I was out riding my GPR today. Cruising around in medium chop and averaging ~60MPH and it suddenly bogged down to about 25-30MPH. At full throttle, I could only get ~5000 RPMs. I slugged into ramp and pulled the plugs any found the rear two cylinders and plugs with some (more than usual) unburned fuel/oil (premix) and the front cylinder/plug appeared to be firing correctly (not too lean/not too rich). Out of the water I can get my Top RPMs. I had run this boat in the past weeks with no problems (70-72MPH topend @ 7110RPMs)

-Powervalves do cycle at startup.

-Thinking it may be bad plugs, I changed them all; NO CHANGE.

-Thinking it may be a timing issue, I exchanged the CDI with the stock one; NO CHANGE….CDI good.

-Intake was not plugged.

-No CAT converter involved.

-Being that two cylinders were running rich with one still running good, I couldn’t think of a carburetion problem that would cause this.

-One of thoughts was a twisted crank but I saved this thought for last.

Does this sound familiar to anyone, any thoughts? Any feedback is appreciated

[ 06-15-2003, 08:11 PM: Message edited by: THiNCNet ]

Reed petals broke or warped.

Thx Mark; I'll put the reeds on my list of things to check...

I just found my pump liner distorded on one side and a rub mark at the same spot. BUT, could that cause the symptom of having good RPMs out of water but -2000 RPMs in the water (under load)? Ya' think.

Man, if the liner can cause a lose of RPMs under loaded, do I have a second issue with my cylinders burning even. I hate secondary problems when trouble shooting.

As mark said check your reeds this can and will cause the problem your having and no the liner collapsing will not cause a 2000 rpm loss.MARK RPM RACING

Sounds good, I go check em' out. Again, thx

A quick check down by the carbs should show if you have blown a set of petals.

It sould be dripping with fuel & oils down there as the crank case pressure will blow back through the reeds.

Do you have F/A on that ski?

Anothe possible is that the flywheel has moved on the snub of the crank / twisted the snub.

You show no list of mods, that might help.


Cheers

Peter

Heres what got:

Got those carburators off last night and found two of the reeds starting to chip off in one corner (not open gaps yet but it looks like they were on their way). Glad ya pointed me in this direction. Another signifcant thing I found was the one of the hose/nipples to one of the carburator's pump cover was snapped off. I'm not sure if I did this removeing it but I hope that this had broke on the water and is the source of my problem. Now, seeing this, I may have read my cylinders wrong when looking through the plug hole. It may be that the two rears appearred rich in comparison the the front which may have been running dry due to carb pump hose being snapped off. I guess it time to pull the head and get a better visual, ay?


Flame Arrestors/Adapter/Pre-filters
Rejetting/no choke>acc. pump
Reed stuffers/stock reeds
Advent CDI
Rec. Head
D-plate
Free flow
PPK
R&D 2B Intake
14/20 depitch / cone
R&D Ride Plate less skegs
Trim tabs
BeachHouse Sponsons
Other non-performance accessories