New 4-stroke 49cc HuaSheng (142F) Build

Discussion in '4-Stroke Engines' started by bakaneko, Mar 19, 2016.

  1. bakaneko

    bakaneko Active Member

    Hello. I just finished and road 10 miles on my new 4-stroke 49cc HuaSheng bike from I will comment on GasBike in the vendor thread but overall I am satisfied with the quality of the kit. This thread is to talk about my impressions of my 4-stroke and comparisons with my 2-stroke. I know there are few new folks in here looking at the 4-stroke.

    Overall, I am impressed and KCVale was right about the vibration difference. I felt hardly any vibrations what so ever compared to my 2-stroke. I installed the engine on a $50 walmart mountain bike (yes, $50). I think it will be okay with the low priced walmart bike because I am not going to jump a hill and there is hardly any vibrations with the 4-stroke. If this walmart bike has my 2-stroke installed on it, I'm sure I will shake the bike apart. Also, because it is a mountain bike I had to remove the carburetor cover and muffler cover, and even then I have a maybe 5 degree imperfect tilt, which I compensate by having a slacker chain. I do not recommend going with a mountain bike or smaller bike (didn't fit BikeBerry's 4-stroke size guide); it is a hassle to mount in a small frame. I might go duo tensioners in the future to compensate more and have a tighter chain but for now it is okay. The only other thing I modified was going with longer mounting bolts to compensate for the mountain bike's large bottom tube and cutting the oil cap to a nub to pass the seat post tube. For the nuts, I double nutted the mounting bolts and surprisingly the rag joint came with friction nuts so no need to double nut those. All the bolts came with either friction nuts or a lock washer.

    A few items to work on. As with many folks with new builds, I need to work out the jetting for the carb. I pulled the 36T speed sprocket from my 2-stroke (to replace 44T) and with the low 1-3 transmission (I believe) so I expected lower torque and higher top speed, which is fine for me since I am a lighter rider and need to workout. In the beginning there was hardly any torque but then as I rode more and stopped it and started it again. The engine developed more torque. The engine is also having trouble idling, which I will need to work on jetting and getting a better spark plug in there. I didn't install the wider crank since there is enough clearance for me to pedal if I lean forward. However, I will put in a longer pedal to help. I also let it idle 10 mins or so before I rode on it. I also need to put a cover or make a new carb cover. Speaking of which, the 4-stroke forum stickies seem pretty bare compared to the 2-strokes stickies for carb, engine, installation problems. I can try to start one but would love help from more seasoned 4-stroke guys like KCVale and etc.

    Well that's it. Sorry for the ramblings. Overall, the 4-stroke engine is a blast. I need to work out the jetting and idling issues to improve performance but with time. I love the low to zero vibrations on it. And, with my gearing I cant tell the engine load and rpms... Here are some pictures and link to the kit that I got from GasBike.

    Attached Files:

    Last edited: Mar 19, 2016

  2. wheelbender6

    wheelbender6 Well-Known Member

    Very nicely done. What gear box are you using?
  3. Lazieboy

    Lazieboy Member

    Thanks for sharing your info. That is the 4stroke kit I've been eyeing. I'm hoping to slowly get stuff to do the build this winter Inside.
    Did you have to get the bottom bracket conversion kit?
    Get back to me.
  4. johnsteve

    johnsteve Member

    Hey,,,,,,,I paid 125 for that bicycle. I guess for 50 bucks its not that bad.......Plan on constant repairs and upgrades. My crank keeps coming loose. The brakes suck...... The latest thing is that a spoke broke so I need to rebuild or replace the rear wheel...... Oh and those tires really suck. Id advise you to get some more thicker and more puncture resistant tires. Flats with those lame tires are only a matter of time,,,,,,sooner rather than later. I am impressed with the 4 stroke on the bike though.......
  5. HeadSmess

    HeadSmess Well-Known Member

    only thing i never like much about the 142F is the square ports... some touch up with a die grinder and ball nose cutter helps ;)

    change your oil as often as possible in the first few hours! dont wait for it to turn black.

    they dont rev as hard as two strokers, but they are definitely smoother :) and no oil mixing. yay.

    tweak the mixture screw when its warm, whilst idling, aim for the "peak" in rpm, then back off a the throttle is still nice and crisp, no bogging/stalling...under load!

    shame theyre so wide...
  6. bakaneko

    bakaneko Active Member

    Err. There doesn't seem to be a screw where the mixture screw is suppose to be. I just have a brass plug. Am I suppose to drill this guy out? :eek:

    Here is a picture of a 4-stroke carb with where the mixture screw should be... but mine is just flush

    ** Nevermind I got the plug out. You need to drill a very little hole about 1-2 mm deep and then press in a wood screw. The use pliers and pull out the plug via the wood screw.

