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Thread: My fzr sho won't run
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10-29-2019, 06:07 AM #11
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10-29-2019, 10:40 AM #12
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10-29-2019, 10:43 AM #13
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10-29-2019, 03:15 PM #14
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Worx grate I fitted to my ski dropped top speed 2-3mph bugs keeps it hooked up in chop.
i went 13/22 to improve fuel economy on long runs rather than top speed or hole shot....
it has dropped max rpm well max rpm is a few hundred lower now at least.
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10-29-2019, 09:32 PM #15
You are looking at it all wrong. If you have not reflashed the ECU you should not touch the impeller. The stock impeller is sized for WOT at factory setup. What you're experiencing now is expected for a ski without a tune. A 22 processes much more water than a 19 at the WOT you are running. So more water moves through it. When you reflash the ECU the impeller becomes too "tall", forcing you to adjust the trailing edge down to achieve the NEW reflashed RPM. Say you reflash for 8650, you adjust your impeller to turn the engine to 8450 or 8500. While you are adjusting the trailing edge DOWN you are running much more RPM's, so the pump ends up processing more water at the new lower pitch.
Now here is where it gets complicated. At 7700 RPM. which is wide open on a stock Yamaha, your supercharger is turning X RPM's. (I don't know how fast its turning, the number isn't important). What is important, however is the fact that when you reset the RPM/rev limiter you can now turn the supercharger much faster. (Remember, it is a step up gear, and turns close to 70,000 RPM at 8500 engine speed). All of a sudden you are making a ton more boost.
A supercharger is nothing more than a simple single stage centrifugal compressor. Centrifugal compressors are not linear in their air/boost output. Now you have raised you SC output by about 30%.
That 30% boost increase turns into extra horsepower to turn the impeller. So once you have your impeller tuned to your reflashed ECU, you will be riding a rocketship all the way to full throttle!
Hope that helps, you seemed a little bogged down in not understanding the basics of impeller tuning. Good luck with it....that boat should run high 70's easily.
Lastly, for the record, if your mechanic recommended you bend the stock impeller from 22 to 19 without an ECU reflash I would NEVER EVER take my ski to him again, for he knows not what he speaks of!
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10-29-2019, 09:43 PM #16
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11-02-2019, 03:31 PM #17
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Impeller hasn’t been bent and it’s been running fine for well over 100 hours.......it’s the solas pitch for a stock sho motor or lightly modded.
YS-CD-13/22https://www.solas.com/exec/msg.php?mid=62&cid=62&lg=E
or are you saying the solas chart is wrong
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11-03-2019, 11:06 AM #18
at this point I think the graph is wrong. It seems strange to me. my mechanic just saw my 13/22 said it was too long a propeller. that helix was shortened to 13/20. I was advised to put in a 13/19. It is also true that a propeller shortened to the pitch chosen does not make it like a propeller that is already born with that pitch
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11-03-2019, 03:54 PM #19
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Mine was 13/22 from solas factory according to the box, and was checked by someone who knows impellers prior to install, interesting point about the boost without installing a boost gauge no idea what boost she is actually making and fuelling will be rpm based? As no stock AFR?
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11-11-2019, 10:38 AM #20
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