I need help! Tired of having a turd.

superjetguy

superjetguy

It's hard to speak without a tongue.
Location
lake hogan
Guys, some of you know i haven't had the best of luck this year with two top ends toasted on my superjet. Most recently my carbs developed a leak and toasted my pistons and I ended up loosing a circlip also. So I got a new to me cylinder and new Pistons from the buzzard and slapped it together, I rebuilt my carbs and changed jetting. I believe it's 135/70 popoff is 55 psi on both, screws are 1.5 on bottom and 1 on top or something close. It is running horrible, bog off bottom and seems boggy everywhere. Compression is great at 190 I'm running 100 octane with Lucas 40:1 mix. I just want some suggestions on what to set jetting to or even my screws. Thanks.
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superjetguy

superjetguy

It's hard to speak without a tongue.
Location
lake hogan
Actually okay that was dramatic. It's not horrible. It just doesn't seem like it's a modded 701, it feels like a stock ski with a bottom end bog.
 
Pablo

Pablo

sqeez bth levrs & lean bk
Site Supporter
Location
georgia
Aggravating for sure. Make sure pop off is correct before u proceed and then use the carb-spec database thread for starting points. The low and high speed adjustments are just a matter of an hours worth of tuning at the water. If uve changed out that many parts on ur ski already I'm sure u can handle the carb tuning. Its a worthwhile process and adds to ur own basic knowledge of how ur ski works.

Seriously.
 
Blue

Blue

Judging your cheapness
Location
St Cloud Florida
If ur running 38mm carbs ur way off. With just a b pipe u should have 75 pilot 135 main. With ported topend ur popoff needs to be closer to 40 psi. Start screws at 1 low 1.5 high. Your bog off bottom is because u are super lean.
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
With my TLR cylinders and OEM 38's I had to run 105 low speed jetting. Every port setup is different. but your way to lean with that 70. I would try an 80 and go from there.
 
TheCoz43

TheCoz43

Jet Surfer
Location
Pismo Beach, CA
Jetmaniac helps me out. I have very similar set up. Also as blue stated above 135 or 137.5 main jets. 75 pilot. 1 turn low Speed and 1.5 high for a good starting point. Also 115 g spring with stock flame arrestors.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
superjetguy said:
Is it best to change jetting first then popoff or all at once and go from there?
Click to expand...

Its best to change only one setting at a time. Go in the order the mikuni manual says.

Low screw, pilot, popoff, main, high screw. You may go back a step or 2 but don't skip steps going forward. Again, one change at a time.

I would suggest starting with my jetting. It may not be right for you but its richer and it's always safer to start richer then lean it out.
 
superjetguy

superjetguy

It's hard to speak without a tongue.
Location
lake hogan
okay i finally just got my carbs off, the screws were 1 on low speed 1.5 on high speed. the jetting is 75/135. i tested popoff and both carbs were leaking at around 30psi, pressing down the needles didnt help so i took out the needle seats and replaced the o rings. the leak was solved and the popoff is 54 on both. ill test soon with the 135s and jetmaniac just sent me some new high speed jets so ill get out and test once i get my back healed up. hoping to be out for pismo
 
superjetguy

superjetguy

It's hard to speak without a tongue.
Location
lake hogan
Guys, what's a better staring point 135 or 140? And how do you guys swap jets, removing the carb and replacing gasket every time? or taking the engine out?
 
Blue

Blue

Judging your cheapness
Location
St Cloud Florida
Just did a couple 2013 SJ's with
Ported cyl
Bpipe
Msd
Dual 38mm carbs
75 pilot
137.5 mains
Popoff 42 psi
1 turn low screw
1.5 turn high
Perfect
 
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