Ouch, sorry, bit my tongue

 

When we perform XL valve jobs, we modify the lower collars and shorten the top of the guide to allow the use of a seal.
Scott

 

first and foremost, stem seals do not stop leakage, it controls it like small pumps.
i have nearly 200k mile on my 1974 ch and it never had a stem seal period.
however, like cam spacing shims, its an oil thread, never ending.
if in doubt, do as the factory did.

 

As promised I'm back to report.

Once warmer weather arrived (i.e., the garage was not reaching temps in the low-30's at night), I pulled the bike back out and started it up before changing anything. There was some smoke on startup, although not a dramatic amount like what was described above. I noticed the smoke (again, somewhat less than before) was related to how much the enrichener lever was pulled on the carb. Decided to shut the bike down without riding and do some troubleshooting.

I changed the oil from 20w-50 Amsoil to Valvoline conventional 50W as agreed upon above. I also completely drained the gas tank and fuel line and replaced with fresh gas. Started up the bike and went for a good ride without even looking for smoke. Just wanted to run the fresh gas and oil for a bit before going back to the drawing board. Parked as usual in the garage after and let it sit overnight. Next day came back and started the bike, no smoke. Hasn't smoked on startup since. I have since also used Seafoam's top engine cleaner treatment (spray can straight to the carb, not the fuel tank treatment) for the first time, and I now endorse that fully.

Ran the absolute **** out of the bike later that week and it purred as happy as it's ever been. No smoke starting it up the day after, either, or any day since then.

Takeaways:

• Most importantly: it was not the valve guides. Sitting in a cold garage overnight (~30şF) probably didn't help to prevent oil seepage past the valves, but now under normal temps/conditions the same guides are not allowing oil seepage. The valve guides are fine.
• Switching to 50W conventional oil probably did help. Again-- first time starting the bike was before the oil change, and the smoke issue seemed to be somewhat improved with temps alone. However, after the oil change I had no smoke at all, and... there does seem to be less (not none) oil on the pavement under the bike now.
• Might also be weather-related (still not quite spring here) but the enrichener does seem to be over-richening the fuel mixture and cause smoke from uncombusted fuel. This may have contributed to the original smoking problem but was not the single cause

For others who are weighing their options between conventional and synthetic fuel, this experience tells me there is some benefit to straight weight conventional oil for the older motors. I have an 82 ironhead that runs 20W-50 synthetic oil in it currently and have no plans on changing that, as it runs perfectly, does not leak any oil at all, and never smokes.

However, I would say for earlier engines (no idea what the cut-off year would be) the marginal benefits of synthetic for these purposes are not worth giving up the also modest but noticeable improvements with straight weight conventional oil. It's not a magical cure-all but I did notice some positive differences with the 50W in the '71.

 

I think the root of the problem I was having is likely described here. Again-- can't discount the improvements after changing to 50W conventional oil either.

 

Yep, 20W50 has NO place in an Ironhead XL.
Scott

 

very true mr. hillside
it is had to find straight weight oils, if i use them, i have to order from a jobber. find one that stock it if possible. i prefer the shell rotella 50, cheaper than a mc oil but still $$$.
now all of that said, the ole iron was very forgiving, i ran whatever i could get from 30 to 60 wt and multi-vis also. i have 200k near abouts and never an issue. i did over-kill the maintenance, cheap insurance. a couple of years ago, i did a frame restoration so bird in hand, i up'd the ponies with S&S wheels, y cams, compression boost 9>10. the stock crank had no notice-able wear and the jugs had a little taper so a .010 over bore cleaned it up for the new pistons. the machine was running strong and used no more oil that it did new, even here, the factory did not consider excessive oil consumption till is was 500 mile to a quart. i was getting 1000>1500 miles depending on how it got flogged.
multi-vis and syn is no killer if you use a GOOD oil.
a plus also was cast iron, very durable. the old police machines ran idle and low speeds sometimes for hours on end and held up well.

 

If that floats your boat and works for you it's all good but as an long time old gray hair mechanic who cut his teeth on cast iron don't push that belief to others. There's multiple reasons the old stuff used straight weight oils and I'm sorry 20-50 and syn while it will work is not the best choice for them.

Evo era and up bikes yes, cast iron no, even the oil pumps on the bikes have troubles pushing enough pressure with multi weights and syn when it gets hot and thins out, those oils aerate something terrible in the old bikes.

 

You ran approx 200,000 miles without a bore, or any re-building of the cylinder heads??
Tappet rollers stayed intact, cam cover bushings all were good, and all was well in the primary and gearbox?
If so, that sir, is truely one of the wonders of the modern world, and I tip my hat to whoever originally built that particular motorcycle engine.
Scott

 

It is burning oil. Keep checking the oil level. Keep riding.