300/440/550 550js Nightmare! - Rebuilt motor now won't rev past half throttle

L

ladmozx

Location
Folsom, CA
Ok so in a nutshell my neighbor bought a couple 550's and it has been a nightmare trying to get them to run. I'll focus on just one of them right now since it's the closest one I've got to running. Basically I'll just say what I've done already and hopefully someone knows how to fix this. The ski is an 88 with a 550 piston port motor.

It all started with just rebuilding the carb in an attempt to get it running until I found out the crank seals were bad. Tore apart whole motor, replaced all the crank seals and put fresh gaskets on everything and even replaced the rings. Used Permatex copper gasket sealer on the head gasket, base gasket, and all the exhaust gaskets. All still stock exhaust. Used regular red permatex gasket sealer on all the intake gaskets. Like i said the carb has already been rebuilt as well which is a stock BN44. All the fuel likes have been replaced as well as the pulse line and I even bypassed the petcock selector for reserve or main just in case it's leaking. Checked the check valve and its operating correctly.

Got it all back together and went out to the lake yesterday and no matter what I do with the settings on the jets it will not rev past half throttle and if i try holding it past half throttle it will just bog down and shut off. It will fire up and idle, but acts like its leaning out past half throttle. I've tried setting everything back at factory settings for the carb and no change. I looked around online and some people say timing could do this which I set back to what it was at before I tore the motor apart, or it could be something with the restrictor for the fuel return. It currently has the factory inline restrictor with that little hose that runs to the side of the carb. Can those go bad?

I really hope someone can point me in the right direction cuz at this point I'm about to set the damn thing on fire and watch it sink. I've got a 750, 650, 440, and a 300 and have never had so many issues one after another, but of course it has to go that way when you are trying to help someone else out right? The ironic thing is he bought the 750 I now own with the 2 550's and the 750 fired right up after a carb rebuild and the 2 550's have been a total nightmare to get running lol
 
stagesrt4

stagesrt4

see ya out there
Site Supporter
Location
St Charles IL
keep n eye on the fuel filter...is it staying full of fuel?

sounds like carb is getting starved of fuel....

still have the rev limiter installed?...if not you have to run a fuel restrictor in the line
 
b.lee

b.lee

Team Cheeseburger
Location
Lapeer County, MI
Ya I'd bypass the fuel filter temporarily... or get a new one and put it in.

The the 44bn's are crap, maybe swap it out with a known good carb? I'm sure someone in your area has one they could let you borrow or rent for the day
 
L

ladmozx

Location
Folsom, CA
Good call on the fuel filter. I'll give that a shot along with bypassing the stock fuel restrictor with a .030 welding tip when I get home. Now that I recall I remember on my 440 I had a similar issue with the fuel filter, but I just reseated it and problem solved. Is there anything special about the factory fuel filter other then the fact it filters fuel? I'd assume I could just use any in-line fuel filter.
 
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Quinc

Quinc

Buy a Superjet
Location
California
Bypass the switch too and run the lines directly to the carb with an inline filter. Don't forget to hook your restricter up. Once you have that done, start with your hi/lo screws turned all the way out and back in the low tell she idles than back the hi in a little at a time tell you get where you want it.
 
L

ladmozx

Location
Folsom, CA
Ok, so I bypassed the factory fuel filter and factory rev limiter by installing a .030 welding tip inline with the return and I finally got a chance to goto the lake today and the problem only seemed to be worse. Now it won't even idle. I can get it to run by giving the primer a couple squirts, but then it will only run if I give it a little gas and then it just sputters out. What else could it be? I've rebuilt the motor, rebuilt the carb, bypassed all factory fuel selector :):):):) and ran brand new lines, replaced the check valve, new spark plugs, and I'm still no closer to getting this thing running then I was day one. I know everything is working as far as fuel goes at this point because I put clear fuel lines on it and I can see fuel going to the carb and coming out of the return back to the tank. Only other thing I could think of is there is something wrong with the carb or maybe the CDI box? I've got another 550 to swap parts with, but I never got that one running either because it was even more of a basket case, although I did rebuilt its carb before just putting it on the back burner and focusing on the one I could actually get to fire. Any other suggestions?
 
L

ladmozx

Location
Folsom, CA
Ok so it did end up being something with the carb. I took the carb off the other 550 he has and was able to get it to fire right up and got it out on the water the other day to tune it and now she rips.

I think you may be right screaming440 about the pop-off pressure on the non-working carb. When I rebuilt the carbs I just stuck whatever spring that was originally in the carb back in because I didn't have a pop-off gauge to properly measure it and didn't know until yesterday you could just build one for a 1/4 of the price of buying the $50 one online. Now armed with this knowledge hopefully that's all it is with that carb and then after making the tool I can now have the ability to properly tune the carbs in my ski's :cool2:
 
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