CDI, Carbs or Timing?

[WaterX117]

I finally got my SN back together yeaterday. Having some bogging or almost shutting down when I hit full throttle. I am not hitting it for a half second until the ski is just falling on its face. I let off the throttle and pump it half throttle a couple times and it is fine again. Any ideas what may cause this? I know there are probably 50 things that could be the problem, but wanted to get your opinions. I was thinking it could be the jetting, the CDI or the timing. Here is what I have in the ski:

• 61X 701 (Mild porting to the cases)
• New Top End w/81.5mm Wiseco Pistons and all new gaskets and O-Rings
• R&D Head (185 compression both cylinders)
• Pro-Tec CDI with Rev limiter removed
• Electrical box, stator and start/stop assembly reworked by John at Jetskisolutions
• Timing advanced 3 degrees
• Single 44 Mikuni carb with Fly Flame arrestor (Not sure of the jetting)
• Factory Dry Pipe
• X-Metal Waterbox w/Dual Exhaust (By the way, you can hear me a mile away...AWESOME)
• Water routing is one into the pipe and one into the exhaust manifold. One coming out of the pipe and two out of the head.
• New starter and new battery

 

[Matt_E]

Sounds like your popoff is too high, or your pilot too low, or both.

 

[Kaveman]

Have you ever run the ski in it's current setup? If so did you have this problem before?

 

[WaterX117]

New top end, porting and dual exhaust. Other than that, I ran it last year with the same setup.

 

[Matt_E]

The porting likely changed jetting requirements. Try a smaller popoff spring.

 

[WaterX117]

Thanks Matt. I will give that a try.

 

[#ZERO]

While you're changing the spring, remove the two screws on the valve body and pull your pilot, main, needle & seat and see what the numbers are?

So if you have to order jets you won't have to disassemble the carb twice. :biggrin:

 

[Matt_E]

Practice makes you quicker.

 

[ANT]

get a hold of whoever ported your motor and get some jetting specs.

 

[Jr.]

Look at what changes were made since the teardown?
What ever you changed would be the first suspect.
I don't belive that case porting alone on a 61x case would affect the jetting that drastic, for a single carb set-up. An easy test would be to open the High adjuster a full turn. Then re-test?
If you see an improvment, jetting would be the culprit
Don't count out your electrical system! Several of the components mentioned, have been altered. Those are easily suspect as well.

ski ya, Paul