I think Im in trouble. Ive had to pull the carbs a number of times due to tuning issues and I pulled them last night. I thought it was in my imagination but I thought I heard a screw or something drop (might have dropped into the intake tube). I normally plug them up but I guess I just wasnt thinking. Anyways get it all back together fire it up and the idle is rough and smoke is starting to come out of the exhaust. Blipping throttle results in a stall.
This morning I see that there has been an oil drip, not major, but there nonetheless from the exhaust. When I tried to fire it up again I noticed the horizontal cylinder stayed cold and the plug was wet.
So, since this is all of a sudden. Im worried something might have fallen into the cylinder, though I didnt notice any missing screws or anything.
If that happened, whats the worst case scenario. I'll run a compression check this evening, but I havent pulled heads before. Can anyone fill me in on how to diagnose and al how extensive possible damage might be?
Which Monster do you have?
Probably best to pull that head off before turning the engine over more.
Quote from: Speeddog on September 19, 2008, 10:48:02 AM
Which Monster do you have?
Probably best to pull that head off before turning the engine over more.
Its a 98 M900. Yeah the key is stored away for now. The horizontal cylinder was running lean prior to this so I wander if its possible I burned a valve or gasket.
Can anyone link me to a diy for head removal or give me some quick guidance. This will be a first attempt after checking compression/spark.
Browse the How To Section - though I'm not sure one's done a head remove one yet.
If you don't have any manuals yet, might be a good time to get some.
IF you can find the factory manual that will have all the details.
This *might* be it (found via google)
http://store.payloadz.com/str-asp-i.169888-n.Ducati_900_Monster_Workshop_Manual_M900_eBooks_-end-detail.html
But you might want to do a little more checking to make sure it's the right factory manual. IF you got a 2000+ 900 manual you'd be SOL on anything to do w/ carbs.
LT Synders, DesmoTimes manual is good, though not model specific
http://www.desmotimes.com/
Haynes makes two Ducati manuals - the 1st one they published focuses more on the bikes of your era.
http://www.ducatisuite.com/maintenance.html - will have some helpful info, like how to the the belts if you do pull the heads off.
Ran a compression check last night. Both cylinders have compression around 140 or 150. I checked the spark and its fine too. What else could cause the oil leak through the exhaust? The plug was covered in gas or oil, Ill have to double check but it wasnt damaged in any way so Im thinking its possible nothing fell into the cylinder.
Is it possible what you thought was oil was a mixtuer of gasoline and condensed water vapor mixed with carbon and oil from the exhaust system?
Quote from: howie on September 20, 2008, 08:34:24 AM
Is it possible what you thought was oil was a mixtuer of gasoline and condensed water vapor mixed with carbon and oil from the exhaust system?
Cant rule it out, there was a lot of smoke from the exhaust though, Ill have to inspect further.
Its definitely oil, I removed the exhaust and oil just poured from the pipes attach. Oddly enough just from the left side but I think thats due to when it was on its sidestand for a few minutes yesterday (on rear stand now). I looked at both exhaust holes on the cylinders and they seem pretty dry so Im not sure which cylinder is leaking. The horizontal wasnt firing and the vertical was running rich (plug is black).
Considering I have compression/spark/fuel, what could be causing the oil leak?
Is the oil at normal level in the sight window (not overfull)? Any chance you have a float stuck open allowing fuel to leak into the crankcase?
Quote from: Preppyr6 on September 20, 2008, 08:19:23 AM
Ran a compression check last night. Both cylinders have compression around 140 or 150.
That's good (not so much the absolute number, although they sound about right, but the thing you're really looking for is that they are both close to the same, you've got to start looking for problems if they're more than about 10% different, which yours aren't.)
QuoteI checked the spark and its fine too. What else could cause the oil leak through the exhaust?
Errmmm, maybe the valve stem seal? Not particularly likely given you were playing with the carbs not the valvegear...
Are you sure it's oil? is it possible it's fuel instead? There's a few possible candidates there, a sticky float valve could be flooding that cylinder, it's also possible the vacuum fuel pump has split it's diaphragm and is feeding fuel down the vacuum hose (I can't remember which inlet tract that goes into).
big
Quote from: bigiain on September 20, 2008, 07:34:15 PM
That's good (not so much the absolute number, although they sound about right, but the thing you're really looking for is that they are both close to the same, you've got to start looking for problems if they're more than about 10% different, which yours aren't.)
Errmmm, maybe the valve stem seal? Not particularly likely given you were playing with the carbs not the valvegear...
Are you sure it's oil? is it possible it's fuel instead? There's a few possible candidates there, a sticky float valve could be flooding that cylinder, it's also possible the vacuum fuel pump has split it's diaphragm and is feeding fuel down the vacuum hose (I can't remember which inlet tract that goes into).
big
Big is onto something here.
Doh, I can't remember if the vacuum for the pump comes from the front vertical or horizontal either :-[ The good news is diagnosis is easy. Pull the vacuum hose. If gasoline comers out of the vacume hose, BINGO!!. Stuck float is a possibility also. Look at the oil level. Too much? Smell the oil. Smells like gasoline? It got there somehow. If not the fuel pump, floats come to mind. With those compression readings combustion chambers should be good enough. If a valve guide was bad enough to cause your problem the valve would not be able to seat well enough for those readings.
Pump hose comes from the vertical cylinder inlet tract.
Quote from: Howley on September 21, 2008, 04:30:51 AM
Pump hose comes from the vertical cylinder inlet tract.
Petcock from the horizontal.
i pulled the pipes off and it is most definitely oil (based on smell and consistency). I cant tell which cylinder its coming from though. The oil pooled up where the two exhaust manifolds meet. There was a good couple tablespoons in there though. I checked the exhaust ports on the heads and I cant tell based on those which head is the culprit though I assume its horizontal due to it not firing.
I thought about hitting the starter while leaving the plugs disconnected to see if oil ended up coming out of one head or the other. I dont know if this would work. Im just trying to troubleshoot everything before pulling heads.
Few things come to mind. Hows the crankase breather system? Is it venalating properly? ie, no kinked or ruputered hoses. The only other way if theres that much oil is the oil control rings on the piston, or crack in the head. One thing to consider, is you can have good compression yet still have oil control ring problems.
Alright, I neglected to mention what may be key information. Before the oil pooled up I had to crank it for several minutes to get it to fire up. A friend suggested the oil built up in the cylinders and had nowhere to go but through the valves.
I had run the battery dead cranking and cranking and then had to recharge and attempt again before it would finally fire up.
This in mind, I put the exhaust back on and Im going to swap in new plugs and fire it up to see what happens. Im hoping its something this simple, the oil symptom appeared out of nowhere.
Update, I put her back together and still only running on 1 cylinder. A little more oil burned too. I traced the problem back to the carbs. The plug was getting soaked immediately and wouldnt fire so I checked the intake valve and nothing had fallen in, whew. I then tilted the carbs and noticed the horizontal cyl side was just draining gas non-stop...bingo. Im guessing the float was pulled offwhen I reinstalled the bottom.
Congrats on finding the problem and not needing a rebuild! You may want to change your oil. Gas in the cylinder can squeeze past the rings and dilute the oil.
Scott