    Attached Files:

    • carb.jpg
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    Last edited: Mar 20, 2016
  7. bakaneko

    bakaneko Active Member

    Thanks, it is possible to put the 4 stroke on a bike that doesn't quite fit the BikeBerry size guide, but you have to remove all of the protective plastic and baby it into there. There is video of a 4 stroke on a fat tire mountain bike, which has an even smaller fram. I am sure they had to cut the frame.

    Yeah, I figure that the lower vibrations of the 4 stroke will be a bit easier on this $50 dollar bike. I already have to readjust the back brake and the brake pads are squeaking on day 2, LOL. I have a nevermorflat tube on my 2 stroke after many tube changes but the rubber tubes provide no shock absorption. Ack
  8. bakaneko

    bakaneko Active Member

    This winter? Do you mean in like 8 months? I didn't have to do anything with the bike crank or pedals, because there is enough clearance to pedal. I am gonna get longer pedals to help even more. I actually bought the bottom crank conversion and don't need it so if you want it just private message me your address and I will mail it to you. As for the kit, I think the quality is good but no instructions, LOL. GasBike do have a video on YouTube for another 4stroke. The 7G kit is probably better than the base one. I also think the amount the 7G transmission sticks out is less than that of the base transmission and better quality of course.
  9. bakaneko

    bakaneko Active Member

    Just the cheap 1:3 one with a 36T sprocket instead of the 44T which might be a mistake now
  10. bakaneko

    bakaneko Active Member

    Not to spam too much, but I am going to continue to post my adjustments and upgrades to the base, cheapest 49cc 4-stroke HuaSheng build ($199). I will do incremental upgrades with a price conscious perspective as well as talk about my mistakes.

    Stock, the motor would not idle and had little torque and top speed. I then found the fuel mixture and idle screw and now the engine does idle. The top speed on a flat stretch is +30 mph (I did 33mph but its 30mph limit here and I'm scared of police) with the 36T sprocket but it takes a while to safely get there :rolleyes:. However, I am not entirely satisfied with the torque performance. I have to pedal substantially up hills. There is a video of a 49cc HuaSheng from a California rider (I know no hills) that just blows my bike out of the water. He has listed a number of upgrades, which I will take a look at. I want to reach this guys level.

    So, listed below is what I've done from stock thus far and the next upgrade.

    Changes from stock engine / settings
    - Adjusted the idle and mixture screw to improve performance and idle

    Upcoming Changes
    - Bought an NGK 7544 Iridium IX CR7HIX spark plug for $10 on ebay (should help with idle and slight power improvements via better ignition, possible some compression; did wonders on my 2-stroke)
    - I might eventually pull the 36T sprocket and put in the stock 44T. I am a lighter rider but the torque is so low. I will see

    Any comments from 4-stroke owners would be appreciated as I get this girl up to her potential.
  11. HeadSmess

    HeadSmess Well-Known Member

    i never did any real mods to mine.

    never had issues with hauling up hills, at about 50km/h...never pedaled much, either. never changed the plug from memory. did die from a strange carbon deposit in the cylinder/exhaust valve in the end...
  12. bakaneko

    bakaneko Active Member

    Hmm, maybe I screwed up or it still needs break in and tuning. What transmission and wheel sprocket were you running, headsmess? I think I was over ambitious with my gearing, I'm at 1:3 to 36T sprocket. If you could can you take a look at the video above in my prior post and let me know what you think about the power level of that HuaSheng build compared to stock? I think this guy has about $100 in upgrades; and I am not sure about his transmission and sprocket. Thanks.
  13. KCvale

    KCvale Motorized Bicycle Vendor

    Cool, you made a 4-stroke and got it go for a record low price!
    Now you'll have some experience with them to build you next new one as that won't last long no matter how much more money you throw at it.

