Imgoodatwhatido said:
yah i should have went over the engine before rippin it down the river.
Yep, that's the one thing you have to be careful about with a ski that has sat for any length of time. Carb diaphragms can be damaged/dry rotted, jets can be clogged, and if you're running ethanol fuel, it can undergo phase separation. Any of these issues can cause a lean condition or detonation. When you're running, if you hear ANY sound like marbles rattling around in the engine, you'd better back it off, that's detonation and if you continue to run like that, you will blow holes in pistons, I know, because I've done it.
I chopped the ski and the engine is sitting in the shop floor now. I suppose since its out im gonna go ahead an build the entire engine. I dont know that i wont have the ports cleaned up by my old race bike guy.
If you don't already have one, get a service manual for that engine, this will help the re-build go a lot easier.
Im DEFINITELY removing the oiling system and usin premix. I might even go up a jet size on the carbs and squeeze all i can out of it.
Smart move by going pre-mix. I don't trust an oil injection system. Get a block-off plate for the oil pump, and go with pre-mix. The only thing is that at idle, it will foul plugs more easily, but unless you're doing a lot of idling, like flounder trolling, you don't have to worry about that. The center carb jetting should be a little more rich than the other 2, as the center runs hottest, at least, that's how it was on the tigershark, I think the front carb was 105, the center was 135, and the pto carb was 120.
Be careful about jetting too rich, this can be just as bad as jetting too lean. If it's jetted too rich, you'll get excessive carbon deposits, and this can interfere with proper heat dispersion across the top of the piston, this can also lead to detonation issues. I would go with the factory jetting, if the high speed is adjustable, then give it an extra 1/8-1/4 turn on the adjustment. If it's a fixed setting, then, I would go up one jet size from factory. Again, be sure to do a throttle chop at WOT, pull the plugs, and carefully inspect them. This is the only way to get a TRUE reading of what's going on.
I am also gonna remove the intake and go with pod filters for each carb, and im gonna look at some after market exhaust options. This stock exhaust is huge and most of all its HEAVY as hell.
Don't use Pro-K flame arrestors with the clear plastic top. I've heard of instances where the suction actually caused this plastic piece to snap, and collapse, gagging the motor. It won't damage it, but if you're in a critical spot like a surf zone, inlet, or traversing some sharp turns, the last thing you want is for the motor to suddenly cut back, this leads to a loss of control. I ran the Pro-K arrestors on my tigershark, never had one collapse, but I heard of quite a few instances where they did.
Finally, if you're going with open stacks like that, you may need to adjust pop-off pressure in each carb (the manual will tell you exactly how to do this) With mine, I think we dialed it up to 21 PSI for the pop-off pressure.
As for the exhaust, yes, it is indeed quite heavy on all jet skis. It's a hollow-wall construction of cast aluminum, the hollow passages allow water to flow through to keep the head pipe cooled. Be careful with any modifications to the exhaust system, as the head pipe is constructed in a very specific manner for the proper amount of back-pressure, altering it in any way may not give you the results you're hoping for.
You may be able to find something like a Kaufman exhaust pipe, but be forewarned, they are expensive, and MUCH louder than the stock exhaust.
Yeah, that chopping and rumbling sounds cool at first, but try riding a couple of hours like that, you'll get tired of a loud exhaust system real quick! At one time, I had my Tigershark straight-piped. When I fired up at the ramp behind the restaurant, it would **** near rattle the giant pane glass windows, and you could just about hear it from one end of the inlet to the other!
If you want to tone it down a little, two things you can do are to build a rear swim/boarding platform like my boat, and make the jet tunnel large enough that even with the pump bolted in, there's enough room at the rear of it (right above the wear ring/stator assembly) to mount an exhaust flange, and run the exhaust into the tunnel. Put some rubber skirting around the back of it, like they do with the newer 4 stroke yamahas, you'll be amazed at what this will do to cut down on the noise.
For some ideas of the exhaust routing into the tunnel, you can check out some of my videos, it's clearly shown on one of our episodes of "American Jetboat" I think it's either episode 3 or 4.
