Motorized Bicycles

From Noah.org

Chris Hill's kit

I really like this guy's site. I was suspicious at first because parts of the page were almost unreadable, but I stuck with it and it seems like he knows what he's doing. So this guy's deal is that he takes Chinese engines and rebuilds them with higher quality components (bearings, rings, seals, electrics) to come up with a Chinese/Canadian hybrid. He lists the engine as 80cc, but he also has a clear disclaimer that the engine is really only 70cc.

    http://www.chrishill.myknet.org/index.html

I also checked some of the motorized bicycle forums and he seems active in the community. He has gotten very good reviews.

    http://www.motoredbikes.com/showpost.php?p=76172&postcount=9
    http://www.motoredbikes.com/showpost.php?p=137267&postcount=5
    http://www.motoredbikes.com/showpost.php?p=138422&postcount=9

Grubee

I also like this site. It's a super badly designed Chinese web site:

    http://www.grubeeinc.com/USA/SkyHawk.htm
    http://www.grubeeinc.com/USA/Total%20Products.htm

Despite the noisy web site I like the enthusiasm and there is good dense info buried here. Plus they sell Russian engines and "Poo Poo" exhaust mufflers. They get bonus points for those items... And they seem honest:

    """ *Disclaimer:  Down thru the years China bike engine factories have
    always advertised their biggest engine as 80cc therefore we have listed it
    the same way. However, the bore and stroke of an 80cc being 47x38mm only
    equals 66cc.  Therefore is no such thing as a 80cc."""

My big fear is getting a shipment seized by customs, but it might not be so much of an issue on single orders. Man, I had radioactive Tritium shipped to me from Hong Kong without any issues...

Assembly pictures

This site has really good assembly pictures:

    http://thatsdax.com/INSTALL_INSTRUCTIONS.html

Sadly, the rest of the site is unreadable. Maybe I should offer one of these guys to trade a decent web site for a motor kit.

Tuning

This site has some good documents on 2-stroke tuning: http://edj.net/2stroke/jennings/

Expansion Chambers

Expansion chambers on 2-strokes recover energy from the heat in the exhaust and increase efficiency through fluid properties of pressure waves. Most of the benefit comes from pressure wave tuning. Neat stuff, but it's complicated and the gains are tied to a specific RPM... So for those of us not closely following the theory and formula on a design spreadsheet I wonder if most of the perceived benefit is due mostly to derestricting the exhaust rather than gaining much advantage from pressure wave scavenging. That may not be hard, but I haven't found any simple instructions.

http://en.wikipedia.org/wiki/Expansion_chamber

Software for calculating expansion chamber profile:

http://www.buildandclick.com/

Boost Bottles -- Tuned intake length

Also related are velocity stacks and boost bottles...

Calculate length: http://www.bgsoflex.com/intakeln.html

Boost bottles for sale: http://www.boostbottleindustries.com/

Diesel?

I've always wanted a Diesel motorcycle (for no good reason):

    http://my.opera.com/bhtooefr/blog/show.dml/91951