Super Jet Superjet low end bog

I've owned this Superjet for about a week now and have ran roughly 20 gallons through it with absolutely zero issues. No hesitation what so ever.

mods are LPW ported 760, Ada head, protec cdi, JetManiac Yamasaki coil, stock flywheel, etc.

Issue 1.
I put 5 gallons through it today without an issue. I went out again and noticed that it would slightly bog right off idle but only off of idle. Ones the RPMs came up it was fine. So I take it in and change plugs ( they looked perfect) and same thing.

Issue 2
I put it on the trailer, cranked it over for 5 seconds, no start.
I try again and it immediately red lines and runs away. I freak, pull plug wires, and pull off a fuel line and it finally shut off after about 15 seconds.

WTF is going on?
 
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I've owned this Superjet for about a week now and have ran roughly 20 gallons through it with absolutely zero issues. No hesitation what so ever.

mods are LPW ported 760, Ada head, protec cdi, JetManiac Yamasaki coil, stock flywheel, etc.

Issue 1.
I put 5 gallons through it today without an issue. I went out again and noticed that it would slightly bog right off idle but only off of idle. Ones the RPMs came up it was fine. So I take it in and change plugs ( they looked perfect) and same thing.

Issue 2
I put it on the trailer, cranked it over for 5 seconds, no start.
I try again and it immediately red lines and runs away. I freak, pull plug wires, and pull off a fuel line and it finally shut off after about 15 seconds.

WTF is going on?

If it runs away again remember to hold the stop button and give it full throttle to kill it. Works way better than pulling plugs or fuel lines.
 
Without taking the carbs and manifold off I do not see any obvious leaks or cracked hoses.
the ski starts up fine in the garage. The only thing that sounds odd to me is when it starts, it almost has to "catch up" to idle.. It takes a second to get to its normal idle? Hmm.
 

yamanube

This Is The Way
Staff member
Location
Mandalor
You could definitely get a lean bog from an air leak, I would refrain from starting and messing around with it to much until you solve the issue or be prepared to shut it down the proper way (cut ignition, add much fuel, and/or choke the carb with something). If you don't have the money to rebuild the motor, pressure testing it is your best bet.
 
Started it up yesterday after sitting for a few days and it ran away again!!! As soon as it started it instantly red lined.
So i Just tore down my intake and i cant see any visual flaws in any of the gaskets. My reeds are perfect. Mating surfaces are flat, no burs, etc.
My plan is to replace all gaskets on the intake side then go from there..

Any other opinions?
 

Blue

Judging your cheapness
Location
St Cloud Florida
Typical air leaks are on the case halfs or the seals. Double check that the throttle is closing all the way and the cable is not to tight there should be a little slack in the cable.
 
Double check that the throttle is closing all the way and the cable is not to tight there should be a little slack in the cable.

The throttle is good.
I do not have the tools to do a leak down test. Where can i get them?
Like i said, I put hours on this stupid thing and it never even hiccuped. Out of know where i got the bog..
 
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