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Discussion Starter · #1 · (Edited)
Hi,I am a newbie here on this forum...and this is an absolutley awesome forum for alot of info for our quads. There are alot of you guys on here with alot of knowledge. I have done alot of research on my question on here over the last 3 hours,and to be honest,I am kinda confused what to go with I have read so much. I have a completley bone stock 2001 Raptor 660R that I bought new in 01 and am thinking about changing the front and rear sprockets along with a new chain,since they are 10 years old anyway(hasnt been rode alot)...and I figured if I was gonna replace them,I might change the gear ratio for more bottom end. I am running 20" RazR tires on the rear and am thinking about changing the sprockets to 12/42 combo instead of the stock 13/40,since my 2001 Raptor has a higher 1st gear ratio than the later models. I am not really concerned with max top speed near as much as alot of bottom end power and quickness. When I first bought this quad new back in 01,I was following a buddy of mine down the highway in his car,and I kept up with him at about 74-75 mph,thats all it had. My question is does anybody know exactly how much top end speed it will lose going to the 12/42 gearing with the 20" tire? If it would still run 65-70,I would be happy as long as is had mega amounts of bottom end with the gear change. I dont race it or anything,just a quad for fun,also we do have quite a bit of wooded area around where I live here in Missouri. The only other thing I may change is the stock foam air filter to a K&N replacement #6601. I thought about re-jetting,but I really dont think it needs it,although the plug is always black in it when I change it,it has always been that way since brand new,maybe running rich in factory form,what do ya guys think about this? The elevation I live at is about 900ft if that helps.....everything will remain bone stock,exhaust,engine,and everything besides the gearing and the air filter,atleast for now......

I would really appreciate the help and good knowledge you guys have...

Brian
 

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Master of the Electron
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going from 13/40 to 12/40 is about an 8% reduction in top end (but an 8% increase in low end torque) - 12/13 X 75 = 69 mph.

An additional change from 12/40 to 12/43 is another 7% reduction in speed (and 7% increase in torque) - 40 / 43 X 69 = 64 mph.

The combined change will be about a 15% increase in torque, and loss in top speed, relative to stock.

THe deal here is that top speed is limited by a sensor that looks at output shaft/sprocket rotation rate, so reducing gearing will have a one-to-one relationship with reduction in top speed.

I am quite happy with the additional torque increase from just the change from 13 to 12 on the front sprocket on my '01, but I also have a full aftermarket exhaust and open airbox with K&N filter, with appropriate jetting. These changes make a huge difference.
 

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Discussion Starter · #3 ·
thank you quadmaniac....so if my calculations are correct,if my quad ran 75mph before,it would run about 66 mph with the 12/42 combo? and have alot more bottm end power?
 

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first gear will be next to useless you'll be using second more often which is something to consider when 2nd is known to be bad in about 40% of the 01's .
 

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+1 on Tommy's post. Plus your gears would be so short from changing both sprockets that I think you would get tired of shifting so much. I loved to torque when I had a 13t on my 700, but it seemed like I was constantly shifting so I took it back off. I think you should try dropping a tooth up front first to see how you like it for a ride since it is the easier one, then decide if you want to change out the back one also.
 

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Discussion Starter · #6 ·
thanks for the input guys....I may just try the 12t front sprocket first....what do ya guys think about the plug being black in it....it has always been this way since new...I havent rode it much,the quad still looks excellent for an 01 model,other than the decals gettin a little worn from sun a weather....but it seems as if it has always ran rich,the plug is always a dry flat black.....from my experiance in the drag racing world,this indicates a rich condition. But its all stock other than the spark arrestor removed, with factory jetting...so I dont know...guess I will just leave it alone....
 

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I there is enough torque to start in 2nd, would it make more sense to gear up? If you do alot of trail riding/cruising this could essentially give you that 6th gear (or overdrive) that I always want. I know I always skip 1st and start in second so I thought about up-gearing next time.
 

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I ride a 12/44 combo and its too low in my opinion. I think just the 12 would have suited me better. I get to 5th and try to keep on shifting. I need an 7 or 8 speed tranny.
 

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you should clean the carbs and adjust the valves and put a new air filter in it and see if that cleans up the plug
 

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Master of the Electron
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I too think you should start with just the 12T change in front - you'll love it and will get an idea if you want to go further.

A flat black plug tells you little about an engine that's being driven around at many throttle/load positions - only if you start with a new plug, ride at WOT and then kill the engine as you come off throttle (rather similar to what you'd do in a drag car), can you use this for information... the real question is - how does your bike run?

In reality, with stock jetting and the S/A removed, you're probably running just a tiny bit lean - but not enough to worry about.

If you REALLY want to wake up your engine, go to a full exhaust, open the airbox and jet accordingly - the difference will amaze you - more than changing the sprocket will.
 
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