That's hardcore stuff right there.
scarred cylinder
So I pulled my head because while doing a spark splug change one of the valve cover bolts snapped.. no worries, I had a spare head laying around it was only when I seen that I have some wall scarring going on and it feels pretty deep in some places.. can I save it? Or do I need to go over size bore and if so what needs to happen?
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Hmmm, that looks like cavitation damage above rings...
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Ya that's what it looks like to accidentally delete the pressure map and then run 25 psi.
There should be 5 letters on the case. Usually split in two groups as in the photo above.
You'll do the same thing with the rod bearing chart. Your crank OD code for the rods is LBBBB. The rods will have numbers on them if they are OEM. If they are aftermarket, you will measure the ID of the rods and use the measurement on the chart rather than a code.
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Assuming you mean all letters are on the LEFT side of case(BB forward of journal and BBA aft of journal).
I mean since the outside of the bearing is held stationary by both the top and bottom case journals, they are not wearing against each other. The case journals(top and bottom) should have no wear. If it does, it spun a bearing, meaning the bearing spun with the crank and caused wear on the case journal. The case would be ruined if so.
The number on the rods you would look for are on the flat areas near the rod bolt. The one below is a "1".
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The number on the rods you would look for are on the flat areas near the rod bolt. The one below is a "1".
Not very long. I think honing the nikasil cylinders is just not a very good idea. If you must try it, here is something I found that might be of use. I copied the notes I had saved concerning nikasil but the website has more info.
bmwmotorcycletech.info
HONING SPECIFICS:
Honing is done on the old-style iron & steel cylinders, but not actual true honing on the Nikasil/Galnikal cylinders when doing a rings job (with few exceptions, see below). Honing may be done by a cylinder reclaiming company during the process.
Finish honing is best done with the SofTool brush hone made by Osborn International. Ball honing is adequate but not as good, as the ball tips wear after awhile and the hone does a poorer & poorer job. The SofTool does not exhibit such characteristics.
The crosshatch pattern is very important for ring break-in and wear, ring rotation, & even piston groove wear. The ideal proper angle is about 28°. If the angle is too shallow, the rings will rotate too slowly, the engine will use oil, the rings might also skate. If the angle is too steep, then starts can be rather dry, with fast ring and piston wear. The common 45° usually is OK ...but I DO think that 28° is better. Usually 220-280 grit stones are going to be OK.
If you must, or want to, hone a Nikasil/Galnikal cylinder, I suggest you use the "Brush Flex-Hone" which is also called a Ball Hone. www.brushresearch.com. Use only the aluminum oxide 240 hone. Do not use the silicon carbide hone 320, as there can be problems with that fast cutting hone. The purpose of the honing, IF you want to do it, on Nikasil/Galnikal, is simply to deglaze and clean up and prepare the surface for the new rings. Be exceedingly careful about using a aluminum oxide 240 grit hone. I try to avoid using such & might consider a much finer grit ...perhaps 600 or higher ...but! ...note what I do and do not. I do NOT hone Nikasil except in heavily glazed situations (very high mileage primarily). Even then I may not. I simply use 3M green industrial pads, soap and water, and my hand. Note that what I do is quite different than what Tom does, just below.
This is what Tom Cutter says (last such posting, AFAIK, was 04/08/2018, at least for the Airheads List):
"I always deglaze all used Nikasil cylinders with a 240-grit silicon-carbide Flex Hone* from Brush Research Manufacturing. and their proprietary honing oil. This restores a clean crosshatch that will facilitate rapid and complete ring seating. When rings are seated correctly, it is normal to see no measurable oil consumption between oil changes. (*This is NOT the material grit used on non-Nikasil cylinders.)"
THIS is what Tom Cutter said on a Facebook Airhead Group (I think this was November 15th, 2019):
"All BMW after 09/1980 production used Nikasil cylinders (or Galnikal, which was supplied by another maker but the same process. For those plated aluminum cylinders DEFINITELY use Aluminum Oxide, 120-grit Flex Hone with their Honing Oil. It is not at all inappropriate to re-hone a cylinder to restore a plateaued finish that will assure good ring seating with new rings.
"
Snowbum and Tom now agree much more closely, with that, above!...differing in the grit, however.
BMW Airhead motorcycle cylinders, studs, shims, sealants, Nikasil, Galnikal, boring, honing
BMW airhead motorcycle cylinders, stud, studs, iron, Nikasil, Galnikal, boring, honing, shims, gaskets, sealants
HONING SPECIFICS:
Honing is done on the old-style iron & steel cylinders, but not actual true honing on the Nikasil/Galnikal cylinders when doing a rings job (with few exceptions, see below). Honing may be done by a cylinder reclaiming company during the process.
Finish honing is best done with the SofTool brush hone made by Osborn International. Ball honing is adequate but not as good, as the ball tips wear after awhile and the hone does a poorer & poorer job. The SofTool does not exhibit such characteristics.
The crosshatch pattern is very important for ring break-in and wear, ring rotation, & even piston groove wear. The ideal proper angle is about 28°. If the angle is too shallow, the rings will rotate too slowly, the engine will use oil, the rings might also skate. If the angle is too steep, then starts can be rather dry, with fast ring and piston wear. The common 45° usually is OK ...but I DO think that 28° is better. Usually 220-280 grit stones are going to be OK.
