XP bogging

[IDoSeaDoo]

:banghead: So I'm still stumped over this stupid bogging issue I'm having with a set of carbs. I installed these carbs into an engine that just got new pistons and rings and one new crank seal. Here are the facts:

Compression: 150 each cyl
Low Speed Screw: 1 turn out on both
High Speed: all the way in on MAG, 1/4 out on PTO
Jets: stock by the book (forgot what they are for 787 SPX)
Pop-Off: low 30's I believe, it's been a while since I checked, but it was on the lower book-setting and even on both carbs (within 1psi or so)
Gray fuel lines replaced long ago
Internal filters clean
Selector switch clean
Fresh gas
Ignition timing/MPEM: not the issue, tested on two diff. skis, which work much better with diff. carbs
Throttle Shaft Bushings: seem solid, no up/down play
I installed new carb. kits on these last summer (aftermarket JetSports company or sorts, though I was getting Mikuni but no such luck), and when I last took them apart, everything still seemed new and clean. N/S isn't leaking, it's got new O-rings everywhere. Transition ports are clear, carb cleaner sprayed thru all 3. Venturi holes clear, carb cleaner jetting thru nicely. All check valves look flush and good. Pulse line is new/secure, no leaks. Base gaskets: new

I've tried playing with the pop-off pressure, going up and down with it to no avail. The needle/seats look okay, move freely. No leaks when doing pop-off test w/ lots of WD-40... It runs great on top-end, but bogs or even dies when you open it from idle.
Has anyone actually ever fixed this problem with anything I haven't yet tried? Please help

 

[JJinSC]

Your symptom sounds like an accelerator pump problem. I have had my 97 xp since it was new and it has done this since I can remember. I have cleaned and checked the function of the pump/diaphragm and have finally had the carbs rebuilt with another check and cleaning and it still does this same behavior (bogs between idle and speed). I have made sure the two lines from the accelerator pump and the two carbs are clean and that the check valves are cleaned and operating as well as the two jets in the carbs. It still exhibits the same behavior. If you find your issue, please let me know what you find. I would love to get this resolved as well.

 

[IDoSeaDoo]

did you use mikuni kits or aftermkt? have you ever replaced the Needle/Seats? The only think I can think of to do is get larger jets... but I'm not sure which one to make larger, the small or big one (don't know which one is Pilot, and which one is Main). Somebody please help!

 

[JJinSC]

I did the previous cleaning and everything looked great and seemed to be set and functioning properly. Stealership did the carb rebuild when they did by engine rebuild. All Seadoo/BRP (mikuni) parts.

 

[IDoSeaDoo]

There's got to be a solution, I'm not sure if I'll have time to try something today, but I have a hunch about sealing the sides of the pump body. I have reason to believe that it may be leaking just ever so slightly around the gasket seals and may be sucking in a little air past the seals... I'll let you know after I try this.

 

[JJinSC]

Cool! Thanks.

 

[IDoSeaDoo]

Ski doesn't run now... can't fix till fall

Stupid ski stopped sparking. I think the pick up coil is dead (and there's something wrong in the MAG cover, strange noises come out when cranking). My work sent me out to AZ and I'm not sure I want to bring a broken ski all the way out here, as I'm staying in an extended stay hotel here (till sept or so). So looks like my season is over prematurely... If you want to try gooping up the fuel pump seals on the outside (or inside on the mating surfaces) of the MAG carb's fuel assembly, I'd be interested to see if that solves it. When I was doing my pop-off tests, I noticed some bubbles issuing from one of the cracks. I think it was between the pump diaphragm and the check valve block. I couldn't make them go away by tightening the screws, but didn't think much of em cuz of how small they were. I'm now thinking that was a mistake... You can check yours by doing a pop-off test and spraying some WD-40 on the pump assembly housing. I'd be curious to see if you had a leak there too...