lecap
Bachelor Dog
OK all you DIY home workshop I fix it all in my garage with bloudraad and a hammer okes:
P*** off and feel free to open your own thread to discuss whatever you want ;D
This one is for people in the industry /pro mecchies. You are welcome to comment:
What would you do?
This issue is not hypothetical and the story will probably bubble up here within the next days:
Quote:"
Hi XXX,
I finally found time to disassemble the top end of the engine and have a look at what's wrong today:
Damages found as follows:
Both exhaust valves are burned from overheating.One exhaust valve is severely burned causing severe loss of compression and preventing the engine to run.
The piston shows early / minor stages of detonation (aka "pinging" or "knocking") damage one the top compression ledge and the bottom end of the exhaust side piston skirt and to a lesser degree on the exhaust side piston skirt adjacent to the gudgeon pin journal cutouts. This damage has transferred onto the cylinder bore and caused the recent emission of blue smoke on slow run / slow engine braking & idling run by damaging the oil ring side rails from cylinder bore scarring & piston slap.
The combination of both valve damage and detonation piston damage points at an extremely lean running condition at high / top end rpm as the causing factor.
The combination of both burned valves AND detonation damage excludes poor piston to cylinder clearance or poor valve & valve seat machining as cause for all damages found as each engineering problem would only cause one of the problems and concurrent occurence is more then highly unlikely. Further, improper piston to cylinder bore clearance or assembly faults (like inverted compression rings et al.) typically cause failure almost immediately or within a few dozen of kilometres and will not allow the engine to run fine and without symptonms for 800 kilometres.
Prior to the top end overhaul: Due to progressed wear on piston, piston rings, cylinder bore and valves as well as valve seats the engine was running with compresion low enough not to suffer damages / CEF before the rebuild.
Once rebuild with rebored barel, remachined valve seats and new piston and rings the lean running condition of the engine became critical and caused the engine to fail.
Further evidence to this claim is given by the fact that the engine ran without any problems during break in whilst not run under full load.
Repair will require the following:
Manufacture and replacement of new cylinder sleeve. Your sleeve is currently bored to 87.5mm, the largest OS bore available from Wiseco. A new sleeve can be made and fitted any size from standard OEM / smallest Wiseco piston 86mm in steps of 0.5mm to 87.5mm
Replacement of piston and piston rings. OEM Yamaha parts might be used depending on machining of inner dia. new cylinder sleeve. Usage of OEM Yamaha pistons will necessitate fitment of new OEM gudgeon pin & circlips (minor).
Replacement of exhaust valve seats.
Replacement of exhaust valves.
Assembly using new gaskets & smalls.
Highly recommended: Replacement of exhaust valve stem seals as thermal damage is likely to have occurrred.
Most importantly: Get the bike dynoed & the carburettors jetted to sort out the lean running or fit the original exhaust and original airbox cover.
Due to the fact that the damages / engine failure of the recently rebuild engine was NOT caused by any faulty engineering or workmanship on my side but by failure of the owner or previous owners to set up the bikes carburettors in accordance with modifications to the motorcycle (in detail: perforated airbox cover and fitment of a "performance" exhaust) I will not accept any responsibility for the engine failure and will not entertain any warranty claims.
Since the motorcycle was in running condition as delivered and since I only performed a partial rebuild of the engine and did not have any reason to work on the carburettors at all I had reason to believe the motorcycle was modified & ok to run safely as it was.
In this context I wish to emphasize that there are absolutely no damages / failures obvious to components repaired by me (cylinder head cracks; various stripped threads in cylinder and cylinder head, replaced piston & piston rings beyond damages caused by detonation).
Should the engine be rebuilt to running condition either using a Wiseco piston or OEM parts I wish to emphasize the necessity to either readjust the bikes carburettor setup profesionally and thoroughly and under load or to return the airbox & exhaust system to their original state to prevent repeated and inevitable CEF.
I am aware that you will probably not believe a single word of what I just typed. I do not have any bad feelings about that as I would - in your situation - probably feel the same.
If you don't believe me - I would suggest and recommend to have the components of the engine to be assessed by a third party.
I am happy to suggest but am also open to suggestions. Please do not send the parts to the component replacers at the "appointed & approved agents" as we all know that they are rather useless. I am happy to either use any of the knowledgeable & skilled local WD forum members (your choice) like Gavin (Bradleys Classics), Andy (Hunday Services), Justin (Superbike Solutions), or Wolf (ex.and ret. Bo Kaap Honda) or any reputable and knowledgeable mechanics shop or any relevantly qualified RMI asssessor recommended and trusted by you.
