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Chingon619

2003 Yamaha Raptor looking for speed

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Ok, so I picked up an 03' Rappy that was supposedly bored up already and has some works. From the sound of it and occasional flame it spits out I believe it. It is super torquie and climbs the hills with ease. It's got a GYT-R pipe and sounds freakin killer (I'm easily amused)... but I think it's lacking overall speed. How can I get more top end out of it? I'm guessing a little sprocket change may be all I need but how many teeth etc. Up or down front or rear? Any input is appreciated. I basically want it to be as fast as a buddy's 700R Rappy is that even possible? His is stock but pulls away on the long end. Not power wise. What se u experts?

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What size tire are you running? When i raced gp races i would go from 18” mx tires to 22” tires. Huge bump in top end. Fastest way to pick up speed is up 1 tooth on the front sprocket or lose a few (2-3) in the rear. 

Probably wouldnt hurt to run that thing over to allen fox in alpine and have him tune it on his dyno for sea level. Im about to do this on the yfz450 i recently picked up

Edited by sausage450r

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Sprockets for sure - that's the cheapest and easiest change. Tire size (if it's off) after that.

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pick your tires and gear to the tires--if u are climbing comp or banshee hill gear for best speed in 5th gear--what works for comp

may not work for banshee due to  steepness of hill---try not to use a smaller front sprocket than stock--either stock or 1 up tooth

in front and then gear the back sprocket from there--a lot less strain on the front engine bearings and much easier for the chain

to roll--just my thoughts--been racing comp at dumont and glamis for 564 full moons

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5 hours ago, sausage450r said:

What size tire are you running? When i raced gp races i would go from 18” mx tires to 22” tires. Huge bump in top end. Fastest way to pick up speed is up 1 tooth on the front sprocket or lose a few (2-3) in the rear. 

Probably wouldnt hurt to run that thing over to allen fox in alpine and have him tune it on his dyno for sea level. Im about to do this on the yfz450 i recently picked up

 

Looks like it's on a 21x11-10 rear wheel. I also found the rear sprocket to be a 40 tooth. Tried to count the front sprocket but couldn't determine what that was. I also have a couple yfz450s and one of them have a 38 tooth rear sprocket. So hmmm... oh and what good is tuning if they are not fuel injected? Do you think it's worth doing the dyno thing? Seems silly to me for a 40hp machine or whatever it is. Maybe I'm wrong but is it cost effective? 

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8 minutes ago, Chingon619 said:

 

Looks like it's on a 21x11-10 rear wheel. I also found the rear sprocket to be a 40 tooth. Tried to count the front sprocket but couldn't determine what that was. I also have a couple yfz450s and one of them have a 38 tooth rear sprocket. So hmmm... oh and what good is tuning if they are not fuel injected? Do you think it's worth doing the dyno thing? Seems silly to me for a 40hp machine or whatever it is. Maybe I'm wrong but is it cost effective? 

His dyno has o2 sensors so can calibrate it to optimal jetting/fuel/air screw settings to make it fuel perfect. His dyno will also tell your hp and top speed. For speed its gonna be gearing. You’re gonna lose some bottom end though. I would at least give him a call and feel him out. He is one of the best there is.

Allen fox, fox engine works 619-445-1415. He is in alpine.

 

Fyi stock gearing is 13/40

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