do i need to put on the wide cranks on a 4 stroke? and a ton of other questions

mark20

Active Member
Joined
Sep 26, 2018
Messages
519
hi, me again,
right now im planning on building up a 49cc 4 stroke (ebay kit, if theres any other kits for around 200, please let me know, and i would prefer chain drive though)
and my bike is a old road master (hard-tail) and it has those 1 piece cranks, vs the typical 3 piece
and i was wondering, would it be worth it on the 3 piece conversion? (this is the adapter i was thinking of getting here, would it fit?)
and what diementions would the complete engine be? (with the engine plate)

main reason im doing this is because my old diamondback frame snapped and ive re welded it, but both the engine and the components are extremely worn (engine runs like a champ!, but the mounts keep snapping, ive tried everything, i even re-drilled new one, but the engine has a very violent shake to it, it started around a month ago, as well as a ton of other problems)
but im still driving it, its just not safe anymore, (in my opinion) and i would love to dive into 4 strokes (if i build this, that diamondback is going to be a 1 mile grocery getter, and this will become my daily driver)


and anything else i need to know?

thanks in advanced!
 


bakaneko

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Nov 16, 2015
Messages
1,310
can u link the kit that you will get. the gear reduction box quality is key. the worst one is not bad but you need to be aware of eventual problems and either proactively address it or risk getting stranded. i love the hs-142f; great motor. i did not use the wide cranks and was still able to pedal though i had to position myself back on the seat to do so. i got use to it pretty quick so not exactly necessary though it depends per bike and if u hit ur shin on the motor it hurts like fkin hell.

for dimensions use the bikeberry video, it is actually very accurate but note you can remove the filter plastic box, air intake box, file down the choke nub and oil intake plastic cap, and remove the throttle guide (make your own). post the pic of the bike if u like.

i like the sound of a 4stroke over 2. it sounds deeper especially at idle than a screaming high pitch of 2 stroke.
 

mark20

Active Member
Joined
Sep 26, 2018
Messages
519
can u link the kit that you will get. the gear reduction box quality is key. the worst one is not bad but you need to be aware of eventual problems and either proactively address it or risk getting stranded. i love the hs-142f; great motor. i did not use the wide cranks and was still able to pedal though i had to position myself back on the seat to do so. i got use to it pretty quick so not exactly necessary though it depends per bike and if u hit ur shin on the motor it hurts like fkin hell.

for dimensions use the bikeberry video, it is actually very accurate but note you can remove the filter plastic box, air intake box, file down the choke nub and oil intake plastic cap, and remove the throttle guide (make your own). post the pic of the bike if u like.

i like the sound of a 4stroke over 2. it sounds deeper especially at idle than a screaming high pitch of 2 stroke.
Yea, i did the bike berry diemention thing and it wont fit, its a 9× 8.5in is what i could squeeze in, its a roadmaster sport, so sadly i have to find another bike (or use my diamondback, which aint happening anytime soon)

Heres a pic of the bike btw
88944
 

bakaneko

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Nov 16, 2015
Messages
1,310
yeh, absolutely no way it will fit even with all plastics remove and nobs filed down. :( you think of trying friction?
 

mark20

Active Member
Joined
Sep 26, 2018
Messages
519
yeh, absolutely no way it will fit even with all plastics remove and nobs filed down. :( you think of trying friction?
yea, i was considering a station friction drive, but that would be close to 400$


i have a craftsman 25cc weed wacker that i could try to make a into one (i tried to make it work for my scooter, but failed as it had a sheered key, my guess it wouldnt of worked anyway)

my options are limited, and i wouldnt want to go 2 stroke (ive been receiving lots of noise complaints with my 2 stroke, i live in a HOA and my school is not a big fan of my little bike, plus i stink like oil whenever i go to my classes)
 

FNTPuck

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Jul 2, 2018
Messages
584
The 49cc 4stroke is a great motor but pleeeaasseee spend the little bit extra on the newer belt drive transmission. It is smoother, more reliable, and quieter than the crappy chain drive trans the older kits used.

Yes, you will need the wide crankset.
 

mark20

Active Member
Joined
Sep 26, 2018
Messages
519
Yea, i gone ahead and built up a friction drive, took a few good ideas from others and put them together, so what do you think?
(I still need to weld the socket to the shaft, as i cant get a Bolt though without causing more damage)
But it runs! (For about 10 seconds, then the socket falls off lol)
 

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bakaneko

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Nov 16, 2015
Messages
1,310
is that hinge solid enough? feels like its gonna vibrate apart. is the spring gonna apply enough pressure on the roller and tire to not just burn the tire? i like 100% home made build stuff. more work but you know you did it from scratch.
 

mark20

Active Member
Joined
Sep 26, 2018
Messages
519
is that hinge solid enough? feels like its gonna vibrate apart. is the spring gonna apply enough pressure on the roller and tire to not just burn the tire? i like 100% home made build stuff. more work but you know you did it from scratch.
Yes its very solid, i might add another bracket to stiffen it up, but the side to side movement is around 1/4 inch) i actually have the opposite problem, the spring is applying to much force (i welded the socket but then the spacer snapped) i had it running, it worked for quite a while, the roller does get hot ( is this normal? I have no idea, tire feels a bit warm but not blazing)

Here's a video of the spacer snapping

Here
 
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