early 90's 440 jag help

[kerryd15]

I have a 440 jag 2 cylinder with single carberator. it starts and idles well. at roughly half throttle it seems one side starts to miss and lose powers. I have installed new plugs a couple times and the right cylinder is black and wet. the left is brown. I have pumped the gas out, put in new. cleaned the carberator a couple times. Cut a half inch off both ends of the plug wires and screwed them back on. checked the fuel pump- gas comes out when its pulled over. checked over the wire harness for rubbed spots. Thinking coil maybe? Stator?

After it misses and let off the throttle sometimes it will backfire a little or cough like it got spark again.

I need to check compression. I did last year at end of season and it was good. put maybe 2 miles on it this year. Any ideas thanks.

[MN Mike]

I've got a repair manual from the late '90s, if you want, I can check and see if there are any ohm readings for your coil's. Sometimes they won't act up until they warm up.

Couple other things to check, I can't remember for sure which cylinder it is but there should be a surge line running from your engine block to your fuel pump, check it and make sure you're not pumping gas direct to the cylinder, sometimes those fuel pump diaphragms would break causing gas to go right to 1 cylinder.

Another item I would check is your kill switch on the handle bars, there's actually 2 switches there, the normal kill switch and also one on the pivot of your throttle. If you pull back the padding, you should be able to locate the plug that disconnects those switches, it should be one plug for both switches.

Mike

[kerryd15]

thank you, ohm reading would be great. I will check the switch and hose.

[kerryd15]

correct me if I'm wrong in my thinking. I should be able to switch the plug wires and see if it changes cylinders. This is a single coil twin cylinder, firing every revolution. that would tell me if its in the coil or plug wire. If the stator was an issue it would cut out on both cylinders, correct? not sure on testing the CDI box.

[MN Mike]

Sorry for the delay, I haven't had a chance to grab my book yet, I'll try today if I can.

I believe both coils fire at the same time, so you should be able to change plug wires to cylinder and test that too.

Mike

[kerryd15]

Checked the compression and both were real close to 130. I found some ohm readings on the internet. They say the plug caps should be 5000 ohm. one of mine is 5400 and the other is 3950 to 4100 depending if its warm or not. Could this cause the problem? Also the coil should test at .3 ohm and I am getting .4

[leech~~]

Checked the compression and both were real close to 130. I found some ohm readings on the internet. They say the plug caps should be 5000 ohm. one of mine is 5400 and the other is 3950 to 4100 depending if its warm or not. Could this cause the problem? Also the coil should test at .3 ohm and I am getting .4

On that old of a sled I would be happy with a even compression at about 110 on each side.

[kerryd15]

for testing the compression I let it idle to warm up. shut it off, pulled the plugs, held throttle wide open and pulled the rope 4 times. is this wrong? Its what the cat dealer told me to do. I borrowed the tester from a mechanic.

[kerryd15]

New plug ends installed. In the dark I noticed one side has less spark like a miss and not as bright. switched plugs and its the same. I can pull the plug wire- one at a time_ at idle and Idle drops but doesn't die on either side. I can get it just to engage the clutch to cross the yard nothing higher.

If the stator was an issue it should affect both sides correct? Not sure how the CDI box affects things. Any input welcome.

[fishingstar]

You need to test the stator cats are known for the coils going bad. You can replace each coil individually.

here are some info for testing the stator.

Piece Color 1 Color 2 ohms

SOURCE 1 BLACK&RED to BLACK 180

SOURCE 2 WHITE&RED to BLACK&RED 17

ALTERNATOR YELLOW to YELLOW 0.4

NB: BEA = Between each other

NB: Tests done at 20°C (68°) with a +/- 20 % margin of error

NB: Notice that a coil can test ok with a OHM'S Test and not produce voltage. This is not a 100 % accurate test !

Alternator output voltage Yellow to Yellow

If your peak voltages are more than 30% out of range or more than 20-25% different from each other

(yellow to yellow to yellow) then the unit is probably bad

Dan