Thread: RXT-X advice?
05-01-2009, 10:12 PM #1
Last Summer I was running 69-70 on my RXT-X (best GPS was 70.2)
this was 3" cold air kit, pump wedge, Modified stock grate, ride plate holes filled, stock prop at 8100+. this spring I was able to pick up the deduction nozzle and install the 15/22R prop with OPAS delete plates. was able to reach 71.5 with 83mm ring, dropped down to 82mm ring and got 72.0
I was hoping the smaller ring would load the pump more, the holeshot and midrange is great. but I have to feather the throttle at about 70-75% to keep it at 8120-8180 otherwise it in and out of the rev limiter. I thought maybe the modified stock grate might not be pushing enought water in to the pump. added the R&D grate but water was choppy and was only able to get 71.7 but again.. I had to be light on the throttle to get it out of the limiter. my goal is to try the 81mm to see if that helps, then possible put the stock prop back on it with the reduction nozzle to see how she runs. maybe even add pitch to the stock prop? or maybe the carbon seal is sucking air? the ski stays totally dry inside. it has an awesome holeshot coming out of the water at the bump of the throttle. any ideas?? am i overlooking something? just feel like it not loading the pump down well? Riva advertises the stage 1 kit for the RXTX to do 73 at 8000 rpms. I am getting 72 and having to have a light grip to keep it under 8200rpms. (on glass water, 72 water temp, air temp 80)
thanks!!! appreciate any and all advice!
05-02-2009, 10:38 AM #2
I think you need to add pitch. You're on the limiter hard. Pitch the prop to run around 8040-8060 rpms with the 83 ring installed. You'll have your 73 or better. It might take a little experimentation but it's worth it. You want to be able to change rings up or down in size to compensate for changing air and water temps and barometric pressure. The 83 is probably the ideal size for the RXT-X.
05-02-2009, 11:35 AM #3
thanks, will bump the ring up to the 83 from 82, and add 2mm pitch and see what happens next change i get to go out. thanks!
05-02-2009, 11:53 AM #4
I am with seagoat...your prop seems to be the culprit, but additionally, have you sucked anything up which might cause excess wear or damage to either prop or wear ring? It does not take much damage at all to affect performance.
Without the reduction nozzle, you should be around 72 with your mods.
05-02-2009, 12:32 PM #5
1. 3" air intake could still be choking down your air, try a 4".
2. I think the pump wedge HURTS performance on the T-X. Take it off, read skoepps thread "tested new mods", he didn't care for it either!
3. Send 15/22r to Eric at speedfreeks for tuning. I have to do this also to get off the soft limiter.
4. I was running 73.5 gps with same mods except 4" air, NO wedge and stock nozzle!
5. My brother in-law is running 70.0 gps on a pair of pure stock T-X's.
6. My 5 hours T-X flooded from the carbon seal area the other day, and now have cracks in the pump tunnel. Thank God I installed a bilge pump! Ski is at dealership as we speek!
05-02-2009, 01:08 PM #6
I installed a new pump ring before I took it out, tolerance is tight, new prop. will re-inspect.
running the GTXL glovebox as well with the garmin 76CS love it!
the pump wedge could be a factor? could be planning to high and causing
the pump not to get a solid flow.
thanks for the info! think next time out will be No wedge and the 83mm ring, see if that makes any changes before i add more pitch to the blade.
05-02-2009, 01:21 PM #7
a lot of good advice and thoughts. I have tested the wedge on T-X several times and see no gains with it and perfer the ride of ski without it.. With your mods a 15/22 with 83 ring should be close to correct rpm. I would bet that your traveling edge might be less then 22 and you just need some more pitch. remember, just cause your running 8100 rpm, make note at what throttle pull that is at. you might be more on limiter then realize.
05-02-2009, 01:45 PM #8
I have to back off about 20-30% on throttle to keep it from surging from the rev limited. my impression is i am not getting enough water flow and the ski has nothing to hold it back, will pull the prop and measure the edges. I got the prop last year, and when I swapped it out I had it in the
rev limiter with no issues, was told i had to run the reduction nozzle with the prop. maybe the prop is off? the stock prop kept me out of the rev limiter. thanks!
05-02-2009, 03:54 PM #9
Hate to say it, but it seems like after reading posts since the initial release of the 15/22r that none of these prop's are identical.
Shameful I might add, especially considering they are marketed as "All "R" model Solas impellers are placed in a pitch-block before leaving Solas to ensure accuracy for optimal performance...."
Anyone in this user group running that R&D 14/24 prop? Pretty pricey, but props make alot of difference on these ski's.
05-02-2009, 06:26 PM #10
Wickedpony, check your blades for consistency if you have a pitch guage. Blueprint the prop by making all leading edges the same pitch and trailing edges the samy pitch. If it's close to 15/22, which I think you'll find errors, then go ahead and add pitch. I know it sucks to be at 3/4 throttle and on the limiter. If you don't have a guage then put the prop on a level surface and use a ruler to measure front and rear. There are pitch guages on here that you can print out on clear plastic printer sheets. I used these the first time I pitched my oem prop and they worked ok. Good luck with it. I think you should be able to hit 73.5 or better.
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