Thanks to all for your input, but I still have a problem. A little background first. The bike ran strong and quick when it was parked.....about 6 years ago! Now, it starts fine and idles fine (when cold), but after a minute on the road, only the front cyl fires. After it warms up and idles, the rear cyl only fires intermittently and makes a funny noise between pops and when I take the rear plug out, it's coated in carbon fluff. Just put in new points, plugs, wires, coil and adjusted the pushrods (which seemed fine). Stuck valve or a malfunctioning mechanical advance maybe? What are the symptoms and do I need to tear the top end off to fix it? Once again, thanks for your patience and input.

 

Pushrod adjustment is a regular maintenance item and the procecdure is in the Factory service manual which you should get a copy of if you don't already have one. You don't have to tear the top end off to make the adjustment.

As to your problem, it might be more than simple pushrod adjustment. That carbon fiber fluff and funny sounds are a little scary. Before you run that thing again, take out the rear plug and have a look down in the cylinder. Might not be a bad idea to pull the head too.


Carl

 

When a valve sticks it always sticks in the open position with the valve spring compressed, so there is no pressure in that valve train {cam, lifter, pushrod, rocker}. You hear a loud clattering noise as the pushrod bounces up and down with the loose rocker.

In my limited experience if i then shut off the engine, pull off the road and re-start, the valve frees up and i am good to go again - until the next time. Usually means that the valve guide needs to be honed.

Anyway, your problem does not sound like a stuck valve.

When a problem is restricted to one cylinder it is usually one of - intake leak, exhaust leak, bad plug, bad wire, bad coil, pushrod adjust. Here are some notes. If you re-do the p-rod adjust follow the part called Option 2.

Intake And Exhaust Leaks Tests

You cannot get a good tuneup if there are intake leaks or exhaust leaks.

1. Check for Intake Leaks

With the engine idling spray propane gas or WD-40 around the carb/intake/cylinder head joints. Propane is best because it leaves no mess, and is most easily sucked in thru leaks. WD-40 is said to work well because it has very fine spray droplets. Be careful to not allow any of either to get sucked in thru the A/C as this will invalidate the results.

Any change in engine RPM is a leak which must be fixed.

EDIT: Experience is that this procedure will identify larger intake leaks, but it may miss very small leaks that also must be fixed. And that propane is definetly the better choice.

EDIT: You have to do a lot of spraying to detect a small leak. Propane will be really clean. Anything else like WD-40, carb cleaner, etc will make a huge mess.

2. Check for Exhaust Leaks

Pour about 1/2 ounce of oil into each cylinder thru the spark plug holes. Run the engine at idle. You will get lots of smoke for about 5 minutes.

All smoke should come from the ends of the exhaust pipes/mufflers. Any other is a leak which must be fixed.

Ironhead Push Rod Adjustment

Do this procedure with the engine stone cold. I usually do it 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 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 [b] and [c] must be redone.

[e] repeat for the other push rods.

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.

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

 

Mick,
I gotta say it......"YOU DA MAN"! Thanks buddy!

 

Nicely done brother very nicely done , I couldn't type that to save my life LOL .

 

I typed it in some years ago. Now i just Cut/Paste it into posts as needed.

 

Only thing I'd change in that whole thing is the propane to check for intact leaks , that's risky for the average garage monkey I've seen a few carb's blown off in somebodies face trying that and one caught fire no joke . I use brake clean , no mess fast dry and it drops the motor off instead of the speed up thing takes any chance of stupid out of it , even the typical ******** can't screw that one up . I always err on the side of caution with tech tips till I get a feel for the skill level involved , you wouldn't believe some of the knuckle draggers and the rigged stuff that come through my garage on occasion .

 

heck i have had more fires with brake clean, about lost my garage once to a can of the stuff, starting fluid, wd 40, there are a few things to use, brake clean is way to explosive

 

Not in Ca. it isn't ............

 

Dear TwizTed Biker,
I would make a comment about your obscene, vulger little video clip on your posts, but I can't stop laughing my *** off! Now thats what I call doggystyle!