4500-6500 RPM at Idle after rebuild
Posted: Sun Feb 07, 2021 7:56 pm
All,
I was having the High Idle issue on my 390-RRS and so I decided to tear it down and clean it up and so on. I found the following things:
2017 Beta 390 RRS 150+ Hours. Bought used with 98 Hours on it 1 Year ago.(March 2020). Its now Feb 2021
Throttle body was very dirty. Large grease/dirt build up especially around the stepper motor. Looks like dirt was getting past the filter. The O2? sensor on the Throttle body was also very dirty.
A high amount of carbon build up on the piston and valves and exhaust ports, Also some white hard build up, Not sure what that was other than possibly poor quality fuel used.
The Valve Clearances were all tight.
The piston wear indicators on the skirt were almost all worn away.
The diode pack was pretty corroded.
So This is what I did.
New piston and all top end gaskets and o-rings.
New Valve Shims in specifications, now At the loose end of the spec
New Valve Seals (I removed the old ones during the cleaning and they require new ones if removed)
Removed the throttle body and cleaned thoroughly.
Did some light porting on the exhaust, Mostly to get rid of the carbon.
Cleaned up the carbon and white build up on all surfaces including valves.
Ground the valves seats.
I used assembly lube on the top end to make sure things had lube at startup.
I replaced the Diode pack and Capacitor (My bike does not have the wire harness update apparently).
So.. after that I put it all back together. Filled with fresh gas. Then It started right up. Only thing is that it is reving up to 4500-6500 RPM ( can't remember witch right now.
I know about the passive ECU/stepper motor reset/calibration procedure but for a fresh rebuild I am not comfortable with this high RPM at idle right off the bat. Especially when I would like the rings and valves to seat in easy.
I probably need to do a throttle position calibration as well but this was not the issue.
Questions:
How does the bike regulate the fuel?
Is the injector regulated somehow?
Is it OK to let the bike Idle at such a High RPM right after a rebuild?
Should I just let it do the Stepper Motor calibration?
Should I have the wire harness updated?
Thanks for any comments you may have. If I can't figure this out I will be taking this bike to the dealer who can plug in and do their magic.
I was having the High Idle issue on my 390-RRS and so I decided to tear it down and clean it up and so on. I found the following things:
2017 Beta 390 RRS 150+ Hours. Bought used with 98 Hours on it 1 Year ago.(March 2020). Its now Feb 2021
Throttle body was very dirty. Large grease/dirt build up especially around the stepper motor. Looks like dirt was getting past the filter. The O2? sensor on the Throttle body was also very dirty.
A high amount of carbon build up on the piston and valves and exhaust ports, Also some white hard build up, Not sure what that was other than possibly poor quality fuel used.
The Valve Clearances were all tight.
The piston wear indicators on the skirt were almost all worn away.
The diode pack was pretty corroded.
So This is what I did.
New piston and all top end gaskets and o-rings.
New Valve Shims in specifications, now At the loose end of the spec
New Valve Seals (I removed the old ones during the cleaning and they require new ones if removed)
Removed the throttle body and cleaned thoroughly.
Did some light porting on the exhaust, Mostly to get rid of the carbon.
Cleaned up the carbon and white build up on all surfaces including valves.
Ground the valves seats.
I used assembly lube on the top end to make sure things had lube at startup.
I replaced the Diode pack and Capacitor (My bike does not have the wire harness update apparently).
So.. after that I put it all back together. Filled with fresh gas. Then It started right up. Only thing is that it is reving up to 4500-6500 RPM ( can't remember witch right now.
I know about the passive ECU/stepper motor reset/calibration procedure but for a fresh rebuild I am not comfortable with this high RPM at idle right off the bat. Especially when I would like the rings and valves to seat in easy.
I probably need to do a throttle position calibration as well but this was not the issue.
Questions:
How does the bike regulate the fuel?
Is the injector regulated somehow?
Is it OK to let the bike Idle at such a High RPM right after a rebuild?
Should I just let it do the Stepper Motor calibration?
Should I have the wire harness updated?
Thanks for any comments you may have. If I can't figure this out I will be taking this bike to the dealer who can plug in and do their magic.