Hey guys just a quick question. So i had my 73 sporty on the highway last week and didnt realize how fast i was actually going (need speedo cable and drive unit) friend following me said was doing about 90. After getting off the highway, one cylinder seemed to be running a bit louder from exhaust pipe. no knock in motor or anything like that. cylinder still seems like its running a bit louder, should i be concerned at all? anything i should be checking?

 

Also seems like it chokes out a little easier getting on the throttle...maybe carburetor issue?

 

I would go thru the pushrod adjustment. If one of the exhaust pushrods is a little tight the valve will not be closing and you will hear it thru the exhaust. This procedure should be done from time to time anyway. The book suggests every 2000 miles.

"Choking out". whatever that means, could be the same cause. The engine will not run as well with pushrod[s] out of adjustment.

Ironhead Push Rod Adjustment

Do this procedure with the engine stone cold. I usually do steps 1 to 3 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 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.

 

It may be as simple as a loose exhaust pipe connection at the head. This is especially true if the exhaust was recently removed/replaced; you need to re-tighten after a heat cycle (like riding 90 for a time). You should be able to hear whether the noise is coming from end of pipe or at the head. Also, think about the exhaust gasket itself. If it crushed improperly during installation it will cause a leak and possibly some blockage. If the gaskets are old (or possibly reused), one may have failed; good time to replace both.

 

+1, except no exhaust gaskets on IronHeads

To seal up a loose exhaust ...

1. ensure that there are 4, not just 2, slits in the exhaust pipe at the cylinder head. Many aftermarket pipes have only 2. Use a hacksaw. Exhaust pipe metal is soft and cuts easily so do not go too far.

2. Use a pop can shim between the clamp and the pipe, especially if when fully tightened the clamp is fully closed.

3. Apply some Permatex Ultra Copper on the inside of the pipe before slipping it onto the head.

 

Perfect! Thanks.

 

How old and what condition are your pipes? Do they have mufflers or are they straight through? Possibly have a rusty baffle that blew a hole in it or blew out some packing?

 

Fixed it for ya Mick.