What sprockets for 70MPH or more.

[gmq09281]

Hello I am wondering what the best sprocket setup would be to get a boost in speed as first gear is really short and my top speed is 55mph. Looking to get top speed around 70-75 so I'm not pushing it riding around town where the speed limits of the major roads I take is 45-50MPH

[Megadan]

Originally Posted by gmq09281

Hello I am wondering what the best sprocket setup would be to get a boost in speed as first gear is really short and my top speed is 55mph. Looking to get top speed around 70-75 so I'm not pushing it riding around town where the speed limits of the major roads I take is 45-50MPH

I'm assuming a Hawk?

If Yes: The best you will do with no engine mods other than jetting the stock carb properly is about 62-ish MPH, no matter what sprockets you have.

With a full exhaust you then push that limit up to about 65-68mph.

If you want any more than that you will be entering the realm of rapidly diminishing returns looking at big engine upgrades. Ported head and a cam at a minimum. Which will get you to, and a bit past, that 70mph barrier. On flat ground with no wind fighting you. You WILL need at least a 17 front and 45 rear sprocket to even have a chance of turning the RPM needed to hit 75 - which will happen right at 8000rpm.

[Do©Hawk]

Originally Posted by Megadan

I'm assuming a Hawk?

Based off the oil leak thread from the same member, appears to be a 21 Hawk DLX.

OP, I'm running a 47 rear and 17 front. On hilly country roads with knobby tires and wind from somewhere always, my max speed has been 68mph.

[Megadan]

Originally Posted by Do©Hawk

Based off the oil leak thread from the same member, appears to be a 21 Hawk DLX.

I am aware, but I never like to make assumptions without qualifying them, because many people here do own multiple china bikes.

[Barnone]

Yep, you need something with more motor.

[Oldenslow]

There's only one source for the Magic Sprocket -- and I ain't tellin'...

[Bill Hilly]

The only reason that I run a 46 tooth sprocket is because I already had 2 , one from my old Brozz , and one that was evidently stock with the TBR7, that I bought slightly used. I tried the 17 tooth with the 46 when the bike was basically stock, and thought about keeping it, BUT on certain long fast hills the bike ran out of steam too fast, so I switched to a 16 tooth front,and the bike did a lot better. I modded my motor, and got noticably more power, and a more fast road compatible power curve, so I put my 17 back on the front, and it was just right. I was still on the stock knobby when I put the 17 on, but have since put a Dunlop D605 , 4.60x18 on the rear, and I can tell it geared me down just a little from what it was with the knobby, which evidently had a larger diameter. I'm still very satisfied with the Hawk now, to the point of being too satisfied, because I am riding it so often, and for longer faster rides, that I bought the KPX for. LOL. I have been riding the KPX more often in the last couple of weeks. The Hawk was taching close to 8,000 at 70( true GPS verified )with the D605, it will still run 70, but is just starting to go beyond 8,000.

[tknj99]

If you gear for 70+ you better hope there's a tornado at your back at all times in addition to always rolling downhill

[alex_in_az]

Originally Posted by gmq09281

Hello I am wondering what the best sprocket setup would be to get a boost in speed as first gear is really short and my top speed is 55mph. Looking to get top speed around 70-75 so I'm not pushing it riding around town where the speed limits of the major roads I take is 45-50MPH

I'm running 17/40 and have hit 75 at a little over 7200rpm. I don't recommend going any faster than that as the front end can get pretty loose. you're going to have to do all the mods I list in my signature for enough torque to pull that speed

[Bill Hilly]

Originally Posted by alex_in_az

I'm running 17/40 and have hit 75 at a little over 7200rpm. I don't recommend going any faster than that as the front end can get pretty loose. you're going to have to do all the mods I list in my signature for enough torque to pull that speed

I know Jerry runs ,or did run similar sprocket sizes on his Hawk, but for most of us that gearing is too high for our Hawks. The popular sprocket sizes that most switched to on the TBR7 is the 42/17, which is about like a 45/17 on a Hawk, because the rear tire has a good bit more circumference.

[Megadan]

Originally Posted by Bill Hilly

I know Jerry runs ,or did run similar sprocket sizes on his Hawk, but for most of us that gearing is too high for our Hawks. The popular sprocket sizes that most switched to on the TBR7 is the 42/17, which is about like a 45/17 on a Hawk, because the rear tire has a good bit more circumference.

Spot on. If you are close to 200lbs, or more, anything lower than about a 17 front and 43 rear is going to start hurting performance. Of if you live anywhere with actual hills to contend with.

[buzz]

17 and 39 on the back,yep 68 mph. Thats all it will do.

[Do©Hawk]

I'm not a big guy. I'm 5'8" and hover between 150 and 155....might be why I get away with my gearing.

[Megadan]

Originally Posted by Do©Hawk

I'm not a big guy. I'm 5'8" and hover between 150 and 155....might be why I get away with my gearing.

It's not really the weight that gets us bigger people. It's the Aerodynamic drag. Bigger and Taller = more frontal area. More frontal area = more total resistance. Put a man like my best friend, who is 5'6 and 120lbs on a Hawk and he will probably be able to hit 70mph on a Hawk with just an exhaust and the right sprocket combination. Put myself at 6'4 260lbs on that same bike, being pretty much 30-40% dimensionally bigger on that same bike, and 68 will be the best I can do.

[alex_in_az]

Originally Posted by Megadan

It's not really the weight that gets us bigger people. It's the Aerodynamic drag. Bigger and Taller = more frontal area. More frontal area = more total resistance. Put a man like my best friend, who is 5'6 and 120lbs on a Hawk and he will probably be able to hit 70mph on a Hawk with just an exhaust and the right sprocket combination. Put myself at 6'4 260lbs on that same bike, being pretty much 30-40% dimensionally bigger on that same bike, and 68 will be the best I can do.

very true, I converted a mid 2000s pep boys dirt bike into a cafe bike with a 200cc CJ engine and it would do 84mph with a handlebar fairing on it and me tucked down