I really need some help (and sorry for the wordy post)! I've been slowly getting my recently purchased 74 Ironhead XLCH up and running, and have basically found the answers to every question that I have had in this forum (THANK YOU!). However, after a recent longer ride I noticed it not running very well. I had ran it pretty hard and after reading the Bike started backfiring then took a dump thread, decided to look at the springs on the counterweights behind the points. They looked fine, although I did replace them while I had it open. One thing I noticed was a bit of oil in there which I figured was somehow related to the fact that I was getting a lot of exhaust coming out of the crankcase breather and did not have a breather tube installed (now installed).

That gets me to what I think are the signs of the real problem. When it started running so bad (after the above ride), I immediately noticed a change in the sound of the exhaust, and that there was a lot more exhaust/oily discharge coming out of the crankcase breather outlet. After getting the circuit breaker re-assembled I re-checked the gap and set the timing in the center position. I kicked it over and it fired right up first kick as it always does (thanx to the advice on this forum!), however it was running rough, which I attributed to the timing being off. I don't have a timing gun (or that skill yet), but have a great indy mech. that will time it once I get it down there. I took it out for a short ride tweaking the timing between laps around the hood, and noticed that there was a serious lag getting it up to speed. Then it started running real rough, like only one cylinder was firing, it got real hot, and died right as I got home.

The next day it started first kick as usual, but ran even rougher than the first day, and would barely idle even after warm. What I noticed was that only the rear jug was getting hot (very hot in just a few minutes of idling), and there was twice the exhaust pressure coming out of that (rear jug) exhaust, compared to the front! I've checked spark, have new wires and coil, checked and re-adjusted push rods, and checked for intake leaks. Nothing seems to help. Am I looking at some possible valve damage? Any advice is apprciated!

 

is there any oil coming out of the pipes? sounds like its time for a compression check, if the rear is alot lower than the front, put a little oil in the cyl. and see if it comes up , the two cyl. should be within 10% of each other, really go back and check the intakes again for leaks,if you got the valves set they are prob. not sank into the seats to far

 

thanx. 135 in the rear and ZERO in the front. I guess there is nothing to do but take off the head and see how bad it is...

 

that aint good, ill bet you will find a hole in the piston if so you are in for alot of work!

 

Before taking off the head:

The compression test must be done on a fully warmed up engine; the choke plate must be open [**** pushed in]; and the throttle must be fully open [grip twisted, preferably locked in place with the throttle lock]. Otherwise the test is not meaningful.

If a cylinder is low add 1/2 oz of any oil to the cylinder thru the spark plug hole and re-do the test.

 

uh, make sure your valve pushrods are set properly before you do anything too major. You should be able to turn them all with your fingers when the valve is at it's lowest position.

 

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.

 

Thanx everyone! I went ahead and pulled off the top of the head and found a nice hole on the outer edge of the piston. I posted a picture in my albmum https://www.hdforums.com/forum/album...747&pictureids[]=78173

It does not look like the Valves were damaged. How diificult is this going to be for me to work on myself? I don't have much experience working on motorcylcle engines but I have worked on car engines and was a Machinist Mate (mechanic) in the Navy working on conventional Aircraft Carrier powerplants. I'm tempted to try it just for the learning experience (and I'm low on cash).

Should I have a professional clean out the lower end to find the missing pieces? Is there any sense in just replacing the one piston (assuming the cylinder is not scarred?). It does have an 020 stamp on it. So I believe I can still have them bored out to 030 if needed.

Lastly, can I remove the lower half of the head to check for scarring without removing the other head? Is this recomended? Any suggestions before I do? THNX!

 

i cant get to your pic but i would say that you are going to have to get into the bottom end to find all the pieces, was the piston broke? or have a hole burned into it?need to get the cylinder off and see if the rings and ring landings are all still there, when you start lifting the cylinder up as soon as it comes up a little cover the hole under the piston with a rag to keep pcs from falling into the bottom end,i have seen pistons get broke from to far advanced timing and holes burned in them from lean condition, like from intake leaks etc.

 

It looks like the piston broke, the piece was on top of the piston, and then some of it melted to the top of the cylinder sleeve. I read in the manual to have the piston at bottom stroke (after raising enough to stuff a rag under it), when removing the cylinder. Any other advice before I pull it off? Once it is off how much scarring is too much to hone out? I've got the notes from the "77 Ironhead Rebuild" forum string (good info!). I'm sure I'll need some more advice once I start looking at the lower end...