Help! Smoke!!

steveboot · Mar 24, 2015

Just got my carbs back from Mike Nixon. Popped em in, and fired her up in the backyard and she sounds so much better.... Except after about a minute smoke started coming out from under the carbs.... shut her down and thought maybe the little bit of grease I put on the manifold boots is burning off.... Finally got her rolled out to the front drive and fired her up again, and more smoke. Not enveloped, but enough that I shut her down.

No flames, but looks like there gas on the #1 cylinder.

I'm thinking maybe I didn't get the #1 carb set fully into the manifold boot, or didn't get it tight enough....

Anybody experience this?

No matter what this weekend the plastic is coming back off and I'll pop the carbs off to see what I can see. But hoping someone else has experienced something similar so they can say "check this dummy!"

Brant · Mar 24, 2015

steveboot said:
Just got my carbs back from Mike Nixon. Popped em in, and fired her up in the backyard and she sounds so much better.... Except after about a minute smoke started coming out from under the carbs.... shut her down and thought maybe the little bit of grease I put on the manifold boots is burning off.... Finally got her rolled out to the front drive and fired her up again, and more smoke. Not enveloped, but enough that I shut her down.

No flames, but looks like there gas on the #1 cylinder.

I'm thinking maybe I didn't get the #1 carb set fully into the manifold boot, or didn't get it tight enough....

Anybody experience this?

No matter what this weekend the plastic is coming back off and I'll pop the carbs off to see what I can see. But hoping someone else has experienced something similar so they can say "check this dummy!"

If removing carb bank again, I HIGHLY reccomend cleaning the grease of inside of carb boots. Grease WILL eventually deteriate the rubber! Clean grease from boots using Brak-Kleen or carb cleaner. Spray inside of boots with silicone spray and carb bank pops easily on carb boots. Hope you replaced the boots with new ones

. The clamps having a 'stop', so as not to be overtightened will not 'pinch' the old boots tight enough to seal, even tho they may LOOK like they're sealing

.

ST1100Y · Mar 25, 2015

Methinks the odour of the smoke might give a clue about the origin/cause ;-)

steveboot · Mar 25, 2015

Just ordered new isolators (boots) and they should be here Friday. With any luck the weather will hold and I can take her apart on Saturday!

Smoke smells like .... well, not exhaust, and not electrical.... And it was not just wisps of smoke; it was coming out pretty good and all on the right hand side. And the #1 cylinder exhaust manifold was damp with what I think was gas (and it was previously discolored). Thats what made me think gas was coming past the isolator.... Just guessing since I have no prior experience with it.

dwalby · Mar 25, 2015

Having not seen/smelled the actual smoke, its hard to speculate, but:

It would seem that loose boots would allow air to leak past the boot rather than blow gasoline out of them since there is generally negative pressure at that point.

Gasoline fumes should burn relatively cleanly, smoke wouldn't seem to be consistent with that unless the burning gasoline was burning something else along with it.

Also wouldn't expect the engine to be hot enough to ignite gasoline after running 1 minute, but who knows?

There are coolant hoses under the carbs, leaking coolant could burn off and produce smoke, which would be whitish in color and sweet in smell. (as in not exhaust and not electrical) And could explain the dampness of your exhaust manifold.

Since you are pulling the carbs again anyway, if you haven't replaced the coolant hoses and elbows under the carbs now would be a good time to do so. They're cheap, and easy enough to install once you're in there.

steveboot · Mar 25, 2015

definitely not coolant smell; I know that well. It's an actual burning smell. Almost like paper.... But there's nothing under there!

I think I'm more worried I'll pull the carbs and not see anything. I kind of feel like the doctor who can't account for all his instruments after surgery... Hmm.... Where could that rag be.....

ST1100Y · Mar 25, 2015

hmm... case vent plugged back onto the air-box? Just saying... ;-)

Grabcon · Mar 25, 2015

dwalby said:
It would seem that loose boots would allow air to leak past the boot rather than blow gasoline out of them since there is generally negative pressure at that point.

Gasoline fumes should burn relatively cleanly, smoke wouldn't seem to be consistent with that unless the burning gasoline was burning something else along with it.

Also wouldn't expect the engine to be hot enough to ignite gasoline after running 1 minute, but who knows?

I agree. With in a minute or two of start up I would suspect some type of residue on the exhaust pipes. An oil or grease residue maybe from a hand or glove.

You look to be in Maryland and it might be a little brisk for this but I would spray some Simplely Green all over the outward facing parts of the motor and the front as well as the exhaust. Do this with the motor cold. Spray it off good with water let it air dry and see what happens.

