Pocket Bike Engine Project
- Thread starter lowracer
- Start date
Gera,
If it doesn't breathe, the engine will run for a short time then get starved for fuel & bog out & die. Mine idled ok but wouldn't go anywhere when I hit the gas. As soon as I opened up the gas cap, it sucked in air like a vacuum...
-Lowracer-
If it doesn't breathe, the engine will run for a short time then get starved for fuel & bog out & die. Mine idled ok but wouldn't go anywhere when I hit the gas. As soon as I opened up the gas cap, it sucked in air like a vacuum...
-Lowracer-
hi my name is Todd! i am building a stage 3 engine like your but one higher obviously lol,
i want to know if you think there's a way i can mid mount this thing and make a jack shaft so the gearing will work? i have been reading all of your thread for a few hours and learned a bit but i don't think this has been talked about...thanks
heres a video of the bike :
http://www.youtube.com/watch?v=FxYR3awR36s
and heres the engine!! :
http://www.ebay.com/itm/53cc-54cc-2...es&hash=item20c025e1f4&vxp=mtr#ht_2165wt_1185
i want to know if you think there's a way i can mid mount this thing and make a jack shaft so the gearing will work? i have been reading all of your thread for a few hours and learned a bit but i don't think this has been talked about...thanks
heres a video of the bike :
http://www.youtube.com/watch?v=FxYR3awR36s
and heres the engine!! :
http://www.ebay.com/itm/53cc-54cc-2...es&hash=item20c025e1f4&vxp=mtr#ht_2165wt_1185
Stage3GT,
Heres one member who mounted it like you want to.
http://motorbicycling.com/showthread.php?t=33877
-lowracer-
Heres one member who mounted it like you want to.
http://motorbicycling.com/showthread.php?t=33877
-lowracer-
Well, if you're using a 5:1 gearbox you normally want a final ratio of 12:1 or 14:1 as the final ratio. Otherwise, since these engines spin so fast you're going to end up having NOOOOO torque. 12:1 or 14:1 is still under geared, so if you run the 5:1 and then run say a 12 off the box and a 36 in the back, you'll be somewhere around 15:1 which ought to be a solid starting point. If the engine is struggling with this, you can change the rear to a bigger sprocket. I hope this helps!
Yes, See, I'm used to doing gear ratios for 4 strokes, but something more in the 20:1 range (5:1 + 11t front, 44 rear) would probably be safer. I can't remember what the required gear ratio is for these peppy little things, but it's pretty high given the high rpms. Peace
STAGE3GT
The 5:1 gear box is tuff and well built, but it use`s gear`s , so the rotation is reversed from that of the engine.
You should be able to mount that combo in frame, but will need to be a right hand side drive. You maybe could use my dual right hand freewheel setup with 8mm 11 tooth on the gear box. There is 8mm 4 hole sprockets with 72, 63, 54 tooth count. 11 with a 72 tooth would give you 32.7 ratio.
A 11 and 54 tooth count would give you 24.5 ratio.
The sprockets were $10.50 each and the freewheel was $7.50. Thinking there is a 17, and 20 tooth gear box sprockets available and maybe one or two more tooth counts for the gear box.
Most 49cc engines do ok with near 18:1 ratio
Lowrider may be able to suggest a startin ratio.
If you add a jack shaft, then it could be left side drive to the rear wheel.
Ron ...
The 5:1 gear box is tuff and well built, but it use`s gear`s , so the rotation is reversed from that of the engine.
You should be able to mount that combo in frame, but will need to be a right hand side drive. You maybe could use my dual right hand freewheel setup with 8mm 11 tooth on the gear box. There is 8mm 4 hole sprockets with 72, 63, 54 tooth count. 11 with a 72 tooth would give you 32.7 ratio.
A 11 and 54 tooth count would give you 24.5 ratio.
The sprockets were $10.50 each and the freewheel was $7.50. Thinking there is a 17, and 20 tooth gear box sprockets available and maybe one or two more tooth counts for the gear box.
Most 49cc engines do ok with near 18:1 ratio
Lowrider may be able to suggest a startin ratio.
If you add a jack shaft, then it could be left side drive to the rear wheel.
Ron ...
Last edited:
stage3gt,
I think I got the headbolts from Mcmaster Carr & the copper gaskets from one of them pocket bike parts stores online (cant remember which but I may have posted it on this forum?)
-Lowracer-
I think I got the headbolts from Mcmaster Carr & the copper gaskets from one of them pocket bike parts stores online (cant remember which but I may have posted it on this forum?)
-Lowracer-
As far as ratio I like to use around a 16:1. I got that now on 2 of my MB's & both run great & get me up to ~40 mph on the 32cc Tanaka & ~50 mph w/the pocket bike stage 2 engine. Also getting close to 150 mpg's when not running WOT.
-Lowracer-
-Lowracer-
stage3gt
IF THE 3:1 TRANNY HAS THE SINGLE #25 CHAIN, YOU MAY WANT TO FIND ONE WITH THE DOUBLE #25 CHAIN.
IF MY MEMORY IS CORRECT OLDMOTORBIKE CHANGED HIS TRANNY A LOT.
THE SECONDARY SPROCKET IS STICKING OUT OF THE CASE, MUCH LARGER DIA, AND MITE BE A BELT DRIVE.
