Normal 49cc Performance?

Discussion in '2-Stroke Engines' started by Jayroma, Mar 2, 2016.

  1. Jayroma

    Jayroma New Member

    Hi Guys, Just came across this forum, and couldn't be happier I recently bought a 49cc 2 stroke kit from the famous eBay. Iv already put about 95 miles on it and I decided to go with a 10 to 1 break in ratio, just to make sure everything was really oiled up. My top speed is about 21 mph and that's with it wide open, it vibrates like crazy at this speed. The sweet spot is around 17mph , with what seems like normal vibration. I'm starting to lower the oil but my top speed pretty much is staying the same. Is this normal? I read of guys going 30 mph, but my motor feels like its going to take off to the moon at a whimsy 21mph. Iv played around with the carb settings and nothing is really helping the top speed. Maybe this is normal for a 49cc engine, idk but I'm sure curious on what you guys think? Thanks

  2. KenM

    KenM Member

    Good to have you here Jay. Yes 20mph is about it for a 49cc.
    The 66cc kits are the ones that will hit 30mph.

    Welcome to the motorbike learning channel. Have fun!
    Keep looking up! Ken.
  3. Jayroma

    Jayroma New Member

    ok thanks, That sure is a bummer. Is their any noticeable difference on the out side between a 49cc and say an 80cc engine. The 49cc engine just barley fits, with in a inch on my bike. Would a 80cc engine take up the same amount of room or will it take up more room?
  4. KenM

    KenM Member

    That I am not sure, never put on a 49cc engine . Someone else will tell you for sure. But a friend has one and it looks the same size as my 66cc engine. Sorry I can not help you much on this. Ken.
  5. bakaneko

    bakaneko Active Member

    The power increases as the engine is broken in properly. However, the excess vibrations will limit your speed due to improper fuel intake and rattle all the nuts off your bolts. Most of the guys reporting 30mph are on 66cc kits; I am not sure what is the speed potential of a well tuned 49cc.

    It looks like you would like to join the 30mph club; don't buy a new engine but try the following cheap upgrades. 1st buy a premium spark plug I mean either iridium or platinum from Champion or NGK or a high end brand. This will help provide more power through better ignition. 2nd, upgrade your stock 44T sprocket to a speed sprocket 36T or lower. This will add about 1mph per teeth reduction so your 17 mph cruise should be about 25-27 with a 36T sprocket. If you are very light you can go even lower to a 30T but note reducing the teeth reduce the torque and acceleration but if you are a lighter rider this is fine. The premium spark plug is like $7-9 and the speed sprocket is like $10-15.

    Also, make sure you double nut your mount nuts. They take a beating.
  6. HeadSmess

    HeadSmess Well-Known Member

    i always ran the 48.(not 49...only 49s are the pocket rocket motors, cylinder lies flat, reed valve block directly into crankcase from the good for pushies, IMHO...)

    never had an issue.

    the cylinder is angled maybe 5 degrees more forward than the larger 66. the cylinder is slightly smaller. as for cylinder height, think its exactly the same. maybe a few mm stumpier.

    the dead giveaway is the size of the cylinder bolts. M6 on the 48, M8 on the bigger one.

    is the vibration from the motor or the chain? always found it was the chain that did it for me on the most part.

    make sure the engine is clamped up TIGHT. dont use rubber in between clamps and frame. using adaptors or anything increases vibration, the shorter and more solid the clamp to the frame, the better.

    a large frame does soak a bit of the vibration up. long tubes. my lil vintage bmx/chopper frame did have more vibration than the 21" shogun. the engine only just squeezed in and needed a cj8 or similar "stumpy" plug, that was prone to arcing on the frame whenever it rained. the shogun had heaps of room(my avatar pic, 21" being the frame size, ie, the length of the seat tube)

    never bothered trying a frame with fat tubes. i always just found standard 1" tubing frames to be easier to deal with.

    its really hard to say just how much vibration is normal, anyways.

    and, on the last thought...i always ran a tuned pipe, did fine doing probably 40-45mph. i hated the only 66cc that i got, by accident.

    the pipe really helps on the vibration for some reason. that i can definitely vouch for. something to do with better combustion, iunno.

    and yes, theres always sweet spots with ANY thing that rotates, be it a mower, bicycle or a highly balanced precision surface grinder spindle. its to do with the natural harmonics of a system coming into tune or resonance with any source of vibration.
  7. Jayroma

    Jayroma New Member

    I appreciate all the amazing feedback. Defiantly learning a lot. I heard from various people that when your breaking in a engine, one shouldn't go above 20mph but my little 49cc tops out at around 20mph. So during the break in period, their would be times that I would be doing 20 mph, thinking the reason its only going 20, is bc of the high amount of oil. Sure hope I didn't damage my engine....... Iv heard that the "boost bottle" helps a lot with vibration. Has anyone had any success with a boost bottle on a 49cc?
  8. HeadSmess

    HeadSmess Well-Known Member

    wait...did you say 10:1 oil ratio? :eek:

    20:1 at least, please... ignore the useless "advice" about break in... just run the things like you stole it, run a bit less oil (never had issues with 50:1 myself) and dont worry about a 150 dollar engine blowing up. they do, and will.

    even with a daily thrashing, full throttle for 50km at a time, expect at least 6 months out of it. fairly good value. as it stands, its simply a matter of luck. some grenade in the first ten minutes, some last for a few years... chinese quality at work ;)

    excess oil is just wasting money and harming the environment. it wont prevent the failure of cheap, mass produced, low quality internal parts.

    boost bottles.... forget about them. theres some logical physics behind them, but... what you buy on fleabay or any other vendor is nowhere near equivalent to the boost bottles that say, honda or yamaha fit in the factory after intensive testing. there is a lot more to it than just strapping on a bottle with a hose fitting. placement is critical, size is cruscial...blah blah, yarda yarda.

