Bullet Train BT80

[Jam-D-Man..! AKA Jamie Mc]

Can any one who has the BT80 2 stroke bicycle engine kit give me some idea of what kind of max speed they are able to obtain and wheel size using the stock engine and stock 48 tooth sprocket which is what mine came supplied with even though the manufacturers manual states a 44 tooth.I get a max speed of 42.5 mph with a 36 tooth rear sprocket. But my wheels are 29 inch. Reached 46.9 mph down slight hill.
I Have tried the china doll engine with a 32 tooth it was ported with expansion exhaust, Hp carb, 1mm planed of cylinder head. Pulling away from stand still with the manual clutch that the china doll uses was a bit much of an ask and would have undoubtedly destroyed itself in next to no time.
So needed to pedal off not just to start the china doll but to help get it rolling from standing start which after a while would pick up speed.
It's like if you said to a car driver your in the middle of no where and your gear selection goes you have to choose just one gear to be able to get you home.... What gear would you choose? I reckon if not to many stop starts to get home I would probably go with 3rd maybe. Well the set up I had on the china doll with a 32 tooth rear sprocket would probably equate to a car driver choosing 5th or 4th ! From this you can probably imagine what in a car this would mean ie ridiculously poor acceleration and around a good chunk of your clutch's life expectancy! Exactly what i got with the china doll using that setup.
My BT80 easily pulls away from standing start on the flat, Even carrying passenger + thats with a 36 tooth sprocket fitted!
I'd personally say if the rider is over 12 stone using stock powered engine with hills to go up don't go below 40 tooth rear sprocket.

 

[Frogslayer]

Looking up 12 stone
Report: 168 lbs
Thanks Google

 

[darwin]

12 stone is more than 11 stone and less than 13 stone Frog, jeez.

 

[HumanPerson]

I just weighed 12 stones from my yard.
Not 168 lbs. bro

 

[DistantWolrld101]

I just weighed 12 stones from my yard.
Not 168 lbs. bro

Try Bigger Stones

 

[Chainlube]

Try Bigger Stones

View attachment 93928

When does a stone become a bolder?

 

[DistantWolrld101]

When does a stone become a bolder?

Sir i looked up BIG STONE and this is what showed up along with tons of other stones this size lol
but i do agree its a boulder since a boulder is 10.0787 in Diameter

but lets just say a boulder is just a big stone


BUT TO ACTUALLY AWN YOUR QUESTION

stones become a bolder when they come together in a orgy fashion and during this fashion they get stuck making BOULDER MAN

 

[Wrench]

12 Stone? First time I got Stoned I was 12

 

[Shugashane]

Can any one who has the BT80 2 stroke bicycle engine kit give me some idea of what kind of max speed they are able to obtain and wheel size using the stock engine and stock 48 tooth sprocket which is what mine came supplied with even though the manufacturers manual states a 44 tooth.I get a max speed of 42.5 mph with a 36 tooth rear sprocket. But my wheels are 29 inch. Reached 46.9 mph down slight hill.
I Have tried the china doll engine with a 32 tooth it was ported with expansion exhaust, Hp carb, 1mm planed of cylinder head. Pulling away from stand still with the manual clutch that the china doll uses was a bit much of an ask and would have undoubtedly destroyed itself in next to no time.
So needed to pedal off not just to start the china doll but to help get it rolling from standing start which after a while would pick up speed.
It's like if you said to a car driver your in the middle of no where and your gear selection goes you have to choose just one gear to be able to get you home.... What gear would you choose? I reckon if not to many stop starts to get home I would probably go with 3rd maybe. Well the set up I had on the china doll with a 32 tooth rear sprocket would probably equate to a car driver choosing 5th or 4th ! From this you can probably imagine what in a car this would mean ie ridiculously poor acceleration and around a good chunk of your clutch's life expectancy! Exactly what i got with the china doll using that setup.
My BT80 easily pulls away from standing start on the flat, Even carrying passenger + thats with a 36 tooth sprocket fitted!
I'd personally say if the rider is over 12 stone using stock powered engine with hills to go up don't go below 40 tooth rear sprocket.

Is this the electric start bt80

 

[GW's Motorized]

I am running a bt80 on my bike. If it's the electric start, depending on your weight you can expect 35 - 40 top speed. You do have 29s while I am running a 26, so probably a bit less. But weight is a factor.