Fire on the first ride

You did use new 0.020 OS rings ? As using bigger rings can cause them to only touch the bore either side of the gap and on the opposite side. Easy to achieve by grinding the gaps to get them to squash down further as I have seen a couple of times with exactly your symptoms.
 
Quite right! Rings for one bore size are no longer "round" (as far as matching with the cylinder wall) if used in another (overbore) bore size. End gap can be adjusted as necessary and competition/performance ring sets often require gap filing but ring size has to match bore size or they will not seal properly.
 
ajscompy said:
You did use new 0.020 OS rings ? As using bigger rings can cause them to only touch the bore either side of the gap and on the opposite side. Easy to achieve by grinding the gaps to get them to squash down further as I have seen a couple of times with exactly your symptoms.
Click to expand...
I used the rings that came with pistons. The machine shop did the gaps.
 
I pulled the head and barrels, and This is what I found:

  • Rings in right places, white chamfer facing up. (Emgo pistons)
  • Oil passages clear in head
  • Oil passages clear in barrels
  • Inlet valves seals appeared in place

Everything was pretty clean, but the exhaust valves had a lot of oil carbon built up on them within the combustion chamber, and a lot of buildup in the exhaust chamber. Thoughts?
 
A crack in the cylinder head into the exhaust duct, or leaks past valve guides * ? Carbon deposit on the exhaust valve head, not on the inlet valve head is mysterious. Maybe oil droplets are sucked into the combustion chamber during valve timing overlap?

* Leaky exhaust valve guides is a possibility if standard replacement guides were fitted. Reaming and fitting O/S guides is the recommended procedure.

- Knut
 
Does the engine breather vent into the airbox or inlet manifolds a la mk3? Perhaps excess oil tank level is putting too much oil into intake and burning on to exhaust valves? Inlet valves tend to stay clean feom the fuel mix jitting them and they stay cooler.
 
Tornado said:
Does the engine breather vent into the airbox or inlet manifolds a la mk3? Perhaps excess oil tank level is putting too much oil into intake and burning on to exhaust valves? Inlet valves tend to stay clean feom the fuel mix jitting them and they stay cooler.
Click to expand...
No airbox on yet as I was syncing the carbs. Good point on the inlet valves!
 
mdt-son said:
A crack in the cylinder head into the exhaust duct, or leaks past valve guides * ? Carbon deposit on the exhaust valve head, not on the inlet valve head is mysterious. Maybe oil droplets are sucked into the combustion chamber during valve timing overlap?

* Leaky exhaust valve guides is a possibility if standard replacement guides were fitted. Reaming and fitting O/S guides is the recommended procedure.

- Knut
Click to expand...
I will inspect on the bench and look for a crack. Thanks for suggestion!
 
ajscompy said:
You did use new 0.020 OS rings ? As using bigger rings can cause them to only touch the bore either side of the gap and on the opposite side. Easy to achieve by grinding the gaps to get them to squash down further as I have seen a couple of times with exactly your symptoms.
Click to expand...
Great suggestion as well. I will look and report back.
 
What kind of head gasket are you using? There could be a leak from the pushrod tunnels past the head gasket. Maybe inspect the gasket and see if there's any sign of that. I used the metal ring composite gasket and it always seals well for me. I had less luck with the copper gaskets that I tried 40 years ago, so I switched. Certainly other's have no problem with the copper gaskets, and some put sealer on them to make them seal better. Just another thing to check...
 
I should probably be the last person to mention attention to detail, however 'a job worth doing is worth doing well'. The last time I raced, I forgot to tighten the clip on the fuel line which is up under the centre of the tank. It came off when I had all of the fastest guys skinned. I was well in the lead with all the tight parts of the circuit in front of me. What those guys ride are rocket-ships on the straights, but I had them beaten. I will never get another opportunity like that. I will go to my grave without achieving my greatest wish.
 
Off topic again Al, about racing but then fires do start from pulled fuel lines, mine caught fire back in the early 80s from a backfire and leaking fuel tap and not running an air filter at the time but had open velicity stacks, did a lot of top of the bike fire damage, was lucky I was able to pull the tank away as it could have been worst, my motor was ticking over while the fire was spreading with me on the bike, lucky a mate seen it before I rode off, happened so quick, too this day my fuel tank is still not locked on the bike.
 
Last edited:
My excessive smoking issue is solved.

