300/440/550 Hose hookups and aftermarket carb questions...

[kmfs91]

Hey guys, I gotta couple questions. A buddy of mine recently offloaded a 1980-somethin JS550 basketcase project onto me. I think it's a mid 80's (85 or 86 maybe?) because it has the big sqaure expansion chamber with JetPower 550 stamped on it. I used to have an 84 JS550 years ago and it was a damn solid ski for years until one day the electronics took a dump on me. I was too young to really every wrench on it aside from spark plugs, I just put gas in it and rode the hell out of it. Actually, I never really had an excuse to wrench on it, it just always ran.

It looks like absolute hell and is all torn apart, but I figured I'd make sure it runs before I put all sorts of effort into making it look good. I dropped the motor back in yesterday, filled the fuel filter, dropped a little gas in the carb, and it would fire continously, so I think if I hooked the tank all up and spent some time with it, it would be a runner.

It had an aftermarket BCW racing carb on it, but I slapped the stock carb back on for ease of getting it running. But after seeing how much bigger the throttle bore is on the aftermarket carb, I'd like to try and get it running with that.

From my understanding, the kid my buddy bought the ski from put the aftermarket carb on it, and then never could quite get it to run right. I've never dealt with tuning carbs, so I'm gonna need some help here.

I also have a few water line questions. There's two hoses running into/out of the elbow in the exhaust that connects the exhaust manifold to the expansion chamber, as you probably all know. I'm pretty sure the bottom run ran to the head, based the the color of the pieces of hose left on each connection. But, I don't know where the smaller top hose leads to off the elbow. I can get pics if needed...

Also, the pisser on the side of the hull still has the hose connected to it, but I can't figure out where the other end hooks up. Any ideas?

Sorry for the rambling, I just wanna knock everything out at once and get this thing on the water. I miss ridin a standup, a sitdown ski gets boring after a while!

Any help would be great, thanks!

 

[vrizi]

on the square jet power exhaust, there was a fitting on the top at the back of the exhaust,(pointing towards the tray) that went to the pisser. The fitting at the back of the manifold, goes to the pump, and the fitting at the expansion chamber goes to the head. those should be the only fittings, anything else would have been added by a previous owner. There should also be a threaded hole towards the front of the "square" with a square head bolt in it. No need to worry about this it goes nowhere, it is suposed to be blocked off. As far as the carb goes,... sorry can't help you there,... the only carbs I have delt with are the bn carbs.

 

[kmfs91]

OK, I think I got it now... But what's throwin me off is the fact that the tubing coming off the pisser is/was completely different than the little piece that was left on the fitting at the top of the elbow. And the little bolt at the front of the chamber is still there, so I won't worry about that.

 

[maddmatt02]

mine has the big square jet power exhaust setup, and the top line from the elbow is to the pisser and the lower line goes to the head.

 

[kmfs91]

Hmm, I guess it does go to the pisser! It's just off having two different kinds of hose... oh well!

 

[cookn]

post some pics of your carbs and motor. I have never heard of the aftermarket carb. I have had good luck with the mikuni sbn44 on the 550. The hose coming out of the jetpower exhaust to the pisser should be the size of fuel line and the rest is the bigger stuff.

 

[kmfs91]

Well I actually just noticed the aftermarket carb has MIKUNI stamped on the side of the bore as well.

I'll get some pics here soon, but you've been warned, it ain't gonna be pretty :biggrin: