Blaster won't run...HELP!

[tuneman]

First person to figure this out gets a billion high fives from me. My WB1 won't start only when I climb aboard. Runs great on the trailer and on the trailer while in the water. It also starts and runs fine with me standing next to it and twirling around as it runs.

As soon as I climb aboard, it won't start. I can climb right back off and after just a couple seconds of cranking it'll fire back up. I looks like I'm getting a bit of water in the cylinders, but from where?

The engine is new and the pipe is new-to-me but used.

- Waveblaster 1 with Carter B rocker
- Engine is JM Big Bore 790
- FPP Waveblaster Limited
- Ex. Manifold decked, bored to 51mm by Blue and new seals
- Dual 38mm carbs
- flow control valve installed
- Water lines plumbed correctly and verified by Blue
- stock waterbox
- Leak down tested by Blue and myself
- cooling system tested at 10psi for 5min

Thinking of getting a new waterbox to test, but I can't see how that could be it. I have pulled box, checked flow with shop vac and no rattles from a loose baffle.

Ski barely tips back when I get on and sinks maybe 2 inches. I've tried leaning forward and back to see if it changes anything, but no.

Any guesses?

 

[tuneman]

I should add, headpipe screws are currently: top and mid closed, bottom at half turn. I've also had top and bottom screws at 1/2 turn, mid closed. Same no-start issue and water getting in cylinders.

 

[TheBuzzard]

water could be getting in the cylinders from a pinched head Oring
since its a big bore, water could be getting in where the sleeves meet the exhaust ports, if it was done wrong or over ported.
I had a cdi going out one time ,where it would start when you let off the green button.
sometimes it would start in the water and sometimes it wouldn't. especially if the prop was under a load.

 

[Quinc]

I had a similiar issue once and it was the reeds.

 

[tuneman]

Could be a Lean Condition. Richen(open) the Low Speed Adjusters by 1/2 turn and tell us what happens.

The Primer Piston maybe leaking air into the fuel line. Disconnect and plug primer tap, then test engine without primer system hooked-up.

Check the Fuel Tank Fuel Pickups, Fuel Lines and Fuel Filter. Did you rebuild the Carbs and jet to Jetmaniac,s specs?

Interesting, I'll check, but my primer is the main pickup straight from the tank. It's not tapped into the fuel line. The reserve pickup is going to the carbs. Main pickup was exended. New filters and lines, but I'll double check the pickups.

I'll also check the reeds. They are almost new carbon V2 reeds, but do have a couple hours of use on them. Maybe something odd happened to them.

Thanks guys, keep the ideas coming.