Gearing up causes overheating??

[tyman]

Hey... just like every other teen in the world, i'm out to prove my parents wrong... i just got a 14 tooth sprocket for my 86 200x.... its got 20in. rear tires on it now and it did have a 13 tooth sprocket in the front... my dad says that the bigger sprocket will make the engine overheat because it will be running lower rpms which makes no sense to me... wouldn't the lower rpms with the same speed as the old sprocket revving high let more air go across the fins, causing it to cool off more and its not running as hard so it wouldn't get AS hot??? hope you all understand me but i'm pretty much asking, would higher gearing cause a trike to overheat easier????

thanks

[tecat-z]

Don't want to get in the middle of your great debate with your dad, but i've never heard of such a thing. Kinda like cutting the lawn with a riding mower. Engine speed remains constant, but depending on which gear is selected determins speed. Maybe with a liquid engine idling or riding very slow would cause radiators to not get any airflow and slow engine speed would cause slower circulation of coolant due to slower speed of pump. But personally iv'e never had a problem. Let the debate begin.

[hondahaulic]

i would guess that this would be more true with a liquid cooled engine because it wouldnt spin the water pump as fast but i dont think you'll have any problem at all. And really, the engine wont be at much of a lower rpm except on take off because with it geared higher the engine wont slow down, you'll just be in a lower gear than normal. Also the motor might be going slightly slower at top speed but at top speed there will be plenty of fast air to cool the fins.

[RedRider_AK]

In an auto-clutch machine it would cause your gearing to be higher, which might cause your slipper clutch to have to slip more and maybe make it warmer, but honestly I don't see where your dad is going with this.

[TimSr]

Your rpms and motor temp have nothing to do with your gearing unless you put in ear plugs and shift based strictly on speedometer readings.

[gravelord]

pulling taller gears is more stress on the engine its self, not anything with temp.
BUT i believe your dad may be trying to relate your bike with alot of older cars (they corrected the problem with newer ones), but alot of old cars at idle heat up, because of no air going over the rad, the hoods shut, etc etc..... anything sitting still really will be hotter, i believe he may be thinking of "lower rpms = sitting at idle" and relateing it to that whole issue. EITHER WAY, your 200x will not over heat from it. trying to pull taller gearing is more stress on some parts of the engine, but its not enough to be of concern at all.... most wont even notice any differnt wear. one thing id be concerned about, if you use 5th/6th gear you might have a harder time pulling those gears.

[super90]

I have 15/38 on my 86 200x and havent noticed any overheating problems, I've never even had any problems pulling 6th. I also have 20'' tires, But when I had 22s I did notice that it was harder to rev it out in 6th. The 15 tooth was not for a 200x and did require some grinding and a half link but it was well worth it, I love the difference.

[McDerry]

Simple principal.

High throttle usage with low rpm, creates greater combustion temperatures, in turn more engine heat, in addition to wear and tear.

[TimSr]

Okay, I have to ask this as I chuckle at this whole thread. To you people who find yourself running at lower rpms after changing a sprocket, has it ever occurred to you to shift? Re-read my other post, and think about it it a little bit. Do you shift based on your speed, or do you shift based on your rpms? Again I will say, gearing will not affect your rpms unless you put in ear plugs and shift based strictly on speedometer readings.