Looking for timing numbers...
09-10-2011 | 09:20 AM
#26
Thread Starter
RE: Looking for timing numbers...
ORIGINAL: airraptor
Generally 180+ on exhaust timing is pipe timing.
What is the measurement where the exhaust port close?
How wide is the exhaust port at the top?
How big is crank hole?
How big is carb? IE (.300 - .330) i think those are .310 on the TT
How is your crank measured? from BDC or TDC. I usually just got of when i can see light coming thru crank and use the back cover screw hole as a reference. The crank starts to open when near the screw hole at the 7 o-clock position and closes around the screw hole at 1 o-clock for around 180 degrees total. normally you want it to open around 40-50 degrees. I will dig in my boxes and get the numbers i have for you ok.
Oh year i think 16,000 is with in reach. on a jett pipe.
Generally 180+ on exhaust timing is pipe timing.
What is the measurement where the exhaust port close?
How wide is the exhaust port at the top?
How big is crank hole?
How big is carb? IE (.300 - .330) i think those are .310 on the TT
How is your crank measured? from BDC or TDC. I usually just got of when i can see light coming thru crank and use the back cover screw hole as a reference. The crank starts to open when near the screw hole at the 7 o-clock position and closes around the screw hole at 1 o-clock for around 180 degrees total. normally you want it to open around 40-50 degrees. I will dig in my boxes and get the numbers i have for you ok.
Oh year i think 16,000 is with in reach. on a jett pipe.
I do know the carb throat is .290", and I made all of my measurements with the piston starting at TDC rotating the engine in normal CCW rotation towards BDC. I made my measurements using a 150 watt halogen light shining into the exhaust and backplate holes and made took measurements from when I could just barely see light shining through for open times and when light was just barely no longer visible. I would estimate my numbers to be within 1/2° +/-.
Thanks for getting back to me. I appreciate it. I'll get those numbers later on today or tomorrow morning and post them up. The crankshaft hole might be a little tricky since the crank is a pain to get out but I'll see what I can do.
10-14-2011 | 08:34 PM
#28
Thread Starter
RE: Looking for timing numbers...
ORIGINAL: airraptor
ok let me know here or shoot me an email.
[email protected] or
[email protected]
ok let me know here or shoot me an email.
[email protected] or
[email protected]
Width of exhaust port in crankcase - .927"
Width of exhaust port in sleeve at widest point - .706" *outer corners are rounded and the port is split in two smaller ports with a divider between*
With piston at TDC, measurement from top of sleeve to top of piston - .163"
From top of sleeve to top of piston with Exhaust port just closed - .710"
From top of sleeve to top of piston with Transfers just closed - .790"
Diameter of channel in crankshaft - .427"
Diameter of carburetor barrel - .296"
Compression ratios:
Head volume + Squish volume = .04562012 cubic inch
Effective Swept Volume = .31405769 cubic inch
Effective Swept Volume + Total Head Volume = .35967781 cubic inch
Total Swept Volume = .45185266 cubic inch
Total Swept Volume + Total Head Volume = .49747278 cubic inch
Geometric CR - 10.90:1
Effective CR - 7.88:1
-With Shim Removed-
Geo CR: 12.84:1
Eff CR: 9.23:1
Advertised Bore: .858" (21.8mm)
Advertised Stroke: .787" (20.0mm)
Displacement .456 cubic inch - 7.47cc
(I was really bored tonight...)
