Need advice Diagnosing engine knock.
Thread Starter
|
Novice
Joined: Apr 2017
Posts: 20
Likes: 2
From: Iowa
Need advice Diagnosing engine knock.
I could really use some help diagnosing a knock on my bike. Performance isn't notisibly different but the last month my bike has a horrifying knock coming from the top end of the front cylinder. It needs to be fixed before something horrible happens. I would rather do the work myself but could really use some advice from someone experienced with the evo.
2002 1200c 28000 miles. as far as I know the motor and is stock outside of drag pipes and intake.
Symptoms:
1. consistent knock in front rocker box.
2. Knock is the same when idling or decelerating but is louder when accelerating.
3. Excessive oil coming out of the breather bolts.
4. I noticed what appeared to be bubbles/ very little white foamy engine oil in intake that I believe came from breather bolts.
5. Engine feels as if it runs a little hotter then before.
6. Very slow drip of oil coming from the bolts that hold the rocker box cover on.
Do these symptoms sound familiar? Im looking for a diagnosis so I know what to fix but don't know where to start. Any advise on what to troubleshoot or do is highly appreciated. Thanks
2002 1200c 28000 miles. as far as I know the motor and is stock outside of drag pipes and intake.
Symptoms:
1. consistent knock in front rocker box.
2. Knock is the same when idling or decelerating but is louder when accelerating.
3. Excessive oil coming out of the breather bolts.
4. I noticed what appeared to be bubbles/ very little white foamy engine oil in intake that I believe came from breather bolts.
5. Engine feels as if it runs a little hotter then before.
6. Very slow drip of oil coming from the bolts that hold the rocker box cover on.
Do these symptoms sound familiar? Im looking for a diagnosis so I know what to fix but don't know where to start. Any advise on what to troubleshoot or do is highly appreciated. Thanks
Thread Starter
|
Novice
Joined: Apr 2017
Posts: 20
Likes: 2
From: Iowa
i took these photos 2 months ago when I started to notice the sound. I was getting slightly white exhaust smoke. soon after I cleaned intake filter and ran a drip line from breather bolts. Exhaust smoke stopped and haven't checked plugs since.
Thread Starter
|
Novice
Joined: Apr 2017
Posts: 20
Likes: 2
From: Iowa
Low on oil in the rocker box or the whole system? I know there's oil in the bike cause it's blowing it out the breather bolts. Could it be a bad oil pump? I change the oil regularly too. Can you go into more detail?
Road Warrior
Joined: May 2014
Posts: 1,875
Likes: 1,350
From: mississippi
Well this is my experience with same symptoms you described. when i bought my sportster it was several years old and very low mileage, so it was barely used by the first owner. I guess from not being used that much, oil was getting past the rings into the combustion chamber while I was riding it. It wasn't enough to make it smoke and it would use it so slow that I didn't notice it at first. Then one day I felt like the bike had more mechanical noise than the day before then some time later it started making a load knocking racket in the front. I thought a lifter blew out but that's not very common of a problem so before i did anything I always check the simplest stuff first, so I checked my oil and it was really low, so I topped it off, cranked it up and the noise instantly went away. After that i kept a close eye on my oil and I rode the hell out of it for several thousand miles and I guess it broke in or something because it stopped eating oil. I rarely have to top it off between oil changes now and she's running strong
Trending Topics
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,936
Likes: 8,036
From: poway
I could really use some help diagnosing a knock on my bike. Performance isn't notisibly different but the last month my bike has a horrifying knock coming from the top end of the front cylinder. It needs to be fixed before something horrible happens. I would rather do the work myself but could really use some advice from someone experienced with the evo.
2002 1200c 28000 miles. as far as I know the motor and is stock outside of drag pipes and intake.
Symptoms:
1. consistent knock in front rocker box.
2. Knock is the same when idling or decelerating but is louder when accelerating.
3. Excessive oil coming out of the breather bolts.
4. I noticed what appeared to be bubbles/ very little white foamy engine oil in intake that I believe came from breather bolts.