IF YOU RUN 17 AND 63 TOOTH WITH THE 5:1 BOX YOU WOULD HAVE 18.5 TO 1 FINAL RATIO.. WITH A 17 AND 54 COMBO YOU WOULD HAVE A 15.88 TO 1 FINAL RATIO, SIMULAR TO LOWRIDERS RATIO.
IMO, IT DON`T GET ANY EASIER THAN THE RIGHT HAND DUAL FREEWHEELS.
JUST TRYING TO HELP, DO WHAT WORKS FOR YOU. WHAT BREAKABLE PARTS ARE YOU REFERING TO?
RON
IF THE 3:1 TRANNY HAS THE SINGLE #25 CHAIN, YOU MAY WANT TO FIND ONE WITH THE DOUBLE #25 CHAIN.
IF MY MEMORY IS CORRECT OLDMOTORBIKE CHANGED HIS TRANNY A LOT.
THE SECONDARY SPROCKET IS STICKING OUT OF THE CASE, MUCH LARGER DIA, AND MITE BE A BELT DRIVE.
IF YOU RUN 17 AND 63 TOOTH WITH THE 5:1 BOX YOU WOULD HAVE 18.5 TO 1 FINAL RATIO.. WITH A 17 AND 54 COMBO YOU WOULD HAVE A 15.88 TO 1 FINAL RATIO, SIMULAR TO LOWRIDERS RATIO.
IMO, IT DON`T GET ANY EASIER THAN THE RIGHT HAND DUAL FREEWHEELS.
JUST TRYING TO HELP, DO WHAT WORKS FOR YOU. WHAT BREAKABLE PARTS ARE YOU REFERING TO?
RON
Last edited:
You can see my engine setup here: http://motorbicycling.com/showthread.php?t=33877&page=13
I use a 3:1 gearbox.
I use a 1 chain gearbox and after reading what Neat Times said I am feeling like I'm lacking some reliability with the gearbox. I just hope my chain in the gearbox won't snap any time soon but I will put motor oil on it to make sure it is operating correctly. I wish I could get the 2 chain gear box, but is it the same dimensions as the 1 chain gearbox?
Is it going to "stick out" the same without bothering the feet/ leg/ pedaling whenever you need to pedal?
I use a 3:1 gearbox.
I use a 1 chain gearbox and after reading what Neat Times said I am feeling like I'm lacking some reliability with the gearbox. I just hope my chain in the gearbox won't snap any time soon but I will put motor oil on it to make sure it is operating correctly. I wish I could get the 2 chain gear box, but is it the same dimensions as the 1 chain gearbox?
Is it going to "stick out" the same without bothering the feet/ leg/ pedaling whenever you need to pedal?
Last edited:
Aren't there 8mm sprockets that'll fit onto your engine and gearbox? Does this box use the six-splined shaft?
5-7
HELLO.
Most all of the pocket bike/scooter tranny`s have the six spline for external sprockets. There is a 12 tooth six spline sprocket with 1/2" pitch for bmx chain, have one on my diy axle mount build with the 5:1 box.
The single chain 3:1 tranny has a front #25 sprocket the size of a dime!! Like on the pocket bike clutch housing.
Dax chain box has the six spline that is longer for , apparently for better rear chain alignment!?
The dual #25 chain box is wider.
The cogged belt drive from "bicycle-engines.com" would be good for $139. but you need an engine with a straight 5/8" crankshaft. There was a model of it that fit all the engines with the 76/78mm clutch system for $10. less, but is only in their kits currently.
Terry Blow had them in Canada, but is shut down for a few more months.
Quenton Gunter may have a Q-matic for the 76/78mm clutch, was talking of it, but would be wider than the regular Q-matic unit.
A 5:1 box could be used with the 12 tooth 1/2" pitch for bmx bicycle chain, then use a 5 hole freewheel sprocket adapter on the back wheel`s right side.
With a wheel threaded on both side`s, a South-paw (left hand thread) sprocket could go on the left side of rear wheel for pedal power, put pedal chain ring on left side and run the 5:1 drive to single free wheel sprocket on right hand side of rear wheel. Imho a spring tensioner should be used when ever possible, prevents problems. Whew, need a nap now!! lol.
Ron ...
HELLO.
Most all of the pocket bike/scooter tranny`s have the six spline for external sprockets. There is a 12 tooth six spline sprocket with 1/2" pitch for bmx chain, have one on my diy axle mount build with the 5:1 box.
The single chain 3:1 tranny has a front #25 sprocket the size of a dime!! Like on the pocket bike clutch housing.
Dax chain box has the six spline that is longer for , apparently for better rear chain alignment!?
The dual #25 chain box is wider.
The cogged belt drive from "bicycle-engines.com" would be good for $139. but you need an engine with a straight 5/8" crankshaft. There was a model of it that fit all the engines with the 76/78mm clutch system for $10. less, but is only in their kits currently.
Terry Blow had them in Canada, but is shut down for a few more months.
Quenton Gunter may have a Q-matic for the 76/78mm clutch, was talking of it, but would be wider than the regular Q-matic unit.
A 5:1 box could be used with the 12 tooth 1/2" pitch for bmx bicycle chain, then use a 5 hole freewheel sprocket adapter on the back wheel`s right side.
With a wheel threaded on both side`s, a South-paw (left hand thread) sprocket could go on the left side of rear wheel for pedal power, put pedal chain ring on left side and run the 5:1 drive to single free wheel sprocket on right hand side of rear wheel. Imho a spring tensioner should be used when ever possible, prevents problems. Whew, need a nap now!! lol.
Ron ...