Bad break in - rings not seating?
Discussion
This is for a 2005 Harley Twin Cam. I took the bore from stock 3.75in to 3.875in (88ci to 95). All machine work done by professional. I did disassemble/reassemble. New pistons, new rings.
This was my first complete top end overhaul so very much a novice. I made the mistake of putting the second piston rings upside down and didn’t find out until after the heat cycle (1-2-3-4min) (please no heat cycle comments, I’m familiar with gentle vs hard break in, just doing as instructed by the shop).
So I tore down again, re-used the rings (and head gasket), reassembled, new heat cycle. Still have oil blow-by, spark plugs shiny and black, rough idle.
(I was a cheapskate the first two times with a crappy ring compressor and it was harder then it should have been. Bought a new one now.)
So I tear down again and replace the rings (and head gasket), reassembled, new heat cycle. Still have oil blow-by, spark plugs shiny and black, rough idle.
I took it for a ride to see if putting a load on it would help push the rings out. It runs fine under load but not down low, dies when coming to a stop. The ride cleared up the plugs (brownish color, no oil) but compression test is way low.
Are my rings not seating due to glazed cylinders at this point (too much heat cycle idling on oily walls)? Should I get them re-honed? Or should I keep riding it in its wounded state and see if the rings will seat eventually?
This was my first complete top end overhaul so very much a novice. I made the mistake of putting the second piston rings upside down and didn’t find out until after the heat cycle (1-2-3-4min) (please no heat cycle comments, I’m familiar with gentle vs hard break in, just doing as instructed by the shop).
So I tore down again, re-used the rings (and head gasket), reassembled, new heat cycle. Still have oil blow-by, spark plugs shiny and black, rough idle.
(I was a cheapskate the first two times with a crappy ring compressor and it was harder then it should have been. Bought a new one now.)
So I tear down again and replace the rings (and head gasket), reassembled, new heat cycle. Still have oil blow-by, spark plugs shiny and black, rough idle.
I took it for a ride to see if putting a load on it would help push the rings out. It runs fine under load but not down low, dies when coming to a stop. The ride cleared up the plugs (brownish color, no oil) but compression test is way low.
Are my rings not seating due to glazed cylinders at this point (too much heat cycle idling on oily walls)? Should I get them re-honed? Or should I keep riding it in its wounded state and see if the rings will seat eventually?
What on earth are you on about heat cycling ?
Cyclists are all
s.
For most part rings not bedding in....are down to poor machining. Assuming of course parts used are correct and installed correctly too.
Which after managing to install rings upside down....would put into doubt all other aspects of the build.
Of course....even a car with poor ring sealing that used a load of oil......I dont think I've ever seen one that had huge "blowby"...so just exactly how are you determining this, or measuring this ? And what crankcase breathing is in place ?
Fouled plugs could be wrong plugs, improper tuning, etc etc.
Cyclists are all
s.For most part rings not bedding in....are down to poor machining. Assuming of course parts used are correct and installed correctly too.
Which after managing to install rings upside down....would put into doubt all other aspects of the build.
Of course....even a car with poor ring sealing that used a load of oil......I dont think I've ever seen one that had huge "blowby"...so just exactly how are you determining this, or measuring this ? And what crankcase breathing is in place ?
Fouled plugs could be wrong plugs, improper tuning, etc etc.
No idea about bikes or Harleys, or heat cycles, but my procedure for bedding in new rings is to accellerate hard in as high a gear as it will bear without bogging. This pressurises the bores, pushing the new rings against the walls.
Then coast, in gear, to slow down, throttle closed. This minimises bore pressure sucking oil up onto the walls.
Repeat.
You need to choose your road and hope for light traffic for this, else you will madden other drivers! But it doesn't need to be done ALL the time, just as much as possible until you are satisfied. 100-500 miles should do it.
John
Then coast, in gear, to slow down, throttle closed. This minimises bore pressure sucking oil up onto the walls.
Repeat.
You need to choose your road and hope for light traffic for this, else you will madden other drivers! But it doesn't need to be done ALL the time, just as much as possible until you are satisfied. 100-500 miles should do it.
John
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