5. Engine feels as if it runs a little hotter then before.
6. Very slow drip of oil coming from the bolts that hold the rocker box cover on.
Do these symptoms sound familiar? Im looking for a diagnosis so I know what to fix but don't know where to start. Any advise on what to troubleshoot or do is highly appreciated. Thanks
2002 1200c 28000 miles. as far as I know the motor and is stock outside of drag pipes and intake.
Symptoms:
1. consistent knock in front rocker box.
2. Knock is the same when idling or decelerating but is louder when accelerating.
3. Excessive oil coming out of the breather bolts.
4. I noticed what appeared to be bubbles/ very little white foamy engine oil in intake that I believe came from breather bolts.
5. Engine feels as if it runs a little hotter then before.
6. Very slow drip of oil coming from the bolts that hold the rocker box cover on.
Do these symptoms sound familiar? Im looking for a diagnosis so I know what to fix but don't know where to start. Any advise on what to troubleshoot or do is highly appreciated. Thanks
If you have a knock on the front cylinder that increases with load (accelerating), I would suspect that you might have scuffed a piston.. Plugs actually look a little rich with the front looking worse which might be the results of poor compression and some oil bypassing the rings.. Oil blowing out the breather can be indicative of poor ring seal. This again is possible indication of a scuffed piston. The knock could be from excessive carbon build up..
I'm not saying that this is the case but in the outside chance that it's simply carbon build up an you have a motor that like to bleed a little oil out the breathers, I'd start trying to decarbon the chambers with seafoam then do a compression check.. I suspect that you will find the fron cylinder compression low..
To decarbon the cylinders with seafoam, get the motor hot. Remove the AC and while running the throttle up enough so that it don't stall, squirt a 50/50 mix of seafoam and water in the intake. Let the motor stall and set for 15 minutes then restart and ride.. If the knock is gone, you got lucky..
Do a compression check to see if the front and rear cylinders are within 10% of each other. If out, the top end needs redoing.. It could possibly extend to the lower end but you'll know more after the top end is off.
If this is beyond what you think you can do, take it to a shop.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Thread Starter
|
Novice
Joined: Apr 2017
Posts: 20
Likes: 2
From: Iowa
I just changed the oil and added Lucas oil stabilized 3 weeks ago. It was a little more quiet but not what I wanted it to be. I've owned this bike for three summers and I put on 3,000 to 4,000 miles a summer with regular maintence. Ill start with 3 quarts and in 3000 miles I'll pour out a 2.25 quarts. I do get a lot of oil out of the breathers and just figured that's where it was going.
I'm down to try to clean the carbon and definitely feel comfortable Removing the ac and spraying seafoam in the carb. Why mix water with the sea foam? Could it separate and cause other issues? ive always tried to keep water out of my motor haha.
I'm down to try to clean the carbon and definitely feel comfortable Removing the ac and spraying seafoam in the carb. Why mix water with the sea foam? Could it separate and cause other issues? ive always tried to keep water out of my motor haha.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,936
Likes: 8,036
From: poway
I just changed the oil and added Lucas oil stabilized 3 weeks ago. It was a little more quiet but not what I wanted it to be. I've owned this bike for three summers and I put on 3,000 to 4,000 miles a summer with regular maintence. Ill start with 3 quarts and in 3000 miles I'll pour out a 2.25 quarts. I do get a lot of oil out of the breathers and just figured that's where it was going.
I'm down to try to clean the carbon and definitely feel comfortable Removing the ac and spraying seafoam in the carb. Why mix water with the sea foam? Could it separate and cause other issues? ive always tried to keep water out of my motor haha.
I'm down to try to clean the carbon and definitely feel comfortable Removing the ac and spraying seafoam in the carb. Why mix water with the sea foam? Could it separate and cause other issues? ive always tried to keep water out of my motor haha.
Seafoam does not mix with the water.. You can use straight seafoam if you want.. You can also use straight water if you want.. Using the 2 together is personal preference.. I prefer doing this just before an oil change..
