Motorized Bicycle - Episode 007

[6 October 2006]

There were four main problems with mounting the engine kit to the bicycle:

--One problem was that the engine bracket wouldn't sit high enough on the quick-release skewer for teh tensioner to work properly and the engine to sit level. The solution to this is to make some bushings that will fit over the 5-mm skewers and that have an outside radius of just about 10mm, or 3/8" inches. This was pretty easy to do, as there's a common size of brass bushing that has an outside diameter of 3/8". It didn't quite fit snug on the quick-release skewer, but I found that a strip of plastic cut from a Cool Whip container would fix that. These bushings aren't really under a lot of stress, they are just there to ensure that the engine sits at the right height and level before the QR is clamped down--and to that end, they work. ...-I made both of mine 3/16" wide as that was the thickness of the engine mount's legs, but the nut on the QR is partially undercut about 1/8"-inch, so one spacer needs to be 3/16" wide and the other should be 5/16". I also later noticed that I had some pieces of a standard size of aluminum tubing stock (3/8" x .058 wall) and that appeared to be identical to the dimensions of the brass bushing.

--Another problem was that because of the extra thickness of the engine mount's legs, the QR skewer wouldn't engage many of the QR nut threads anymore (the round nut that screws onto the skewer, opposite the lever end). The bicycle shop cured that problem when they found another skewer that was about 5mm longer. This is not long enough for the skewer to poke through the nut like usual, but it is enough to engage all the nut threads. The nut isn't fully threaded--the bottom is undercut about 1/8th inch (as noted above) and the top 3/16" or so is a nylon bushing intended to serve as a locking bushing. So the skewer doesn't need to stick all the way through, as long as its' long enough to engage all the metal threads.

--Another problem was that the throttle cable wouldn't reach. The stock cable was 54 inches long, and I ended up needing one 84 inches long. I emailed Golden Eagle asking if it was possible to get a longer cable at all, and I also set about modifying the existing cable to lengthen it. Someone at Golden Eagle wrote back saying that it was possible to get longer throttle cables for $10 more, up to 100" length. An additional throttle cable is $25 and $5 shipping. They also said that if I ordered a longer one and returned the original one, that they would credit me for $15, so except for shipping I still would have paid only $10 more--but by then I had already cut the original one in half to modify it. My modified cable works but not great, so I'll probably test the bicycle out with it ---but I ordered another that will be 84 inches long.

--The fourth problem is that the wire for the kill switch is still too short--but this is a very minor problem to fix, as it only involves lengthening one wire.

--Also today I checked the oil level and found that there was none in there after all, so apparently they test the engines but drain the oil afterwards. There was just enough oil left inside to leave some drops on the dipstick/cap.