Hi guys,
I finally got tired of guessing what my timing was and was about to make an adapter for a dial indicator gauge, and was looking on ebay at gauges when I saw a techumseh gauge with the adapter already in place for 19.95,So i bought it.
It has a .001" increment reading and will sweep up to one inch is the .001" fine enough to be setting timing acurately?Thanks.Jim
i'd say 0.001 inch is a magnitude more accurate than is even practical considering how coarse everything is on a points-type moped ignition. Nice tool to have around.. good price too.
I just bought one of THESE inductive timing lights for $13 .. cheap-o special, but the thing works and i'm happy.
How do you use the light on a points type system? I know how to use it on a car with the timing marks.
I have a light similar to that myself "inductive".I have no timing marks on the puch fly wheel maybe i'll have to find TDC with the indicator gauge and scribe TDC on the flywheel and mark it + and - of the TDC mark a few milimeters? and use the light to see where the static timing is from then on.Jim
yeah.. make a few marks on the flywheel and one on the case. maybe TCD and BDC .. maybe a few between TDC and 20 degrees BTDC for ignition timing purposes. If you do any cylinder porting it may be nice have marks on the whole wheel.. 360 degrees.
There are degree wheels like THIS ONE the net that can be d/loaded, resized, printed and pasted to the flywheel. I think there are even degree tapes that wrap around and fit some popular bike flywheels.
The light is powered by any 12 volt battery. (i haven't tried it on a 6Volt battery or by connectng it to the moped's lighting circuit yet but it may work..)
Clip the inductive lead to the plug wire, fire the engine up and point the light at the flywheel... same as on a car.
Pi x D = circumfrence or 3.1416 x diameter of fly wheel = circ. then put your 360 degrees on a tape the right length of the circuference.Only problem is the manuals use measurements rather than degrees but this could be overcome.Jim
you can use a 12volt battery for the light it only powers the light keep it seprate from the bikes magneto system .jim
btw.. i dunno if you can do math, but here's a way to convert the dial indicator reading into degrees of crankshaft rotation.. It originally came from a book (Bell's Two-Stroke Performance Tuning) but the equation is debated on THIS page .. seems the book had a misprint? So:
A = Cos (... shoud have been
A = Cos -1 (...
Yeah I have bells book to.You have to read and reread it so you can get what they are talking about. like I said if i'm interested no prob., But most of that stuff I'll never do so I just put the unimportant to me stuff aside.
i'm not that good at math but could stumble through the formulas that interested me.thanks for the up date on that formula I'll make sure to change it.Jim
i guess it doesn't matter what the actual numbers are or where the marks are, other than as a convenient point of reference... tweak a little this way.. tweak a little that way.
I found this thread with google search "puch timing"
..amazed at how many people manage to spell 'push' wrong..
Anyway.. three entries below the Moped Army on googles first page (you guys ranked #1) is the following..
http://home.concepts.nl/~staal/electrofaqse/main.html
It takes you to 23 pages of a moped propellerhead's wet dream
regarding timing and electronics - it's even got excellent illustrations, or I should say thank god it has illustrations because it's all in SWEDISH! Babelfish? Sorry, it's in HTML. (anyone know how to get around this?)
Anyway.. again.. if you scan down the illustrations, there are photos of what looks remarkably like a puch flywheel and with
the timing marks indicated. I was thinking that I might blow up
the photo and get a good estimate of spread between the setting mark and TDC when I scanned the text and was able to determine that that distance is 17-18mm. Regardless of your Puch model, this has to be a good ballpark reference.
I'm headed out to the garage to find TDC, dremel reference marks in the flywheel and case, dremel a setting 17mm CC of that, get out dad's old timing light, (when's the last time I needed that?), and give it all a whirl.
thanks for the great forum here guys.
The dial indicator is a bit of over kill. TDC can be found with a screwdriver in the spark plug hole. just turn your flywheel in the normal direction (there should be an arrow) until the piston gets to it's highest point in the stroke. There will be 1-2 degrease of slop (when rotating the flywheel dose not move the piston. There should be a mark on your flywheel it should be pointing to where your case half's meet on the right hand side or pointing directly at your rear wheel. If there is no timing mark then scribe one. This is your TDC mark.
There are several ways to find when your points open. The way I use it this. I spin my flywheel 180 degrease from where my TDC mark is. I disconnect my blue wire from my coil and connect one lead to that. I take the other lead and ground it to somewhere on my frame. When my meter is on Ohm's and there is no signal (circuit is open) it shows O.L. I turn the flywheel in the normal rotation direction. The meter will show O.L. Until the points just open ( when the points open it completes the ignition circuit causing the spark plug to fire. When this happens you will get a reading on the meter. This is where your points open. Mark this point on the flywheel and measure the distance from that line to TDC. You can convert this to degrease if you like since you know the circumference of the flywheel. I just keep it in distance. Off hand I do not know the "correct" timing but you can find it in the manual.
Make sure your points are opening at some point in the rotation of your flywheel or this is all a waste of time.
Happy timing
Here's the procedure for doing the timing on a puch with the dial indicator gauge.Jim http://www.mopedarmy.com/forums/discuss/1/202066/188637/
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