Powerbands on a motorbike?

witchy

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Apologies if posted in the wrong place, it probably is. :(

My mate has an old 80's style Suzuki RM250, it's a great bike and can reach some spooky speeds for such a small engine :)

Today I was riding the bike having the time of my life in a local field when all of a sudden the thing seemed to have a life of its own, I was cruising along at about 40mph over some rough ground when it suddenly went CRAZY, the bike shot away from me and i landed on my arse!

lol

My mate came running over pissing himself laughing and told me I had 'hit a powerband', WTF is a powerband?! My mate just said it was when the engine is running at 'optimum' ?!?!? WTF does that mean?, How can it be running at optimum when i was only doing around 40mph, and why on earth would it do this anyway??

Fooking dangerous if u ask me!
 

Dutcho

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It's the rev range when all the nice parts work together perfectly and give you a kick out the ass, only way I can think of is it 1 you were in a low gear so the rev's where high or 2 the back wheel has left the ground and span up then on landing has kicked you off.
 

cupra.john

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It is the "usable" rpm range between idle and redline of ANY motor. A 2 stroke offten will not make a whole lot of power from idle until say 70% of redline, thus making the last 30% of the rpms to redline: a very narrow powerband.

Say idle is 1000 rpm and redline is 10,000 rpm and there is little power from 1000 to 7,000 rpm, but plenty from 7,000 to 10,000 rpm. Then that is a powerband 3000 rpm wide and starts at 7,000rpm.
 

Erbs

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hi all

i have a tzr250 and has a YPVS system on it which basically stands for Yamaha PowerValve System.


the basic principal of powervalves and bands is the exhaust port is altered thru these valves and let exhaust gases out quicker

it gives you that range of extra omphhh,my bike starts around the 6000rpm al the way to 12-13000
here is a pic of a powervalve
 
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theseeker

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lol, sounds like one hell of a powerband if it threw you off the back !
like dutcho and co said a powerband is when the bike hits its optimum rev range, everything goes smooth and the exhaust hits a lovely note !!

I do remember the old crossers being a bit of a handful though, its quite possible that you have been chugging around the field in low revs and got caught out by the awesome power these bikes produce.the rm250 produces something in the region of 50 bhp, not bad for a 210 lb lightweight.
 
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