951 Engine RPM????

[prowan]

Quick question.. What kind of RPM's should I expect out of a 951 Engine in a 1999 GSX Limited?? I'm getting around 6700 to 6800 max on a good day!! Should I be looking for something to be wrong??? THANKS!!

 

[shArky10010]

I'm not sure. But I think it's limited to 6850 rpm. Correct me if I'm wrong.

 

[prowan]

Thanks for your reply... Well my book says the rev limiter is set to somewhere between 7150-7250. I don't really expect to hit the rev limiter, but it seems that I'm a little ways from it.

 

[shArky10010]

Check fuel lines, compression, fuel pump, fuel filter, carbs. They could all affect it.

 

[SabrToothSqrl]

stock prop or not? if the engine is BRAND NEW or rebuilt brand new... 7k is your goal, but 6800 is acceptable. RPM limiter is 7200ish.

I run a Solas Concord 15/20 on mine, and it won't break 6,800, but the ski will do 64-65 MPH.
OEM prop I get 7,000 RPM and only 60 MPH. (02 XP)


fuel lines, filters, carb filters, correct oil? new plugs? clean RAVES. water regulator operation? RAVE hoses / 1 way all in tact?

 

[Dr Honda]

6800 RPM on an engine with some hours on it is a good number. But... clean/adjust the carbs... put in new spark plugs... and clean the RAVE valves. You may get an extra 100 rpm out of it.

 

[prowan]

It is a stock prop. I don't believe I have ever seen 7K since I have owned it and it was brand new when we got it!! I just put new fuel lines on, new spark plugs, and trying to snuff out any other Gremlins...

I did find something interesting last night.. I was checking the resistance between the ignition coil spade connector and ground. I was getting approximately 1.0 - 1.1 ohms. Book calls for 0.33 - 0.6 ohms. Well if I measure from the ignition coil spade connector to the 'Ignition Coil Ground' I get 0.5 ohms. Well there is a wire that comes in to the electrical box from the MPEM that is to supply ground to the starter solenoid, bilge pump, and the ignition coils. I'm guessing I have a weak connection somewhere. What are your thoughts about running an auxillary wire directly from the negative pole on the battery to provide a good solid ground for the ignition coils??? I'm thinking this can cause some of my low speed missing and my top end performance.. Thanks for your help!!!!

 

[prowan]

stock prop or not? if the engine is BRAND NEW or rebuilt brand new... 7k is your goal, but 6800 is acceptable. RPM limiter is 7200ish.

I run a Solas Concord 15/20 on mine, and it won't break 6,800, but the ski will do 64-65 MPH.
OEM prop I get 7,000 RPM and only 60 MPH. (02 XP)


fuel lines, filters, carb filters, correct oil? new plugs? clean RAVES. water regulator operation? RAVE hoses / 1 way all in tact?

I just saw this... Where is there a water regulator?? Is that part of the exhaust?? I did replace fuel lines, filters, carb filters, and I run synthetic Bombardier oil. I do have new plugs and I did clean the raves a little bit. Is there a good procedure for cleaning the RAVEs?? Thanks again for the help!

 

[Dr Honda]

There is a write-up in the "How To" section on how to clean the RAVES.


Yes... the water regulator is part of the exhaust. It looks like a "RAVE" valve on top of the waterbox.

Yes... running a new ground from the battery directly to the ignition box is a good idea. (it can't hurt)

 

[prowan]

GREAT!! I haven't done anything regarding the water regulator. I will definitely clean it out and check its operation. I will check out the RAVE cleaning procedure also. Appreciate your help!

 

[SabrToothSqrl]

Here's one I missed, replaced a whole engine and futzed with shit endlessly till I figure this out:

Check the throttle cable adjustment screw. it's a little 10mm screw with black cap looking thing on the throttle cable, most likely under your front storage compartment... the 99-02s have a TPS on the throttle cable gizmo and when I tightened mine, i went from 6,100 RPM wide open to 6,800 RPM wide open (Solas). so.. yea, I wasted who knows how many damn hours not trying that adjustment.

Also, in a 99 you should have the brass pump, toss on a Solas Concord 15/20, you shouldn't lose any RPMs with that pump, but it does get up and go quicker, as well as I gained 4-5 MPH WOT on mine....

 

[prowan]

Sweet!! I will definitely try that prop. So you are saying that there is an electronic Throttle Position Sensor that reports to the MPEM???? Boy I didn't know that. Is it a little electronic box under the steering column?? Thanks for the TIP !!

 

[SabrToothSqrl]

it's very basic, it only reports 0-79% throttle as 5v then 80%+ as 0v. (I think)... it's basically on/off at 80% but does affect the performance.

it's about the size of an elongated box of cards, black, 1 wire in from steering, 2 out, one for throttle one for oil pump, with 3 wires on top of it. I know it's on the 02s, I don't know 100% if it's on the 99s.

 

[prowan]

man I can't thank you enough for that tid-bit of info. Even when my ski was brand new (i.e. new hoses, clean carbs, etc). It would have spells where it would run 6800 - 6900 rpms on one day, then wouldn't go past 6300 on another day. It was still under warranty when this would happen. I took it back to my dealer, where a bunch of knuckleheads couldn't find anything wrong. Anyway, it sounds like I definitely need to investigate the TPS. It may have been loose/inop from the factory?? THANKS!

 

[SabrToothSqrl]

Mine would hit 6k then 6800 then 7k then 6k like it was STUCK at 6 all the time. I even replaced the engine and had this on/off performance... the carbs open full at full, but without that TPS switched right, I think it causes some serious issues / stress... then I found a thread explaining the 80% setup, etc, and i hope I fixed it, as it hit 6800 WOT for me now, and I'm happy w/that. Although I have a 93 octane engine on order... because... well.. fast isn't fast enough for me...

 

[prowan]

LOL... Where are you getting your engine?? What's the difference, higher compression??

 

[LittleAl]

Yes the 99 951 carbed motor has the tps throttle cable. Mine ran 60 mph at 6600 rpm with two people. Now runs 6100-6200 and only 50 mph. I checked the TPS and it is not switching to 0 volts at 80% and above throttle, ordered a new one from SBT. Seadoo wants around $300, SBT $100. Looks identical to oem. Haven't installed yet. I have a post about it. 951 Carb Throttle Cable

 

[El Toro 33809]

Sabr knows his 951 engines so whatever he says should be golden. Earlier today I read a post from the good Dr. that Seadoo made a high compression 951 engine for racing. I think it gets 25+ more HP than stock.

Good luck with your ski!

 

[98limited]

Does the 98 951 carbed have a tps?

 

[LittleAl]

I dont think the 98 has the tps, but not 100% sure.