The sporty has been peacefully sitting in the garage during the cold months, but I decided to take her for a spin the other day in about 33º weather. Figured I'd baby the motor given the low temps, so I started her up, got a good idle going, and then went inside to suit up with boots, gloves, and jacket and the like to give it a longer engine warm-up time than usual (probably ended up being ~10 minutes).

I come back outside and am walking around the bike when suddenly I notice white smoke coming out of both pipes. I give the throttle a twist and more smoke. Quickly hop on the bike and head down the road and smoke clears. Continued riding -- everything feels and sounds good-- for about 15 minutes and pull over, stop the engine, look things over. Everything seems to check out. Kickstart the bike no issues/no smoke, went on a nice long ride, and return home happy. Bike is running great as usual.

Two days later, we had unseasonably warm weather (50ºF) so I decided to check out the bike again. Rolled her out, kicked her over, and this time I immediately saw a lot of smoke coming out of the exhaust. Cleared up right away when I got down the road, stopped at idle-- no smoke. Returned home and garaged the bike.

The bike has been stored with a full tank containing Stabil for a couple of months and I use a quality 20W-50 oil. She drips oil out the bottom cases like they all do and I check levels before every ride, though I have never had smoking issues on startup before with this bike, ever, even after sitting.

Next chance I get I plan to --> drain the tank and put fresh fuel in, treat carb intake with Seafoam Top Engine Cleaner spray, replace spark plugs, and potentially, do an oil change with 50W oil.

What do we think? Newly worn intake valve guides letting thin 20w-50 synthetic oil seep through, burning on startup? Too long idle resulted in piston wash? Simply water buildup/condensation/steam from the unusual temperature changes? Bad fuel? etc etc etc

Again, never had smoke from the exhaust on this one. Then significant "smoke" on startup twice in a row. Still runs great, but I want to address this. Thankful for any thoughts and advice.

 

Iron heads don't have valve seals so oil will leak by when sitting and they also DO NOT like synthetic or multi weight oil, they were designed to run straight 50 or 60, you will notice a difference.

 

Usually smoke only at startup after sitting a while, is leak down around valve stems.

 

I've heard the heavier oil advice before, and while I've never had issues with the 20W-50 this might just be the time I switch to straight 50W after all.

While there are not valve seals in this bike, I was worried somehow the long idle time wore down the guides just enough to create seepage.

A valve guide issue doesn't make a ton of sense to me though since I've never seen smoke on startup before (even in hot weather when oil would be thinner and more likely to leak), and now after just two days sitting, it smokes a second time, and quite a bit. It was a long warm up period, but I would be surprised if that was enough to wear down my valve guides.

 

It's the syn. oil, it's nature is to get into and out of everything, while it works the old bikes do not do well with it, leaks where you never had them before, sealed seams weeping, very noticeable smoking at start up , increased oil usage and a noisier engine in general.

Bad guides over a 2 day period you have other indicators, motor would sound real bad if it was that sudden.

 

Alright... I think I'm with you on this one, mostly because it gets me out of pulling the heads. If that's the answer though, what would explain the smoke being a first-time issue after using 20W-50 for some time now? Simple as the colder temps letting the 20W-50 oil get thin enough to seep past the valves?

As a compromise I'm thinking about changing out to Lucas SAE 50w. Still synthetic but heavier weight at cold/garage temps. Best of both worlds?

 

Skip the syn, get your head around that now please. Bike was not designed for it, materials and manufacturing processes back then weren't up to syn specs plus she got miles already. Newer bike yes use it, early 80's back waste of money. Valvoline dino 50 or 60 is your friend, done my shovels just fine the last 45 years.

 

Sold-- 6 quarts of Valvoline conventional 50W headed my way.

I'll check back when I've had a chance to change out and take a few rides.

 

Just to re-inforce,,stay away from synthetics with your bike.
m

 

first of all, WHITE smoke is not oil, that smoke is BLUE.
white smoke is fuel that is not completely burned, common on cold ambient start ups.
that is an misnomer that syn oil is a sneaky snake.
one issue i see on a machine that has set long enough to have even a wee bit of wet sumping and cold start is the the oil does not miraculously reappear in the bag. the wheels will pick it up and toss it onto the jug walls in particular the rear jug. the oil control ring can only do so much and with cold temps, even less so. one way to tell if the guides are leaky is to have someone ride behind you and observe a long coast down and throttle up, normal to have some huffing but does get worst with time.
perhaps your idle/low speed mix is off.