GP1300R Top End Advice

[flying dutchman]

Hey Guys its been awhile since on this forum because been pretty satisfied with my ski.
Took the ski out for first time this season and a newer Sea-Doo wanted to race and I just barely pulled away at top end.
The embarrassing part was that the Sea-doo had 3 people on it.

I then GPS my ski and best I could get was 69.6 mph which concerns me since my previous best was 72.3 two seasons ago same place similar conditions.
So two questions.

1. What would cause a loss in top end? Is there any thing related to gradual wear of components?
I have 125 hours on the ski now. I rebuilt the top end at 88 hours due to spun ring on #3 piston.

2. Some of the new ski's are pretty fast out of the box and I would like to get my top end speed in the 75 to 77 range with least amount of pain.
When I had my head milled by Oside Bill he told me that I would probably be hitting my rev limiter with the 13/19 impeller that I have from Island Racing.
I installed a Tiny-Tach and the WOT RPM is 7240 and not sure where the rev limit is but I never have felt it. Should I go up in Pitch?
Do I need more RPM? I dont know what the best target spot is on the hp/torque curve and what pitch to run to match this?


Any way here are the specs for my ski and I kinda mostly followed the build plan that Andy used back then.

2007 GP1300R
Milled OEM head by Oside Bill (comp test 132,134,134), VF3`s, R&D PP FA, Riva FF,
D-Plate, Riva EFI controller 3, 9, 1.5, 8. Premix 36:1 Maxima Super M, Tiny-Tach
R&D Ride Plate, Shimmed stock tabs, R&D AquaVein intake grate, Stepped stock sponsons,
PPK, Stock steering nozzle, Stock exit nozzle, Impeller YG-DF 13/19 IR,
Cowell and seat mods for air flow, Iridium Plugs.
Max Speed: 72.3 (2 bars fuel level, 150# rider) WOT RPM 7240.

Thanks in advance for any Advice, Regards, Ceril

[OzarkYamMonster]

Hello Ceril, I have simular mods ... except VF3's, FF, but I have the Dyna 14/20 prop. My best on GPS is 69.9 .... my heads were milled and put out 150 psi. However, I am still trying to tune in my fuel controller. My max RPMs on my Pet 2000, show I am only hitting 7040 ... so I think if I can get the controller right I might find that elusive 200 more RPMs. Rich @ WFO, said that I should be getting the numbers you are getting @ 7240 RPMs. If I do I hope to get about 71 + . My ski only has 47 hours total on it. Please let me know what you find out ... I am very interested in how you get there. Regards, Steve

[leejax01]

Did Jim cut your plate or just aftermarket? Check your wear ring for clearance and impeller for dings.

[flying dutchman]

At the time I did my mods (2009) I worked with Carl at Island Racing so the R&D Ride plate came from him.
It was advertized as being based on the successes of the GP1200 Ride plate and associated tweeks.

Will check the clearance, what is acceptable tolerance?

Impeller does have small dings and burs on leading edges.
With WOT RPM of 7240 and my engine mods should I be running a 14/20?
It seems the forums suggest a RPM target of around 7150 to 7190.

What is the useful life of VF3 reeds, how many hours before replacement is recomended or do guys just run till fail?
Can the reeds be replaced in the cages or do you have to buy all new assemblies?

I'm in southern CA and premium pump gas is 91 octane. If I get a 3 deg timing key is 91 ok or do I need 93 like forum suggests? Any concerns of 3 deg key shortening engine life? Mainly concerned about bottem end of engine.

Sorry for adding questions. I am pounding the forums every night now to get a strategy to solve my original loss of a few mph and then go to then next step up to 75+ top speed.

I used to have Oside Bill to consult with but I now found out he passes away which is a great loss.
Not sure if there are any other knowledgeable GPR guys in San Diego area.

Regards, Ceril

[WFO]

7240 is a little high, but its still cool outside and rpms will drop as it heats up this summer

VFIIIs will last 100+ hours in an EFI ski, and yes you can just replace the pedals instead of the whole cage

If your compression is in the 130s, you will be fine with a keyway and 91 octane. The good thing is you can add more fuel with your controller

[flying dutchman]

Thanks guys for the support.

Hey WFO, can you supply the performance parts I may need?
I sent a contact email to www.wfoperformance.net

Regards, Ceril

[2fast4u]

FYI, R&D now does a reflash to the Fuel injected GPR's ECM that works good. With the reflashed ecm there is no need for the 3* key and fuel controler either. My buddy did the reflash from R&D and picked up a solid 1.5 mph and much better accleration. Also IMO you need a 14/20 prop also. ---------------------------------------------R&D GP1300R ECU Reprogramming Service $499.95 , Tommy Jordan

[flying dutchman]

Hey Thanks Tommy,

So are you saying that with the reflash I wont need the Riva EFI Fuel controller that is currently installed?
If the fuel curve is reflashed also then does that mean you no longer have the ability to adjust (add) fuel when conditions or modifications change?
Anyway since I already have the fuel controller then it's hard to justify spending another 500$ instead of just installing a 3deg key.

Is the Solas DF 14/20 still the best overall impeller or are there better choices? skat-trac? Concord?
I really like the strong bottom end and mid range acceleration that I currently have and would prefer not loose any of that plus now I would like to gain some top end speed also.
I expect the extra hp with a 3* key should improve response and acceleration over the entire speed range even while pushing a higher pitch impeller, please confirm.

Then there is "Race Finish", "Set-back", are these worth pursuing?
Also I was reading some old paper from IR that mentioned reduction nozzle bore sizes of 13/19-87mm and 14/20-88mm.
I still have OEM/stock reduction nozzle which I believe is 85mm, please advise.

When converting the Pump from grease to oil do people do the front/intermediate shaft bearing assy also?
It looks like you would have to move or remove the motor to get that bearing assy out.

Regards, Ceril

[OzarkYamMonster]

Hi flying dutchman, I got the 4* key way from Rich @ WFO, I had my heads milled from Jim, @ Jim's performance. I have the Dyna 14/20 .... I also have fuel controller and yet best GPS 69.96 .....?

[Honroman]

Ride plate angles?