I’m stuck I have 02 701 superjet with aftermarket f/a , bpipe 135 main stock pilot 1.5 needle 115 g spring with stock popoff of 55. I have lean hesitation just off idle and I know I need to lower popoff to correct. just rebuilt carbs with oem parts and checked popoff with mikuni popoff gauge and its 55. Changed to 95g spring and it’s at 25 psi. With 65 g spring it’s at 15. I’m super confused as it should be at 43psi with 95g spring which is what I’m going for. Took several readings just to make sure. Any thoughts? The only thing that’s not been replaced is 1.5 needle but I doubt it would be that off. Not sure what to try as I ran it at 25 psi popoff and it was not good even with playing with low jet. Appreciate any help
Superjet popoff dilemma..stuck
- Thread starter Tjenk455
- Start date
- Location
- Charlotte, NC
Did you lubricate the needle and seat between checking pressure? Thats what it sounds like is happening. Wd40 works well. Open the seat and spray a little lubricant down the needle and seat before each test. Definitely wont get proper readings without doing that. Also you didnt mention your pilot jet size. You should be at 75 pilot with dual 38s and a factory pipe. Your pilot and popoff work together on the low end. Also worth noting that sometimes the springs need a little stretching to read the same psi that the manual says. You should be good if the pressure is within 2 or so psi + or -
I also had the same issue. I used 95g springs and I was getting about the same pop off. I have about 8 spare fulcrum arms and each one produced different results. I’ve never bent the arms but it seems as some get bent somehow. I was able to find a couple arms that sit flush when seated (parallel) when looking at the carb from the side and they both pop around 32psi.
Thanks for the reply! I did use wd40 each time to lube the needle and took at least 3 readings. I currently have a stock 70 pilot jet and was gonna try to get to a 43 psi popoff first and see how it ran. good to know about the springs I’ll try and stretch the 95g spring and bend the arm to try and get close to 40. I was worried that something else may be going on that would get my popoff so far off what the manual,says it should read. or should I try to get around 32 and change the pilot to 75?
I am not your guy for Popoff or carb tuning lol I was just letting you know I had the same issue. I have read that it could be a multitude of things ranging from springs being iffy, arms being bent, needles not being wet, Popoff gauges being off, etc etc. I don’t currently have a running ski to tell you if 32psi Popoff works for a 701 bpipe, head, etc. because my motor is being rebuilt.
- Location
- Charlotte, NC
The only reason you would need to lower the popoff from stock 55psi is if you install open filter style flame arrestors. The 95g spring would be the go to. If you're running a 70 pilot I would suggest going to a 75 pilot and 95g spring and it should be good. If going with the stock arrestor, run the 115g spring.