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Old 11-30-2005, 08:59 AM   #1 (permalink)
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Question Cuyuna 440 Engine Help Needed

Hi all,

Iím trying to get my sonsí sled running and I have a question that I'm having trouble getting a definitive answer to. He has a1980 Scorpion whip 440 where the PTO side (#1) cylinder that does not appear to be firing correctly. The points and condensers have been changed and so has the PTO side coil. The timing has also been reset to .110 BTDC when fully advanced.

From the looks of things the PTO side seems to be firing intermittently (you can really hear it when the exhaust is pulled off). That cylinder is also not capable of keeping the engine running at an idle, when the mag side (#2) cylinder spark plug wire is pulled off.

Does anybody know if this engine should be able to stay running when only the PTO side plug wire is attached?

FYI Ė I have another 440 that will not stay running on only the PTO side cylinder, but unlike my sonsí it runs great and never fouls a plug.

Does anybody have any idea as to what else might be causing the PTO side firing problem? I should also mention that the compression and ignition settings all appear to be within tolerance and the PTO side piston, rings and crank seal have all been replaced. Iím also getting fuel to that cylinder because the plug is constantly getting wet fouled. I also installed a full carb kit in late last year.

One more question. Even though itís new, does anybody know how to test the coil to see if it is really good. Also, is there a way to test the wires that come from the points to the coil without pulling off the flywheel and disconnecting them?

Any ideas will be greatly appreciated.

Thanks

Scorp80
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Last edited by Scorp80; 11-30-2005 at 09:10 AM.
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Old 11-30-2005, 09:11 AM   #2 (permalink)
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if the plug is wet fouled have you tryed going up 1 heat range with the plugs? Have you checked the starter side for problems, with the older f/c engines, since that cyl ran cooler, if they had an air leak (crank seal) it was not noticable untill the cyl burned down. If that is the case, the pto sice will actualy pull more fuel and foul out.


for the intermitant fireing problem, did you replace the plug wire with a solid center or a resister wire. they don't like the resister wire. reduces the voltage to the plug and since the ignition voltage is lower to begin with compared to a cdi fired motor, it will act like it's not getting enough juice.

If the coil either works or not, there is no middle ground here.
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Old 11-30-2005, 12:44 PM   #3 (permalink)
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I did repalce the plug wire and cap with the NGK parts that matched the original Bosch braided wire and plug cap.

The mag side cylinder seems to be fine and does not appear to be running hot.

Man this thing is driving me crazy.

Scorp80
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Old 11-30-2005, 01:54 PM   #4 (permalink)
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remove both plugs from the engine....pop em in the spark plug boots on the wires........let the electrode end lay on the cyclinder head( making sure they make contact with the head)....turn key on.. and pull the start rope.......and see if you can see a blue spark........then swap coils to test to see which one is bad.......the coils can also be tested with an ohm meter......it should have full continuity between the(wire that goes to the points/condenser) and its chasis ground.......at the X10 ohms setting(all really) and it should have less continuityhalf sweep (on the X10,000 scale) when checked between the (wire that goes to points/condenser) and the spark plug wire(to plug) termanal......if any of these are "open" its bad......and check the plug wires they go bad too......remove them from the coil and test from there....and double check your solder conections with the ohm meter(on the condenser...if aplicable...my moto-ski...you had to solder the wires to the condenser)
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Old 11-30-2005, 02:00 PM   #5 (permalink)
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I tested my wires that came from the points(the ones that plug in to the coil) by setting my volt meter to d.c. at a 2.5 scale.....and with ign. on....pulled the rope(one probe grounded and the other hooked to the wire you want to test).....they both should sway the meter the same....and the meter swayed about half a sweep in either direction.......as the mag turned.....(the mag is really a.c. but that will overload the meter.....I found that on the d.c. setting it just gently sways when its getting juice from the points/condenser......)hence....you know the coils should be getting some juice....
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Old 12-05-2005, 03:32 PM   #6 (permalink)
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sounds like you have a PTO side seal going out.
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Old 03-24-2009, 09:19 PM   #7 (permalink)
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hey i have a cuyuna 440 i bout out of a sled and it has no spark..its out of a 79 whip 440 ..maybe because the key is not turned on but i only have the wires coming out of magneto..what wires do what ive been trying to figure that out..thanks
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Old 02-05-2011, 08:42 PM   #8 (permalink)
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Join the two black wires for "run".
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Old 02-06-2011, 05:57 PM   #9 (permalink)
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Hello scorp80 does the ignition [primary] on the stator plate inside of the magneto have two primary igniton coils one for each set of points and condensors.Is there a possibility that you have a pweak primary coil for the #1pto side.Iwould test the ristance reading of coils[primary] to see if they are close in readings obtained.
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Old 02-06-2011, 06:06 PM   #10 (permalink)
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Yes, that motor has a primary coil for each cylinder. It's possible that one for the pto side is bad.
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