Engine Misfiring

[dirkwrong]

Originally Posted by catilover

the fact they are pretty even on both cylinders is also another sign that the are probably ok, seems really strange for them BOTH to go at the same time and read just as low as each other.

the cold test is good with oil but also do it hot, you want the expansion etc in the cylinders as well, incase you have a sticking ring or something, again with and with out oil.

I did test it warm, the other day. It wasn't much different. I just didn't add oil. It's hard to add oil to a horizontal cylinder! and messy too. No, I didn't put very much in there... duh.

Well, I guess if it was running too rich in both cylinders for several years this could happen. According to what I know, I'm supposed to be seeing about 160 in each cylinder. Even if the gauge is off by 10%, it's not enough to make up the difference. More than likely, the gauge is +/- 5%, so these readings are pretty close to what is really going on.

The timing marks on the cam pulleys all line up exactly as they are supposed to, so it's not cam timing leading to the low compression.

Right now, I think my only choice is to take it apart and inspect it. I may change my mind though. I have too many other things to do as it is. I'm getting married in the spring, so I'm busy with that. I just didn't need this to be put on my plate as well. I want to ride again, dang it!

[SussexDuke900]

sorry to throw up some more variables.

• Has the engine been rebuilt with thicker then stock gasket?
• Have you checked the cylinder head bolts, length and torque?
• Could it be a possible exhaust valve blow by, Cam timing?
• Is your throttle opening fully?

Is there any members near you dirk that you can compare compression test figures with run yours then theirs side by side so to speak.

Check your loom, possible wire failures on the coils and check the contact surfaces, try spraying some contact lubricant into the connections?

hope you get this fixed sounds liek a bummer, I was suffering with a cylinder with no spark which was the coils plug.

[dirkwrong]

Originally Posted by SussexDuke900

sorry to throw up some more variables.

• Has the engine been rebuilt with thicker then stock gasket?
• Have you checked the cylinder head bolts, length and torque?
• Could it be a possible exhaust valve blow by, Cam timing?
• Is your throttle opening fully?

I doubt the motor was rebuilt since I got it with 600 miles on it and a service receipt from a local dealer who said it was all fine. I'm unable to do a leak down test right now, but it appears to be rings at least. The cam pulleys line up perfectly. I don't recall if the throttle opens up completely when the grip is all the way open, but it appears to be so. Thanks for the suggestions.

[catilover]

i cant see how runing rich would effect a nicklesealed bore, nickeseal is pretty strong and can withstand alot more punihsment then your ordinary cylinders.
if anything it will be the rings.

[dirkwrong]

Originally Posted by catilover

i cant see how runing rich would effect a nicklesealed bore, nickeseal is pretty strong and can withstand alot more punihsment then your ordinary cylinders.
if anything it will be the rings.

From what I have read, 120 psi is the bottom end of the acceptable range that Ducati allows. The upper end is about 165. My engine seems to have fallen below the lower end. The only way that I know of to really figure this out is to take it apart. Doing a leak down test would give more information, but the top end still has to come apart to fix it, regardless of where the problem lies.

I'm just pissed that this is going to delay me getting back on the bike even more, and it's going to cost me more money too. I'm loosing my riding skills and not having much fun either.

[dirkwrong]

The thing is, if I do take the motor apart, which is becoming more and more clear to me that this is what I have to do, where do I draw the line on parts replacement/improvements? If the pistons are still good (likely I think), then do I just replace the rings and put it back together, or do I make some upgrades at the same time? For example, instead of using the old pistons, I could get higher compression ones from JE for $320. I could get the heads machined for dual plugs also. I think getting Tuneboy is going to be a must for me. I could get the combustion chamber coated by Swain Tech for not much money, as well as the tops of the pistons too. This has many benefits.

But really, I'd rather be riding than working on it. I guess it's my fault for buying a broken bike in the first place. I don't want to be one of those people who own a bike but never ride it.

[duczilla]

Before you tear the sucker apart, you need to confirm you have low compression. Your gauge may be maladjusted. Try another comp. tester, or use yours in something else. Your readings are within 10 percent of each other which is acceptable. Just because they are low means not so much, till you know if it's the tool or the motor. To absolutely find out what is wrong you gotta do the leakdown test. It will positively tell you whats wrong. That way if/when you tear it apart you know what you are looking for. Air out the exhaust means ex. valve. Air out the intake, in. valve. If you take a length of hose and slide it down the oil filler hole and stick your ear to it and hear a hiss its rings. etc. etc. Confirm the problem before you start to wrench and it will save tons of work.

