Gearing help and such

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big-e

New Member
Jan 21, 2011
16
0
0
st augustine FL
I plan on using a very new Chainsaw for a bike build. Here are my expectations: I'd like to see 25-30 mph and be reliable. I have a McCoulugh ( however u spell it) chainsaw. I think its 28 or 30cc. I chose this because i figure the clucth on a saw would be a bit heaver duty than say a weedeater. I dont have cash to get another clutch so id like to use what i have if i can. Here's what i have to use as frames. I have 2 26" mountain bikes and a 20" bike. I'd like to use the 26" frame with 20" wheels. I feel that would be more stable, and 20" wheels are more rigid than 26" wheels in regards to side to side flex, and well i kinda think the big frame smaller wheel combo might look better. I might put the bigger fork on the 20" frame too. Its dreary outside so i havent went out to play with it yet.
Anyway, Im 200lbs, and florida has no hills so , like i said, i have no real need for take off grunt. Im nore interested at higher speeds as if this works out ill be using this for about a 15 mile ride a few times a week. I'd like to gear it as high as i can without tearing the clutch up though. The best part is, i have access to a huuge metal shop and a CNC machine. I can make my own gears and mounting accessories.
Would a coaster rear tire work well with an engine? i kind have the idea of centering and welding a bigger sprocket to the coaster gear for rear drive. I dont plan on having Pedals at all. Mounting some foot boards or pegs of some sort.
Any Info would be great. Once i build this and prove it'll work reliably, ill be dissasembling and possibly powder coating and making it look as cool as possible. I'm anxious to start! Ya'll let me know what you think!
usflg dnut
 

old motorbike

New Member
Sep 21, 2008
352
2
0
78
Fl.
Without pedals they can give ticket for no license. (then it's a motorcycle or scooter)
I've made 3 with various engines (no chain saws though)
If it turns the right direction and has a clutch and sprocket of some size? You can make a custom gear for whatever chain size you run (being a machinist)
You need a ratio of about 14-16:1 for 26" wheels. Don't know about 20s
I rigged a jackshaft from left to right side of engine (like SBP) Shift kit. Used their pedals and driven sprocket to drive the bikes 6 speed rear gears. In Fla its great, Take off or cruise.
 

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big-e

New Member
Jan 21, 2011
16
0
0
st augustine FL
thanks for the info/ havent taken a single p[hoto but im to the point of building the gas gas tank and running fule lines and brake/throttle cxables now. i did leave room for a short crank with pedals just incase the law requires pedlas to be legal(* since i have no license as of yet). Unfortunantly have a 20 tooth cluctch gera nad a 40 ttoth rear gear ( which im sure ill be changing soon enough). il get picks as soon as i van since i dont have a cam phone now. i stretched a set of 14" forks today and muonted a set of foot pegs. I trued up the engine mount pole that extends behind the seat post area also. ill get a pic of it tonight from my buddy thats at the shop to show progression though. thank for the input
i do intend on bringing it to the local sheriffs office to make sure i can ride it without any issues though b4 i ride it.