exhaust smoke

[Beetlegeuce]

So I finally got this 82 650 started up today...after not running for probably a couple of years.  Didn't have any trouble getting it started really (of course after a good carb cleaning/adjusting).  A minute or so with the choke on (partially) and it runs fine with no choke...takes throttle just fine (these suckers rev quickly don't they!).  Problem is there's a good amount of smoke from the exhaust (all 4 pipes).  It is definitely not oil...I know the color and smell of burning oil all too well.  It was hard to tell the color very accurately with the way the sun was positioned...I'll have to check again in the morning, but I would have called it a light gray-ish color.  Didn't smell at all like a rich exhaust either (I know that all too well also from tuning chevy V8 engines! lol )...in fact didn't really smell like anything, just a typical "exhaust" smell.  Maybe it IS rich and it just takes so little with these bikes that the smell is not as distinct as with a car engine? It has no cooling system, so can't be that.  When I shut the engine off the smoke kindof lingers out of the exhaust for a few minutes too.

The exhaust pipes came from a "donor" bike of the same year/size, that as I understand sat outside for quite a long time.  Maybe just burning off accumulated "crap" inside the exhaust pipes? (the "lingering" smoke makes me think of that possibility)

[Brittles]

Could very well be old crap burning off. Good luck.

[ERAU-944]

if the bike sat for any length of time, it could also be condensation burning off from inside the exhaust.  my advice would be to take it on a few rides a short distance from home, but around 1/2 hr in length.  that should give the engine and exhaust enough time to heat up and burn off any stray moisture, but keep you close enough to home to not have to push the bike too far in the event of a problem.

[Bumblebee]

Greyish and hasn't been run in years and sat outside?

Possibilities:
It's most likely condensation and crud in the exhaust pipes. These specific 1-1 pipes tend to do that if they're left sitting up for a long time in the weather. Lingering exhaust after shutdown is typically from who knows what being cooked in the exhaust pipes.
Possible minor rich condition caused by any one of several carburetor related reasons.
If there is any bluish color to the exhaust it's very likely from oil seepage though the valve guides while sitting. It'll likely go away after an hour of riding.

IMO, it's a non event and will go away as soon as the crud in the pipes are burned off. Take it easy riding for a few hours and keep an eye on the exhaust to see if it goes away.

[coffee_brake]

+1, ride it gently and near home, the smoking should clear out within a few miles/minutes.

[Beetlegeuce]

No it is not at all blue in color...nor has the very distinct odor of burning engine oil.

Also in addition to the "lingering" after I shut it down, it does not start smoking right away...only after warming up for a couple of minutes.

[Laminar]

+1 to everything so far. Just crap burning up, no worries.

[Bumblebee]

No it is not at all blue in color...nor has the very distinct odor of burning engine oil.

Also in addition to the "lingering" after I shut it down, it does not start smoking right away...only after warming up for a couple of minutes.

It's just burning crud that got into the mufflers while parked outside. Water and probably bugs or spider webs or such. No biggie. Just ride it and watch it just to be overly cautious.

BTW, you lose no points for being overly cautious and asking about stuff like this. That's how you stay out of trouble even if it turns out to be completely benign.

[Beetlegeuce]

No it is not at all blue in color...nor has the very distinct odor of burning engine oil.

Also in addition to the "lingering" after I shut it down, it does not start smoking right away...only after warming up for a couple of minutes.

It's just burning crud that got into the mufflers while parked outside. Water and probably bugs or spider webs or such. No biggie. Just ride it and watch it just to be overly cautious.

BTW, you lose no points for being overly cautious and asking about stuff like this. That's how you stay out of trouble even if it turns out to be completely benign.

hahah...yeah I ain't here to collect points, I'm here to make sure I don't do something stupid and destroy my bike!  You all have been extremely helpful!

[HawkFuzz]

Thanks for the update today on the smoke, ect.  I hope you found by changing the oil that the mystery shaving dissappeared with the oil change.  Let me know, I'm working on Salma Hawk tonight so I will be around.

