Another slight modification was needed for the chain tensioner. Not sure this would work with the two bolt type but it’s excellent with the 4 bolt one.
20 inch bicycle build
- Thread starter Larry Trotter
- Start date
So far the most difficult part is the chain and sprockets clearance. With a small frame there’s not a lot of options. I used a 32 tooth rear and if I did it again I would get a 28 just to get a little more room for routing.
Yeah, a 28T would net you 31 MPH @6000 RPM, so it would be do-able. This really looks great. The tensioner is genius- it'll be a LOT harder for that thing to ever rotate into the spokes, God Forbid.
I think I wanna STEAL that idea from you and try it on my Cranbrook!
It’s easy to make. I just cut it in the right place and welded it on the side. It’s really rigid this way and you can bend it to align it with the chain. I got the throttle and clutch cables installed so now just the brakes and some chain adjusters to keep the rear axel in place.
Got all the cables hooked up and routed. Here’s a little neatness clue, if you are careful you can put the end of the clutch cable inside the return spring and clean up the end of that cable.
Not much today. Made up some axel mount chain tensioners from pieces I had sitting around and also ran an 1/8 inch npt pipe tap into the fuel tank so I can use a granger ball valve for the fuel. I have only had grief with every factory fuel valve I have had so I will try this. The tank is tapped with a 10mm by 1 straight bolt thread and a 1/8 pipe is a taper about .018 larger and a pitch of .94mm so very close. Tap went in nicely and cleaned up about 5 threads totally and the rest partly. I will take pictures Monday when I get the valve and fittings.
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Picked up the 1/8 npt ball valve today. Already ran in a pipe tap and cleaned up the threads. The tap was $6.75 delivered from eBay and the ball valve was $6.51 from Granger. I will see how it seals up but it get tight with a couple of threads still showing so I think things will be good.
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Fuel system finished. Now just the wiring and start it up and test it out.
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Pretty much finished. Need to make a support for the bottom of the muffler and tomorrow I will start it up.
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Well I put some gas in it and it started right up. Only two things were needed, I had to slack off the throttle cable some to get the idle down and it’s probably running a little rich because it’s 4 stroking at about 25mph. This thing is really a fun ride and lots smoother than my 27 inch.
Finished everything off a installed and calibrated a speedometer. Hit 30 mph pretty easily so I really don’t need more than that. One last little mod is using the front motor mount adapter to support the bottom of the muffler. Pretty easy with a little plumbers metal strap. That pretty much wrappes it up.
Picture of muffler support. Takes some load off the exhaust studs.
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Another little observation. Yesterday I was riding and had forgotten to turn on the fuel. I switched it on while still rolling and when the engine fired up this short little thing pulled a pretty big wheel stand. So be careful it can surprise you lots.