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Old 07-21-2009, 10:44 PM   #1
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Default Gearing vs runtime

Hey guys, dunno if this has been asked before but... Is there any direct relationship between runtime and gearing? I have always thought that running taller gearing (bigger pinion, smaller spur), would consume less fuel since the engine needs less RPMs to reach its goal.

Although, lately I have been hearing the complete opposite. Can someone shed some light on this and explain the theory behind it?
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Old 07-22-2009, 08:12 AM   #2
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Originally Posted by Riketsu View Post
Hey guys, dunno if this has been asked before but... Is there any direct relationship between runtime and gearing? I have always thought that running taller gearing (bigger pinion, smaller spur), would consume less fuel since the engine needs less RPMs to reach its goal.

Although, lately I have been hearing the complete opposite. Can someone shed some light on this and explain the theory behind it?
I am curious who stated that. By the way, it depends also on the type of track you run.

In general: With a taller gearing your engine has to work harder to reach max rpm. With a smaller gearing the engine will reach max rpm sooner.
The speed of reaching max rpm is depending upon finger speed If both movements are exactly the same, the consumption of a taller gearing will be less. And ... you dont need to open the throttle as wide to reach the same speed
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Old 07-22-2009, 08:29 AM   #3
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A faster gearing makes indeed a lower rpm but the engine has to work more to give the power, whith that knowledge you know you can not go that lean.
With a gearing for high rpm the engine can go leaner without loosing power.
On the other hand more rpm means more combustions....

I think the real story is somewhere in the exhaust. The working of the exhaust is optimal with only a smal band in the rpm range, if you are not on it the engine will create a loss.
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Old 07-24-2009, 11:38 PM   #4
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Taller gearing will only help you in a long track, where you can "use" it, as soon as you are runing a track where you cant stretch that second gear, you are putting more gas in your engine than what the engine is actually using, or "working". the same goes for short gearing on a long track, youll be on the throttle a longer time since the engine "stops pulling" half way through the track.

you need the right gearing for your track, your engine AND!!! the setup you have in it; pipe, fuel, plug, compression, restrictor, etc.

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Old 07-27-2009, 06:44 AM   #5
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i have issues with gears as well, my os speed engine is a real drinker, so i gear it up higher on my 2nd speed set while maintain first speed ratio. indeed it reduce fuel consumption. made almost 6mins/tank compare to just 5mins.temperature was slightly low. side effect was inconsistent 2nd speed engagement on my second continuous tank. could it be my tuning?engine? clutch etc?
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