plug wire ohm measurement

[bobbymcgee]

My motor is a 1995 Johnson 70hp 2-stroke 3-cyc outboard.<br /><br />In my quest to find the reason for my rough idle I am preparing to ohm my plug wires.<br /><br />Should they ohm out at 0 ohms?<br /><br />By the way I have rebuilt the carbs & choke, new plugs, compression is at 125 to 130 across the board. At 1000 rpm idle is quite rooouuugghh, sometimes just dies. Starts great. Top end rpm seems fine.<br /><br />Could the VRO be involved in a rough idle?

 

[CATransplant]

Re: plug wire ohm measurement

If your outboard starts OK and runs OK at WOT, it's very, very unlikely that the plug wires are the source of your rough operation at 1000 RPM. Faulty plug wires tend to cause symptoms at high RPMs, more than at idle.<br /><br />A rough idle or rough running at 1000 RPM is more likely to be related to the low speed circuits in your carbs.

 

[bobbymcgee]

Re: plug wire ohm measurement

I disassembled each carb and cleaned quite well. Visually inspected all passages, channels and jets. Did see a thing in any of them.<br /><br />Note that the mixture adjustment settings seem to make little change in the way the motor idles; only at the extreme settings when the motor dies.<br /><br />I've checked the timing and seems to be at 4ATDC (-4).<br /><br />If a fuel line had an air leak could that result in a rough idle?<br /><br />What about the reed valves - could the motor run okay a higher RPMs but not idle well with a fault reed??

 

[CATransplant]

Re: plug wire ohm measurement

Did you soak the carbs and blow out all passages with compressed air? Your symptoms sound a great deal like a slightly cruddy carb. It doesn't take much on the idle circuits to bollix things up. You really can't see through all the passages.

 

[bobbymcgee]

Re: plug wire ohm measurement

I must say I didn't use compressed air. Okay I'll do it again with compressed air. Second time is always faster right. And I didn't soak 'em.<br /><br />What should I soak them overnight in?...I mostly have the spray carb cleaner.