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Carb over feuling

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Bclark96

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Hello everyone. First time poster. I've owned my 94 GTX for a few years now, and I can't seem to get the carb adjustments right. I've had the engine out, and done a top end rebuild. I also rebuilt the carbs when it was out and replaced the fuel lines to prevent filter gumming. The problem is they seem to be getting fuel to the engine even with both low and high speed screws all the way in! And not a little fuel. There's quite a bit spraying out with the choke butterflies closed. I've removed both carbs (mikuni super bn38 sp) and I have one apart, and nothing is sticking out to me. The needle appears seated. I made sure pop off psi was perfect when I rebuilt them. The only thing I notice is excessive wear on the high speed screw, but I can't imagine this is causing fuel to be spilling into the engine. It's soaking the spark plugs as well (I have spark). I want to rebuild these again, I'm just afraid I might have the same problem. Is there something else I should be looking for?
 
Sounds like you used aftermarket parts on the rebuild, and fuel is just peculating in. Make sure the needle, seat, spring, and diaphragm are all oem parts.
 
I absolutely did. I suppose I should go OEM. I just thought $50 per carb was a bit much, and I couldn't find it any cheaper. Before, it would idle just fine. Give it full throttle and it was so sporadic. Power, nosedive, power, nosedive, etc. I guess I'll source out an OEM kit, new OEM needle/spring/seat, and replace the low/high speed adjuster needles as well. If there's any recommendations for good places to buy, please let me know. Thanks for the reply.
 
In pricing out rebuild kits, new 2.0 needle valve/seats, low/high speed adjusters, low (65)/high (107.5) speed jets. Two of everything and genuine Mikuni comes to about $160. Sound about right?
 
Not a problem. I'd rather do it right. I should have known the first time. I'll clean, rebuild, sync, and see where that gets me.
 
OK. Update. Just got back from the first run.

Carbs were rebuilt with genuine Mikuni parts. In addition, both low/high speed adjusters were replaced. As well as pilot and main jets and needle/seats. Popoff PSI was set to ~25psi (cut springs. Had no choice. All springs I had were either over 30psi or under 20psi.) All fuel lines replaced, vent check valve was de-gunked and tested with my PSI gauge. Synced carbs using the light method.

Thing idles great. Seems to not skip a beat through 1/4-1/2 throttle. Runs like a top.

Anything past 1/2 throttle and it's a bit wonky. High speed adjusters were pre adjusted by me on the bench at 3/8 turn out (as is stock setting). It didn't run bad, but I felt it could run better. I read that most of these come preset turned in all the way at 0, so I gave that a shot. Thing ran much better. But it was very inconsistent after it warmed up. At times it would just bog down (too much fuel) and the speedo wouldn't go past 15mph at WOT. It actually stayed that way for about 20 minutes and then it seemed to clear itself out a little bit. The speedo never went past 40mph (I feel like it has a lot more in it than that) and it wouldn't stay there. It would bog a tad, then pick up, etc.

So I get her home and pull the plugs. Black and wet. Running rich. My question is: How can I correct this when my high speed adjusters are leaned all the way in? Do I need to buy new factory springs, remove the carbs, and reset my pop off psi? Spec says 22-29psi, and mine are at 25psi. And if so, what color spring should I buy? Gold?

Any help is appreciated. Sorry for the long post. The kids want to go tubing, lol.
 
Never ever cut the springs, that is the wrong way to do it. Get the correct springs before you do anything else, including riding it again.
 
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