How fast can your 49cc Really go?

Cabinfever1977

New Member
Mar 23, 2009
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Upstate,NY
my 48cc engine manufacturer says upto 40mph,i didnt think it would go that fast but anything over 15mph was good for me,i had it up to 35mph,my speedo is fixed.my cruising speed is 25-30mph..
 
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raindroptree

New Member
Aug 7, 2015
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West Palm Beach FL.
my 48cc will sit on 55km/h on the flat but with a little tail wind it will sit on 60km/h, top speed down a moderate hill has been 68km/h
only mods that i have done is matched the inlet and exhaust manifolds to the ports removing any burs, leaned of the carby as the stock carby is the same for both 66cc and 48cc (much to rich for the 48cc), fitted an expansion chamber off a 48cc pocket bike and changed the rear sprocket from the stock 44 tooth down to a 28 tooth :)
Is that for a 2-stroke or 4-stroke engine?
 

Greg58

Well-Known Member
May 1, 2011
4,084
995
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Newnan,Georgia U.S.A.
Raindroptree welcome to the forum, if you notice the last post date on this thread it has been over 5 years. From the info in the posts its a 48cc 2 stroke. I have a couple of 48cc engines that run well, one with the most port work has done 31.8 mph on flat roads. That is with a 44 tooth rear sprocket, I don't run it that hard for long because its really turning that little engine.
 

androosaybeau

New Member
Mar 15, 2016
1
0
0
california
mine can do a solid 31-32 mph and hold it on flat ground. It's a stock kit, but I just ordered one of those free-wheel HD axle kits from bikeberry (42 tooth sprocket) so we'll see after the install. I'll post pics and a step by step of the install and post it.


Androo
brnot
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
51
48
Phoenix,AZ
Is that for a 2-stroke or 4-stroke engine?
Very important point in a really old topic but what the heck right?
A chance to learn.

2-strokers commonly come in 48cc and 66cc though the bad joke of anything being called 80cc is a flat out lie, it's so persistent it just won't die.

4-strokers the 49cc HS 142F and Honda 50cc are common and it's a thread saying 49cc.

Most anything around ~50cc get engine gears to take advantage of the small power source.

Unless I purposely limit power for a given customers needs or abilities, 30+MPH on ~50cc is common in my builds because of gearing.

What I have been doing the last few months is try to get away from 2-strokes as much as possible and use lower power 4-stroke engines like the 49cc 142F and 53cc 144F HS engines.

With the right 3-speed back hub ~35+mph is the baseline for them.
This is a 53cc 3-speed that does 40mpg with ease, even maintained 30 uphill for a mile+ stretch.





It's not so much how much power you have to start with, it's how and when you put it to the ground.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
6
38
Ridin' inSane Diego, CA.
Very important point in a really old topic but what the heck right?
A chance to learn.

2-strokers commonly come in 48cc and 66cc though the bad joke of anything being called 80cc is a flat out lie, it's so persistent it just won't die.

4-strokers the 49cc HS 142F and Honda 50cc are common and it's a thread saying 49cc.

Most anything around ~50cc get engine gears to take advantage of the small power source.

Unless I purposely limit power for a given customers needs or abilities, 30+MPH on ~50cc is common in my builds because of gearing.

What I have been doing the last few months is try to get away from 2-strokes as much as possible and use lower power 4-stroke engines like the 49cc 142F and 53cc 144F HS engines.

With the right 3-speed back hub ~35+mph is the baseline for them.
This is a 53cc 3-speed that does 40mpg with ease, even maintained 30 uphill for a mile+ stretch.
I really gotta say that 40mpg is not very good gas mileage for 53cc, heck my 212cc race bike gets at least 40mpg ...

laff
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
51
48
Phoenix,AZ

Bobalou

New Member
Aug 22, 2017
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Hehehe, 40 MPH not 40 MPG ;-}
Realistically on the shifter bikes I build it's ~75MPG, or ~50 miles with a 2.5L 2/3 gallon tank.

50 miles on pocket change with today's gas prices is pretty cool, bus fare is more than that.
Most stock mopeds advertise 5mpg. I would think that a motorized bike could get at least what you say. Is the 40mph on the flat? How is the torques for hills and takeoff?
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
51
48
Phoenix,AZ
Is the 40mph on the flat? How is the torque for hills and takeoff?
A direct drive will get you ~32mph and not be too sluggish off the line.

Putting a SBP shift kit on it changes everything.



It jumps of the line and will do ~40mph with that 3-speed internal rear hub.
 

mbearden

Member
Mar 2, 2016
38
1
8
Florence, KY
A direct drive will get you ~32mph and not be too sluggish off the line.

Putting a SBP shift kit on it changes everything.



It jumps of the line and will do ~40mph with that 3-speed internal rear hub.
KC!
I know this is completely off topic, but I wanted to say thank you for the inspiration to build my Cruiser! Genesis 29" with a 66cc and sbp shift kit! Other mods too, including a mega-range bicycle sprocket for the rear wheel. My only complaint is that the aluminum on the front tube/front mount is crushing a bit. Next build will be a steel frame with an internal 3 speed hub. 7 is way too many, but that first gear is tall enough to take off from a dead stop. Thanks again KC! Ive built 4 gas bikes so far, and this one by far is my favorite!
 

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KCvale

Well-Known Member
Feb 28, 2010
3,967
51
48
Phoenix,AZ
KC!
I know this is completely off topic, but I wanted to say thank you for the inspiration to build my Cruiser!


Sweet!
And you are welcome for the inspiration ;-}

Bummer you went with the old cheap knock off shift kit though...
Use the real thing from Sick Bike Parts next time, you have the outdated mounts and the el-cheapo freewheel bearing, and that will likely bite you in the ass soon.
 

mbearden

Member
Mar 2, 2016
38
1
8
Florence, KY


Sweet!
And you are welcome for the inspiration ;-}

Bummer you went with the old cheap knock off shift kit though...
Use the real thing from Sick Bike Parts next time, you have the outdated mounts and the el-cheapo freewheel bearing, and that will likely bite you in the ass soon.
No way man! That IS the SBP shift kit, hd freewheel. I just have the case for the left side chain tensioner on there without the tensioner. Here's a picture from the other side. Didn't go with cheap ANYTHING on that bike, lol. Notice the shock front fork with disc brake and ape hangers. This one was build to LAST (hopefully!)
 

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Nanfoe

Member
Oct 15, 2016
39
4
8
Florida
I've gotten one of my bikes to 53 MPH+ I built the motor piece by piece, first time for me. I bought a SR Super Rat bottom, a worked jug with 3rd transfer port, an aftermarket head, a piston that I windowed, Copper head gasket. an MZ expansion exhaust, 4 reed valve and a Mikuni OEM 26mm and now just a regular speed carb all tied down to a 26 tooth on a 26" rim.


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No fuel or escape leaks but I cannot get her to idle though. If I cut her off then it's a mission to start her like she's flooded. she had a 86 jet when she was hitting over 55 MPH. She's giving 170 psi. I have the plug gaped like at 30. Does she need to idle high from having super high compression? I dunno I'm stumped any help would be grand thanks.