New to me 91 ST1100 blowing blue smoke

[smoker1]

Wow! Much more response than I anticipated. Thanks, all.

Short story: I don't have the right adapter for my compression tester, but when I pulled the plugs, #4 had obviously been burning a ton of oil, and was severely coked up. 2+2=4, so I have my fingers crossed and the cylinders full of ATF.

Longer story:
-the PO gave me a receipt for work the the owner before him had done. Date 1/5/16. Mileage 178,087. When I bought it this week, the mileage was 178,094. That receipt had the guy's name and number, so I called him. He claimed that it didn't burn oil when he had it. He didn't sell it to me, and I can't think of any reason he'd have to lie about it.

-when I bought the bike, I inspected it in daylight. I am 100% sure it wasn't smoking at that point.

I'm not an expert, but I can only think of 2 possibilities: it broke a ring the very first time I rode it, or the rings became "stuck". Anyone have any experience with either of these situations on these motors?

I'm scheduled to take a ride with my dad, uncle, great uncle, and grandfather tomorrow. Grandpa is 83, and his riding years are dwindling. I think I might put it back together, take a few quarts of oil with me, beat the piss out of it, and keep my fingers crossed.


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[Whooshka]

Well I'd hold off on the "beat the piss out of it". Why risk a breakdown and ruin everybody's day.

 

[smoker1]

Well I'd hold off on the "beat the piss out of it". Why risk a breakdown and ruin everybody's day.

Bad choice of words. I should've said keep the revs up, within reason.

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[Christianncg]

-the PO gave me a receipt for work the the owner before him had done. Date 1/5/16. Mileage 178,087. When I bought it this week, the mileage was 178,094.

So the guy bought it, and rode it 5 miles in 2 years before selling it to you? That usually screams red flag to me. Like the guy found something he did not like or could not fix, and parked it.

 

[smoker1]

So the guy bought it, and rode it 5 miles in 2 years before selling it to you? That usually screams red flag to me. Like the guy found something he did not like or could not fix, and parked it.

Right. The guy I got it from got it in a trade, then supposedly found out it was too tall for him. I knew I was taking a chance. It was $800 and has brand new michelins.

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[smoker1]

Ok, I've got a new theory. Cylinder 4 started allowing combustion to get into the crankcase over 2 years ago. The reason it didn't smoke when I bought it is because the last owner cleaned out the intake. Because of where the vent dumps into the airbox, it would take some time to pool up, saturate the filter, then work it's way into the carbs.

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[red one]

So the guy bought it, and rode it 5 miles in 2 years before selling it to you? That usually screams red flag to me. Like the guy found something he did not like or could not fix, and parked it.

That's why I would never touch a bike with that many miles. The previous owner could of put some snake oil in it to stop the smoking till it left his property. Too many lower mileage ST1100 and 1300's out there.

 

[smoker1]

That's why I would never touch a bike with that many miles. The previous owner could of put some snake oil in it to stop the smoking till it left his property. Too many lower mileage ST1100 and 1300's out there.

Not near me in my price range, there's not. I've owned well over 100 cars, trucks, and bikes. Some of the best ones I've had were higher mileage examples. Plus, it's already at max depreciation. A ring job looks to be fairly simple, and I need to do the timing belt, etc, so I'll already be heading in that direction. Worst case scenario, the motor is trash and I part the rest out on ebay and probably break even.

I love an adventure. To each their own.

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[Bush]

A well maintained ST1100 can go double that mileage easily, on the same engine, without major engine repairs. They are renowned for being bullet proof, but nothing lasts long if you don't take care of it.

Have you determined that the cobbled up crankcase breather is not the problem?

 

[smoker1]

A well maintained ST1100 can go double that mileage easily, on the same engine, without major engine repairs. They are renowned for being bullet proof, but nothing lasts long if you don't take care of it.

Have you determined that the cobbled up crankcase breather is not the problem?

I plan to replace it with the right part, but it's definitely not the main issue.

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[Christianncg]

Do not be discouraged from this motorcycle. Just look to me as an example.

I got a Hyosung GT250R as compensation for motor work I did. Despite being reliable, it rode like a lawnmower engine stuffed inside a Zx6R frame. After posting it for 1500, a guy approached me saying he was waiting for a trade to happen but would buy it immediately afterwards. When I found out what it was, I traded it outright, without doing my usual rounds of inspections.

Not surprisingly, about a week after buying it, when I removed the carbs I was greeted with a crack in the block, between the coolant inlet and one of the cylinder outlets. On top of that, the rear brake rotor was down to less than a millimeter being locked up and ridden for the past few years on bare metal pads, the air filter clogged, the carbs in need of a rebuild, and most of the right side plastics in need of replacement. After purchasing a used motor (55k miles for only 300 bucks shipped) and installing it, replacing all the coolant hoses, radiator, carb float needles and seats, rear orings, front tire, rear rotor and pads, fluids and filters all around I now have a bulletproof bike that hauls raw *** and tours quite well. I can't say it will be worth it for you. But after about 1k in parts, and well over a few months time in labor, I do not regret investing the time in the bike.

That being said I have a spare motor with a hole in the block if your looking for parts.

 

[Christianncg]

I plan to replace it with the right part, but it's definitely not the main issue.

