Thread: Underpowered GPR
06-24-2007, 06:29 PM #1
Hi everyone i am new to this forum but i have been on the riva one for almost a year.
I am having some probs with my 01 gpr. It has on it
D-plate and chip
new fuel filter
The comp on the cyl are 110, 130, 110, The middle cyl was replace around 20 hrs due to pv dropping. We bought the ski brand new. The ski has 104 hrs on it and from the time i took it out in april it has gotten slower and more underpowered.
Philip_gpr has been helping me to try and figure out y my ski isnt running right. I am only getting 6480rpms 52.7mph in 4-5"chop with the pv's opend and the servo motor disconnected, and around 6100 and 50mph with the servo motor connected, no mid-top powerband feeling at all now. I did a comp test with the pv's open and closed and i got the same results doing it both ways. When i took the ski out in late april it flew the powerband was strong like it has always been and the topend was good dreamo was at 64 with 3/4 tank of gas. So what do u guys think the prob is? im waiting to hear back from philip on what i postd on the riva forum but i thought i would give this site a shot also and see if anyone else might have some imput. i used to love me ski and now i wont even ride it!!!! i was out on it today and thats the results i posted. I hope i can fix my prob cus im sick of getting beatin by everything on my lake. thanks for any help i may get from the members on this site.
Last edited by gpr_redneck; 06-24-2007 at 06:32 PM.
06-24-2007, 08:04 PM #2
My 2002 1200 did the same thing one time... I beat my brain against it.. finnily i tried a set of plugs that I was running in my other ski (KNOWN GOOD PLUGS).. found my NEW PLUGS where falling out at 5500 rpms..
That IS step one. try KNOWN Good Plugs.
2 try a plug chop at wide open. (at wide open pull the teather and the plugs).. Note color of plug CERY closely.. Are they wet? are they oilly?
From the plug chop,, you can know if you are rich? or lean.
if rich. plug, coil wire? carbs? ect.
If lean, reeds,carbs need rebuilt or filters or leak
I take it the prop is stock?
JMO but the plug condtion at the trouble RPM RANGE is a good starting point,
06-24-2007, 09:02 PM #3
06-24-2007, 09:05 PM #4
06-25-2007, 09:34 AM #5
- Join Date
- Jan 2006
- Texas City, Texas
Normally a dropped PV would mean a grenaded cylinder, piston and rings, but not always. What would cause higher compression in #2? How often do you maintain (clean) your PV's? Do you use yamalube? Those things can stick in there. Have you considered another dropped PV?
I realize that this is a long shot, but if PhillipGPR has been working with you and you haven't found the problem yet, then it must be something way out of the ordinary. He's pretty good at this sort of thing.
06-25-2007, 09:50 AM #6
If it was me I would try replacing plugs, put fresh fuel in it and OHM the plug wires to make sure that they are good.
Something out of the ordinary might be a crank out of phase maybe??? This may be a long shot but I guess its possible.
06-25-2007, 09:59 AM #7
I have the same problem. But I don't think my powervales are working, they do not cycle after I turn off the ski. I have only had the ski out once since I got it (yesterday). Ran a whole tank of gas through it. I need to check the motor. I rebuild the ski for a dropped valve and have 120 psi on all cylinders.
06-25-2007, 10:12 AM #8
pull all 3 PV covers off and manually turn the PV wheel. see if they are all in phase.
06-25-2007, 11:12 AM #9pull all 3 PV covers off and manually turn the PV wheel. see if they are all in phase.
Last edited by philip_gpr; 06-25-2007 at 11:22 AM.
06-25-2007, 06:52 PM #10
thanks for the welcome RX951
The one cyl with higher comp was replaced due to a droped pv. All plugs are firing checked that last night.
Salty. No i havent cleaned the pv's and i have always used yamalube but now that i have the d-plate i will be running better oil. I'm sure that with all the yamalube ran through it it would need a good cleaning so i will be doing that next.
I posted this on riva and i agree with philip to only have one thread so PLEASE respond on riva if u have anything else to suggest.
I just got off the lake and while i was out i did the zip tie thing but i used a sharpe marker and made a mark. And sure enough the pv's would not open at wot, but the weird thing was that every 10 sec's or so the ski would surge from 47mph to 52mph but then would go slow again.
With the servo motor disconnected and pv's open (i put a mark on each pin and all marks moved when i opend the pv's) i could only get 52.7mph,53.2mph and it would surge up to 55 and 57 on my gps but then drop down to the lowe speed again. And my rpm's are 6130 at 52mph and when it would surge i was at 6570rpm's at 55mph.
I am going to go take the covers off the pv's and check and make sure all 3 are opening and if they are then what else could be wrong because my impression is that if all 3 pv's are open then i should be at 62-63 even if the servo motor is bad right? thanks for all the help and im sure sooner or later we will fix her up right.
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