I just thought I should get this out here. I got my motorized bicycle kit from thatsdax.com about three weeks ago. I installed the kit on my Trek 3700. The fit was VERY tight and I was forced to remove the air filter to get everything to fit in the frame. Once I removed the air filter, I decided that the best option would be to simply pull the strip of foam that was inside of the filter off and place it over the area meant to mount the filter very lightly...held on simply with a bit of tape. Up until yesterday, I just simply could not get the bike to stop running rich. I had already completely fouled the plug twice and it was still black and oily, despite moving the clip on the throttle needle up to the top slot. It was also very noticeable that the bike died down at full throttle, ie it would rev up to high RPM's and then quickly choke... Finally, I considered that maybe the way the piece of foam was on, and considering how close it was to the frame itself, may have been effecting the air intake and thus causing the mixture to be too rich. The circle that the air filter mounts on on the carburetor was just 1/2 a centimeter away from the frame and I had simply placed the foam from the filter in front of this...It seemed like it wouldn't obstruct the airflow, I could fit my finger under the foam, but sure was I wrong!! I removed the air filter and suddenly it was like a brand new bike. The speed I could travel at doubled and full throttle no longer bogged down. I could also quickly gun the throttle and the response would be immediate. After removing this filter I adjusted the throttle needle by moving the clip to slot number two which seemed like the best. Number one seemed like too little fuel and the engine would not pick up quickly when given throttle, and position three seemed like a bit too much fuel and it would bog down when given throttle quickly. Position two, however, seemed clean and climbed the hills without any misfiring!
I realized, however, that I still needed an air filter, so I went ahead and bought a package of pantyhose. Yes, I went to the store and bought pantyhose. I got an odd look from the cashier, but I was able to explain! I cut a bit of the material, stretched it over the area for the air intake and rubberbanded it on! Perfection! (I live in SoCal, and I store my bike indoors, so getting water into the carburetor is not much of an issue).
I just thought I should let you guys know that something as simple as having the carburetor close to the seat tube and placing the foam in between the two caused the bike to literally starve of air. The difference in power and performance between taking the foam away and replacing it with the micro thin pantyhose was amazing. I will say, however, that if you have the room, you should definitely use the stock air filter, but always test to see how the engine performs with and without any filter you EVER put on with any engine EVER. Cars, motorcycle, motorized bicycle.. All of them!
. Just two minutes of testing with the filter on and with it off could save you a world of trouble. Trust me, the difference was amazing. The throttle picked up quickly when gunned quickly (no hesitation), the bike didn't bog down climbing hills or misfire because it was drowning in fuel, and I could give the bike full throttle and it wouldn't bog down after a few seconds as a result of lack of air. If you see these issues in your bike now, this might be what's happening too you! Take the filter off for a minute and see how she runs then..