1999 speedster questions

[yamaha188]

Just bought a 99 speedster and it has holes in the pipes. I removed them and will be getting them tig welded. I know the leaks can cause it not to run due to water on electrics, but a friend who owns a 96 speedster say's that the pipes somehow help push fuel to the carbs, sorry but cant see that. Could someone tell me how the fuel system works? i see the fuel pumps but was wondering how they work.

I also see alot of threads saying to remove the gray fuel lines, are these the fuel lines coming off the pumps and going into the front part of the motor and do you need to replace any other lines or filters on the fuel system.

Air filters, do you need to clean them, mine do have a little black sooty build up on them.

Fuel gauge does not work, does anyone have a link on how to fix it, i cant seem to find one that explains it.

Sorry for so many questions, but this is my first boat and would love to get it running ASAP. Thanks.

 

[racerxxx]

Just bought a 99 speedster and it has holes in the pipes. I removed them and will be getting them tig welded. I know the leaks can cause it not to run due to water on electrics, but a friend who owns a 96 speedster say's that the pipes somehow help push fuel to the carbs, sorry but cant see that. Could someone tell me how the fuel system works? i see the fuel pumps but was wondering how they work.

Not sure what your buddy has in his pipe, but you better tell him to stop smoking it, it's effecting his ability to think straight. The fuel pumps are driven by vacuum generated in the crank case, thru the pulse line, which operates the fuel pumps

I also see alot of threads saying to remove the gray fuel lines, are these the fuel lines coming off the pumps and going into the front part of the motor and do you need to replace any other lines or filters on the fuel system.
If you're talking about the pulse line you can inspect it/replace it, there is no fuel that goes through it, it's just a vacuum line to operate the fuel pumps. I don't think the jet boats have any gray line(other than the gray on the accelerator pump lines) that actually has fuel running through it that would clog the carbs up. You do need to remove the carbs and clean them/rebuild them, the jet boats take a thicker carb to manifold gasket. You want to look for any green goop, if you see it replace the lines in the fuel system, it wouldn't hurt to do it anyway I guess. About 12" out of the top of the fuel baffle there should be two white fuel filters. They are no longer available. A lot of guys use the Fram G2 filters, just make sure it fits the 5/16 fuel lines.

Air filters, do you need to clean them, mine do have a little black sooty build up on them.
You can remove the flame arrestor and spray it down with carb cleaner real good and let it dry out.

Fuel gauge does not work, does anyone have a link on how to fix it, i cant seem to find one that explains it.

It's probably the fuel float has dropped its magnets. Just do asearch here for fuel float replacement of fuel baffle repair.

Good luck with the boat!

 

[USAF_Pride]

Just bought a 99 speedster and it has holes in the pipes. I removed them and will be getting them tig welded. I know the leaks can cause it not to run due to water on electrics, but a friend who owns a 96 speedster say's that the pipes somehow help push fuel to the carbs, sorry but cant see that. Could someone tell me how the fuel system works? i see the fuel pumps but was wondering how they work.

What your buddy is probably thinking is that the tuned pipe creates a pressure differential that helps pull the fuel/air mixture into the cylinders (not the carbs). Read Section 4, Subsection 5 of the shop manual (Engine Description) in the shop manual for more details (or any 2-stroke motor operation theory)

From Factory Pipe

The purpose of an "expansion chamber" is to return to the exhaust port a negative sound wave then a positive sound wave at precisely the right time. If the pressure wave returns too late, you lose some of the fresh fuel charge in the combustion chamber and performance. If the wave returns too soon, it pushes hot exhaust gas back into the combustion chamber contaminating the fresh charge and creating hot spots on the piston.

Another Link with pictures.