49cc Huasheng straight shaft clutch replacement

Wow I got an old Honda 50 sitting on a shelf. Hope to switch it out in the near future with the current RS 35 I use now. I hope I don't run into the same issue.
Gotta spread the fact; if I knew much earlier, with the amount of effort that I put into getting things running, I wouldn't have bought the chinese kit.
 
Kings Motor Bikes and GasBike has a four stroke clutch for a 5/8 inch shaft. Staton-Inc sells the clutch shoes and plate for his super duty 49cc clutch rotor, You could call David Staton and ask if the rotor is available. He once told me that of all his super duty clutches that he sold, he never heard of one that wore out or needed replaced. I had one on a Honda GXH50, it is a very good clutch for motorized bicycles. A typical 4 stoke clutch for a 5/8 inch shaft sold by motorized bicycle dealers is not too good. I would buy a Max Torque go kart clutch for a 5/8 inch shaft from a go kart vendor. There is a world of difference between a go kart clutch and a motorized bicycle clutch. The Max Torque is strong and it locks up solid. The Max Torque is for an engine that idles at @1600rpm and maybe locks up at 1800 or 1900rpm I'm guessing. The 49cc Hausheng idles at what @2500rpm? You would have to change out the springs in the Max Torque to engage at 2700-2800rpm.
 
Kings Motor Bikes and GasBike has a four stroke clutch for a 5/8 inch shaft. Staton-Inc sells the clutch shoes and plate for his super duty 49cc clutch rotor, You could call David Staton and ask if the rotor is available. He once told me that of all his super duty clutches that he sold, he never heard of one that wore out or needed replaced. I had one on a Honda GXH50, it is a very good clutch for motorized bicycles. A typical 4 stoke clutch for a 5/8 inch shaft sold by motorized bicycle dealers is not too good. I would buy a Max Torque go kart clutch for a 5/8 inch shaft from a go kart vendor. There is a world of difference between a go kart clutch and a motorized bicycle clutch. The Max Torque is strong and it locks up solid. The Max Torque is for an engine that idles at @1600rpm and maybe locks up at 1800 or 1900rpm I'm guessing. The 49cc Hausheng idles at what @2500rpm? You would have to change out the springs in the Max Torque to engage at 2700-2800rpm.

Hi Zean, in the past there was a straight shaft clutch on Staton Inc, but the seller claimed which it was off a few thousands of inch and would have damaged my shaft, as I measured it with a digital caliper and it turned out to be a 15mm metric shaft; I requested if there was any chance to get a custom machined rotor, but I never got a reply back. I'm not satisfied at all from the Staton Inc customer support :/

I checked out the Max Torque clutch; looks like I'd have to contact the website's admins to get a pulley shipped.
I dunno how I can get an HTD 5m toothed pulley on that drum; assuming it's steel, I could get a custom machined pulley out of the right material, slide it into a 5/8" (15mm) rod to act as a guide, and TIG weld it into place to the best of my abilities; but that's far from ideal:

It most certainly will get welded untrue.
 
I don't think Otto is gonna call David all the way from Italy...lol...lol.
I did once in the past, at least I contacted the customer support via email; a pretty regrettable experience.
Considering I'm not a machinist but a TIG welder, and I didn't knew a lot about tolerances a few years ago, the reply was something like "No the rotor won't fit into your shaft because it's a few thousands of inches off, don't ask for the obvious".

And that's pretty much how Staton inc has gotten any of my future purchases out of the window lol
 
So what kind of 3 shoe clutch are you trying to get? The typical swing arm shoe or a KTM clutch like you have in the picture?

One night later, I sorted my ideas:

I think I'm giving it a go with the KTM clutch; I'll get one and I'll swap the shoes, at most I'll drill and tap larger shoe bolt holes if required, and I'll see if things will work out; if not, I may attempt to design some sort of shaft adapter on which I could fit a two piece GX-50 clutch.
 
One night later, I sorted my ideas:

I think I'm giving it a go with the KTM clutch; I'll get one and I'll swap the shoes, at most I'll drill and tap larger shoe bolt holes if required, and I'll see if things will work out; if not, I may attempt to design some sort of shaft adapter on which I could fit a two piece GX-50 clutch.
The clutch on my RS 35 is 14 years old. The secret to its longevity is I have a shifter bike and use a tachometer to shift by. The clutch engagement point is around 4000 rpm; max torque is at 5000 rpm, max hp is at 7000 rpm, and max rpm is at 9000. Therefore I'm always in a gear that isn't overloading the clutch. If I drop below 5000 rpm at full throttle, I shift to a lower gear. If I go above 7000 rpm at full throttle, I shift to a higher gear. I have a level ground take off gear and an up hill take off gear. I also always pedal assist on take-offs and while riding.
 
The clutch on my RS 35 is 14 years old. The secret to its longevity is I have a shifter bike and use a tachometer to shift by. The clutch engagement point is around 4000 rpm; max torque is at 5000 rpm, max hp is at 7000 rpm, and max rpm is at 9000. Therefore I'm always in a gear that isn't overloading the clutch. If I drop below 5000 rpm at full throttle, I shift to a lower gear. If I go above 7000 rpm at full throttle, I shift to a higher gear. I also have a level ground take off gear and an up hill take off gear. I also always pedal assist on take-offs and while riding.

I managed to fit a 2 stroke belt drive kit on my bike by drilling new holes in the sprocket using a 3D printed center tool, and I slipped the drive pulley into the transmission's 15mm axle by taking it off and rolling it on a vertical drill against some very soft sand paper, until the drive pulley slipped in with some effort, I took advantage of the moment for swapping the bearing with SKF ones, because the stock ones were trash, the axle would occasionally become harder and then suddenly loose to spin.

According to my calculations that belt drive setup offers more or less the same ratio of a 52T rear sprocket.

The bike itself takes off fairly well with a 43T sprocket, and even if I'm not very fond of it, even while riding the clutch itself; now it should get a little extra torque to help the clutch's longevity; my old one lasted for a decent amount of time, undergoing some abuse due to the engine running rough (stock carb was junk and the SHA 15.15 would run lean on a 66 and rich with a 67 jet, enough to cause the plug to fowl after sitting on idle for 10 minutes), I'm pretty sure it's gonna be sweet.
 
I have the same engine and clutch as yours Otto. This is the only place I have found for a replacement.
Could it be you just got a bad one in your post #3? You could always put a sleeve over your shaft to bring it up to 15.87mm or 19.05mm. That way you could use a go kart or minibike style clutch. I just had mine opened up today and it looks as good as when new 2 years ago.
 
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I considered to get a genuine KTM clutch and just swap the shoes, as they certainly will be more durable, but should anything not match with the rotor's central piece, it'd be other moolah going down the drain.
The only concern I have with using a centrifugal KTM clutch, is that they are used as a wet clutch in an oil bath within the case (The Junior 50SX engine as an example). I would worry about their potential longevity when used dry. Unless there is a dry clutch version I am not aware of, which is possible.
 
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