[dirkwrong]

Originally Posted by duczilla

Before you tear the sucker apart, you need to confirm you have low compression. Your gauge may be maladjusted. Try another comp. tester, or use yours in something else. Your readings are within 10 percent of each other which is acceptable. Just because they are low means not so much, till you know if it's the tool or the motor. To absolutely find out what is wrong you gotta do the leakdown test. It will positively tell you whats wrong. That way if/when you tear it apart you know what you are looking for. Air out the exhaust means ex. valve. Air out the intake, in. valve. If you take a length of hose and slide it down the oil filler hole and stick your ear to it and hear a hiss its rings. etc. etc. Confirm the problem before you start to wrench and it will save tons of work.

What do you use to hold the crankshaft stationary for the leak down test? I broke one tool trying to do that. I also destroyed a nice carbon fiber brake rod, my own fault, but still, I'm breaking more things than fixing them.

I think what I am going to do next is check the valve clearances, since if they are way off this could be part of the problem. Then I will do a leak down test once I figure out a way to hold the crank stationary. Then I will try different plugs and wires to see if that fixes the misfire. If all of that fails, then it's tear down time.

[dirkwrong]

Originally Posted by st2lemans

By this I take it to mean non-resistor plugs and wires?

You should use resistor plugs and wires with any motor that has electronic ignition, or you risk misfires.

Tom

Tom, where do you buy Magnecor products? I can't find a source on the internet. I cannot find any pre-made wires either, except for the ones I have.

[yellow blur]

Originally Posted by dirkwright

What do you use to hold the crankshaft stationary for the leak down test? I broke one tool trying to do that. I also destroyed a nice carbon fiber brake rod, my own fault, but still, I'm breaking more things than fixing them.

I think what I am going to do next is check the valve clearances, since if they are way off this could be part of the problem. Then I will do a leak down test once I figure out a way to hold the crank stationary. Then I will try different plugs and wires to see if that fixes the misfire. If all of that fails, then it's tear down time.

+1 on the leakdown. The trick is getting the piston “Directly” dead nuts TDC (rod straight up) - not all that easy to do but doable. I just went through this but for other reasons. The cams were out (infamous flaking rockers) but all the closers were still in place so valves were closed with cam belts obviously off - so it didn't matter where the piston was as long as the valves are closed - just takes a little longer for the cylinder to pressure up.

My engine has less then 5000 miles.. ALL the intakes were leaking, and as you can see in the photos - from right where the build-up was. The exhaust were sealed - heard no leaks but once apart could see they were leaking some. Doing the leak down I only had 5% which is very low, but I could here by using a mechanics stethoscope with an open tube the valves were leaking in only one spot on the valve. There was the usual ring leak into the crankcase but nothing to worry about and can be deceiving but the gauge said otherwise. Your rings are probably just fine - wouldn’t touch them unless you can verify a problem with them!!

I don’t know what engine you have, but my 996 seats are cut WAY TOO WIDE, using only 2 angles - 45 degree seat and 30 degree for the top cut. This allows the bottom of the valves face to overlap into the valve seat as there is no definition (seats too wide to create a good seal). See Photos.. Carbon will build up under that and cause issues. If there is carbon build-up holding the valve open slightly and you adjust your valve to that the problem will only compound itself (as I see it).

If the bike is running too rich - and by looking at the spark plug example you pointed at and your comments, carbon is building up under the seats/valves. I don’t know how hard you ride it but before you start taking it apart, I’d try some strong Fuel Injection cleaner (Seafoam maybe?) and ride the thing like you stole it. Clean up the combustion chambers, valve seats, etc… then recheck your compression (Sitting idling etc isn’t helping readings or the engine) - Preferably using a leak down tester. I ride my bike fairly hard but not abusive hard - not bouncing off the rev limiter, mixture set at 3% and the plugs have a nice gray/white look. Been using Lucas fuel conditioner/cleaner, and have noticed since about 2000 miles earlier some of the build-up has been removed, but it couldn’t keep up with the leaking valves.

I ended up taking the heads off and in process of a 5 angle valve job with new guides since the exhaust are WAY out of tolerance, intakes are on there way and I just want to be done with it… I’m like you, would rather be riding it then working on it.. Maybe my choice in bikes was wrong for this.. But there’s just something about this bike…