If you must, or want to, hone a Nikasil/Galnikal cylinder, I suggest you use the "Brush Flex-Hone" which is also called a Ball Hone. www.brushresearch.com. Use only the aluminum oxide 240 hone. Do not use the silicon carbide hone 320, as there can be problems with that fast cutting hone. The purpose of the honing, IF you want to do it, on Nikasil/Galnikal, is simply to deglaze and clean up and prepare the surface for the new rings. Be exceedingly careful about using a aluminum oxide 240 grit hone. I try to avoid using such & might consider a much finer grit ...perhaps 600 or higher ...but! ...note what I do and do not. I do NOT hone Nikasil except in heavily glazed situations (very high mileage primarily). Even then I may not. I simply use 3M green industrial pads, soap and water, and my hand. Note that what I do is quite different than what Tom does, just below.
This is what Tom Cutter says (last such posting, AFAIK, was 04/08/2018, at least for the Airheads List):
"I always deglaze all used Nikasil cylinders with a 240-grit silicon-carbide Flex Hone* from Brush Research Manufacturing. and their proprietary honing oil. This restores a clean crosshatch that will facilitate rapid and complete ring seating. When rings are seated correctly, it is normal to see no measurable oil consumption between oil changes. (*This is NOT the material grit used on non-Nikasil cylinders.)"
THIS is what Tom Cutter said on a Facebook Airhead Group (I think this was November 15th, 2019):
"All BMW after 09/1980 production used Nikasil cylinders (or Galnikal, which was supplied by another maker but the same process. For those plated aluminum cylinders DEFINITELY use Aluminum Oxide, 120-grit Flex Hone with their Honing Oil. It is not at all inappropriate to re-hone a cylinder to restore a plateaued finish that will assure good ring seating with new rings.
"
Snowbum and Tom now agree much more closely, with that, above!...differing in the grit, however.
Thanks, I believe I’m going to use a scotch brite and go that route. I can still see the cross hatch very well with this motor. So I’m measuring clearances and I’m pretty much getting .025mm or .038mm with most being closer to .38mm.Not very long. I think honing the nikasil cylinders is just not a very good idea. If you must try it, here is something I found that might be of use. I copied the notes I had saved concerning nikasil but the website has more info.
BMW Airhead motorcycle cylinders, studs, shims, sealants, Nikasil, Galnikal, boring, honing
BMW airhead motorcycle cylinders, stud, studs, iron, Nikasil, Galnikal, boring, honing, shims, gaskets, sealants
HONING SPECIFICS:
Honing is done on the old-style iron & steel cylinders, but not actual true honing on the Nikasil/Galnikal cylinders when doing a rings job (with few exceptions, see below). Honing may be done by a cylinder reclaiming company during the process.
Finish honing is best done with the SofTool brush hone made by Osborn International. Ball honing is adequate but not as good, as the ball tips wear after awhile and the hone does a poorer & poorer job. The SofTool does not exhibit such characteristics.
The crosshatch pattern is very important for ring break-in and wear, ring rotation, & even piston groove wear. The ideal proper angle is about 28°. If the angle is too shallow, the rings will rotate too slowly, the engine will use oil, the rings might also skate. If the angle is too steep, then starts can be rather dry, with fast ring and piston wear. The common 45° usually is OK ...but I DO think that 28° is better. Usually 220-280 grit stones are going to be OK.
If you must, or want to, hone a Nikasil/Galnikal cylinder, I suggest you use the "Brush Flex-Hone" which is also called a Ball Hone. www.brushresearch.com. Use only the aluminum oxide 240 hone. Do not use the silicon carbide hone 320, as there can be problems with that fast cutting hone. The purpose of the honing, IF you want to do it, on Nikasil/Galnikal, is simply to deglaze and clean up and prepare the surface for the new rings. Be exceedingly careful about using a aluminum oxide 240 grit hone. I try to avoid using such & might consider a much finer grit ...perhaps 600 or higher ...but! ...note what I do and do not. I do NOT hone Nikasil except in heavily glazed situations (very high mileage primarily). Even then I may not. I simply use 3M green industrial pads, soap and water, and my hand. Note that what I do is quite different than what Tom does, just below.
This is what Tom Cutter says (last such posting, AFAIK, was 04/08/2018, at least for the Airheads List):
"I always deglaze all used Nikasil cylinders with a 240-grit silicon-carbide Flex Hone* from Brush Research Manufacturing. and their proprietary honing oil. This restores a clean crosshatch that will facilitate rapid and complete ring seating. When rings are seated correctly, it is normal to see no measurable oil consumption between oil changes. (*This is NOT the material grit used on non-Nikasil cylinders.)"
THIS is what Tom Cutter said on a Facebook Airhead Group (I think this was November 15th, 2019):
"All BMW after 09/1980 production used Nikasil cylinders (or Galnikal, which was supplied by another maker but the same process. For those plated aluminum cylinders DEFINITELY use Aluminum Oxide, 120-grit Flex Hone with their Honing Oil. It is not at all inappropriate to re-hone a cylinder to restore a plateaued finish that will assure good ring seating with new rings.
"
Snowbum and Tom now agree much more closely, with that, above!...differing in the grit, however.
UPDATE:
So I put green bearings in 2 of the journals which are the next size up and the plasti gauge was smushed a little further out and reading closer to .025mm. They’re all just so close together I’m having trouble deciding which bearing I need to go with.
I think you should place the plastigauge parallel with the shaft and measure like below. You may have some squeeze into the oil groove the way you did it which would affect the outcome.
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