Pedal-less acceleration?

motorizedinDC

New Member
Sep 8, 2016
1
0
0
Washington D.C.
Hi,

Would there be a way to modify the bike in such way that my motorized bicycle would accelerate without a pedal? I have come up across too often when I could not accelerate on uphills after stopping at a red light or stop signs. I had always walked my bike to a flat ground or downhill for it to catch enough speed to accelerate.

My motorized bicycle has a 49 cc on a huffy bike. It's pretty heavy :-0

.shft.
 

ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
Not really, other than adding a huge rear sprocket like a 54 tooth, adding a reed valve, expansion chamber, porting. If you did all of these changes you might be able to tackle bigger hills because you would be adding so much more low end torque. But with the big sprocket you will also give up speed. These 2 strokes really need high rpms and flat ground to get a running start at hills. Cheapest thing to try through is the huge rear sprocket to add that low end slow grunt. Hope this helps.
 

ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
Also/ the 49 cc just has a bit less horsepower as you know so an up grade to a 66 cc for a bit more grunt. I have never used a 49 cc engine, I do hear they run very smooth though.
 

Ghost0

New Member
Mar 7, 2008
764
0
0
Bellingham, WA
Well there is such a thing called a Shift Kit allowing you to use the gears on the bike so that one could have a low gear for acceleration and taller gears for cruising at higher speeds without over revving the engine. Of course if you have a typical beach cruiser that is a single speed that's not going to work.
 

Bruce Lee

New Member
Dec 13, 2010
46
0
0
California
Well there is such a thing called a Shift Kit allowing you to use the gears on the bike so that one could have a low gear for acceleration and taller gears for cruising at higher speeds without over revving the engine. Of course if you have a typical beach cruiser that is a single speed that's not going to work.
79cc 4 stroke
 

QuietRiot522

Member
Aug 31, 2010
60
0
6
Rochester MN
Hi,

Would there be a way to modify the bike in such way that my motorized bicycle would accelerate without a pedal? I have come up across too often when I could not accelerate on uphills after stopping at a red light or stop signs. I had always walked my bike to a flat ground or downhill for it to catch enough speed to accelerate.

My motorized bicycle has a 49 cc on a huffy bike. It's pretty heavy :-0

.shft.
I have a centrifugal clutch kit on my 66cc and I love it. I just have to kick off with my feet at a stop and ride the gas as I move my feet back on the pedals. Still need to give a couple pedal turns to get up to speed but, its still so much easier than pedaling then dropping the clutch. Doesn't work on really steep hills but most occasions it has made my riding experience better. Something maybe to consider. Maybe a clutch + a bit of a gear reduction would work to get you taking off at the bottom of hills with less effort.
 
Aug 26, 2015
472
5
18
Overgaard AZ
High compression head, adjust port timing to match (can be done with gasket thickness under jug), expansion chamber and proper jetting. Oh and like ZipTie said, get the bigger motor, there is no replacement for displacement. A change of gear ratio might help, but it doesn't change the fact you need more power. Proper jetting also helps, you shouldn't be fourstroking climbing a hill, maybe on the flats or going downhill, but it should smooth out on any kind of grade, two smokers like to be a little rich under load. A bigger rear sprocket might reveal the need for leaner jetting. Its good to know how to do, and very easy.
 

Agreen

Member
Feb 10, 2013
792
11
18
Southeastern GA
Hybrid sounds like what you want. Gas rear wheel drive, electric front wheel drive. If all you use it for is take-off assist, you don't need a massive battery.
 

sbest

Member
Nov 3, 2015
343
2
18
Nova Scotia
I'm with Mongo.
I have a 49cc two stroke. With very little work it will pull away from a dead stop and do hills.
1) Use a 54 tooth back sprocket
2) improve the head by adding a bit of squish and compression.
3) bring the new-found squish to 0.5mm to 1.0mm by adjusting head and base gaskets
4) drill the exhaust flange and gasket with a 3/4" (19mm) drill
5) jet the main by plug chops and the needle by performance.
6) widening the top of the exhaust port will help too, but don't raise it.
7) a longer intake tract or filter will help too

Even the 49c will pull away with these mods done right.

Steve
 

racie35

Active Member
Nov 17, 2012
1,702
5
38
usa
I guess this is directed at the China girl bikes..I know my whizzers don't need help , but one of them is pullied smaller on the clutch to wheel helping that one. The stock wc1 though, hardly struggles if you use its manual clutch right.
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
52
48
Phoenix,AZ
I have a 49cc two stroke.
Steve
Hey Steve, where did you get your 49cc 2-stroke?
Every one I have worked with is 48cc.
The thing is, 49cc is a valid size for 4-stroke but not for a 2stroke and why I asked if he had a 2 or 4 stroke.

I'd just like to know who is faking the 48cc number and folks like you buying the 1cc claim is all.
It's not as bad as the 66/80cc scam, but enough to be annoying in topics like this.
 
Dec 11, 2014
604
0
0
Tucson
A properly ported and set up 66cc will pull you strong right off the line and up to about 43mph with the stock 44 tooth kit sprocket. If you want more, a real expansion chamber, higher flow air filter, better plug wire & booth, and really seal up the carb, intake, etc from all the tiny vaccuum leaks. If you get it right you will blow by shift kits and keep going. They very much have thier place in high end comfortable to ride at a much lower cruising RPM builds but for performance, simplicity, and dollars you won't get close to a high quality 66cc. I have countless hours with the best kits SBP offers and I love them and even use their 4 stroke mount in non shifting builds.
The short answer, if you want to pull off the line and reach any reasonable speed a 66cc kit from DAX, CRmachine, me, whoever will build you a proper one will outperform anything else short of spending a ton of money.
If you have the money to drop a 53cc shifter bike by KC will pull you right off the line I bet real well AND be the nicest to ride but you have to drop the dollars.
The best thing I have found with the 48cc bikes is they are already motorized so it's quick and easy to yank the 48 out and drop the bigger motor in lol.
All just my opinion.
 

sbest

Member
Nov 3, 2015
343
2
18
Nova Scotia
Hey Steve, where did you get your 49cc 2-stroke?
Every one I have worked with is 48cc.
The thing is, 49cc is a valid size for 4-stroke but not for a 2stroke and why I asked if he had a 2 or 4 stroke.

I'd just like to know who is faking the 48cc number and folks like you buying the 1cc claim is all.
It's not as bad as the 66/80cc scam, but enough to be annoying in topics like this.
Yeah, yeah, yeah, I'm busted...
THOUSANDS of numbers floating around in my head and I messed up.
And you are right KC, it is important.
I mean, who would drive a 352 Chevy? or a 288 Ford?
I humbly submit to public flogging... <SHAME>

Steve :)
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
52
48
Phoenix,AZ
Yeah, yeah, yeah, I'm busted...
THOUSANDS of numbers floating around in my head and I messed up.
And you are right KC, it is important.
I mean, who would drive a 352 Chevy? or a 288 Ford?
I humbly submit to public flogging... <SHAME>

Steve :)
Hehehe Steve, I just thought maybe there was something new I didn't know about is all ;-}



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