Gotta Need 4 Speed

[Friction]

Is it possible to build a gas bicycle with maybe a 50cc or a 80cc engine (safely!) with out falling to pieces that maybe could achieve speeds of maybe 30 to 40 mph.
keep in mind with these speeds ive listed im not going to throttle it all the time so you cant and you dont say its overkill, how could i make a contraption like this is it possible? would I need a larger engine? i guess its like a whizzer bike.





(Gotta Need 4 Speed)

 

[Friction]

A couple of other things 2 say:
I while ago I was going to make a 6.5hp go kart capable of reaching skin tearing speeds of 40 maybe 60 mph but i soon found out from my dad that people might get suspicious and the cops might get involved if i drived it on the road. So my idea was maybe to make a really fast bike!!Also I might go and look into chain drive bikes too if they are much more efficient.but i have also heard that chain drive bikes are complicated to setup and they are a hassle to length the chain is that so?? I think chain drive bikes might be nice because you have the advantage of toying with the speeds because you could experiment with different sizes of sprockets. Meanwhile I am enjoying building my first ever bike project!! which i have got much and most help and ideas from this website (Thanks!!) for the project I am using my purple 1994 specialized rockhopper which is a great bike to work with and I am hoping that my little 31cc ryobi engine and friction drive power will assist me well on my build.
(Im also keeping in mind that go karts also use chain drives)

 

[jasonh]

I know you posted this in the non-kit forum, but the 70cc China kits are capable of 30mph..faster with a smaller sprocket. My bike currently goes 35-40 (I have a shift kit), we'll see how it does with more go-fast mods.

So yeah, if it's built well it'll totally go that fast.

 

[deacon]

I have had a friction drive up to 20 but then I got a little shaky so I backed off. I have had the hain drive I used to have well over twenty and I didn't care for that much speed to be honest. All that said chain drive is the way to go for speed and efficiency. Friction drive for ease of build and maintenance.

However a chain drive can be just fine if you remember to check it when you ride. I personally wouldn't feel safe much over 25 but then I am not really safe at ten mph either.

 

[GregLWB]

I know you weren't looking for a kit but, I have a 35cc R/S 4 stroke GEBE installed on my LWB recumbent bike. I use this bike for commuting (53 mile round trip, 2-3 days a week) and have over 1500 miles on this setup. I am usually riding ~28 mph but I can hit about 34-35 mph on the flats.

Where I live we have many hills and a lot of rain and it doesn't affect the belt drive at all. I do have a friend with a friction drive setup and he can't ride in the rain (it slips too much) and he really wears his tires out fast.

Just my opinion.

Greg

 

[jasonh]

BTW, I just went 40.2 on my bike yesterday. It's a little unnerving, especially when it comes time to stop.

 

[Friction]

I think i might go to chain drive and have some fun with that and i think ill get it in kit form so i dont have to hastle and improvise thing together which is whats is happening in my bike that I am doing right now. Ithink Ill order the kit off of zoombicycles.com they seem to have good prices and free shipping which is great. I think i shall go with the 80cc kit which says on the webpage that it can preform speeds of 38 to 50kmh which is pretty fast and another question is whats all these
shifter kits about? Zoombicycles Motor Bicycle Engine Kits FREE SHIPPING - 80cc Stealth Bicycle Engine Kit | 1-Bicycle Engine Kits | RuiHong Enterprises Ltd.
thats the kit i might buy from zoom bicycles in that link so check it out and tell me if its any good so yeh not 2 exspensive and it wont take me long to save up for it
(I think i might spray my bike black so it matches it all and my dads friend can airbrushes so maybe i cud get flames on the tank or somethin LOL that wud be pretty cool)

 

[jasonh]

I got my replacement motor from zoom - didn't get the black one though, just the regular. So far it seems to be fairly good quality. Don't know about the rest of their kits.

What are the shifter kits about? WELL...

Welcome to Sick Bike Parts

basically you get rid of the left side sprocket and it uses your bikes gears to give you a greater range of gears to use. I have enough torque to get going from a dead stop without pedalling, and can cruise at 30mph with the motor barely off idle.

 

[Friction]

thanks all keep that in mind for my next build !!

 

[ZnsaneRyder]

A couple of other things 2 say:
I while ago I was going to make a 6.5hp go kart capable of reaching skin tearing speeds of 40 maybe 60 mph but i soon found out from my dad that people might get suspicious and the cops might get involved if i drived it on the road. So my idea was maybe to make a really fast bike!!

Really, you want 6.5HP bike capable of skin-tearing speeds..............

I'm running a slightly modified 6.5HP engine (making about 8HP) on my push trailer that gets me to 50. Max speed I've ever hit was 51.9Mph. Once you are over about 30, it almost feels like riding a motorcycle, until you look down, and see the bicycle frame and the ground rushing by you!

BTW, the 80cc kits are also very fast as well, as I saw when I rode with several folks in St. Pete. The question is how fast do you really want to go, LOL.

Crazy Riding,
ZnsaneRyder

 

[Friction]

My dad eased of the idea of not allowing me to make my gokart kart so any time soon
i will be making a go kart but i have the idea of maybe converting my friction ww engine bike to a
chain drive and see ho w that works