Wisconsin AP4, 4 cyl. air cooled, 31hsp. Engine

Denny R.

New User
I have this air cooled engine which needs service- won't start. Of course I did not follow the old rule: If it ain't broke don't fix it! Operates a cordwood saw, cut up about 1/2 cord then blew all the dust, dirt, grease, and sawdust out of it, changed the oil, cleaned the oil type air cleaner and sprayed the carb. exterior and linkages with gumout. Well now it won't start. Seems to be getting gas. Can't get a plug out- too narrow for my plug socket to fit into. I am looking to get my hands on any manuals for this engine. A search of antique engine website as well as Wisconsin one came up with model AP4 but said engine info N/A. Any help finding manuals wood be awesome! Love this site!

Denny R. :cry:
 
Do you have spark. Can check without removing plugs. Probably has a magneto? Is the ground wire grounded causing no spark, no start?
 
Does it have that push button by the magneto to ground it out to stop it? Did you blow something in behind it to ground it out?

Paul
 
Check the spark at each plug wire bet you have lost if due to something shorting or the mag which is most likely has. All it takes to check spark is an old good plug and then you pull a plug off one at a time and hold to plug on the block someplace and spin it over. Have a friend who owns a Bobcat skid steer with that engine in it and found his ignition switch had gone bad and was shorted out so it had no start till I unhook that switch
 
Make sure you don't have the plug wires crossed. I think the firing order is 1-3-4-2. No1 plug is on the left side near the flywheel. Hal
a210310.jpg
 
Denny,Are you sure that it is not a Wisconsin VP4, 4 cyl. air cooled,If it is a VP4 I have a manual PDF that I could email it to you.My email is open.
 
Den N Ms,

i have been picking up those v-4 Wisconsins at auctions when i can. I checked for your email, modern and classic and it didnt show up. i think mine if, if you could email that manual that would be great!

Thanks!
 
El Toro, are you not concerned about painting the cylinders and heads as far as overheating the engine? All the Wisconsin and other air cooled engines I have been around, none have paint on those components! Roger
 

Gas but no spark my small engine mechanic is pretty familiar with these engines but it is difficult to find parts. We ordered new points and condenser but need rotor and cap which is proving to be difficult. Any suggestions?

Thanks for contacting me Roger!
 

Just a ground wire that we leave disconnected then touch to the motor to cause it to kill the engine.
 
It is a AP4. I found a picture of the manual from a seller on eBay. The front of the manual says, "Manual, instructions and Parts book Model AM4 - AP4." The seller wants $10.00 but says temporarily out of stock.

It is a straight 4 cylinder not a v - type engine. Has a push button electric starter and a magneto. Think it needs a replacement rotor and cap. I checked the site at Wisconsin and it does not show the manual but the serial search showed it was built in Jan. Of 1943.
 
If you are patient, one of the best places to find parts for your Wisconsin motor is off of ebay, unfortunately.
 
Does the motor have a VIN plate on it?
I have found a place in Wichita, KS C & B Equipment 316.262.5156 who are very helpful on these engines. I have a single cylinder on a Log splitter.
 

Thanks, I called that Company in In Kansas and yes they had a manual for the Wisconsin AM4-AP4 motors. The rep. Said in 22 years he's has been there no one has ever called about the AP4. I ordered Magnito parts from a place in MA. Hoping to have it running again soon. Can't figure how to get the plugs out? The space they are in is so tight a deep socket won't fit in and the plugs are a larger nut size than the largest auto ones I have seen. Bought the manual and hope it gives some direction to plug removal.

Thanks again very happy to be getting that manual!!! :)
 
(quoted from post at 19:44:59 01/09/16)
Thanks, I called that Company in In Kansas and yes they had a manual for the Wisconsin AM4-AP4 motors. The rep. Said in 22 years he's has been there no one has ever called about the AP4. I ordered Magnito parts from a place in MA. Hoping to have it running again soon. Can't figure how to get the plugs out? The space they are in is so tight a deep socket won't fit in and the plugs are a larger nut size than the largest auto ones I have seen. Bought the manual and hope it gives some direction to plug removal.

Thanks again very happy to be getting that manual!!! :)

Just google "spark plug wernch". There are some made out of sheet metal.

Dusty
 
Well now I have the manual which says upon delivery of the Ap4 included was a SPECIAL spark plug wrench, which not being the original buyer I did not get the wrench. If I can get the old plugs out I may want to replace them. Any idea where I can cross reference vintage Champion 84 plugs with 18mm thread to today's plugs? Not necessarily looking for vintage plugs just new ones that are equivalent. Wisconsin lists in the manual their part number for the special wrench as DF-45-A, (spark plug wrench). Again this baby was built in 1943?

Any ideas?
 
sent him an email last night in addition to this posting but he earlier told me in 22 years he had worked there no one had requested anything for the Wisconsin AM4 or the AP4. I figured it is a long shot but everything about this motor has been.
Thank you for the suggestion. I will let you know if it turns up anything. :)
 

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