1997 gsx 787 help

[Seadogsx1997]

Hi i recently bought a1997 gsx 787 didnt run got it cheap got it home got it running in about an hour took it out had no power and very hard to start on water after it been running so took it off did a compression test mag piston was at 150 and pto at 60 so just did a top end rebuild all good took it out today and started ok started running in was running a bit laggy down low didnt idiol stalled had to keep revs up but was ok at revs brought it in after 15 mins plugs fouled so put new plugs in wpuld start had to lift back of ski out of water to start ran ok up high when took it back out did another 45 mins on it still bad on low revs and want start without cleaning plugs heating up and back of ski out of water good compression on both

 

[tobytd]

what were the comperssion test results after rebuild?

 

[Seadogsx1997]

engine was warm when i did it and both were 140

 

[etemplet]

I would begin by checking for carb issues or fuel delivery. Fouling plugs in my experience is running rich. What color are the plugs and is it one or both cylinders??

 

[Seadogsx1997]

It was both both were black i also took toil pump off and blocked off running 40-1 i thought carby ill start there and hope it fixes it

 

[mikidymac]

Well first of all no reason to remove the oil injection on these.
Second if it doesn’t run correctly stop riding it or you’ll just do more damage as they never fix themselves by continuing to run them.

It is always the fuel system on these that cause your symptoms.

Replace all gray fuel lines with standard automotive fuel line. Rebuild the carbs with only genuine Mikuni kits and new needle and seats. Replace the fuel selector. Clean the fuel strainer and replace the o-ring. Unless you do this now you will just be chasing your tail.

You have to keep the oil tank and oil in it for the rotary valve even if you run premix. And mix at 32:1.

What is your compression now? You might have already toasted that new top end.

 

[etemplet]

It was both both were black i also took toil pump off and blocked off running 40-1 i thought carby ill start there and hope it fixes it

I replace the gray fuel lines as Mikidymac states. I always have some blue or green goo coming out of the gray ones. I'd rebuild the carbs and set them up properly. Premix is what I run, no oil pumps.... my preference.

 

[IDoSeaDoo]

Carbs should be rebuilt on principle if you just got a ski and put a new top end on it. There's no telling when they were rebuilt last. You have to chase down the reason for the bad cylinder, or the same thing will just happen to the new ones. Luckily, it sounds like you're running way too rich. This should have kept you from losing your new top-end, but now you have to figure out why. Is the carb just out of tune, or does it have a leaky needle? Wrong jets? You will not know until you crack it open. For less than $100, I'd just go ahead and throw a rebuild kit at them for good measure.

 

[Seadogsx1997]

I've took carby apart all good pop off good needles are good replace seat rubber replaced Evey thing else in carby engine still good 150 per cylinder I've did lins before rebuild still getting so much fuel and flooding got me going crazy might try putting mates carbys on mine to see if his fix it

 

[snikwad003]

Make sure your adjuster screws are where the manual sez to put them

 

[mikidymac]

Make sure the carbs hold 10 psi when back together. You’ll have to cap the return fitting to check.