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

[dougsr.874]

Hello. I just finished and road 10 miles on my new 4-stroke 49cc HuaSheng bike from GasBike.net. 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.


http://www.gasbike.net/collections/...-drive-kit-with-huasheng-49cc-4-stroke-engine

You are already screwed with the type of gearbox...it will break in a few days......cheap not always the best...

 

[bakaneko]

You are already screwed with the type of gearbox...it will break in a few days......cheap not always the best...

It has been 5 weeks and about 450+ miles. The gearbox is fine; I cruise well at 25-30 mph and have a top speed of about 35mph with a 36T sprocket. The only real problem I encounter is the alignment of the chain on my engine due to an imperfect tilt of about 5 degrees. The imperfect tilt is not the transmission fault but the small bike I am using with the kit. I was able to overcome this with a double chain tensioner setup at the rear sprocket and above the drive sprocket. I am a lighter rider too and help pedal start it from stop to about 17 mph because I have such a smaller rear sprocket. I think this transmission works best for light riders and those willing to help the motor a little from a dead stop. If you want it to make a burnout from a stop and propel you to 40mph then yeah you are going to break it. And, if you are a heavier rider then yeah you are probably going to break it. But, for me, it is working perfectly

 

[Pedallazy]

Thanks a lot for this very informative thread bakaneko. Great help. Maybe this thread will turn out to be THE recourse for us new guys, if you want it to be.

A few points that may help some readers:

1. A MTB works fine, but one needs a big frame (for example 23 inch) of the old school design where the top tube does NOT slope back. Plenty of space.

2. A gear ratio of 1:3 is very high, and for us normally built types (fat) is not good at all ad will burn up the clutch. Gear boxes of apprx 1:6 are available, those have dual internal chains for longer life and a one way bearing. I got one from ebay Australia, it was cheap. It was not a direct fit, and require some work. It only has two hours on it at the moment so I don't know about reliability yet. With this transmission getting moving is easy, I pedal just to get moving before engaging the clutch. With this transmission hills, even steep ones, are not a problem.

3. The drive chain will stretch a lot when new. Stop and check/adjust every few minutes on a new build.

4. Engine mounting bolts will loosen on a new build. Check all engine mounting bolts after the first ride but DO NOT over tighten. The Chinese bolts are not of great quality.

 

[KCvale]

It has been 5 weeks and about 450+ miles. The gearbox is fine...
...double chain tensioner setup at the rear sprocket and above the drive sprocket. ..
And, if you are a heavier rider then yeah you are probably going to break it. But, for me, it is working perfectly

Cool.
I hope it holds up for you.
Just don't make the same mistake and order another when it fails, get a real Skyhawk 4G replacement.

 

[bakaneko]

Thanks a lot for this very informative thread bakaneko. Great help. Maybe this thread will turn out to be THE recourse for us new guys, if you want it to be.

Yup, you are right. The gearing is very high and probably will not work for others. I can get away with this because I am a lighter rider and want the speed. Now, after a few weeks, I actually want to decrease the speed, LOL. Also, very good points, I also hope that this thread will help others. There isn't a sticky thread for 4-strokes, which while the 4-strokes HuaSheng is relatively fool proof there are a few things as you pointed out that would help in a sticky. One thing I think is important to note is that you don't have to overtighten the nuts because 4-strokes are relatively low vibration as compared to 2-strokes. I stripped a transmission bolt because I was in the 2-stroke mindset.

Once, this transmission goes I will look into the 4G as KC suggested and other transmissions. I double nutted the mount bolts and also the chain tensioner. But, I am loving the low hassle of the 4-stroke compared to my 2-stroke.

 

[KCvale]

Yup, you are right.
The gearing is very high and probably will not work for others.
I can get away with this because I am a lighter rider and want the speed.

That's what gears are for, and a simple 3-speed internal hub works dandy.
Rocket off the line in first, second is all around cruse gear, third is overdrive that mathematically can do 50mph at 6800 rpm.

A small rider tucked in all aerodynamic might get close to 50 but wind is hard to overcome and these little engines don't have enough umph.
~40mph+ sitting up all nice and comfy is plenty for me ;-}

 

[bakaneko]

That's what gears are for, and a simple 3-speed internal hub works dandy.
Rocket off the line in first, second is all around cruse gear, third is overdrive that mathematically can do 50mph at 6800 rpm.

