656 ignition

Been using my neighbor's 656 gas utility for my cattle shed remodeling. It starts hard in cold weather and the neighbor said it's been that way awhile. Cranks fine, but no start-until I let up on the key and then it pops right off. This tells me there's low voltage to the coil while cranking. I have almost no experience with the 656 ignition arrangement so I have to ask some questions.

I pulled the side hood and took a look at the ignition. For starters, someone has put an electronic ignition in it but I'm not questioning that. The coil is 12v, as is stamped on the side of the coil and it appears to be a standard coil, not a flame thrower. There is also a ceramic resistor. The primary ignition wire comes out of the harness and to the resistor and then from the resistor to the coil. There is no shunt wire to shunt around the ceramic resistor for starting and I don't see one coming out of the harness. The harness appears to be origional factory and in good shape. I have the feeling there should be a shunt wire to the coil for starting but if there isn't one in the harness evedently there never was one. Should the external resistor be there with a 12V coil? Lots of questions.

As a side note, this tractor has a Westendorf TA 26 loader and it's about the handiest little loader tractor I've ever used. Wouldn't mind owning it. Jim

OK, I'll simplify the question. Does a 656 gas have a 12 volt coil with no external resistor or a 6V coil with an external resistor? I think I have it narrowed down to that. I spent about an hour pooring over the internet trying to find out and I still don't know the answer. I tried the CIH parts website but it looks like someone needs to hold my hand to guide me through it LOL. Jim

All the 656s I was ever around were factory 12 volt. I don't know about the coil for sure but by pass the resistor and see if it starts better. They are cold natured but that's Carb related. Generally they start well but won't lug until warmed up a little. Generally have to choke them on first start even in the summertime.

I'll try that tomorrow morning. My sneaking suspicion is the coil has an internal resistor and someone else add an external one to it. If the external resistor was there from the factory I'd think there would be a bypass wire. Right or wrong? Jim

A bypass can be made with a 5 amp mrated diode, and 12ga. wire. Put a connector on the starter side of the starter relay (assumes it has no S terminal on it) This will provide Bat volts when the starter is energized. Put the diode in series with this wire, and from there to the coil side of the ballast resistor. Make sure the diode is placed so the flow of electricity can only go to the coil, not from it. (I do not know which ground it has, so when setting this up, brush the connector that will go on the starter side of the solenoid on the bat connection. If it sparks like it is turning on the ignition it is correct. if it does nothing it is backwards. The diode prevents the ignition system from trying to run the starter motor! Very important. Jim

I didn't think about the diode. The CIH dealer sells a diode with spade connectors but they call it a rectifier. Maybe I'm imagining things, but I get the feeling this tractor is lacking for a strong spark. The owner said it has been fouling plugs so he put in plugs that were one step hotter. The book calls for a champion D16Y and he put in D18Y's. The D18's fouled for me so I put in straight D21's. The 21's don't quite have the reach but they work. This tractor is cold blooded and I need to have my hand by the choke for the first fifteen minute or so after startup, so it's not running rich. It does not burn oil and the compression is up to snuff. When I changed plugs, # 1&2 were very dry sooty. 3&4 were white and clean and 5&6 were just moderately sooty. I don't know if the plug wires are carbon or copper, but they look newish. After I put the D21's in it purred like a kitten at idle and no load but there just seemed to be a not-so-strong sound to the exhaust when loaded. It seems to have power but there is just that certain sound in the exhaust tone that perks up my curiosity.

My first intuition is still telling me the external resister is resisting a coil that has built in resistance. I didn't take the time yet to do voltage readings at the coil. I just wanted to get this thing running well enough to do dirt work this afternoon before we freeze up for the season, and I did get it done. Jim

Unless it is misfiring, the spark strength will not make difference in sound. The timing will make a big difference in sound.
A diode is a rectifier. A rectifier is not necessarily a diode. Jim