| Author | Message | ||
     Dlwilson |
I've been chasing a lack of power issue, and today I fired up the engine while I had the airbox off. Both breather hoses were blowing a lot of oil vapor. There was no oil smoke in the exhaust, but the breather hoses put out enough oil vapor to fill my carport in a few minutes. Part of the symptoms with my loss of power is that the last road trip I did the engine lost power until after about 100 miles it wouldn't run anymore. But it died in front of a Harley dealer. They said when they opened the airbox they found about a cup of oil. They weren't sure where to look next, so I trailered it home. Now I'm wondering if this much oil vapor is normal, or if that's what caused all the oil in the airbox. I suspect my problem is related to the timing not being set correctly. Could that be causing all this oil vapor? | ||
| M1combat |
Too much oil? How much was put in at the last oil change? What's the dipstick at when checked? Check it after a ride long enough to warm the engine. | ||
| Brianb |
The vapor, if excessive, is coming from a failing compression ring. I say if because you need to do a consumption ck. Fill the case with a known amount and ride X number of miles. Ck oil level. Make sure to not overfill as this can be blown out the top as well. Under filling is better than overfilling to a certain extent. You should probably not loose more than 1/2-3/4 qt every 3000 miles. You can ck the health of your cylinders by doing a compresion or a leak down test. Two different tests. The engine loosing power could be a number of things. Dying gradually sounds more like fuel starvation(vapor lock). Especially if it runs fine when cooler or cold. If the engine is ingesting so much oil to degrade performance it will have blue smoke from the exhaust and the plugs will be fouling. Rough idle and terrible accleration will be symptoms of the engine. Check your fuel lines. This all assumes the engine was healthy to begin with. (Message edited by brianb on March 13, 2008) | ||
| Dlwilson |
Wow, fast responses. Thanks. I changed the oil shortly before the road trip, and didn't do much highway riding before the trip. I've never overfilled the oil before, but I guess I could have this time. I hope that was it, but I don't know. I changed the plugs after the road trip, because they were completely fouled. The engine has been running rough, but tonight when I saw the vapor the engine was running normally. I'll try to do a compression check this weekend. That's going to be interesting trying to get the compression gauge threaded into the rear cylinder. I'll also check the timing, as I figured out this evening that ECMSpy will show me the cam position sensor instead of me fooling around with a meter jabbing at the connector. I will report back. | ||
| Dlwilson |
I put the compression gauge on today, and there's 5-10 psi in the rear cylinder. I kind of figured something was wrong when I removed the rear spark plug and it was still shiny clean. I guess this is a broken ring, or could it be a burned valve? I haven't had the bike on the road since the failure, but when I idle it and rev it in the carport with the airbox off, it sounds fine. So the next step is to pull the engine and look at the rear head/piston/cylinder rings. We're planning on moving to a house with a garage in three months, but until then I'll be working in my carport. Maybe I'll be lucky and it will just be rings. Or maybe I'll be replacing pistons/cylinders, or a cylinder head. I'm getting more familiar with wrenching on the Buell. | ||
| Hogs |
5-10 psi in the rear cylinder the bike wd. not SOUND good I don`t think and 99.99999 percent sure it would not even start or idle check that gauge and the plug should be BLACK if that was the case.. but when I idle it and rev it in the carport with the airbox off, it sounds fine. Then you don`t have a serious problem as you may think...! (Message edited by hogs on March 15, 2008) | ||
| Dlwilson |
I checked it twice. I guess I could try it again. It's pretty simple -- the threaded hose screws into the spark plug hole and the gauge connects with a quick disconnect. Crank the engine and the needle barely moves. When I check the front the needle jumps right up (I forget the exact reading, around 125). Maybe it's a stuck compression ring, and I need to warm up the engine before I check the compression. I'll try that tomorrow. | ||
| Dlwilson |
I keep following up my own posts... Bristol's done racing for today, so I went back out to the carport. I put the plugs and wires back and fired the bike up. It sounded pretty good, although a little rough. I ran it for 5-6 minutes until it warmed up. Then I pulled the plugs and put the compression tester on the rear cylinder. It still barely twitched the needle. I figure I can remove the engine and pull off the heads and cylinders in a day. It will go quicker if I can do the work just by rotating the engine. I dream of the day I will have a garage and I can do a little work each night, instead of having to do it all at once in the carport. | ||
| Jos51700 |
You are holding the throttle WIDE OPEN to do your compression check, right? Timing has NOTHING to do with oil consumption, or blowby out the breathers. No way, No how. Your bike sounds like it is broken, plain and simple, if you hold the throttle wide open, and you KNOW the adapter is threaded completely (No cross-threading, please), into the rear cylinder, and you crank until the guage stops moving, and it only shows 10 PSI. IF you do all that, and get 10 PSI, (Or much more 10% difference from number one, you'll have some neat pics of expensive parts that don't work anymore, to post on BadWeb. And if you do need to repair this, don't go back to that shop. They should've had an answer in about 30 minutes. | ||
| Sgthigg |
+1 on Jos51700 | ||
| Brianb |
