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Goo day everyone, I have a 2009 Yamaha FZR, 1.8L, 4cyl, SHO engine with a Vi-PEC V88 legacy ecu installed. I watched the tuning fundamentals video and understand alot more about tuning my Vi-PEC now than ever before. One thing I'm a little skeptical about is tuning the ignition timing on a Jetski since it can't be dynoed the conventional way, only by BHP. How would I begin tuning timing on the water. Should I get a knock sensor and just advance the timing till I start hearing knock and then back off a little? I would love to here some of your suggestions as to how I would get around tuning without a dyno to know my MBT. Thank you.
I would just find an engine dyno that could work with the engine.
Getting the engine onto a dyno is obviously your best option and the Land & Sea option Chrisccm posted up looks really interesting.
One aspect of optimising the ignition timing with an engine running a jet unit is that as the engine produces more torque, the engine rpm will increase. This actually makes tuning something like a jet ski on the water quite plausible - When you add timing and see no improvement to rpm, you've seen no torque gain so the timing hasn't helped you. You can use the same approach to tuning cam control as well.
On the water you will likely see the rpm move around a little even at a constant throttle so you do need to do some filtering to confirm if you've seen a gain.
Thank you for the replies everyone. I know the best way possible to tune, would be on an engine dyno but due to my location and application that isn't going to be plausible for me. I am a recreational rider who likes to tinker with my management but not trying to go all out. We don't have any engine dyno's here in Trinidad and the dynomite dynamoter looks great but it cost nearly as much as my ski does.
So for the time being should I keep advancing timing at WOT until I see no more RPM increase whilst using a Knock sensor. Also my ski comes with a knock sensor but are they any good compared knock sensors such as plex?
Thanks for the help.
Plex don't use specific knock sensor, just regular Bosch knock sensor.
The Plex knock monitor should have come with a knock sensor. As Ludo mentioned, this is just a generic knock sensor though and isn't specific to the Plex unit.
One thing to be wary of if you're using the OE sensor is that a lot of late model engines are fitted with narrow band knock sensors tuned for the specific knock frequency (actually typically these will be a second harmonic sensor). The Plex on the other hand uses a wide band sensor that is effective over a wider range of frequencies.