1997 GTX 787 . 1 clean plug and 1 brown plug. what does this mean?

[Sparkieboat]

I got 140 PSI on each cylinder. I am pretty sure that I have cleaned and rebuilt both carbs properly. I am getting a very thin spark on my spark gap tester but it seems that is just how jetskis do I guess. I only get about 4700 RPMs top. if I let it idle down and punch it I can feel the power kick in for about 1 second then it dies back down. pulled the spark plugs, front plug is brown and the rear plug looks like brand new. (they are both brand new plugs.) What should I test? If I hold my hand over either carb it starts to die down. If I rev it up I can feel the gas splashing on my hand over the carb. I think that maybe I did not feel as much gas on the rear carb. Maybe it is lean. What is your thoughts?

 

[Coastiejoe]

I don't know the answer to this, but can't the carbs be switched around. If so, switch the cabs and see if the spark plug condition stays in the same hole or the swap,,,, This will at the very least help you figure things out.

 

[soccerdad]

You really can't swap carbs front to back with changing linkage stuff. Did you set the popoff? Are they the same? What are they? How are the low and high speed screws set? Have you checked the raves? FYI, they don't run the same with the flame arrestor off. Does it get better if you pull the choke out a little. Always if you are testing, try going rich first. You can fry these things quickly if you are too lean. Is this on a water test or on the trailer?

 

[Sparkieboat]

I cleaned the rave valves they looked good and seemed to go in and out properly. I have no idea what a popoff is and I have not touched the low or high speed screws, not sure where they are, I will go look.
I had the flame arrestor and the plastic cover all on. maybe it is in the high speed screw. it idles great. hitting on both cylinders seemingly. but defiantly appears lean at high speed on the back cylinder. How do you set the high speed screws?

 

[Sparkieboat]

which screw is for the high speed?

 

[AdamXP800]

59



96 XP800!
Keep the 2 strokes alive!

 

[Sparkieboat]

thanks a bunch.. so I screw it all the way in (soft set) and the a certain number of turns out?

 

[CReynoldsMIZ]

Correct. I believe the high should be all the way in, and the low about 1.5 turns out. Double check that

 

[Sparkieboat]

i did some reading. looks like you are dead on. I do not have a way to check the popoff. I used the same springs that were in there when I rebuilt the carbs. I may try to rig a popoff tester.

 

[Sparkieboat]

ok, i recleaned the carb and put on a new set of plugs. when I first put it in the river it did the same thing as yesterday, then in about 2 mins. it lurched a few times and jumped to 7K RPM about 48 MPH and ran great for about 30 mins with lots of stopping and taking off. go figure. anything you guys think I should check to make sure nothing is going to go boom?

 

[Sparkieboat]

I was expecting over 50 MPH, but I was using the stock gauge so maybe not so accurate. I will GPS it.