Thread: Cavitation or Rev Limiter?
07-09-2009, 10:24 AM #1
Cavitation or Rev Limiter?
A couple weekends ago, I installed an R & D intake grate on my FZS. Now it hooks up initially upon WOT and just when it gets on plane (which seems like a nanosecond later) it makes a noise/feeling that I can't tell if it's cavitating or hitting the rev limiter.
Other than the grate, I have a Riva FF exhaust and the foam is MIA.
Is it possible to cavitate shortly AFTER it hooks-up or does this have to be the rev limiter?
Incidentally, my buddies supercharged Sea-Doo does this REALLY bad out of the hole (not sure it is the same problem as mine as I haven't ridden it--it's a Sea-Doo after all ).
Feel not so bright because I can't figure this out but I guess there are no stupid questions--just stupid people that ask them (at least that's what my DI used to say way back when).
07-09-2009, 10:29 AM #2
If it was cavitation it would most likely be during the intial hole shot. It sounds to me like you're on the limiter. Can you describe the sound a bit more? Does it also make the sound when making top speed runs in smooth water?
07-09-2009, 10:33 AM #3
Yea, I think that the FF exhaust put you on the limiter.
07-09-2009, 10:40 AM #4
I gave it the thorough bath it needed badly Monday evening and it looks so good that I haven't got it off the lift since then. I need to ride it tonight and see if I can get a better idea after asking myself more questions today.
It looks fast just sitting there!
No symptoms at top speed runs but haven't had glass since before I installed the grate.
07-09-2009, 10:44 AM #5
Cavitation doesn't really make a sound. It's just the prop spinning faster than the pump can suck water. So your RPMs come up but you're not really gaining as much speed as you should be.
You can hear the rev limiter if you listen for it in the engine RPMs. When you hit it it will give a slight "wah wah wah wah" sound. My ski cavitates on hole shot, and as a result, I bang the rev limiter a few times on hard hole shots.
07-09-2009, 10:51 AM #6
Doesn't cavitation let the motor rev--possibly to the limiter? Seems like it could as it's like spinning the drive wheel on a car.
I posted initially on the other thread because GREAN HULK said the pump seal kit will help with cavitation problems. I don't have that kit yet but am thinking it would be good to buy (along with all the other things I just have to have for this). Can't hurt and just might solve my problem if it actually is cavitation.
Am I making the simple complicated?
07-09-2009, 11:16 AM #7
07-10-2009, 08:58 AM #8
Thanks for the info Hitman. I rode it some last night and I really think it's the rev limiter. It bounces off it about three times as you described earlier.
I ordered some more parts today (pump seal kit, engine/intercooler cooling kit, intake manifold upgrade, power filter and the HKS BOV ) and now I am guessing the rev limiter will be hit even more on take-off.
ECU time??? I wish I was rich.
I searched some and can't find anywhere on the forum where the HKS installation has been documented. I know a lot of guys have one based on the "Known HKS BOV Issues" thread but can't seem to find any documentation on one that has been installed. Anyone know of any info/documentation for this (love pics)? I assume there are good installation instructions included with the BOV?
07-10-2009, 09:20 AM #9
07-10-2009, 09:24 AM #10
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