96 XP 787 - Pulses?

[ronmvdb]

I just rebuilt the carbs on my XP with the original problem being you could not open it up past half throttle without it dying or losing power. Now after rebuilding and installing the carbs, it starts but it will pulsate when idling and you cannot give it any throttle. I've removed the carbs and went through everything again and it's still doing it. I've set the low idle screw to 1 turn out per specs. Can this be anything besides a fuel problem? I'm at a loss at what to look at next. Any ideas would be appreciated.

[gr8jpn]

Re: 96 XP 787 - Pulses?

have you checked compression? replaced plugs?

[ronmvdb]

Re: 96 XP 787 - Pulses?

Compression is 120 in both cylinders. The plugs were replaced prior to the carb rebuild so they have less than 30 minutes on them.

[gr8jpn]

Re: 96 XP 787 - Pulses?

120 is kinda low.. I am guessing that you did not hold the throttle wide open when you did your check? (I made the same mistake on mine and it came in at 124 in each one, then I re-did it the correct way, and got 149 with WOT. the 787 is supposed to be 150.

But since they both came in the same for you..

Is the pop-off pressure correct? Any fuel flow restrictions? old gas? water in the fuel?

[dsolie]

Re: 96 XP 787 - Pulses?

did you actually rebuild the carbs, or just clean them. did you put the right spring back in place for the N&S assembly?

[ronmvdb]

Re: 96 XP 787 - Pulses?

Problem fixed. After working on it all weekend I finally found the issue this morning. There's more to the story than just rebuilding the carbs. The ski had been rolled over several times and had a lot of water in it. Prior to it being rolled over (by my son-in-law couldn't get on it) it was doing the hesitation and could only go 1/4 to 1/2 throttle. After drying the cylinders out, the same symptoms were still there so I rebuilt the carbs and thats when the pulsing-surging started occuring. After reading several threads on this forum, I checked the coil box and it was completely full of water. Amazing it even ran! I dried it out, replaced the corroded terminals and it started right up. The carbs were still in need of a rebuild so I'm anxious to see how it runs on the water. Thanks for everyone's input. I'd be lost without these forums.