 gram spring and a 1.5 n/s set it at 1.5 on the high and low screws. That will be rock solid for MI