I made a very stupid mistake. Due to wrong installation instructions from the machine shop that upsized my cylinders, my rings were install incorrectly. I had the proper top compression ring in the top slot, but I mistakenly put the thin ring (That was part of the three piece oil control ring set) in the second slot, and then just the spring like ring in the bottom oil control ring slot. I then had 2 rings left over per cylinder that I was told were “Extras”. After replacing my valve seals, I found and watched the below video from “Mighty Garage”, and I realized my error. After I added the compression rings to the top two slots, and installed the three piece oil control ring on the bottom slot, the bike did not smoke at all when I started it up. At least I now have new valve seals and oil lines. I one again learned that I am never too old to make dumb mistakes. Thanks for everyone’s suggestions. I really do appreciate it.

Cheers,

Gatsby

Mighty Garage Video for EMGO Piston ring assembly reference. My box did not contain any instructions.
 
I have only 20 miles on my top end rebuild. I have not yet seen any smoke. Hepolite pistons. Rings gapped tp .016.
New Kibblewhite valves and nos Rowe guides, Maybe just lucky.
 
gatsby said:
My excessive smoking issue is solved.

I made a very stupid mistake. Due to wrong installation instructions from the machine shop that upsized my cylinders, my rings were install incorrectly. I had the proper top compression ring in the top slot, but I mistakenly put the thin ring (That was part of the three piece oil control ring set) in the second slot, and then just the spring like ring in the bottom oil control ring slot. I then had 2 rings left over per cylinder that I was told were “Extras”. After replacing my valve seals, I found and watched the below video from “Mighty Garage”, and I realized my error. After I added the compression rings to the top two slots, and installed the three piece oil control ring on the bottom slot, the bike did not smoke at all when I started it up. At least I now have new valve seals and oil lines. I one again learned that I am never too old to make dumb mistakes. Thanks for everyone’s suggestions. I really do appreciate it.

Cheers,

Gatsby

Mighty Garage Video for EMGO Piston ring assembly reference. My box did not contain any instructions.
Click to expand...

gatsby said:
My excessive smoking issue is solved.

I made a very stupid mistake. Due to wrong installation instructions from the machine shop that upsized my cylinders, my rings were install incorrectly. I had the proper top compression ring in the top slot, but I mistakenly put the thin ring (That was part of the three piece oil control ring set) in the second slot, and then just the spring like ring in the bottom oil control ring slot. I then had 2 rings left over per cylinder that I was told were “Extras”. After replacing my valve seals, I found and watched the below video from “Mighty Garage”, and I realized my error. After I added the compression rings to the top two slots, and installed the three piece oil control ring on the bottom slot, the bike did not smoke at all when I started it up. At least I now have new valve seals and oil lines. I one again learned that I am never too old to make dumb mistakes. Thanks for everyone’s suggestions. I really do appreciate it.

Cheers,

Gatsby

Mighty Garage Video for EMGO Piston ring assembly reference. My box did not contain any instructions.
Click to expand...

gatsby said:
My excessive smoking issue is solved.

I made a very stupid mistake. Due to wrong installation instructions from the machine shop that upsized my cylinders, my rings were install incorrectly. I had the proper top compression ring in the top slot, but I mistakenly put the thin ring (That was part of the three piece oil control ring set) in the second slot, and then just the spring like ring in the bottom oil control ring slot. I then had 2 rings left over per cylinder that I was told were “Extras”. After replacing my valve seals, I found and watched the below video from “Mighty Garage”, and I realized my error. After I added the compression rings to the top two slots, and installed the three piece oil control ring on the bottom slot, the bike did not smoke at all when I started it up. At least I now have new valve seals and oil lines. I one again learned that I am never too old to make dumb mistakes. Thanks for everyone’s suggestions. I really do appreciate it.

Cheers,

Gatsby

Mighty Garage Video for EMGO Piston ring assembly reference. My box did not contain any instructions.
Click to expand...

There is nothing worse than a "teacher" doing something for the first time and doing everything wrong. He did not check the gap in the bore. He did not install the oil rings the easy way. I believe the ring would have marks to let you know the"top" side. Hasting rings do have dots.
gatsby said:
My excessive smoking issue is solved.

I made a very stupid mistake. Due to wrong installation instructions from the machine shop that upsized my cylinders, my rings were install incorrectly. I had the proper top compression ring in the top slot, but I mistakenly put the thin ring (That was part of the three piece oil control ring set) in the second slot, and then just the spring like ring in the bottom oil control ring slot. I then had 2 rings left over per cylinder that I was told were “Extras”. After replacing my valve seals, I found and watched the below video from “Mighty Garage”, and I realized my error. After I added the compression rings to the top two slots, and installed the three piece oil control ring on the bottom slot, the bike did not smoke at all when I started it up. At least I now have new valve seals and oil lines. I one again learned that I am never too old to make dumb mistakes. Thanks for everyone’s suggestions. I really do appreciate it.

Cheers,

Gatsby

Mighty Garage Video for EMGO Piston ring assembly reference. My box did not contain any instructions.
Click to expand...
 

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