Hot Rod HS40-Powered Full Suspension Cat 250

That' 50th anniversary' Cat will be good for miles of smiles! Rolling art-work with a mean flathead that sounds, and performs, well beyond its advertised HP! I know that Arizona weather adds to your enjoyment.
 

delray

Well-Known Member
dave, I had to put you on my 55 flatscreen with surround system. I could really here it good when you throttled on it. just crazy when you think that's supposed be a 4hp motor. nowhere near that now and your a bigger guy and that bike/engine has no problem pushing down the road and it's only a clutch. just think what it would do with a torque converter? kind like the clutch too on my 4hp build. makes it a lot easier to throttle into it and not wheel stand the bike.
guy can still have a lot fun with a flathead....:scooter:
maybe a 5hp block next time with a 255 cam......
 

Biffmini

Well-Known Member
Needed a chain tensioner because that modified hub isn't perfect and the way in which I mounted the swing arm and fabricated the JS plates just made the chain routing too close to the swing arm. I didn't like any of the commercial mini bike offerings, with a silly little spring and a skate board wheel. It might be fine for some applications, but not mine with this much weight, and a tire shredding four horsepower Tecumseh with a cam and a carb and a high rise intake manifold and headers.

So knowing this is not brain surgery, or curing cancer, I spent about two weeks thinking about it and writing stuff down, and looking at motorcycle tensioners out there for $100 and made this thing. If you want to know more about it, or lessons learned or parts used, PM me, although (see brain surgery comment) I will have forgotten already.

Parts I made and used. Torsion spring is 19 LBS.


Assembled. Can you find the Tecumseh alignment dowel?


Upside Down. Honda XR Brake Anchor Arm shown.


Shitty Welds, but they hold.


Right Side Up


From the Side
Any chance you can help with spring source? I would like to Fab up a chain tensioner like yours. The same set up right side swingarm. I know it's been a while. My search for torsion spring is very overwhelming. Especially since I don't know exactly what what I'm after.
Any help would greatly appreciated. 20220104_211524.jpg
 
Any chance you can help with spring source? I would like to Fab up a chain tensioner like yours. The same set up right side swingarm. I know it's been a while. My search for torsion spring is very overwhelming. Especially since I don't know exactly what what I'm after. Any help would greatly appreciated.
Hi, at some point, I opted to watch this thread, so got your request in an email. Been awhile since I logged in here, and longer since this build. I got the torsion springs from McMaster-Carr. Unfortunately, I can't recall if LH or RH springs was what I used. I ordered both, just in case. Look under McMaster's torsion springs for 120 degree springs, and something like 5 pounds of torque. Get as long of legs as you can, as you can always cut them. I got the idler sprocket off of Ebay. Both the idler and the torsion spring need to work off of "axles" and you need those. If you have some fab skills, and I know you do, it will all come together once you start cutting and welding.
 

Biffmini

Well-Known Member
Hi, at some point, I opted to watch this thread, so got your request in an email. Been awhile since I logged in here, and longer since this build. I got the torsion springs from McMaster-Carr. Unfortunately, I can't recall if LH or RH springs was what I used. I ordered both, just in case. Look under McMaster's torsion springs for 120 degree springs, and something like 5 pounds of torque. Get as long of legs as you can, as you can always cut them. I got the idler sprocket off of Ebay. Both the idler and the torsion spring need to work off of "axles" and you need those. If you have some fab skills, and I know you do, it will all come together once you start cutting and welding.
Thanks for the tips!
 

desert rat

Well-Known Member
Hi, at some point, I opted to watch this thread, so got your request in an email. Been awhile since I logged in here, and longer since this build. I got the torsion springs from McMaster-Carr. Unfortunately, I can't recall if LH or RH springs was what I used. I ordered both, just in case. Look under McMaster's torsion springs for 120 degree springs, and something like 5 pounds of torque. Get as long of legs as you can, as you can always cut them. I got the idler sprocket off of Ebay. Both the idler and the torsion spring need to work off of "axles" and you need those. If you have some fab skills, and I know you do, it will all come together once you start cutting and welding.
It's good to see you back.
 
Hi, at some point, I opted to watch this thread, so got your request in an email. Been awhile since I logged in here, and longer since this build. I got the torsion springs from McMaster-Carr. Unfortunately, I can't recall if LH or RH springs was what I used. I ordered both, just in case. Look under McMaster's torsion springs for 120 degree springs, and something like 5 pounds of torque. Get as long of legs as you can, as you can always cut them. I got the idler sprocket off of Ebay. Both the idler and the torsion spring need to work off of "axles" and you need those. If you have some fab skills, and I know you do, it will all come together once you start cutting and welding.
Ain't been the same without your "shit paper" jokes... good to see you post Dave...
 
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