300/440/550 Is My Carb the Devil

[Mag]

Just brought an '89 650 back to life, it has all the bolt on mods you could ask for except intake. I think the stock carb is a 28mm But not sure. As soon as I can get an intake mani that will accept a bigger carb it is gone but for now it's what I have.
No matter what I do I can not get this thing dialed in. It will run great for a while then either starve for fuel or flood. The screws aren't moving, I really think this b!tch is possessed. Any ideas/experience?

 

[DoGoodDrugs]

First when you're adjusting the carbs did you remove the plastic caps so that you are turning the metal jet? If they aren't turning you can't turn it at all.

Did you check for air leaks?

 

[Mag]

Yeah, there are no caps on the screws and no fuel is leaking so I assume no air leaks. Also from my experience the motor will run on after you kill it when there is an air leak. This thing is pissing me off!

 

[DoGoodDrugs]

I'm thinking two things
First you have intermittent spark which is causing the flooding because it's not burning fuel.

Then you might have something in the carb that is keeping the fuel from getting through.

I don't really know but I'd start with those two things. Clean/Rebuild the carb, and make sure you're getting good constant spark.

 

[Mag]

Carb should be clean, I've had it apart about 20 times in the last 2 weeks.:17:
I'm not sure how I would test for intermittent spark. It always happens in the water, on the trailer it always sounds great.
Any ideas?
Thanks!

 

[jetski9010]

I dont know those 28 carbs that came with them real well but I would guess they are similar to a mikuni sbn. Does that carb take jets and pop off adjustments? If so what are you running right now.
If its to lean at low end but to rich at high end or some setup like that it will starv for fuel then flood itself out.

 

[Polish jet pilot]

Probably the seat and needle need repalcing as well as the othe rgaskets - not worth it. 28mm suck. Change to 44sbn and be happy till you sell the ski and get a Yami.

 

[DoGoodDrugs]

Any carb is going to better than that 28. It does have jets and I believe pop off adjustment like jetski9010 was saying. It is certainly not worth even the price of a rebuild kit. You could probably find one for free (I have one, should work, you pay shipping). A 44sbn would be the best route but if you can find a cheap 38mm keihn that would be a cheap and reasonable route to take.

 

[sflsurfrider]

i have an adaptor plate that lets you put a mikuni 44mm carb onto the stock keihin based manifold. youll have to open the manifold bore to 44mm with a dremel. $55 will get you the adaptor, hardware and two gaskets shipped to your door.

 

[flipside]

get a Yami.

:bananalama:

 

[Mag]

Yeah, 28 belongs on a lawn mower. I have a SBN 44 and a CDK 38 to slap on there. Hopefully on the way back home from OBX I'll stop in Chesapeake and get a mani that will work with them. It's good to know that I can bore the stock one out too.
I know I need to get this right and sell it so I can put the $ towards an SJ.
Thanks for all the help! If this doesn't work I'll be taking ya up on the offers.
I seriously appreciate it. Except for that flipside dude, WTF is his problem?