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Old 12-14-2012, 03:02 PM   #152
FJ_Kevin OP
Gnarly Adventurer
Joined: Dec 2010
Location: Maryland ==> originally from Long Island
Oddometer: 365
Books and other resources...

Books and other resources... continued

So straight forward (if there is such a thing) copying of another makers porting is not so straight forward . So with that I began reading up on two stoke engine theory. There seems to be several good books on the topic, here are a couple of the more popular ones,

The Two-Stroke Tuners Handbook can be downloaded free from a couple of sources (google is your friend). I found the Grahm Bell book to be pretty good too (about $25 on amazon).

If these books dont put you to sleep, try the Eyvind Boyesen patents on porting and reed valves...

After reading these, the take away for me is that blue printing is about the best I can shoot for with the finite time I have. Yamaha knows quite well what they are doing (certainly more than me) and it would require a great deal of effort and experimentation (access to a dyno) to improve upon the original design.

Also when I look at what a guy like Eric Gorr charges for port work, it's a bargin compared to the time it would take to replicate his know how from scratch.

So my focus was and remains a high quality, reliable rebuild with focus on proper running and jetting. Sometimes I simply forget the bike is too fast for me anyway .

Still, it would be fun to take port area/timing measurements, crank through the equations, and see how the yz design stacks up agaist the recommendations of these books. If I get through all of this I will be sure to post the results here.

Next up will be pistons and the rest of the top end.

First, recall this bike was stolen and then recovered, here is a recent picture after repairing the (minor) damage. The thieves never started it so I am happy to say it still runs great!

My '81 YZ465 Factory Race Replica

My Vintage Husqvarna/Motocross Restoration Extravaganza Thread

FJ_Kevin screwed with this post 12-14-2012 at 03:26 PM
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