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I would also undo that pipe joint, and start the bike with the vents out to open air. See which pipe it's coming out of, the bottom or top. Or both :O

 

[smoker1]

I would also undo that pipe joint, and start the bike with the vents out to open air. See which pipe it's coming out of, the bottom or top. Or both :O

I'm open to being corrected, but I don't think it matters which one it's coming from. The fact that there's enough pressure in the crankcase to push it the whole way up and out that hose is a problem. It's not mist/spray coming out, it's liquid. And when I shut it off I can hear it gurgling as the level goes back down.

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[Christianncg]

You are most likely right; but I'm an optimist. I like to exhaust every possible solution before I go that route. Besides, you would have to remove the joint anyways, along with 50 other things to remove the motor. As someone who has swapped motors, I wouldn't wish that fate on anyone else unless necessary.

 

[smoker1]

You are most likely right; but I'm an optimist. I like to exhaust every possible solution before I go that route. Besides, you would have to remove the joint anyways, along with 50 other things to remove the motor. As someone who has swapped motors, I wouldn't wish that fate on anyone else unless necessary.

Oh yeah, I'm not tearing the motor down. I'm just putting fresh oil and gas in it, along with a little ATF and marvel mystery oil, and I'm gonna try to go ride 500 miles tomorrow and hope the rings get happy! [emoji106]

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[smoker1]

Fresh oil, fresh gas, fresh plugs. Oil level was in the middle of the sight glass. Took a 14 mile test ride. Oil level is nowhere to be seen. It actually ran pretty good with almost no smoke till it got up to operating temp. I'm starting to wonder if the missing pcv valve/trap thingy really is my bigger problem.

I need to find an adapter for my compression tester.

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[John OoSTerhuis]

You sir are a victim of POS(Previous Owner Syndrome). The missing oil trap is definitely your problem and being plastic, probably broke on the PO and he was too cheap to fix it right the first time. Slam in a new one and call it a day. Most cars/trucks have a combo oil trap/PCV nowadays for the strict EPA emissions regulations.

I agree with Clutch, Brian, Christian, and Terry. Only the ‘91s have the external crankcase breather chamber that is apparently missing and replaced with the plumbing in the picture. Install one and report back. Can’t explain why it just started smoking now though... FWIW

Edit: here is a picture of the chamber on my ‘91: http://www.st-riders.net/coppermine/displayimage.php?album=33&pid=829#top_display_media

John

 

[Christianncg]

I have done more research thanks to ebay photos of disassembled transmissions. So far, I have deduced the following for your information.

1. The bottom breather hose is just on par with the oil level of the bike, a little above and connects to the bottom of the transmission case, through a passageway all the way to the crankcase. No provisions for preventing oil puking are detected here internally, which makes me believe having a straight tube go from there to airbox is silly...

2. The top breather hose is isolated from the transmission with a semi-sealed collection box internally, designed for what appears to be the purpose of keeping oil out and allowing crankcase fumes through. An apx. 1 inch hole on the front top part of the transmission case allows fumes from the motor to come through, but not oil. Appears to be similar to the chamber that the KZ750 has.

3. One could technically plug the bottom tube on these bikes, and still have ventilation from the top port. They are not isolated from one another. In fact, I would hypothesize that the top hose is for crankcase fumes, and the bottom hose is simply a drain for the oil that happens to collect inside the black collection box during fume processing, hence the need for two hoses.

Given what I have dug up, I would bet money that your bottom port is the one puking up oil. You may very well have a motor with blowby too. Given all of this, if the top port was plugged, the bottom port would shove the oil all the way on up I would imagine. If the bottom one was plugged, you would eventually puke oil from the hose leading to the airbox because of the residual oil that accumulated from crankcase gases.

 

[smoker1]

I agree with Clutch, Brian, Christian, and Terry. Only the ‘91s have the external crankcase breather chamber that is apparently missing and replaced with the plumbing in the picture. Install one and report back. Can’t explain why it just started smoking now though... FWIW

Edit: here is a picture of the chamber on my ‘91: http://www.st-riders.net/coppermine/displayimage.php?album=33&pid=829#top_display_media

John

I'll be calling the dealer today. If anyone has any other ideas for where to buy one of these, please let me know!

I also checked ebay for complete engines, just to get an idea of the worst case scenario. There are a few on there, much cheaper than I expected. Cheap enough that I would consider buying one and swapping it, then taking my time to rebuild this one... if necessary.

 

[MaxPete]

I'll be calling the dealer today. If anyone has any other ideas for where to buy one of these, please let me know!

I also checked ebay for complete engines, just to get an idea of the worst case scenario. There are a few on there, much cheaper than I expected. Cheap enough that I would consider buying one and swapping it, then taking my time to rebuild this one... if necessary.

There is a great thread on the forum by ERROR85 in which he rebuilds an ST1100 engine - and as far as I can tell, it’s one of very few treads in which someone gets inside an ST engine. I guess these darned things are just so tough.

On finding the part you need - try to get the OEM Honda part number and then just type it into your search engine (JUST the part number - no words or any other descriptors). You might be pleasantly surprised to find that precisely what you need is available at very low cost.

I also restore and ride a couple of 1970s Yamaha XS650s (think Triumph / BSA / Norton - but with actual working lights) and I usually find parts by simply sticking the part number into google - and in virtually every case, something comes up. You can find the parts numbers from parts schematics at web stores like Partzilla or Discount Honda Parts.

The other source is motorcycle wrecking yards. There were quite a few STs around back in the day and because of their age, they are being taken off the road and so lots of parts are becoming available that way too.