I think they are OK, just slightly on the lean side. If the suggestion to run higher octane doesn't change anything, I would look into richening the fuel/air ratio via power commander or similar device. I am with Raplh though, why would you run 87 octane on the track?
Higher octane in and of itself is only delays ignition, it does not increase the fuel/air mix. Detonation is an issue, but if the bike does not have a detonation problem, raising the octane level really won't change anything. The ratio is still the same. Lean.
When you put the slip on pipe onto your bike, the back pressure dropped in the exhaust. This allows more volume of air to move through the engine, the fuel was not adjusted and now the air ratio is slightly higher than the fuel at stock settings.
Some pipes can be run with nothing adjusted. Some can't.
You can also put in a fresh set of plugs and the OEM can to see what happens when you increase the internal back pressure to the exhaust. It will become more rich because of the lessened volume of air going through the motor.
Horsepower is a direct result of moving the most fuel and air through the motor in the least amount of time. Pipes, cams, pistons, and all related engine work is dedicated to this goal.
When you put a slip on system onto a bike, generally all that happens is the bike has lower exhaust back pressure and you get an increase in sound, and internal engine heat from burning a higher volume of air. Burning more air without increasing the amount of fuel is the definition of a lean mixture.
Richening the mix will cool the motor and increase power output, it also drops your fuel economy. On a track bike this is not really a concern.
Demand for octane is a result of higher compression ratios. A motor with high enough compression or residual internal engine heat can detonate fuel just based upon compression in the cylinder (like a diesel engine) which generates heat on the compression stroke. New fuel enters the cylinder at the begining of the compression stroke with the piston coming back up and a low octane fuel runs the risk of detonating prior to the piston reaching slightly before TDC where the spark plug kicks in. Detonaton is harmful to the engine and robs serious power from a motor. Detonation attempts to push the piston back down prior to getting to TDC while its still rising on the compression stroke. Due to piston location, the compression is terribly low and that stroke fails to make power. The detonation itself is harmful to the piston, rings, connectiing rod, crank and combustion chamber.
Simply adding higher octane won't cure the issue of a lean mix, it will just prevent the risk of detonation. The amount of fuel still has not increased sufficiently to enrich the mixture going into the motor.
Another indicator is the engine temp. With stock exhaust, take note of the engine temp. With the slip on, it should read a somewhat higher operating temp if its lean and the plugs will be darker.
http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html
Ken
Is She Runnin Lean?
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