[7 October 2006]
Early this AM (about 4: 15) I got off work and decided to take a spin on the bike. The weather was clear with a full moon, and the temperature was around 45 F. I put 100 ml of 10W-40 in the crankcase, dumped some gasoline into the tank, put a bit more into the MSR fuel bottle (thinking that I might be out long enough to run out of the 1/3 or so that I poured into the tank) and stuck that into the water bottle cage, and fired the engine up. I pulled the cord a few times and the engine didn't start, and then I remembered that I forgot to prime the darn thing. After I did that, it did start on the first pull.
The first thing I found was that the kill button did not work. It's difficult to say what might be causing the failure, there's a few places that might not be conducting. I had already pondered the idea of running a return-wire back to the engine mount somewhere (I was thinking of the clamp where the engine mount joins the seatpost) to make certain that the kill switch worked. I suppose now I'll need to.
The engine worked like it was supposed to--the top speed I saw was around 30 mph, which is pretty fast at night with only a 1W LED headlamp lighting your way. There didn't seem to be a lot of modulation in the throttle--the engine was either totally on or totally off, but that may have been a side-effect of my home-lengthened throttle cable giving things an extra-mushy feeling. I will need to wait for the longer one to find that out.
One new problem with the throttle supplied is that if your bicycle uses Grip Shifts, then I found that there was really nowhere that I could put the throttle that was comfortable to reach, AND that allowed activating the throttle fully. The throttle trigger is a standard lawn-trimmer type, and doesn't fit anywhere real well on the handlebars. If you put it below the handlebars, when you pull the throttle lever, it is stopped partway by bumping into the grip shift. If you twist the throttle lever so that it points upwards (when not activated) then you can't comfortably hold it down with your hands in a normal position on the handlebars. I'm thinking this can be solved with a bit of wire and some string, but it is a lower-priority item right now.
There was also a problem with using the MSR fuel bottle in the water bottle cage. At some speeds the MSR bottle would vibrate badly in the water bottle cage and make a lot of noise. If you put some plastic silicone tubing around the water bottle cage in a few key spots, this could probably be prevented. ....But I still constantly worried that I would hit a bump and the MSR bottle would decide to take a trip of its own. I've had it happen many times with MTB's and even road bikes, I just don't have a whole lot of confidence in water bottle cages anymore. A normal water bottle is soft plastic and will just bounce harmlessly around, but the MSR bottles cost $12-$15 each and might be damaged by falling out at speed.
The engine was a bit loud for my taste. I'm planning on trying to add on another muffler, bolted to the engine mount leg, under the engine. The OEM exhaust pipe is pointing out sideways and you can hear it a lot more if you turn your head to the right, and the engine seems especially loud when you go by a wall on the right side of the road. The outside diameter of the exhaust pipe is 7/16", and there looks like enough room to clamp an extending tube on.
I got cold pretty quickly, I only ended up riding for about ten minutes. I had on some decent windbreaker-type pants and jacket but nothing to protect my hands or face. If I had only gone bicycle riding at 10-15 MPH this wouldn't have been a problem, but at 30 MPH it definitely was.
At one point during the ride I noticed that the back tire felt really soft over bumps. I had not yet put any air into the tires (or checked their pressure even) and didn't know how much air the bike shop put in. When I got back home I decided that the back tire felt soft and tried to pump it up,,,, and that's when I found out that neither of my pumps would fit on.
The image above ( _08_valve_clearance... ) shows how close the drive ring comes to the tire valve. The ring has notches that clip about a quarter-inch over the spokes on one side, and so the ring edge extends to just about the center of the rim, and only about two inches from the rim itself. And I'd also point out that the valve stem above happens to be rather short--there are many that are 1/2" to 3/4" longer than that.
The image above ( _09_blowjoe_clearance... ) shows that the siamese head of the pump does not have enough clearance to slide on. The red line is the angle of the air stem and the green line is the angle that you can ge the JoeBlow head to it.
( _10_serfas_clearance... ) The Serfas minipumps that I've been carrying on my bikes the last couple years wouldn't fit on either. You can see here that the Presta valve isn't even the hole on the end of the pump's head--but in the previous photo ( #09 ) you can see that the Serfas pump head is too tall anyway, it's just about as tall as the floor pump, and the lever needs room to flip up besides.
So, I guess I'm shopping for a new mini pump.....