300/440/550 help/ problems

[the flying dutchman]

ok here is my problem i have a 1990 550sx with the pp motor it blew up. i had another ski before that that was all built up pjs reed motor that had the msd total loss on it when it quit working we tore it apart and found that the problem with it was the magneto behind the flywheel was broke, so since that motor was good we went ahead and put it over into the 1990 550sx hull using its electronics and stock flywheel to make it reliable? but we also took of the revlimiter. so anyways the ski runs great and sounds like a bat out of hell hooked up to water in the driveway but as soon as you put it in the water and get it under a load is just bogs around wont even go fast.

any ideas would help we have checked several things (cracked reeds compression ect) aslo this motor has dual carbs

thanks guys hope i explaned it good enough

 

[303550]

i have limited experience with stand-ups..been riding and tinkering for 2-3 years, but from my experience with 2-cycles in general i am guessing that if it dies under load, it's dumping too much fuel into the carb(s). that's where i would start, but it could be a hundred things. hopefully someone a lot more knowledgeable than me jumps in.

 

[the flying dutchman]

i have limited experience with stand-ups..been riding and tinkering for 2-3 years, but from my experience with 2-cycles in general i am guessing that if it dies under load, it's dumping too much fuel into the carb(s). that's where i would start, but it could be a hundred things. hopefully someone a lot more knowledgeable than me jumps in.

thanks man, its just something so simple im sure of we have rebulit carbs and everything and adjisted them everyway you can amagine

 

[Big Kahuna]

I would guess too rich also. Did you use your carbs from your PP motor or the carbs that you had on the PJS Motor? If PJS Motor, with the Total Loss you would have been able to burn the richer mixture. With the stock ignition not so much.

 

[the flying dutchman]

no the carbs that were on the pjs it was orignally running 110 octaine fuel, and i have still tryed to use that in it? actually i think ive tryed both 93 pump gas and 110 and doing that 50/50 also?

 

[N2 H2O]

Check your compression before you do anything. You need to be running race gas if your much over 180psi. I would bet it's the carbs too. Try turning the adjustment screws in in 1/4 turn increments and see if it gets any better. The total loss has a stronger and hotter spark, so it burns more fuel. The stock ignition has a weaker and cooler spark, which burns less fuel, so you are running rich.

 

[the flying dutchman]

so you are saying i should be runing the msd to make it run right? what about timing?
also have i explaned everything about the ski good enough

 

[N2 H2O]

The motor will run and burn fuel differently with the msd vs stock ignition. Either one is fine to run, but you will need to tune the ski differently for each one. What is your timing set at with the stock ignition?


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[Big Kahuna]

if your running the same carbs from the PJS Motor (I could not tell from your response), you need to try and lean it up. Also you need to check your compression and run octane levels that match your compression.