Landracing Forum
Loring Timing Association (Maine) => Loring (AFB) land speed venue => Topic started by: mtiberio on June 19, 2021, 07:39:23 PM
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I have raced at El Mirage a number of times, and I'm going to try pavement for the first time at Loring. I race a ~70 HP 400# Motorcycle. What changes or general direction should I go with my gearing for the pavement, if any? FWIW, my last run at El Mirage I went 141 at 7500 RPM.
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Maybe what we experience will be of some help on your gearing decision.
What we do is gear the same way we would at Bonneville. Since Loring is a lot closer to sea level than El Mirage you will have more Horse Power.
The speeds we see at Loring in 1.5 miles is extremely close to what we run in three miles at the higher density altitudes when running out West. We run the same tires at both locations. The tune up is slightly different we go up on the jetting at Loring two to three sizes to compensate for the additional air.
Ronnieroadster
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If it was me, I would keep the same gearing for the first run but bring several sprockets. I normally have +1 to -2 rear sprockets on hand. On at least one of the days during the event, the weather conditions can be very favorable. You don't want to run out of gear. I am going to assume MPS or APS...141 is a very stout speed for 70 HP.
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You didn't say what your redline is but Ransom gives good advice.
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Redline determined by valve train at this point. Has pulled 7700 RPM with some reversion. But I think I'm past peak there (Guzzi w/78 mm stroke). Using varios rear gears and rear tires, I have a number of gearing options +/- ~3%.