    Nothing like first hand knowledge of why good parts make a difference bakaneko, you will get to experience all of things that will start failing with a $50 toy bike and $30 drive train.
    A valuable lesson for when you want to build something reliable but not that costly a lesson for $200.

    Ride safe and check it often bud.
  14. HeadSmess

    HeadSmess Well-Known Member

    couldnt say what transmission i used, it was a homebuilt chain double reduction, i think it was around 14:1 in total, for 26" wheels. still have half of it attached to a frame somewhere.

    the "maxtorque" clutch i had lying around was pretty lousy, i vaguely recall modifying a chainsaw clutch after a while... quite some time now, since that thing was in use.

    KC is right, you gotta spend money...but dont spend it on what you got! i spent money on a lathe, tools, sprockets and bearings etc... others choose to spend it on good kits n bikes. even a few thousand sounds like good value when something goes wrong and you are lying in a hospital bed...

    use the 44t. the kit my engine originally arrived with had a 55T! it was the cheapest way to get the engine, getting someone elses unused low-grade kit....$50 :)
  15. KCvale

    KCvale Motorized Bicycle Vendor

    And that is just the $ to fix your battered body..
    The original pain and scars however stick around forever, and you still have a broken POS bike.

    The bottom line here is just build a safe machine to start with and yours is not one is all, not with those parts.
    I'm just trying to save you from some anguish is all as I have felt it, and I see it coming your way with that build.

    Just a warning, take it or leave.
    Last edited: Mar 22, 2016
  16. bakaneko

    bakaneko Active Member

    I got it on sale for $50. Now, we know that it has been up to $125. It isn't a based price of $50... And, yes, I rode on worse at fast speeds. Thus far, the bike has been handling itself well. I had to stop from 23mph to 0mph today and it did it within 10 feet with both brakes. I went up to 35mph and it performed well no vibrations or iffy wobbling. My only complaint for a sale price bike at $50 is that the seat cushion is like a rock and it is suppose to be one of those comfy styles...
  17. johnsteve

    johnsteve Member

    I forgot to mention the seat. it also was replaced. I am planing to use it on my next bike. Sooner or later, things will start to happen.... But if you need extra parts, please let me know after I am done with my next MB

    If you check the wheels you will see that they are not perfectly tru,,,,thats because they are put together with a machine........ Just my experience and everyone else's thoughts. That bike is not a good bike. If you look at craigslist you can see good quality bikes there all day long, that are moderately priced.
    Last edited: Mar 22, 2016
  18. bakaneko

    bakaneko Active Member

    Thanks for the reach out John. I will keep an eye out for her (80 miles thus far). I had to adjust the handle bar alignment right when I got the bike and realign the rear brakes after inflating the tire to the proper psi.
  19. bakaneko

    bakaneko Active Member

    So, listed below is what I've done from stock thus far and the next upgrade.

    Changes from stock engine / settings
    - Adjusted the idle and mixture screw to improve performance and idle
    - NGK 7544 Iridium IX CR7HIX spark plug provided more torque and mid range speed via better ignition. It feels like 3-5mph more speed for optimal torque and ~3-5 mid range speed improvements. I love this small upgrade ($10) and I think it is on sale at sickbikeparts for $7 atm. Idling has improve too

    Upcoming Changes
    - One of the centripetal springs broke (not sure how for new engine) and chewed up some of my clutch pads. Ordered a replacement so this should provide even more power than I am seeing now
    - I might eventually pull the 36T sprocket and put in the stock 44T. I am a lighter rider but the torque is so low. I will see
    - Might get a performance exhaust or just regular 2-stroke exhaust for better air flow

    Any comments from 4-stroke owners would be appreciated as I get this girl up to her potential.
  20. KCvale

    KCvale Motorized Bicycle Vendor

    Yep, I use that plug in every 4-stroke build, they make a difference you can feel.
    Anything is better than the stock can exhaust but there is no 'performance' exhaust on a 4-stroke engine like a 2-stroke engine. All you can do is make it as free flowing as possible.