3 replies to this topic

[miller 666]

Hi all
I have no spark on my 850 mini engine in my buggy and have found no spark at the points so im going to buy a service kit from ebay. I know its deffinatley an 850 engine but not sure about the dizzy. Just confirming before i buy it, that it is the right kit?
Cheers
Oscar.

[dklawson]

If you look carefully around the casting that is the main dizzy housing you should find a 3 or four digit number cast in the body. Look for something like 25D4 or 45D4. That will tell you which series distributor you have. You may find a second set of numbers stamped in the body. They will be of the form XXYY where XX is the week and YY the year of manufacture. You should also find a 5 digit number stamped on the housing. It will likely begin with "4". That will identify the specifics about the distributor (its initial application, curves, etc).

Does your 850 run? You don't always see the spark as the points open. You can also take a set of points and dress them by wrapping a piece of 240 grit wet/dry paper around a piece of cardboard and drawing it through like a file until the surfaces are smooth and flat. You can do this several times before they are truly worn out.

[miller 666]

It doesn't run because it has been stood for about 6 months and i can't see a spark at the plugs and have traced it to the points.
I will try and get the numbers of the dizzy but it has been painted so there probs gonna be wrong.

Have found the numbers=
45D4
41417
And an arrow with 0379 in front of it

Edited by miller 666, 17 September 2007 - 09:25 PM.

[dklawson]

The numbers you found completely describe the distributor. It's a 45D4 built the 3rd week of 1979, advance curve 41417.

OK, so you've traced the problem to the points. The points are nothing more than a switch. Download my PDF on ignition systems and read it over:
http://home.mindspri...tsIgnitions.pdf
Also visit:
http://auto.howstuff...tion-system.htm
and be sure to follow the ignition related links at the bottom of the page.

Read over the PDF and its troubleshooting steps. As a quick test before even reading that, disconnect the white/black wire running between the coil and the distributor. Disconnect it at the dizzy end. At the dizzy cap end, remove the high-tension wire between the coil and the dizzy. Hold this wire about 1/8" off the engine block with the ignition "ON" (don't touch the end of the wire and hold it with a dry rag). With the ignition switch "ON", tap the free end of the white/black wire against engine ground. You should see a spark between the high-tension wire and the engine block. If you don't see a spark, the problem is NOT with the points or anything in the dizzy.

If you've got spark, remove the dizzy cap and look at the points. Turn the engine until the points are open. With the ignition switch "ON" tap the white/black wire to its lug on the distributor. Do you get a spark between the high-tension wire and engine block? If you do, the problem isn't in the points, either the condenser is shorted or the dizzy internal wiring is shorted. With the points open you should NOT have a path to ground and therefore you should NOT have a spark.

If with the points open you do NOT have a spark (which is correct) push the white/black wire back on its dizzy lug. With the ignition "ON" take a screwdriver and in a tapping motion use its tip to bridge the gap between the points. Do you have a spark now? If yes, the points are working correctly. If not, you have perhaps got a problem with the wire that is supposed to provide a ground connection between the breaker plate and the dizzy housing.

Again, the points are just a switch. If you dress them flat and set their gap properly, they'll work... they'll work well enough to give you a spark anyway. If you have no spark at the points rule out everything that passes current through the points. Again... the PDF will help and the web site above is great for giving a general understanding of the ignition system.