The parts bike I brought you had been sitting outside for at least 18 months.  I don't know about before that.  The kid I got it from had traded a roommate for it.  It was running when it was first put in the back of the house.

[Beetlegeuce]

No more signs of shavings...however compression test fails.

Bummer.   

[coffee_brake]

Is it rideable? Can you put it in gear and ride it under load?

If it's not smoking a lot, compression can be pretty low and still be OK.

It's a subjective thing.
What numbers did you get, and what process did you use? Did you do the compression check hot or cold? Did you do the check, and then put a bit of oil into each cylinder, and then do the check again (isolates ring damage)?

If it needs rings, that's really not very hard. You must be careful and slow and methodical, but it's not hard.
But, maybe your testing method allowed false numbers to creep in.

Tell us more?

[Beetlegeuce]

Warm engine, 90psi dry, over 200 wet (with oil).  At least 25% variance between cylinders. 

Slapped on a different exhaust system (that hasn't been sitting outside, just needed a set of baffles installed), still smokes...just doesn't "smell" like oil.  Weird.

Oh yeah and I do have a second complete engine sitting here (thanks to Hawkfuzz!)

[Laminar]

Over 200??? How much oil did you dump in each cylinder? You were almost certainly pushing oil up into the compression tester.

[Beetlegeuce]

Yeah I know...I saw it jump over 200 and was like "what the...!!!".  Wasn't much...MAYBE a spoonful, but I don't think so.  Then again I'm used to working on cars...these are much smaller cylinders!

I did crank it over a few times before hooking up the compression tester.

[Munkey]

Pull the head and cylinders. Hone the cylinders. Replace the rings. Lap the valves. Replace valve stem seals. Reassemble and ride for many years.

[Beetlegeuce]

Or swap the extra engine I have sitting here (assuming good comp. test results) for zero $$ (which is about what I have right now), and overhaul this one over the winter once I have income again... 

Decisions decisions!

[Laminar]

The one that sat outside neglected for 18 months? No way compression is any good.

[Munkey]

Or swap the extra engine I have sitting here (assuming good comp. test results) for zero $$ (which is about what I have right now), and overhaul this one over the winter once I have income again... 

Decisions decisions!

Yeah, if you want to take the chance that it's in better condition. For all you know, it may be worse.

[coffee_brake]

Can you do a compression check on the spare engine?

[Beetlegeuce]

Can you do a compression check on the spare engine?

Working on it...

[noahnsteph]

Ninety PSI should be enough to run. Not well and definitely underpowered but still run if the donor engine doesn't have good compression so maybe you can ride with the engine currently on it and rebuild the donor engine over the winter instead.

[Beetlegeuce]

Oh it runs...seemingly pretty good (though not able to take it out yet).  Its just the smoke, which again is NOT blue nor smells at all like oil, that bugs me.

Have to keep in mind also that I'm at about 6000 feet...which means a roughly 20% drop in cranking cylinder pressure.  Even still, 90 is pretty weak, but I'd live with that for now if it weren't for this darn smoke.

I'm going over carb adjustments again.  There "may" be an issue with the pump valve not having any clearance.  Seems the stem on the replacement diaphragm is a tad longer than the old one. 

Is it possible with this engine that it is just too rich, but doesn't "smell" like it?  (again, I'm used to Chevy V8 engines!)

[Snoopy]

after my bike sat in storage for a good part of 5 yrs, when we had it running, it "smoked" for a good week after, burning stuff off.  your motor will "smoke" too after a long run. don't worry about that either as its just burning the muck off.

[HawkFuzz]

Hey Beetle,

I just scored a 93 Nighthawk with 14,000.  Needs fork seals and a new front tire.  If the sitting engine is not so good, lets talk. ;)  I will post pics later.

I say start doing a four or five mile loop. That way you are never very far from home if the bike decides to stop functioning.  No reason not to put your butt on it and feel it.