Tuesday, March 12, 2013

Getting serious about timing

Setting a moped's timing could mean the difference between blasting your max to running sloppy or burning a hole in your piston.  For anyone who doesn't understand, you need to set when your spark fires as the piston is moving forward and nearly reaches the top.  You want the spark to fire JUST before it reaches top dead center when the compression is becoming the greatest.  I normally set my Polini at 1.25mm and then set my Parlini kit at 1.35mm.  I bought a Buzzetti timing tool from Treats, and it worked decent.  There was still a little play in the tolerance of the threading and I knew it wasn't perfect... So I went to Harbor Freight and, using some coupons, I walked out with the Pittsburgh digital dial indicator for less than $25.  It has US measurements and metric.  I ONLY do metric when it comes to mopeds and it was accurate down to 0.01mm.  So one hundredth of a millimeter.  Or if you prefer inches, 0.00039 inch.  Pretty darn accurate.  

So let's begin:
I did like the threading on the Buzzetti and how it gave a great feel for TDC, Top Dead Center of the piston.  So I wanted to outfit the new digital (pictured at the top) with threading.  Luckily I do not throw away my spark plugs.  I had a handful to play around to experiment.  The first one I tried getting the ceramic out was a nightmare.  I spent half an hour pounding with a hammer.  Then I got wise and asked for help on Facebook.  One of my friends said to grind off the top lip.  So if you look at the ceramic shaft you can see bevel between that and the hex head.  That bevel is what is holding the ceramic in the housing.  Grind or cut that bevel off then pour some cold water... or beer, on it.  You will likely go from cherry red during the grinding to room temperature, which will make the ceramic contract.  Flip it over to the side where the electrode is in the motor and hit the electrode with a hammer (or use an old bolt as a punch tool to get in there)
It should only take about two hits for the ceramic inside to fall out of the metal shell.  BOOM!  So much less headache.
The inside of the plugs I had laying around had an 8.55 mm ID.
The shaft on the dial caliper had a 9.45 mm OD, so you have a couple options to open that up 0.45mm each way.  You can either use a Dremel and open it up, but that gets sloppy and I am too much of a perfectionist to do that.  Plus it would take a while. 
So grab your 3/8" (9.525mm) drill bit and drill press (to keep that puppy nice and straight) and go to town!  Make sure to use your cutting oil and it shouldn't take too long at all.
This is the point where I stopped last night.  I was pretty happy with the threading on there and thought I was done.  Nope.  The fins on any air cooled head would get in the way, so we have to go deeper.  It turns out the threading of the spark plug fits fairly well inside the housing of another plug (Based on measurements)  So bore out another plug.  The longer the threading the better because you an always shorten up the non-threaded part of the plug... just grind or cut it off.
Insert the plug into the other and then connect them.  I wish I had a welder, but instead I rely on JB Weld when applicable and can pass for my perfectionism.  It did the trick nicely.  Maybe I should invest in a welder or at least keep an eye open for one on Craigslist. Anyway, you want to make sure that it is a very straight fit, so find something that is 3/8" to slide them on... in my case, an old junk 3/8 drill bit.  Let it dry up and remove the jig or old drill bit.
Now you have about 12 mm of room to compress and that is WAY more than you should have your bike timed.  The plugs should be a fairly snug fit on the shaft.  Some people permanently attach the spark plugs to the dial caliper, but, I and not a huge fan of that.
Leaving the dial indicator and plugs as two separate parts you can screw the plugs into the head and then insert the dial indicator.  If you are still leery, then wait... See how there is a gap between the two plugs?  That is the perfect place to loop a rubber band through itself and it will sit securely in the gap.  Now take the loose end of the rubber band and stretch it up onto the dial indicator. BOOM!  You now saved yourself over $75 bucks on a metric dial indicator... and you had fun making one!
On to the weather.... Spent Monday doing a story on a proposed Bill to prohibit traffic violation cameras in Ohio.  Scattered showers most of the day, but was able to catch a double rainbow heading home from work.  The second rainbow is fairly faint in the photo, but it is so hard to capture the vibrancy of rainbows on camera.  Ever noticed that?

Still looking at a weak disturbance tonight into tomorrow with a light accumulation of snow possible for much of Ohio.  Should be less than an inch for most of us.  Wednesday we dry out and another weak system Thursday that could bring a rain/snow mix.  Friday a little rain is possible with yet another weak system.  Our temperatures warm up a little heading into the end of the week and the next system after that will roll in sometime late Sunday into early Monday... which, again, looks pretty weak with light rain.  You could take all of the precip from the upcoming systems and it wouldn't amount to the rain we say Monday.  I would just keep the umbrella handy.  I will be heading to West Virginia in the morning for work the next few days.  I will probably be blogging from the road, so be sure to check back in for all the fun.  Have a good one!

Andrew Buck Michael

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