If you can, blow approx 60-80 psi shop air into the rear cyl with it at TDC. Then listen to exhaust, intake, and breather hoses. The position with most air noise leads to problem. If most noise is coming from the hoses, then it's a bad ring. The others lead to a valve not seating. No compression could also be a collapsed lifter. I'd go with the ring since you have an oil problem though. Compressions should not vary more than 15-20 psi for a fair engine. Within 10 for a strong engine. The engine loosing power also leads to a bad ring or loss of compression. Look at all the indicators. This is how good troubleshooting progresses. (Message edited by brianb on March 15, 2008) | ||
| Blake |
This will sound harsh, but it is truth. You have no business working on the engine. Take it to a pro. | ||
| Zac4mac |
If there's diddly compression AND a clean spark plug, the intake lifter is collapsed. Zack | ||
| Dlwilson |
Thanks, Zack, that makes a lot of sense. Blake, you have no idea what you're talking about. I've maintained every vehicle I've owned. I haven't been to a dealer or other mechanic for 15 years. I don't think I'll have any trouble inspecting the lifters, pulling the engine, removing the rear cylinder, or replacing the lifter, rings, piston or cylinder as necessary. I posted here looking for troubleshooting suggestions, like Brianb's. His suggestion to use a compressor to diagnose is great. Maybe other people can just lay their hands on a motorcycle, or whisper in its intake and find what's wrong, but it takes me a little longer. I look, I test, I think, I read, and usually I find the problem and fix it. I'm not taking this bike anywhere. I'll post back here when I find what's wrong with the bike, and fix it. | ||
| Zac4mac |
Good luck. I didn't mean to sound flippant, but I can't think of another scenario that leaves the plug clean too. Z | ||
| Jos51700 |
My only issues with Zack's diagnosis: A collapsed lifter still lifts the valve, just not fully (the Lifter plunger travel is a lot less than cam lift). You WILL hear this. He's not said anything about abnormal noise so far. That theory does not address the excessive blowby issue. I guessing either a broken ring, tossed wristpin clip and cylinder damage, or possibly detonation piston damage/broken ringlands. That's all I could see that would be such sudden failure... | ||
| Starter |
5-10 psi, even with no rings you will get more than this. I would be rotating the engine forward to get a better look for a hole burnt in the crown of the piston. It would also explain all the blow by and oil mist. | ||
| Bad_karma |
Dave what is the compression of the front cylinder? Oil or blue smoke coming out of the exhaust? joe | ||
| Dlwilson |
Joe, the front cylinder is about 125-130. I didn't write down the number because it pumped right up in a couple revolutions, and I assumed it was fine. There is no oil or blue smoke in the exhaust, although there is plenty of oil vapor (not smoke) coming out of the both breather hoses. Starter, I haven't heard any excessive clatter or banging from the rear. I plan to tear into it this weekend and find some broken parts. Thanks for all the suggestions. | ||
| Azxb9r |
A collapsed lifter still lifts the valve, just not fully (the Lifter plunger travel is a lot less than cam lift). You WILL hear this. He's not said anything about abnormal noise so far. I agree with that, a collapsed lifter would make a bit of a racket and the compression should be higher. A hole in the piston could be the problem. The plug would be wet from oil, but it would be clean. It would also explain the blow-by. A stuck or broken ring will usually have more compression. If you have access to compressed air, that is a quick and easy way to find the problem. Just make sure that the valves are both closed so that you don't get fooled. | ||
| Blake |
"I've been chasing a lack of power issue, and today I fired up the engine while I had the airbox off. Both breather hoses were blowing a lot of oil vapor. There was no oil smoke in the exhaust, but the breather hoses put out enough oil vapor to fill my carport in a few minutes. " There is one thing and one thing only that I know of that would cause such symptoms. A holed or broken piston. I'm sorry to have offended you but this shouldn't be a tough thing to diagnose. I'm no engine expert by any stretch, but there are very few things that will wipe out compression as you describe and send exhaust out the crankcase breathers. Actually just one that I know, a holed piston. | ||
| Brumbear |
maybe a hung valve but more probably something catastrophic sorry but I think Blake may have hit it with aholed piston it don't have to be a big mind you | ||
| Blake |
Hung valve wouldn't blow large amounts of oil and exhaust out the breather. | ||
| Starter |
Yep, a hole burnt in the piston, now rotate the engine forward like you were told to a day ago and have a look down the spark plug hole. | ||
| Brumbear |
I stand corrected I got hung up into the low compression on 1 cyl. blowing smoke out the tubes means compression into the crank case I do have an old 45CI that will ocasionally turn itself into a compresser but does not drop compression I fixed that by attaching a chevy PCV valve to the breather so it cant suck in air only clear it out but only if you have equal or close to compression | ||
| Dlwilson |
Okay, I have an answer. I pulled off the rear cylinder head today, and the problem was immediately obvious.    Apparently those piston rings are really important to compression. I don't know why it melted down. The head looks okay, but I'll get it checked out. The intake valve was beating some of the little bits of piston and ring. The cylinder doesn't look so good. I see a new piston, rings, and cylinder in my future.   | ||
| Moosestang |
Did you get the bike fixed? Any mods to the bike that might have contributed to that? Like running an open air box and aftermarket exhaust without a race ecm or richer map? |
