Thread: Gpr 61mph about good?
07-11-2010, 11:48 PM #1
Gpr 61mph about good?
2001 gpr. My mods are dplate, 1200 grate, solas 13/19, sealed pump and that's it. My GPS was 61.0 with 3/4tank. Does that speed sound OK, or should I check something out before I put on my modded ride plate and other mods?
Also, my ski has almost 150 hours now, and the compression has dwindled to just about 100-105 across the board. I know it's not just my gauge either since another stock carbed GPR I tested showed up at 120 with the same gauge. Would adding new pistons and hopefully getting the compression back add some top end speed? Thanks
07-11-2010, 11:52 PM #2
About right with your mods. Whats you rpm?
07-12-2010, 02:08 PM #3
I don't know the RPMs sad to say. I'd like to get a tach eventually.
07-12-2010, 09:28 PM #4
Yeah that sounds kind of slow, sorry to say, esp. with your mods. I recently purchased a 2000 1200R did nearly the same mods as you and GPS'd at 67 peak, 65 average....Sounds like the compression is the issue, and others would have to help you there b/c my dad's the mechanic and knows his stuff, but he's on vacation this week and thus not on here (LT1GMC is his handle)
I am no newb, but anything too deep into the engine I let dad help with. That is a low compression number, new pistons couldn't hurt I guess. Sorry I am not of much help, but I did want to let you know that speed is a bit on the slow side. At least you have it nailed down to low compression though....
07-12-2010, 09:35 PM #5
- Join Date
- Jul 2010
- Bensalem, PA
Hi, I'm new and dont know a ton about these ski's, but recently bought one, bone stock with 110 hours on it. It didnt run right initially. I determined the catalytic converter had broke apart. Removed it, installed a d-plate, new plugs, waveeater clips/couplers and it does 62mph on smooth or light chop. At the end of the season, I'll do a compression test and some minor mods. Sounds like your low compression is hurting your performance.
07-12-2010, 09:39 PM #6
3/4 tank fuel
it goes on and on.....these are some things what will determine your speeds. Did you test compression with plugs out? What was your cranking rpm?
The 1200 grate, D plate, 3/4 tank fuel will decrease speed/rpm. . Your pump shoe can also be hanging down. Gimme a call if you need help. 775-315-0222 Kevin
What guage you using?
07-12-2010, 09:42 PM #7
take into mind conditions ur in jersey where the water is rough most of the time which is gonna slow you down try and do some gps runs near some of the coves where the waters calmer. where in jersey are riding. i say this cuz i was out this weekend and bay was alil rough at times but once you you got into the coves or mash areas that are shielded its was very noticable in speed change aslo take into concideration current did you do speed runs both ways?? alot comes into play dont just go off that one ride out, you can go out tomorrow and be 2mph faster just from current change water temp air temp wind everything comes into play but do this when you test your ski always go to the same area so atleast thats the same. when i use to test skis and even now i ride in in barnegat bay now theres lots of areas you can go for calm waters around there usually i would go by flat island or there are some mashes people like to ride in that are pretty calm over by mud city. hjope this helps man
07-12-2010, 10:00 PM #8
Thanks everyone. I will record my numbers next time with less fuel, different positions, different direction, cooler engine etc. I'm really hoping to squeeze at least 1.5mph more to put me where I was hoping I would be at around 62-63 with the 13/19 prop. Will post back in about 2-3 weeks next time I will be able to ride.
Kevin, yes I tested compression with one plug out at a time. I'm using a cheap gauge from Autozone, it gets the job done for me. Last year the compression was 110 with a Snap-on gauge but that was 40 hours ago too. I will check the the shoe and thank you for offering to help
This speed was on perfect glass in the back bays of Wildwood. Hard to find a good area, but there was a nice little stretch I found that was really long and straight. If anyone is going to be around Wildwood in August hit me up.
07-12-2010, 10:25 PM #9
good points...i guess i should validate my 67 MPH run with the following....
73 degrees, near sundown
slight chop (GPRs are actually faster in a light chop than glass smooth)
1/4 tank gas
I'm 220 lbs
Trimmed full nose up
engine was not heat soaked, it had been sitting
So yeah there are a ton of factors that go into speed runs. I ran mine intentionally when I did (lucked out with the air temp and humidity that day) to get the best speed I could...
Real world? probably 64 or so in decent chop, maybe a bit less even....
So don't feel too bad, get those compression numbers back up and you'll probably be ok...
as for the pump shoe, when you sealed it did you caulk everything? That's a must, around all the rubber seal pieces, in the gaps between the shoe and hull, etc. I used marine grade quick dry caulk from West Marine...and like Water Woody mentioned check to make sure the shoe isn't hanging down....
And by 1200 grate, what does that mean? Is it stock? If so, change it if financially possible. That stock grate on the GPR is pretty much junk...creates tons of cavitation, is a weed trap, etc...R&D Aquavein 2 bar is what I have and combined with the pump seal, it really helped with cavitation (a common problem with bone stock GP1200Rs)
07-13-2010, 07:23 AM #10
Icky,let me know next time your out, i'm not too far from you, we can meet up (Edison), a few of us wanna ride the Raritan river.
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