Hi, I recently bought a st1100 1998 with a 1990 engine. Yes it isnt great but it was cheap and I'm fixing it up. The bike runs and rides ok and has lots of power but has bad white smoke when it's cold and when it's hot first thought is the head gasket is blown. The coolant res tank doesnt seem to have gone down at all since I've owned the bike, when draining the oil I noticed it was very watery and discoloured. I put new oil in and took it up and down the road a new times and drained a sample of the oil to find it had gone watery like the last oil I took out. As a last hope before biting the bullet I had a look at the breather hoses as if blocked they can create condensation and the plastic breather box located on the right side seems to be blowing air out of the bottom and it seems I'm missing a hose where it's coming out but I cant find where the hose should go to... any help would be appreciated before i strip it apart and get the heads skimmed and new gaskets fitted. I'm waiting on a new compression tester as the old one was broken. The left side is the new oil before going in the engine and the right is after 5 a minute ride. Is there anything else for me to check? Thanks
St1100 blowing white smoke
- Thread starter Alfst1100
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John OoSTerhuis
Life Is Good!
You have the one model year engine that has the external crankcase breather (the black plastic box in your picture). In the USA that was the 1991 model year. I have one. The parts are shown in this online ’fuel tank’ microfiche (lower right in the schematic):
www.ronayers.com
I don’t think I have any clear pictures in my archives to show the hoses and their routing, sorry. But I think you’re correct… the oil separated from the crankcase air by the breather box should be returned via a hose to a port on the rear of the engine. I’ll look for some images.
Is the water coolant or just plain water?
John
1991 Honda ST1100A Fuel Tank | Ron Ayers
Shop online for OEM Fuel Tank parts that fit your 1991 Honda ST1100A, search all our OEM Parts or call at 252-758-3084
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I don’t think I have any clear pictures in my archives to show the hoses and their routing, sorry. But I think you’re correct… the oil separated from the crankcase air by the breather box should be returned via a hose to a port on the rear of the engine. I’ll look for some images.
Is the water coolant or just plain water?
John
John OoSTerhuis
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Here’s an image showing the breather-to-case hose (lower right corner):
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Does your oil smell of gasoline at all? In other bikes I have had, the white smoke was caused by the crankcase being over-full from a sticking float causing gasoline to overfill the crankcase and the liquid being sucked out into the hot mufflers via the crankcase vent.
your symptoms seem to indicate you're getting coolant into the oil, and the combustion chamber, so a blown head gasket is one possibility. The other is an internal crack in the head, but I don't know how common that is. Wouldn't hurt to have the heads pressure tested while you have them off, just in case.
John OoSTerhuis
Life Is Good!
I know nowt about the external breather, but luckily JohnO does.
That oil ain't right, but I think you knew that. You need to investigate further and Doug is probably on the right track with cylinder head. Have you checked the coolant at the radiator, not the overflow?
Good luck.
Upt'North.
That oil ain't right, but I think you knew that. You need to investigate further and Doug is probably on the right track with cylinder head. Have you checked the coolant at the radiator, not the overflow?
Good luck.
Upt'North.
I have done a compression test and all cylinders are within 10 psi of each other. I would have thought with a blown head one or 2 cylinders on a side would be significantly lower than the rest. The coolant in the radiator doesnt look too bad, I think someone has put the braided hose at the bottom of the breather box in the wrong location. I will investigate into that now. I will have a look at a sticking float tomorrow I have noticed another hose connection near the front of the engine without anything attached it's hard knowing what goes where when the previous owner had been messing with it, thankyou for the responses
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I had half a tank of fuel I've probley ridden a mile or 2, and it seems to have virtually no fuel in now, the oil I took out smells of fuel. I will have to check all the floats to be able to tell which is causing the issue. A job for tomorrow I think... considering the coolant level hasn't gone down but the fuel has it would probley be best to check before pulling the cylinder heads
turbomaker
I live one commute mile at a time
The cleanest looking spark-plug plug once removed would point to the carb in question?
I will have to pull the petrol tank tomorrow to have a proper look into themHere’s an image showing the breather-to-case hose (lower right corner):
I had them out when checking the compression but they all looked the same. I'll run the bike for a while and check again tomorrow
John OoSTerhuis
Life Is Good!
Your second picture appears to show the port that sends air from the internal crankcase breather of all other years to the right underside of the air cleaner case. This vents from the front of those engine cases through the water pump casing. Your 1990 doesn’t have/use this vent so it appears you have a later year ST1100 water pump installed. This is not a problem for you as the 1990 engines don’t have the hole in the engine case so this is a blind hole. They vent to the air cleaner through the hose on the top of the external crankcase breather box. In the USA, the 1991 water pumps are no longer available but other years’ pumps can be used in their place.
Thankyou for the knowledge. So should I just leave the port at the front of the engine without a hose on as it would have no where to go since it's a later model water pump?
If it runs good a compression test will not show up a head gasket with a slight leak. A leak down test would be better. If the exhaust smells sweet its burning A/F . By removing the spark plugs and look into each cylinder the cleanest piston is the one that's been steam cleaned from the leak.
John OoSTerhuis
Life Is Good!
Yes, you’re fine. You just need to insure you get your engine’s breather system functioning correctly. I’ll look for the thread from a while back wherein I helped an inmate here put together a complete USA 1991 engine crankcase breather system on an engine he’d purchased without.
John
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John OoSTerhuis
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OK, found the thread:
www.st-owners.com
Christopher (misterguitar) hasn’t been on the forum for over a year now so don’t know how it all worked out. I suspect that he was successful though based on his responses.
HTH, John
Questions regarding breather connections and transmission case covers | ST1100 Related
I bought a 93 ST100 and have been trying to sort out the breather/emissions connections. So it would seem there are two versions of the transmission case on these bikes? One that has a hose connector in the main housing and one that is cast with no connector. And there is also a connector on the...
HTH, John
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If your oil smells of fuel, do not run the engine until this issue is corrected as you run the risk of doing further damage to the engine.
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white smoke is usually coolant getting into the cylinder; it will also be evidenced by the condition of your plugs; sometimes you can pull all the plugs for a photo op and crank the engine a couple times to blow out water.
Here are the spark plugs. There is no water inside the cylinders
