sbt 760 idles good, will not accelerate

[stevee]

new parts:
* pulser & charge coil
* spark coil
* sbt engine

starts good, idles OK.
will accelerate to ~9mph then dies
then starts right up

recent problem. machine ran great, then the above

any suggestions?
carbs?
cdi?
regulator?

steve

[Technical Support]

Re: sbt 760 idles good, will not accelerate

Rebuild the carbs, check the reeds.

[David3aces]

Re: sbt 760 idles good, will not accelerate

Look for water in fuel filter. if found, Clean carbs, fuel lines, and gas tank, and your gas cans................

[stevee]

Re: sbt 760 idles good, will not accelerate

OK then, I installed new mikuni carbs (44mm I believe) and power reeds (carbon fiber)!

I removed the old jets (both low and high) from the old carbs and installed them in the new carbs. I had a stuck needle jet that I fixed. It was dumping lots of gas so I guess that this would indicate that I did not have a fuel restriction.

Next, I set the low and high speed adjusters per the book (1 & 1/2 turns low and 1/2 a turn high). It started right up. I tested in the lake. As before, the engine would not take off. The best I could get was 9 to 11 mph.

The only things that are not new are, CDI, regulator/rectifyer, start switch, and thermo switch.

I did try turning the low speed adjuster in 1/4 turn. It then was hard to start. By the time I got it started, the battery was dead and I had to leave. I charged the battery and will try something next weekend.

What should I try next?

thanks,
steve

[Technical Support]

Re: sbt 760 idles good, will not accelerate

Are these Yamaha carbs specifically for this model or what? Where did you get them and what is the part number?

[stevee]

Re: sbt 760 idles good, will not accelerate

these are 44 mm Mikuni replacement carbs. I used my old jets. They came from the jetskimechanic.com.

[Technical Support]

Re: sbt 760 idles good, will not accelerate

Well, I have no idea what they are or what condition they are in, but if they aren't the correct OEM parts, I can't tell you where they need to be tuned, if you can't tune them yourself. I would contact jetskimechanic and see what he suggests, he's the only one that knows what he sold you.

[stevee]

Re: sbt 760 idles good, will not accelerate

These are new SBN44 Mikuni OEM replacement carbs specifically for yamaha jetskis.

Do you think electronics would cause this problem?
I installed a pulse and charge coil assembly because I did not have a spark. I then installed a spark coil because I had a weak spark. Could a CDI unit cause this problem (will not accelerate, idles good)?

[Technical Support]

Re: sbt 760 idles good, will not accelerate

It's possible, yes. Unfortunately the only way to find ou is to swap the CDI.

[stevee]

Re: sbt 760 idles good, will not accelerate

It runs now. The problem was broken wires from the pulse and charge coils. They were damaged by the flywheel. It was my fault for not installing the wire harness hold down plate on the inside of the timing cover. This plate was not secured and fell out when I originally removed the timing cover. So, I soldered the broken wires then installed the hold-down plate and reinstalled timing cover. It ran great for about 10 minutes then quit. The oil gage was flashing but the tank was full. I guess that the sending unit quit. No matter, I will install a block off kit and use premix.

My question is, if the oil level sending unit quits and shows no oil, will it shut-down the engine (I think that it will but am not sure)? If so, how do I disable the oil gage circuit? If not what should I check next?