CBR600RR running rich at low RPM
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CBR600RR running rich at low RPM
Hi,
I just recently purchased a 05 CBR600RR track bike. The bike had problems flooding at low RPM, so much so it would often drown the plugs with fuel at low RPM and the bike wouldn't run until the plugs were removed and cleaned which was a huge job. In trying to diagnose the problem, surprisingly a bike mechanic and I discovered it had a HRC engine and ECU. The frustrating thing is we could not find any history on the bike making it hard to know what was done to it in the past. The VIN REVS, as well as what we could locate on the engine number check didn't give us a lot of info either. We put the bike on the Dyno, and it was running very very rich at low RPM (I think for memory it was around 8:1), and start to lean off as the RPM got above 10K, but still ran rich. At full tilt it also only produced about 105 hp which is low for this bike spec which in average according to the mechanic will put about 110-115 at the rear wheel.
The mechanic was at a bit of a loss without pulling the engine down and suggested it could be a burnt valve, timing or a few other things and suggested to start with a compression test and valve clearance check.
Since then I have been working on the process of elimination trying to nut out the issue. I have checked valve clearances and they are all in spec. Compression tests were 150, 151, 150, 149 on a cold engine which eliminates compression rings and valves not sealing for whatever reason. Valve clearances and compression is good.
Thinking it through I am thinking it could be a non standard cam that may have been put in it at some point in its life, or timing ?
While I am continuing working through the process of elimination, I thought I would throw my problem out here and see if anyone here had any other ideas to start looking at. Its rather a peculiar problem that I assume has surfaced on other bikes at some point.
Thanks in advance of any ideas of help.
I just recently purchased a 05 CBR600RR track bike. The bike had problems flooding at low RPM, so much so it would often drown the plugs with fuel at low RPM and the bike wouldn't run until the plugs were removed and cleaned which was a huge job. In trying to diagnose the problem, surprisingly a bike mechanic and I discovered it had a HRC engine and ECU. The frustrating thing is we could not find any history on the bike making it hard to know what was done to it in the past. The VIN REVS, as well as what we could locate on the engine number check didn't give us a lot of info either. We put the bike on the Dyno, and it was running very very rich at low RPM (I think for memory it was around 8:1), and start to lean off as the RPM got above 10K, but still ran rich. At full tilt it also only produced about 105 hp which is low for this bike spec which in average according to the mechanic will put about 110-115 at the rear wheel.
The mechanic was at a bit of a loss without pulling the engine down and suggested it could be a burnt valve, timing or a few other things and suggested to start with a compression test and valve clearance check.
Since then I have been working on the process of elimination trying to nut out the issue. I have checked valve clearances and they are all in spec. Compression tests were 150, 151, 150, 149 on a cold engine which eliminates compression rings and valves not sealing for whatever reason. Valve clearances and compression is good.
Thinking it through I am thinking it could be a non standard cam that may have been put in it at some point in its life, or timing ?
While I am continuing working through the process of elimination, I thought I would throw my problem out here and see if anyone here had any other ideas to start looking at. Its rather a peculiar problem that I assume has surfaced on other bikes at some point.
Thanks in advance of any ideas of help.
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