850 Commando Cylinder Head Problem with Combustion Chamber
- Thread starter thackero
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
It looks to me like it ingested something, a stone maybe.
It's a bit hard so see in that photo. but sometimes detonation can pockmark a head, but my money would be on the stone/bit of metal going through there.
Personally I'd prefer to find a replacement head, but it might be fixable. Pull the valves and check for damage to them and the seats.
It looks to me like it ingested something, a stone maybe.
It's a bit hard so see in that photo. but sometimes detonation can pockmark a head, but my money would be on the stone/bit of metal going through there.
Personally I'd prefer to find a replacement head, but it might be fixable. Pull the valves and check for damage to them and the seats.
ashman
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
I would fix it, why spend money on another head that probly would need rebuilding anyway, pull the valves and see what else has happen inside but seats can be replaced as well as valves and chambers can be cleaned up.
Ashley
I would fix it, why spend money on another head that probly would need rebuilding anyway, pull the valves and see what else has happen inside but seats can be replaced as well as valves and chambers can be cleaned up.
Ashley
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
ive seen this in pre-Ms Peel Combat head after ingesting a thumb nail piece of Amal pot metal slide to spit out as sand size but didn't seem to bother running any way I could tell starts idle off road drag strip runs, so also shocked Blank B.I. Starring State, then looked at carbs, ugh. Bend a lip in ext valve and chip intake so had British Toys in NC put Kenny Dreer valve kit and new seats in. Its possible a 2 into one manifold inhaled a stud that got caught before blow up and just run again afterwards.
ive seen this in pre-Ms Peel Combat head after ingesting a thumb nail piece of Amal pot metal slide to spit out as sand size but didn't seem to bother running any way I could tell starts idle off road drag strip runs, so also shocked Blank B.I. Starring State, then looked at carbs, ugh. Bend a lip in ext valve and chip intake so had British Toys in NC put Kenny Dreer valve kit and new seats in. Its possible a 2 into one manifold inhaled a stud that got caught before blow up and just run again afterwards.
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
It obviously had some dents in it probably from a broken slide.
The major damage looks like corrosion damage from setting with water in the cylinder.
If there is corrosion damage that has gotten down around the valve seats I would look for another head as the seats may come loose. It's hard to tell for sure from the picture. Jim
It obviously had some dents in it probably from a broken slide.
The major damage looks like corrosion damage from setting with water in the cylinder.
If there is corrosion damage that has gotten down around the valve seats I would look for another head as the seats may come loose. It's hard to tell for sure from the picture. Jim
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
Looks like a candidate for Dunstall /Norvil eriseing . Hemisphered Chambers & re Angled inlets . Not a fan of repairing junk - but sometimes its Not Junk , if you see youre way around it .
I would be having a very close look at the valve train & rod & bearing on that side too , it possable thats not the end of the story .
Looks like a candidate for Dunstall /Norvil eriseing . Hemisphered Chambers & re Angled inlets . Not a fan of repairing junk - but sometimes its Not Junk , if you see youre way around it .
I would be having a very close look at the valve train & rod & bearing on that side too , it possable thats not the end of the story .
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
Yes have seem this before with sloppy worn out carb slide fracturing into motor. Piece was never found , probably broke up and out the exhaust so inspect carbs and bank account for healthiness.
Yes have seem this before with sloppy worn out carb slide fracturing into motor. Piece was never found , probably broke up and out the exhaust so inspect carbs and bank account for healthiness.
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
It is not corrosion and I believe the carb piece or spark plug electrode debris would possibly be the cause. Pistons have been replaced. I will clean up and pull valves to check seats. Thanks for all your help.
It is not corrosion and I believe the carb piece or spark plug electrode debris would possibly be the cause. Pistons have been replaced. I will clean up and pull valves to check seats. Thanks for all your help.
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Re: 850 Commando Cylinder Head Problem with Combustion Chamb
A stone would have knocked the plug gap to,and caused running on one cylinder before all that damage happened...could it be from a earler problem? have you seen this chamber before the pocks?
A stone would have knocked the plug gap to,and caused running on one cylinder before all that damage happened...could it be from a earler problem? have you seen this chamber before the pocks?
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