Superjet 650 not Restarting

[rob2337]

Hi Guys,
New to stand-ups but not PWCs and just bought a SN 650. The ski has me pulling out my hair with the issues it has. The latest is that it never started easily when stopped in the water. I need to crank for a while and play with the throttle or let it sit for 15Min. It seems like it is flooding out when I kill it and is way too rich to start. So Far I have checked the following:
- rebuilt carb with pop off at 40psi.
- bought a new OEM mikuni stock superjet 650 carb as I was still convinced it was a carb issue.
- swapped CDI
- checked stator resistance
- compression is 150
- checked reeds
- checked spark.. seems good even when it doesn’t want to start
- new plugs
- check the fuel tank vent
- went really lean on the low screw which helped the restart but creates a hesitation on acceleration
- have a primer installed and when it doesn’t like to start, if I give it a pump it is way worse so this is why I am thinking it is too rich to start.
- stock engine as far as I can see and stock air box.
I haven’t check for an air leak, it seems complicated to do in place, but that might be my next step if I can’t find anything else wrong.
Really appreciate any suggestions....

 

[john zigler]

Yamaha's are typically VERY easy starting, especially with the carb tuned correctly. At 1st I would have guessed you have a carb / fuel issue, but with you saying you have a NEW oe carb, I am guessing you are good there.

We see many issues with old Yamaha's with ignition coils being weak, bad plug boots, etc.

I would start by changing out the plug boots, use MSD crimp on type. "IF" you have an old coil with the inner wire not being a solid core type wire, I would for sure swap the coil out.

Gap your spark plugs at .0022 to .0024

Please report back.

 

[rob2337]

I have the MSD crimp boots already installed. Primary coil resistance checks out from boot to boot. Gap was .030 so I regapped them to to your suggestion. I’ll try again at the lake but I am thinking there is something else going on. I forgot to mention that it won’t idle well in the water and eventually die out unless I crank up the idle stopper. Start stop and idle on hose are perfect. It will however run for an entire tank of gas as long as I don’t kill it or the idle drops to the point that it stalls. I feel that I am getting too much fuel at idle, but after rebuilding the first carb, then replacing it with a new OEM one I am at a loss.

 

[john zigler]

It should idle smooth in the water. Sounds like your carb tune is off.... You cannot tune out of the water as the engine is not underload like in the water.

 

[rob2337]

Ok, I finally found the issue. When I first inspected the reeds, I only looked quickly at the pedals. Since I was still having major issues, I decided to pull the reeds again and look closer. I finally found that the gaskets between the reed cage and manifold had blown out on both cylinders creating a small air by-pass of the reeds. New gaskets solved the issue and now it starts and restarts very easily.