So i have a 75 ironhead that fires on one cylinder, while i was switching out the wires i noticed the cylinder would fire when the wire was put halfway on and then would stop firing when i attached the wire all of the way. i was wondering if any one has run into this issue...

 

I had the same exact problem on the first bike I ever owned, a 1975 Kawasaki KZ400D. With that bike, if I let it warm up for a few minutes with the plug wire halfway on, I could eventually put it on all the way and it would keep firing. I never dug into trying to figure out what the cause of the problem was, but I know it wasn't the spark plugs or the plug wire.

A quick Google search found the same issue on another motorcycle forum. Here's a post from there. I have no idea how much of this is correct. The front cylinder was the one with the problem.

Back in tech school the instructor explained it like a horse that jumps hurdles. It may have problems jumping the low hurdle for whatever reason, but if you put a big hurdle in front of the short one, as soon as the horse clears the tall hurdle it is already over the lower one behind it.

So, the problem is with the cylinder. Maybe low compression, or plug gapped wrong, etc. The extra gap makes the coil produce more voltage to jump it, and that is enough to make it fire the plug.

Check compression, check your plug gap, replace the plug again, read the rear plug and see if the mixture is near right. How's your ground to the engine? If it's got resistance then it will need more voltage to jump the gap.

This is telling you that you have a problem, so it's just a matter of locating it.

 

thank you for response a little back story, the bike was running fine, then one day i was getting off work and my key chain arced with the positive terminal and before i knew it one of my grounds was smoking so i turned of the ignition off. i then proceeded to kick start it and she fired up then turned off. i got her going with the electric start and took off knowing one cylinder was running fine with the second coming off and on as i gave her more throttle when i got home a wire burned from the ground terminal to a solenoid looking thing behind the battery. im going to replace the grounds, and the points and condenser is there anything you suggest i also take a look at?

 

What positive terminal did the key arc with? of the battery? of whatever? If you are uncertain what it is called please post a picture of it.

A picture of the solenoid looking thing behind the battery would also be helpful.

 

Every time my ironhead starts up with only one cylinder firing, the pushrods need to be adjusted. It's always the rear exhaust too.

Adjust your pushrods after letting the bike sit cold overnight.

carl

 

Ironhead Push Rod Adjustment

Do this procedure with the engine stone cold. I usually do steps 1 through 5 in the evening, then the rest first thing in the morning.

1. Remove the spark plugs. Remove A/C to make room to work.

2. Using a flat blade screwdriver pry the spring keeper off of each push rod; the bottom of the keeper pops out first, then the top. Alternately, use a 3/4" open end wrench to push down on the top of the spring retainer, then pry out the spring keeper with the screwdriver.

3. The lower push rod covers may be stuck tight against the bottom o-rings, but they can be loosened by pinching between thumb and finger [or carefully using a shop rag and a pliers] and twisting or rotating. Lift these up and secure each with a tall-S-shaped piece of 12 or 14 gauge household wire [not cable] [or a long piece of Plumbers solder such as 95/5 hooked over the rocker cover and under the push rod cover.

4. Jack up back end of the bike so that rear wheel is off the ground, shift to 2nd gear, rotate wheel until it clicks, repeat until you get to 4th gear. Now by rotating the rear wheel you are rotating the engine. Almost impossible with the plugs in; very difficult in lower gears.

5. To adjust a particular push rod, its valve must be fully closed [the valve spring is relaxed]. Valve position for a particular cylinder is determined by observing the corresponding push rod of the other cylinder. For example, when the rear cylinder intake valve tappet is raised [valve fully open, spring compressed], the front cylinder intake valve is fully closed, and the front intake push rod can be adjusted.

6. Check [and adjust if necessary] the push rods:

[a] use the rear wheel rotate the engine so that the rear cylinder exhaust push rod tappet is fully raised. The front cylinder push rod is adjusted correctly if it has no vertical or horizontal play, and you can just rotate the push rod between thumb and forefinger with no trace of binding or dragging.

[b]to adjust if needed: hold the adjusting screw in place with a wrench; with another wrench loosen the split locknut. Then turn the adjusting screw using fingers only until the pushrod's ball end is seated in the tappet with a "slight amount of play". Then tighten further as follows:

Option 1: Adjust on the tighter end of the range: There should be no vertical or horizontal play, and you should be just able to rotate the push rod between thumb and forefinger with no trace of binding or dragging.

Option 2: Adjust on the looser end of the range: Set the adjusting screw to finger tight so that you cannot turn the push rod between forefinger and thumb. Undo it a tiny bit so that it is just barely loose. Then loosen it 1 "side" for an exhaust or 1/2 "side" for an intake. "Side" refers to one side of the 6-sided adjusting nut.

EDIT: Experience here is that Option 2 is the better and most likely the correct choice.

[c] hold the adjusting screw in place with the one wrench; with fingers then the other wrench tighten the locknut.

[d] recheck the adjustment; it is common for the adjustment to go out as you do step [c], in which case and [c] must be redone.

[e] repeat for the other push rods.

[f] rotate the engine checking each pushrod.

7. Use a flat blade screwdriver to push the upper push rod covers up, and seat them into the upper o-ring or cork washer that is in the rocker cover.

8. Install the spring keepers, top end first, by prying them in under the bottom with a flat blade screwdriver.

 

this is bottom right of the negative side of battery, this wire smoked and burned up, it is one of two wires that run to the battery, the other runs to the engine block.

 

pic does not show up here ???

 

thank you for all of your replies, i checked compression and it passed, replaced the burnt wires and spark plugs and she fired up, took her on a long ride then the clutch cable broke, Stuff happens! anyways thanks again

 

All cables need to be cleaned and lube'd each year. I do it as part of my Winter Project...

https://1drv.ms/w/s!Aqi8K9NoC4jihVozOvct2xipdtjV

Also, here is my regular maintenance chart...

https://1drv.ms/w/s!Aqi8K9NoC4jihDn2rIIWybMutyW-