  9. Greg58

    Greg58 Member

    I've run the smaller 2 stroke for 5 years, I have 2 at the moment that will do 30 to 31 if the conditions are right. I have a 48cc 2010 grubee that has been the best performer, with a little cleaning of the ports and better exhaust along with correct jetting higher speed is possible. I cruise at 25 to 26 for best ride, I have rode 75 miles in a day running in that range.
  10. Greg58

    Greg58 Member

    I start a new engine at 24/1 with good oil, then after a couple of tanks I go to 32/1. I like the smokeless synthetic oils, these engines seem to last longer using better oil. To cut down on vibration make sure the engine is mounted solid, any movement will cause it. I have found that using a thick back strap on the seat post mount reduces vibration.
  11. Jayroma

    Jayroma New Member

    ok, Thanks....what kind of oil do u use Greg, and where do u get it? So after doing hours of research on the boost Bootle, I decided to go for it. Got the hose and brass fiting from Ace Hardware, and used a 59cc Tabasco bottle. Then sealed it up with gasoline gasket maker puddy. I have noticed their is less vibration. It idols way way low, much quieter, almost like its about to die but it doesn't. Their is less engine noise. And it cruses easyier at 18 mph than it did before. Definitely a plus so far. These performance exhaught, u can get from ebay around $20, is their a major difference in performance with this?
  12. skyash

    skyash Active Member

    2 stroke oil motorbike if you can but kids around here use lawnmower oil it's fine. Have you taken the end cap off your muffler already?
  13. Greg58

    Greg58 Member

    I like the Lucas semi-synthetic, I buy it by the qt at O'Reillys' auto parts. Like I said no smoke and mine run well. The exhaust on both I made or modified, both are a little louder than stock but they run much better. Learning how to tune the carb will really help, I've had to drill out jets on some and solder up and drill some smaller.
  14. Jayroma

    Jayroma New Member

    Thank you.... I got the Lucas oil. Iv heard some people say Don't Use Synthetic oil with these 2 strokes, is their a difference between full synthetic and non synthetic? Pro's Con's ? I have not taken the end cap off the muffler yet bc I have heard people doing this and having problems with the back pressure, what's your thoughts?
  15. Greg58

    Greg58 Member

    The synthetic oil is man made, the regular or non synthetic is petroleum based. No matter which oil you use you need to make sure its made for air cooled engines, don't use outboard oil that is for a water cooled oil injection engine. These engines rely on exhaust back pressure to keep the fresh charge of fuel mixture in the cylinder, on a bike that is rich removing the end cap might make it run better, on a bike that is tuned fairly close to where it should be if you remove the end cap it will hurt the power. Almost 2 years ago a friend was riding his bike to work one morning and the end cap center stud broke and he lost the end cap, he limped on to work but lost about a third of top speed. We fabricated and installed a end cap from plumbing supplies to control cylinder back pressure.
  16. Greg58

    Greg58 Member

    This is one of mine.

  17. skyash

    skyash Active Member

    Try it it's very noisy but 50 percent better take off I never seen a stock motor that didn't like the cap off
  18. HeadSmess

    HeadSmess Well-Known Member

    back pressure schmuck pressure a term bandied around by people that know no better. just makes them sound like they know what theyre on about, except to people that DO know better :D

    you can run without the exhaust at all with no issues other than loss of hearing and noise complaints. yes, you do need to tune it to do so, otherwise, yes, they can run too lean as they can suddenly breathe a lot better.

    if you want true power, you have to learn about positive and negative "backpressure", and get a tuned pipe that uses such things, and do require a certain amount of this so called "back pressure"...

    synthetic oil is still made from petroleum. just costs a lot more. rather than just crack (distill) crude oil and bottle a particularly suitable fraction of it, they crack crude oil down to base molecules, ie, propane, butane etc, then recombine them into the same, a particularly suitable fraction. this way they can know with 99% assurance that a particular density oil is made of hydrogen and carbon, and doesnt contain the odd atom of silicon or sulfur or something similar... maybe even tellurium!

    yes, the tower they crack oil in is called a fractionating column, so all products from the oil, are called fractions.

    you want to spend excess money on oil for an engine that cost virtually nothing, go for it. is it more viscose? usually not. these engines do like a certain "thickness" to their oil, it helps things stay sealed up and lubed. hence why we run the same cheap stuff the commercial mowers use... and it doesnt seem to affect their expensive equipment thats usually worth 4-5 times what this engine cost.
  19. Greg58

    Greg58 Member

    You are correct, that's why I buy my oil by the qt. at $8 a qt. thats $1 per gallon of fuel, that's cheaper than buying Dino oil at wallyworld.
  20. Greg58

    Greg58 Member

    The carb can be tuned to run without the end cap, but why? I like to enjoy my riding without disturbing others. With a lot of states moving toward more restrictions on our bikes we don't need to draw attention.