I am asking advice here on four strokes-

[Sgt. Howard]

Assuming, just for grins and giggles. that you had a carte blanch for a new engine on your in-the-frame 4 stroke build. And assume that you were not overtly concerned about mounting as much as final drivetrain configuration (I don't want to engineer the hook-up to the rear wheel). And it HAS TO BE less than 50cc displacement.

What engine would you buy?

Tell me please why you would choose such a mill as what has your fancy.

I have several times now come face-to-face with the fragile nature of the China Trollop... people warned me about building on Hufffys, yet the BIKES have held up fine (once I re-did the supports for the fenders) while the motors and the tires keep crumping. Quite frustrating. I am putting a great deal of effort into straddle tanks for a worksman I have recently acquired, but the idea of putting a disposable, non-housebroken two-stroke into what will be an aesthetically pleasing machine is... well... depressing. I want a four stroke, and I would prefer that my "Sunday go to town and rub everybody's nose in it" shiny toy not be covered with slime and sound tinny. Or break down due to shoddy engineering or quality control.

If I am hoping for too much, please let me know. Two strokes are fine for cheap Huffys- if my $100 WalMart special is all oily, I could care less as long as it isn't in my clothes. But I want my next build to be housebroken.

 

[Sgt. Howard]

Having done a bit of research, it appears that 4 stroke kits have an availability issue- meaning that I might jolly well have to buy an engine and figure it out from there, am I right? The mount does not look too hard to figure out, but the drivetrain situation seems ... daunting?... perhaps more of a challenge than I care for. I can figure how to hook up a chain and all, but the numbers, the gear ratios, will be trial-and-error unless there is a chart telling me how to make it work that I have missed.

Anybody?

 

[joshua97]

honda gxh5o or the clone huashen 142f

 

[IbedaYank]

What ever 4stroke you choose with a Qmatic or a 79cc preddy with agk'S jACKSHAFT KIT
The 4strokes are great motors if you do not redline them and blow them up.
The cheap chaindrive boxes are JUNK. 4G is better but still has some problems.
5G box is a POS chaindrive not worth it's weight in scrap

 

[MotorbikeMike]

Hi Sarge, I have owned a bunch of different engines, and have ridden and become acquainted with others. The Robyn Subaru 35 is a fine little engine, as is the GX35 Honda. I am a big guy, and have ridden both successfully with completely different drives. BUT these small engines are just that.....small. I would then be choosing from the only 49cc 4-strokes that I am aware of, the GX50HA and the Hua Sheng 140F 49 cc clone of the Honda.
The Honda is .........well.......Honda! BUT, the Cost of the Honda (Mine was a bit over 300.00), lack of warranty, need to dis-assemble the governor, and the fact that it does NOT have a cable-operated carb, and the main jet is smaller, causing slightly less performance, well......you wanna guess?

The Hau Sheng is a VERY good clone, much less money, carb is ready, performance better, no Governor to mess with, same EXACT appearance, readily availble, and for me, the clear winner.
Mike

 

[butterbean]

If you set aside the displacement limit, there are several other options. I'm currently running a 98cc Lifan flathead (side valved) minibike engine. Gear ratios are not too difficult to figure out. You can find a program here that will help calculate gear ratios for you. http://jimsitton.net/ratiocalc/ download the .exe file and double click on it after downloading to launch the program. Start by entering tire size and engine rpm (you'll need to know the max rpms of the engine you'll be using before you can accurately determine the appropriate gear ratio). Then play around with different gear sizes until you come up with a gear ratio that will give you the top speed you want. Your other alternative if you're abolutely set on 49cc is to buy a qmatic kit for around $600 bucks, its got the best transmission around and the transmission is american made primary belt drive.

 

[Sgt. Howard]

I pretty much have to stay with 48-49 cc as in Washington State anything bigger is a motorcycle and has to be registered as such- then I gotta get a motorcycle endorsement on my license and get insurance. I am doing this to get away from that rubbish. Granted, there are bigger motors that look real tempting- and if I do indulge, I will go the full monty. But for now, I suspect the Hau Sheng 140F might be the weapon of choice for motor. I will be doing the tanks and other stuff, as well as the mounts. Drive train seems the challenge now, but I bet this is familiar ground.

 

[butterbean]

Pennsylvania's laws are similar. Anything over 50cc is a motorcycle here as well. I simply drive unregistered. But the cops here don't bother me. Its not as if they can tell the displacement by looking, especially if you're moving. Ghost pedal when you see a cop, you be allright. Just dont put some 200cc monster on the bike and you will be fine, especially if you limit your top speed. My top speed is only 32mph.

 

[HeadSmess]

the absolute best engine of the required capacity, that will never die, is relatively easy to fit, fourstroke, and has a great parts backup?


honda C50

single speed auto. two speed auto. three speed semi auto...

all you gotta do is add chain to the wheel...

bit on the heavy side.


lifan clone with race cams would be my preferred choice


having seen the insides of four huashengs in a short period, i hate them now. though having people drop the bike and break things is no fault of the engine, i did find the ease with which the coil broke off slightly disconcerting.

my own huasheng lasted for quite some time but still, bin model when things do go wrong.

i would probably choose a robin or huasheng clone of, before a honda in the 35 sizes. my only real reason being... cam belts have service intervals on cars.... pushrods usually dont snap unexpectedly. rather a moot point, but im sticking with it

they both work equally well as brushcutters?


on the gearing side...while a $600 kit may seem expensive, unless you have made a few redux drives before, its the easiest option.

the ratios themselves arent too hard. diameter of wheel, rpm of engine, desired speed, and maybe wishful thinking on how powerful the engine is small engines like 18:1-20:1, big fat torque monsters can run 10:1... a 2stroke ht stock on 26" rims is 16:1 aprox.

staton? has a two speed auto belt drive...

 

[joshua97]

i use the stock ebay trans from my 142F and no problems at all otherthan it revvs high so use a 32 t sprocket and then its sweet