I currently have a 14,15 and 35 and 37 rear. I am 210lbs and I am trying to get to 50mph. How low would I need to go in the rear to acheive the 50mph mark. If I keep the current gearing of 14/37(stock) I am stuck at 32mph, that's what my GPS says I can go stock.... I am plan on droping to 35 and see what happens. The lowest I can find so far is 33. Is anyone running a 33 for the rear?

Thanks,

JQ

I plan on joining XR50 support group! These things can get spensive!

 

With my 88 kit I run a 15 front and 32 back. Right now it runs about 45mph. I don't know what other engine mods you have, but I got the most common. When I get a xr70 head and put on the 20mm carb., I'm hoping at least 50-55. If you want a smaller sprocket, hit up sprocket specilities. Also, bigger street tires (2.75-3) might give you a little more speed. I'm sure SilverSurfer can vouch for some of this stuff.

 

first off 210 lbs on a fiddy aint goin 50-55 mph
well if you pull it behind a truck maybe
17/30 is the tallest gearing you can buy without
actaully making special sprokets although the 88 kit wouldnt pull it
you need to build a 100 then youll pull it
i run a 103cc 14/37gearing, runs a radared 52 mph, but i only weigh 135lbs soaking wet, add 120lbs and im sure that would drop way off
build you a good strong 100 and you will see 50 or 55
but with an 88 kit and that much weight its gonna be hard to get there

 

What if I change the tranny to a 5 speed? I am planning on going to 106cc in the very near future. I met a guy at the track a while back who had a 115cc kit and he was keeping up with the ysr's that do 55-60. I don't know what gearing he was running.

Thanks

 

mine is a four speed if you go manual get a 70 motor all the aftermarket
trannies and clutches ive seen are junk and break even takegawa trannys
are you road racing im taking it?

 

put a 4 speed in it. i built one with 15/37 and a 4 speed that does 53 mph.

 

when i was 1 up in the back on my 86cc RCmotor, i did 47mph, but my motor isnt a bigbore addition to the stock motor.

Im back to stock gearing now, so im sure i can go close to 50,

 

50 MPH with stock gearing just aint gonna happen bud. it dont matter how big yer motor is. horsepower doesnt make u faster. gearing and rpm does. in order to go 50 with stock gearing your motor will have to be turning at almost 20,000 RPM. and neither your ignition, nor your bottom end, will allow that to ever happen.

 

Your valves wouldnt either. I could see 35 on stock gearing, and with 1 up rear 30.

 

like i said i dont have a fiddy motor

 

like i said, the motor has nothing to do with it. unless that RC has a 4 speed in it. if its a stock 3 speed and stock gearing, it aint happanin'

 

:YEAH it does have a 4-speed

 

thats all u had to say man.

 

 

 

i gut a 30 tooth in the rear i neva run outta gear i got it at
performance factor
1-781-391-6969

 

my fiddy does 56 mph i gut 88cc kit 15t in front 30t in rear heres me on the highway https://www.stuntlife.com/forums/293-fiddy-groups/71158-beatupgsxr-hits-highway-video.html

 

man that gixer is fubared!
that is a bitchin video gixer cuddos