A small rider tucked in all aerodynamic might get close to 50 but wind is hard to overcome and these little engines don't have enough umph.
~40mph+ sitting up all nice and comfy is plenty for me ;-}

Yeah, I know that with a jackshaft and dynamic gearing I would probably never have to pedal and can achieve higher speeds. But, I am on a budget and decided on the simple rear spoke sprocket with a speed sprocket (36T) over a general use sprocket (44T). Now, after riding at higher speeds (33mph+), I like to have a slower cruise and top speed not for the torque sakes but for safety sakes. However, I am too lazy to change out the sprocket.

That being said, I was thinking about the jackshaft system and cost. I was wondering how many gears folks typically use for day to day rides. It looks like you only use 3 gears on yours. I was thinking if it would be possible to machine up a derailleur system with 2-3 sprockets for a low cost (~$50). So, rather than just put one sprocket in the rag joint lets put 2 or 3. And, then engineer up a simple derailleur system to switch between 2 or 3 gears. I think something like a 36T, 44T or 36T, 44T, 52T would work nice for most bikers. Maybe just a dream but I do have a 36T and 44T so...

 

[KCvale]

Yeah, I know that with a jackshaft and dynamic gearing I would probably never have to pedal and can achieve higher speeds.

Now you are getting it ;-}

But, I am on a budget and decided....
I was thinking about the jackshaft system and cost.
I was wondering how many gears folks typically use for day to day rides.
It looks like you only use 3 gears on yours.

I find 3 to be good for most, but a 5-speed might better for some.
The speed of the top and bottom speed ranges don't change much, the 5 just gives you more choices of range between high and low.

I was thinking if it would be possible to machine up a derailleur system with 2-3 sprockets for a low cost (~$50). So, rather than just put one sprocket in the rag joint lets put 2 or 3. And, then engineer up a simple derailleur system to switch between 2 or 3 gears.

Didn't you say were on a budget?
What the heck do think $50 will get you?

I'll just leave this post at that as for gears on the left has been talked about for over a decade and it just don't work now and would be thousands if someone was silly enough to produce them as everything on a bicycle is powered by the right side.

 

[bakaneko]

I'll just leave this post at that as for gears on the left has been talked about for over a decade and it just don't work now and would be thousands if someone was silly enough to produce them as everything on a bicycle is powered by the right side.

Not sure if we are talking about the same thing. I noticed that the bolt holes for different spoke sprockets are the same and I was wondering if it would be possible to put two or three sprockets on the same bolts. And, add washers to help clear the frame if needed and between the sprockets. The hard part is coming up with a derailleur system that can move between the big sprockets. You mentioned that you really only use three gears on your shifter so if one can get two or three spoke sprockets on the left and have a derailleur capable of changing gears between the few gears than this would fulfill the torque and speed needs for most folks. If this has been attempted and it is just an utter dead end than that is fine. If not, I might give her a go at some point since I have a 36T and two 44T sprockets.

 

[KCvale]

Not sure if we are talking about the same thing. I noticed that the bolt holes for different spoke sprockets are the same and I was wondering if it would be possible to put two or three sprockets on the same bolts. And, add washers to help clear the frame if needed and between the sprockets.

Sure you can, it just won't work is all.

The hard part is coming up with a derailleur system that can move between the big sprockets.

Take a look at any derailleur sprocket cluster.
They use thin chain that can bend and the gears only jump in a size by a tiny size to make moving the chain from sprocket to sprocket easier.
In short forget 415 chain and sprockets meant for that size chain, heck you can't even use 410 single speed chain to work on a derailleur.

You mentioned that you really only use three gears on your shifter so if one can get two or three spoke sprockets on the left and have a derailleur capable of changing gears between the few gears than this would fulfill the torque and speed needs for most folks.
If this has been attempted and it is just an utter dead end than that is fine.
If not, I might give her a go at some point since I have a 36T and two 44T sprockets.

Not just a derailleur but a tensioner as well to deal with the excess chain when it's on the smallest sprocket.

And none of it can be done with regular bike parts as they are all right side based clockwise rotation.
In short, there is a proven way to reliably use bike gears and it's on the right side.
I know that is disappointing, but many have tried including me, and it's just not feasible.