A warning to those looking to mod their motorized bicycles:

Most, if not all, of the hacks and mods featured on this site were made by individual hobbyists. If you are new to working with 2-stroke bicycle engines, please by aware that there's a possibility that a mod featured on this site could seriously damage your engine. Please don't try any mod from this or any other site unless you fully understand what you are doing. The owner of this blog will not be held responsible for both material and bodily damage caused by performing a modification featured on this blog. Also remember that opening up your engine may void your warranty!

Tuesday, August 16, 2011

Low-profile "ram" air system

Yet another post from an ancient motorbicycling.com thread I came across.  User pedalpower took what looks like a tobacco can and mounted it on the back of the carb to "catch" more air.  A very interesting idea, and a very inexpensive mod... but does it work?  This is one I definitely want to follow up on.  I can find no other example of this.  The only thing that does something similar is the "boost bottle", which is generally considered to be a bust.  However the boost bottles push gas into the intake after the carb has mixed air and the fuel, but this mod in theory would help to push more air into the carb as the bike gains speed.  Very interesting!

UPDATE: I tried doing this today using the bottom of a pineapple tidbits can.  I'm not sure how much more power it really gives the engine, but the engine seems to run nice and smoothly with it attached.  It seems to make it easier for the engine to inhale, so there's a bit less 4 stroking.

UPDATE 2: So far, this seems to be working really nice.  I'll upload a picture at some point.  I actually had to remove it the other day in order to fix the air filter(the carb sits really close to the frame).  I rode my bike without the ram air, and I could really tell the difference.  My bike runs very well anyway, but I could tell that the bike was running slightly richer than it needed to.  Some people say that having a ram air system leans out the mixture too much and that it wrecks the vacuum that's created between the carb and the engine and that it will eventually ruin the engine, and while that may be true for a pipe-based ram air, I think using the bottom of a can works great.  The NT carbs tend to run the engine a little richer than necessary anyway, and I think having a simple setup with something to "deflect" moving air into the carb nicely balances it out.

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