http://www.motoredbikes.com/attachment.php?attachmentid=13533&stc=1&thumb=1&d=1229559622
POST 20 PICTURE
on this pic there is a blank spot MIDDLE left back page asking for
EXHAUST PORT OPENING ANGLE [degATDC]
yeah im still not sure what they wanted there but i just put in 90, because it asked for a number between 70 and 105 so im assuming that its talking about the angle of the port ceiling in relation to the piston wall. which on our Chinese engine is pretty darn close to 90 degrees.
heres the info i came out with for the "80cc" engine.
(mm)
DX:24.1
D1:26.0
D2:40.7
D3:60.2
D4:18.1
LX:27.9
L1:111.4
L2:571.3
L3:195.1
L4:153.3
L5:334.4
L6:334.4
TTL: 1393.4
(total tuned length)
these results were with these numbers
Two stage diffuser
max power engine speed: 6000rpm
EGT: 500c
Exhaust port Effective diameter (DX): 24.07mm
Diameter at the barrel flange (D1):26mm
Length from piston face to flange (LX):27.94mm
Exhaust port opening angle:90
Midsection diameter: 2.125
tail pipe diameter: .7
now a few things im not sure of are the following.
1. the exhaust port opening angle at TDC.
2. what the true max power RPM for these engines is.
3. not sure if the EGT i chose was to hot or to cold to what our engines read. if someone could take a temp reading of their exhaust pipe after a good hard run that would be sweet.
4. what diameter our engines would prefer. i used fairly small ones as suggested because i doubt out engines will flow very well and i doubt they will rev anywhere near what a enduro bike will. let alone GP racer. so thats kind of a estimation to.
but how ever you look at it, im sure pretty much any close calculation you toss into that program is going to yield a pipe that will blow your mind in performance gains in comparison to what they come with. in fact i would be inclined to think that any serious research and testing to custom tune a precision pipe for these bikes would be like throwing pearls before swine.
hope this helps
