Super Jet Ski won't hold tune

[bondra131]

Been deal with this for a long time now... It isn't the carbs; I sent those to jet works and had them looked through, rebuilt and correctly jetted and set up for my build. I have tuned 5 times since then and I get it running great then go out riding the next day and it is instantly rich as can be... Hardly runs and I find fuel inside the engine compartment when this happens. I can lean out the low speed circuits and get it running well again for the day but the next time I ride... It's crap again. Only thing I can think of is an air leak but I can't imagine how this is possible since I thought I had an air leak, tore it down and found a bad crank seal. Did brand new seals yamaha brand ones and used yamabond on the cases and every single gasket on the motor is brand new. Yet still having head problems... Sometimes it idles down after a rev up out of the water, other times it holds it's rpm's for the most part and very slowly winds down and not to idle. This is when out of water. Another thing that says air leak to me but I can't imagine how . I literally tore it down THREE TIMES and resealed the cases. Twice with one set and then found stripped threads in a case bolt, bought new cases that are in very nice shape and all new gaskets again and it's still doing this bs... Anything else that it can be besides an air leak? I'm lost here and very frustrated. Haven't had a good running ski for two years now and I'm getting pissed lol

 

[Sanoman]

Run a pressure test on it

 

[Jp79]

I'll second the pressure test n have some soapy water is a spray bottle to give a squirt.

 

[bondra131]

I'm not set up for pressure testing and don't know what I'm don't with that at all..

 

[bondra131]

Don't know what I'm doing*

 

[SterlingSilva]

Pressure testing/leak down testing is part of building and re-building any 2-stroke motor.
I fought what I thought was bad carb tuning for a long time only to find out my cases werent holding a seal.

the needed parts can be found locally

heres a vid i found of a leak down test on a 750

 

[bondra131]

Ok thanks man!

 

[bondra131]

Too bad a tennis ball won't work on my big ass exhaust manifold lol will have to rig somethin else up

 

[SterlingSilva]

You can get rubber plugs from lowes or home depot. prob could lay a peice of rubber over the ex manifold opening and bolt the headpipe back on to pinch it.

 

[bondra131]

I have a dry pipe. Will have to find some rubber thing that will work for a plug. No big deal

 

[Balduccimoto]

I use plumbing test plugs. I have found at local home depot and ace hardwares. There was correct size for manifold opening and intake manifold to carb openings.

 

[masterblaster]

if you have resealed cases 3 times you have another issue,you could have a ignition issue,as heat builds,cdi,stator,among others can start working intermittently,causing a rich condition

 

[bondra131]

I do know that my stator does not charge my battery anymore... Battery goes dead every couple months so I keep putting a small charger on it after every ride now. I have no idea what to do here. Brand new motor and carbs. I've done so much work to this ski and it just does not run like it should... Ready to sell and buy a brand new ski