|12-14-2012, 07:16 PM||#1|
Joined: Sep 2012
Location: Southern Ontario, Canada
Figuring out my old Dwell meter?
My father gave me his old Snap On dwell meter and timing light. I remember using it on my Charger when I was younger. My tach is broken on my newly acquired R100, and I plan to get it fixed, but in the meantime I was hoping to use the dwell meter to check dwell & rpms.
The meter has 8 cyl & 6 cyl buttons, plus it looks like you can do the math for a 4 cyl on the 8 scale. There is also a button for 1000 rpm and below, and 1000 rpm and above. So, there has to be some way for this to work, if I do the math? Should I use the 8 cyl and divide by 4 for rpms? Does the R100 have a 'wasted spark' system?
And for dwell, do I use the 8 cyl and divide by 4 (so 78 divided by 4?)
The meter has a positive clamp and a negative clamp, plus a yellow clip. Do I put the clamps on the battery and the yellow clip on the black side of the coil?
I swear I thought I used to know this stuff?
Any help would be awesome. Thanks!
2005 Suzuki DR650, 1987 BMW R80
CanadaBiker screwed with this post 05-27-2013 at 12:06 PM Reason: spelling
|12-14-2012, 07:49 PM||#2|
Joined: Mar 2011
Location: Silver Spring, Md
Yes the red and black leads go to the battery and the yellow is to the right side coil points wire. It is a wasted spark ignition system, all Airheads, whether electronic or points ignition, are a wasted spark system.
For the math I think you might have to go to Snowbum's site. He's one of the few that can do math. I have used a dwell meter but I have to go look that up every time so I'm pretty sure it's there.
Never memorize something you can look up.
Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
|12-14-2012, 08:01 PM||#3|
Joined: Sep 2009
Location: Melbourne, Australia
An eight cylinder motor fires 8 times per 720 degrees of crankshaft rotation.
An airhead fires twice in 720 degrees.
Therefore an airhead turns through 720 degrees 4 times before it has fired 8 times.
Multiply the indicated RPM for an 8 cylinder motor by 4 for the correct 2 cylinder RPM.
An eight cylinder motor fires once per 90 degrees.
An airhead fires once per 360 degrees.
If the meter shows a duty cycle of 67% or a dwell angle of 60degrees for an 8 cylinder motor, this is equivalent to 240 degrees for a 2 cylinder motor.
Multiply the indicated dwell angle for an 8 cylinder motor by 4 for the correct 2 cylinder dwell angle.
|12-15-2012, 01:34 AM||#4|
Joined: Aug 2007
Location: Easton Wa
From Anton's site that has dwell info.
It's eight and a half gallons of gas; and an engine. What more do you need?-- BMW R80G/S
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