BMX with 35 cc 2-stroke engine - 3rd

[denmasardhy]

hello builders,

this is the 3rd build and just tested last night
started when i got $25 used 35 cc 2-stroke engine at flea market
tried to use 24" front wheel but doesn't seems nice with the frame geometry
the rpm reducer using the same method with 2nd built, front pulley and rear chain

had to trim the frame middle axle to get center positioning of the engine, and correct alignment between engine sprocket to wheel sprocket to prevent derailed chain

disc brake is used for the front wheel and rear with V-brake. engine mounting using double-layered slim plate to reduce engine to frame vibration. the plate at 2nd built is thicker and cause engine vibration propagate to frame

the max speed and acceleration is not yet per expected approx 35 km/h only, also compared with the 2nd built. will need to check the ratio, carburetor and clutch

 

[Dan]

Howdy Den, welcome.

Cool looking build!

 

[Ludwig II]

It's lovely, what brand name is on the motor?

 

[denmasardhy]

@dan: thanks
@ludwig:i use tanaka 35cc 2-stroke engine. the frame got burnt when i weld the engine mounting plate, so just paint it black and put some sticker to camouflage it.

 

[Wild Bill]

Very cool and definitely one of a kind!

 

[wheelbender6]

That's the best looking motorized BMX I have ever seen. Well done.

 

[denmasardhy]

just done long distance trip together with 2nd bike, learnt lot
got an issue with the spark plug, the carburetor is too wet
also the middle pulley/sprocket is stuck with the axle, the belt tension is too high and cause internal friction as the clearance is bigger than internal bearing tolerance

 

[Dan]

Den, I'm curious about your engine drive set up. Are the parts off the shelf or did you machine a sleve and add bearings? I really wan't to try some thing like that. A couple yrs back went to an aerospace shop and they wanted buku bucks. (now am in school for precision machining, lol. Got tired of trying to get shops to make stuff for me.)

 

[denmasardhy]

Den, I'm curious about your engine drive set up. Are the parts off the shelf or did you machine a sleve and add bearings? I really wan't to try some thing like that. A couple yrs back went to an aerospace shop and they wanted buku bucks. (now am in school for precision machining, lol. Got tired of trying to get shops to make stuff for me.)

hi dan,

good that i dismantled the pulley/sprocket last night.

i drill 3$ pulley in axle diam size, then make bigger opening for both end using lathe for bearing housing (you can see the outer bearing and just the same for the inner). and the chain sprocket, weld into mounting that fit with inner side of the pulley (also as stopper for inner bearing). the stopper for outer bearing is the 4 bolts that also act as holder for entire assembly.

once the pulley assembly put into the axle, you can have the idea that between pedals/axle and pulley/sprocket are independence due to the internal bearing.

here is some pic and let me know for more detail required

 

[Dan]

Just plain brilliant and simple Den. Really, that is some great work. Beautiful too.

 

[The_Aleman]

That thing looks like fun!

 

[curtisfox]

hi dan,

good that i dismantled the pulley/sprocket last night.

i drill 3$ pulley in axle diam size, then make bigger opening for both end using lathe for bearing housing (you can see the outer bearing and just the same for the inner). and the chain sprocket, weld into mounting that fit with inner side of the pulley (also as stopper for inner bearing). the stopper for outer bearing is the 4 bolts that also act as holder for entire assembly.

once the pulley assembly put into the axle, you can have the idea that between pedals/axle and pulley/sprocket are independence due to the internal bearing.

here is some pic and let me know for more detail required

Be cool if one could incorperate a freewheel in there you could pedal start it.

Nice build love the simplisity of it,GREAT JOB............Curt

 

[denmasardhy]

just reassembly the sprocket, bought new spark plug and lower the belt tension by sliding backward the engine
race with 2nd bike (still the 2nd faster)

 

[denmasardhy]

just got 40$ used tasco engine from flea market
- check the clutch and replaced
- good condition carb
- good arc flash from CDI
- good piston compression at top side
- good compression at suction (from carb) side
- replace some bolts
- and try to mount on the 3rd bike, pls notice the mounting method. just release 1 bolt from the rubber mounting at top and 2 bolts base plate at bottom