There is not much in the valley under the carbs to make smoke. But when you have the carbs of check to make sure the float bowl screws are snug.

steveboot · Mar 28, 2015

another cold day here in Baltimore, with flurries none the less! So not sure whether I'll unbutton her or not today. One way or the other I'll have the parts ready for when the weather decides to cooperate.

steveboot · Mar 28, 2015

Braved the cold once the flurries stopped and unbuttoned her to pop the carbs (still in the 30's though). Got the carbs off and cleaned up the boots, and they looked really good, so I decided to give it a try just putting her back together. And it worked. No smoke at all.

But that's not the end of the story.... I left her running to see if any smoke would develop. After 5-10 minutes I started buttoning her up, and noticed the temperature gauge was reading higher than I ever remember.... and the fan wasn't running!

Well, it was starting to snow again so I finished putting her back together and came in out of the cold.

Wondering now whether the fan circuit/relay runs through the carburetor bay and I've damaged it somehow. The fuse is good, so tomorrow I'll start doing some diagnosis.

Any thoughts from the collective pool of wisdom?

dwalby · Mar 28, 2015

fan is controlled by a thermo switch in the radiator, its easy to locate. Remove the single wire that is attached to it and ground that wire to an unpainted engine/frame location with the ignition on, the fan should run. If it doesn't run you need to trace out the fan electrical.

If fan works, then figure out why the switch isn't closing. It could be a bad switch, or another possibility is your t-stat isn't working correctly and the coolant isn't circulating into the radiator like it should, so the thermo switch isn't getting enough hot coolant to close it. You can test the switch by removing it from the radiator and putting it in a pot of boiling water.

Brant · Mar 28, 2015

Combine the higher erratic temp gauge with your #4 post, I vizulize coolant leak, with it going up in steam before hitting ground, and now coolant level too low for fan sensor to correctly operate. Checking coolant level cold at this pointshould tell the story. Re-pulling carb bank, replacing coolant elbows/o-rings if you haven't, checking hoses cond, and thermostat housing area for 'seepage' may be next step.

vinny · Mar 29, 2015

Brant said:
Combine the higher erratic temp gauge with your #4 post, I vizulize coolant leak, with it going up in steam before hitting ground, and now coolant level too low for fan sensor to correctly operate. Checking coolant level cold at this pointshould tell the story. Re-pulling carb bank, replacing coolant elbows/o-rings if you haven't, checking hoses cond, and thermostat housing area for 'seepage' may be next step.

dwalby · Mar 29, 2015

agree with vinny and brant, in my haste I left out the most basic check, make sure there's coolant in the radiator.

steveboot · Mar 29, 2015

Time to end this thread. I checked the coolant level and it was just a bit low. Added maybe a cup to bring it to the upper line. Crossed my fingers and let her idle for about 15 minutes. The temperature gauge went up higher than I remember, but just a bit before the last white tick mark the fan turned on and brought the temp back to mid range.

Looks like my tribulations made me gun shy....

Now I'm off for my first test ride on the newly rebuilt carbs.

Thanks folks for your patience and good suggestions.

dwalby · Mar 29, 2015

The fact that it brought it back to mid-range is encouraging, but the fan should have come on with the temp needle just past 12 o'clock. Keep an eye on it, it sounds like it still isn't working as well as it should, unless your definition of "a bit before the last white tick mark" is much wider than mine.

John OoSTerhuis · Mar 29, 2015

What is the coolant level in the radiator (not just at the overflow tank/reservoir)? Any dried coolant marks/stains on the back of the engine between the 'V'?

dwalby · Mar 29, 2015

good catch John, I see his mention of the "upper line" would not apply to the radiator, he was talking about the overflow tank. If you don't know the coolant level in the radiator, you're not finished yet.

steveboot · Mar 29, 2015

Did not look into the radiator itself; just the overflow tank. But there were no stains in the "V", no drips, no sweet coolant smell.... I rode all afternoon off and on with the temp needle staying in the low region, but it was just mid 40's here so not much of a challenge.

I'll keep an eye on it...

On a side note, the ST with her newly Mike Nixon processed carbs performed flawlessly

John OoSTerhuis · Mar 29, 2015

Steve, it only takes a few minutes to check the radiator. Do you have tupperwarephobia?

. You did knowingly buy a fully faired motorcycle, after all. OK... OK... I'm teasing a bit, but I personally couldn't ride another mile without knowing my whole cooling system was right.

Just say'n...

John

Help! Smoke!!

steveboot

Brant

ST1100Y

steveboot

dwalby

steveboot

ST1100Y

Grabcon

steveboot

steveboot

dwalby

Brant

vinny

dwalby

steveboot

dwalby

John OoSTerhuis

Life Is Good!

dwalby

steveboot

John OoSTerhuis

Life Is Good!