How fast can your 49cc Really go?

stock762

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Jun 7, 2017
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That doesn't look like a 49cc engine, it is kinda off topic but if the o.p. doesn't mind its OK.
Oh my bad man I didn't even know what cc this is everyone says they aren't actually what they are like the 80s ain't 80s. But ya my bad mine is a 66cc
 

Greg58

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May 1, 2011
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It depends on the bore and stroke, if its 40mm its a 48cc, if its 47mm its either a 66 or 68.5 depending on the stroke. Some are 38 mm and others are 40mm stroke.
 

KCvale

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Feb 28, 2010
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The OP also started this thread way back in 2009!!!! (back when you could actually still find real 49cc engines). :p
Actually Skyhawk 48CC 2-stroke engines that are legal here in AZ.
A little gearing and this little legal 48c could really rip it up.



Note it has the original Slyhawk 48cc factory plate on the engine ;-}

This bike was built light and for speed hence the disc brakes.



It could go real fast ;-}
 
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MattK

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Apr 7, 2018
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46 km/h and I reckon I can get it to 50 km/h with a bit more tweaking.
 

Nanfoe

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Oct 15, 2016
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Yeah mines a SR-5 just rebuilt/replaced rings gaskets and she did 45 MPH with the stock pipe without the pipe cap cover and a 26 tooth on 26 in .
20180507_131904.jpg
Screenshot_20180507-132902.png
 

KCvale

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Feb 28, 2010
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she did 45 MPH with the stock pipe without the pipe cap cover and a 26 tooth on 26 in .
A 26T back wheel sprocket?
That is 1/2 the teeth as the stock sprocket, do you have to pedal most of the time?
You must really go through clutch pads too if you don't.

If you want usability of the pedals and speed go with a JackShaft Shifter conversion.



Once you 'get' the shifting you wonder why you ever rode without using bike gears with the engine.



That was a popular build for me but I usually used 66cc SkyHawk engines, or 49cc HS 144f-1g 4-stroke engines with a Skyhawk 4G or my 10G long shaft like this.



Legal, easy to ride, it will jump off the line and do 40mph all day, but capable of faster (45-50mph) with minimal maintenance required.



Gears change everything if you want to fast.
 
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Nanfoe

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https://www.ebay.com/itm/Motorized-Bicycle-Sprocket-26T-Disc-Brake-Hub-Stainless/172759483787?_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=20160727114228&meid=87f0dc7a827a406ba50ced13a2896d46&pid=100290&rk=1&rkt=4&sd=172759483787&itm=172759483787&_trksid=p2060778.c100290.m3507

20170817_162141.jpg

Yeah stainless steel 26T from Russia. Better than Aluminum. Not a fan of those spoke rims cause I bend them all, that's why I go Mag Wheels. I hardly peddle 20 feet and she cranks and goes. I dunno for my main mode of transport daily after over 15 months and like a 1000 mi. 3 sets of piston rings in I think I'm doing good. I did changed the clutch pads once several months ago so I dunno. All I can say is I wish I could find SR-5 bottoms or complete motors, they are hard to come by. I've gotten the best speeds and pretty much reliability from these Super Rats. The in internal cdi is nice as well.
You bikes look well thought out. I should have gone jackshaft.

Edit: I forgot to mention using Opti2. I ran another enige with it and ran out, used some other oil and did not make it home from a short 1 mi trip. IMHO that Opti2 lets you get away with adding only 2 oz per gal even when it says 1 oz per gal on the bottle. I'm out now goto get some mo.
 
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KCvale

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Feb 28, 2010
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I dunno for my main mode of transport daily after over 15 months and like a 1000 mi. 3 sets of piston rings in I think I'm doing good.
You have a low bar for "doing good" if you think having to replace your rings every ~600 miles or so is Doing Good.
 
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MattK

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Apr 7, 2018
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A 26T back wheel sprocket?
That is 1/2 the teeth as the stock sprocket, do you have to pedal most of the time?
You must really go through clutch pads too if you don't.

If you want usability of the pedals and speed go with a JackShaft Shifter conversion.



Once you 'get' the shifting you wonder why you ever rode without using bike gears with the engine.



That was a popular build for me but I usually used 66cc SkyHawk engines, or 49cc HS 144f-1g 4-stroke engines with a Skyhawk 4G or my 10G long shaft like this.



Legal, easy to ride, it will jump off the line and do 40mph all day, but capable of faster (45-50mph) with minimal maintenance required.



Gears change everything if you want to fast.
This green bike is a perfect bike. I want it. If only they could be silent. They are illegal in Australia. Which is absolutely ridiculous considering the size of our continent and the distances we need to travel. Anyway nice bike! Love the built in tank and the jack shaft the gear system the wheels all of it. If it was mine I would probably have taller handle bars because I'm getting a bit older and comfort is starting to out way cool. LOL
 

KCvale

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Feb 28, 2010
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This green bike is a perfect bike. I want it. If only they could be silent. They are illegal in Australia. Which is absolutely ridiculous considering the size of our continent and the distances we need to travel. Anyway nice bike!
Love the built in tank and the jack shaft the gear system the wheels all of it.
If it was mine I would probably have taller handle bars because I'm getting a bit older and comfort is starting to out way cool. LOL
Thanks for the Kudos Matt.
I use the new Grubee gas tank frame with rear disc mount, weld in an engine mount plate, and powder coat it.

That green one as well as this red one have Textured powder coat, it's not smooth to the touch.



The only real way to appreciate textured power coating is in person as you won't find any production textured bikes.

This red bike sports an SA internal 5-speed disc brake rear hub so she really scoots in style and stops great, but not only that it doesn't look like a shifting bike so you might get away with it ;-}
 

MattK

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Apr 7, 2018
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Definitely nice bike. Top speed isn't a concern for me, mine does about 45 km/h thats enough. Definitely enough. Coped a flat rear tire at high speed, I reckon I slid for about 20 m. What really saved me was that after about 10 m I slid from bitumen into grass. 3 months it took to grow the skin back on my left knee. That is a really nice bike. We can make them silent with acoustic feedback, but I think it requires too much energy to neutralize the noise. I'm just waffling now. Nice bike.
 

KCvale

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Feb 28, 2010
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Thanks again for the Kudo's on my builds Matt ;-}
We can make them silent with acoustic feedback, but I think it requires too much energy to neutralize the noise.
If you have a combustion engine you are going to have noise.
If you want to ride quiet go electric.

Something like this 640W 3-speed shifting Micargi Rover.



Heck, you can build one for under a grand with a battery like that, and it scoots 56KPH (35MPH), and it is scary quiet if you want to be.
 
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Hickory Hill

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May 13, 2019
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Out of box & stock AAAAnd a dang vacuum leak, im pulling 24mph... it doesnt really matter how fast your actually going, its always going to feel like 200mph on a rickety ol bike! I LOVE THIS HOBBY!