I've got a rather annoying noise that sounds like the gates of hell are about to open.
It's the 899 engine in my Robin which has a pancake style air filter on it. At about 5k RPM it starts to make a mostly induction but also sounds mechanical kind of noise, almost a diesel knock. By 6k it sounds like Thor himself is trying to escape from the block. It also happens if I use light throttle at high RPM under low load, so at 30 MPH in 2nd.
I'm not too worried about it as under high load the engine is really quiet, no noise on the overrun either, but the times that it happens are where the ECU would be advancing the timing, which is slightly concerning.
I've got an ECU and lockset on the way so I should be able to swap that out when it arrives and rule out an ECU issue. The (frankly awesome) fella that gave me the engine and electricals said the ECU had been tempremantal in the past, and there was no sign of it having been open before when I read out the EEPROM to remove the immo so I think advanced timing from tuning isn't a cause either.
Alfo if anyone has an airbix and hose for sale I'm after one (if it will fit!).
It's the 899 engine in my Robin which has a pancake style air filter on it. At about 5k RPM it starts to make a mostly induction but also sounds mechanical kind of noise, almost a diesel knock. By 6k it sounds like Thor himself is trying to escape from the block. It also happens if I use light throttle at high RPM under low load, so at 30 MPH in 2nd.
I'm not too worried about it as under high load the engine is really quiet, no noise on the overrun either, but the times that it happens are where the ECU would be advancing the timing, which is slightly concerning.
I've got an ECU and lockset on the way so I should be able to swap that out when it arrives and rule out an ECU issue. The (frankly awesome) fella that gave me the engine and electricals said the ECU had been tempremantal in the past, and there was no sign of it having been open before when I read out the EEPROM to remove the immo so I think advanced timing from tuning isn't a cause either.
Alfo if anyone has an airbix and hose for sale I'm after one (if it will fit!).