Lost spark coil

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Gordon

Well-Known Member
HMEM Supporting Member
Joined
Jan 4, 2011
Messages
1,332
Reaction score
343
Folks refer to lost spark ignition when running two cylinder engines. They seem to be using motorcycle or snowmobile ignition coils. Specifically what should I be looking for when trying to find a coil? Some folks talk about using a very cheap coil but what I find doing a search is frequently pretty expensive. I am having a problem with the distributor on the engine that I am working on and I think that I am getting internal arcing.

I can find a two cylinder coil for a Toyota Camry which looks hopeful but I am not sure. I have successfully used the Ford Coil over plug coils on other engines.
 
Last edited:
Gordon---I went to a snowmobile repair shop and picked up the coil off a two cylinder skidoo for $10---used. It has two low tension wires and two high tension wires. Feed from battery goes in one low tension wire, other low tension wire goes to points. Two high tension wires run to the two sparkplugs. Cam operates off the crankshaft. So on every revolution, the points open, breaking the circuit. Hi tension spark goes out one wire to sparkplug, jumps the electrode gap making a spark, continues thru the crankcase and jumps from the electrode of the other sparkplug to the sparkplug barrel creating a second spark, then travels back to ground. Since the engine is a two cylinder, one piston will be up on compression and uses the spark to ignite the fuel. The other piston is up on exhaust stroke, so even though it gets a spark, the spark is "wasted" because there is no fuel to ignite.
 
I found a coil by Spectra on Amazon which looks like it will work well. I ordered it at noon and the price was $15. I went back later to see if they made a similar coil for single cylinder and the price about 4 hours later was $25.

1633537852110.png
 
Seems to be the way it is done on Amazon - 4 Years ago
I was making gears for a friend for his radial engine and although I make internal
gears as well found one on Amazon for $ 40 and bought it for him.
Then a third friend wanted the same gear and when I went back, it was $125 .!!!
Seems prices drop until a sale is made then it returns to original desired price ??
Rich
 
I have seen a number of listings like this one, you need to click the "See All Buying Options" button:

1633694068353.png


You then get a list (just one Seller in this case):

1633694141339.png



You will see different prices for identical, brand name items, even two or more prices for the same item that are Amazon Prime. I believe these are due to costs and stock on hand, etc. I try to dig around for the best price, usually buying only Prime Eligible for the return policy unless there is a big price difference AND I trust the item/Seller.

I haven't seen one in a while, but every so often when doing a search you would come across a grossly over-priced item (like an iPhone case for $999.98) - I don't know whether the Seller was just trying to make a quick fortune (hey, the listing says "case" not phone, so you gt what you ordered) or they needed to have new listings just to keep their account open. I believe that Amazon has improved their filters to eliminate these type of listings.
 
Back
Top