Please feel free to see me or contact me at yor earliest convenience.
Kind regards
Jürgen
Le Cap
"end of quote
I decided to take the first step as this will most probably - according to the customer threatening me repeatedly - escalate into a mud slinging contest here on the forum.
Have fun! :happy1:
typos edited
P*** off and feel free to open your own thread to discuss whatever you want ;D
This one is for people in the industry /pro mecchies. You are welcome to comment:
What would you do?
This issue is not hypothetical and the story will probably bubble up here within the next days:
Quote:"
Hi XXX,
I finally found time to disassemble the top end of the engine and have a look at what's wrong today:
Damages found as follows:
Both exhaust valves are burned from overheating.One exhaust valve is severely burned causing severe loss of compression and preventing the engine to run.
The piston shows early / minor stages of detonation (aka "pinging" or "knocking") damage one the top compression ledge and the bottom end of the exhaust side piston skirt and to a lesser degree on the exhaust side piston skirt adjacent to the gudgeon pin journal cutouts. This damage has transferred onto the cylinder bore and caused the recent emission of blue smoke on slow run / slow engine braking & idling run by damaging the oil ring side rails from cylinder bore scarring & piston slap.
The combination of both valve damage and detonation piston damage points at an extremely lean running condition at high / top end rpm as the causing factor.
The combination of both burned valves AND detonation damage excludes poor piston to cylinder clearance or poor valve & valve seat machining as cause for all damages found as each engineering problem would only cause one of the problems and concurrent occurence is more then highly unlikely. Further, improper piston to cylinder bore clearance or assembly faults (like inverted compression rings et al.) typically cause failure almost immediately or within a few dozen of kilometres and will not allow the engine to run fine and without symptonms for 800 kilometres.
Prior to the top end overhaul: Due to progressed wear on piston, piston rings, cylinder bore and valves as well as valve seats the engine was running with compresion low enough not to suffer damages / CEF before the rebuild.
Once rebuild with rebored barel, remachined valve seats and new piston and rings the lean running condition of the engine became critical and caused the engine to fail.
Further evidence to this claim is given by the fact that the engine ran without any problems during break in whilst not run under full load.
Repair will require the following:
Manufacture and replacement of new cylinder sleeve. Your sleeve is currently bored to 87.5mm, the largest OS bore available from Wiseco. A new sleeve can be made and fitted any size from standard OEM / smallest Wiseco piston 86mm in steps of 0.5mm to 87.5mm
Replacement of piston and piston rings. OEM Yamaha parts might be used depending on machining of inner dia. new cylinder sleeve. Usage of OEM Yamaha pistons will necessitate fitment of new OEM gudgeon pin & circlips (minor).
Replacement of exhaust valve seats.
Replacement of exhaust valves.
Assembly using new gaskets & smalls.
Highly recommended: Replacement of exhaust valve stem seals as thermal damage is likely to have occurrred.
Most importantly: Get the bike dynoed & the carburettors jetted to sort out the lean running or fit the original exhaust and original airbox cover.
Due to the fact that the damages / engine failure of the recently rebuild engine was NOT caused by any faulty engineering or workmanship on my side but by failure of the owner or previous owners to set up the bikes carburettors in accordance with modifications to the motorcycle (in detail: perforated airbox cover and fitment of a "performance" exhaust) I will not accept any responsibility for the engine failure and will not entertain any warranty claims.
Since the motorcycle was in running condition as delivered and since I only performed a partial rebuild of the engine and did not have any reason to work on the carburettors at all I had reason to believe the motorcycle was modified & ok to run safely as it was.
In this context I wish to emphasize that there are absolutely no damages / failures obvious to components repaired by me (cylinder head cracks; various stripped threads in cylinder and cylinder head, replaced piston & piston rings beyond damages caused by detonation).
Should the engine be rebuilt to running condition either using a Wiseco piston or OEM parts I wish to emphasize the necessity to either readjust the bikes carburettor setup profesionally and thoroughly and under load or to return the airbox & exhaust system to their original state to prevent repeated and inevitable CEF.
I am aware that you will probably not believe a single word of what I just typed. I do not have any bad feelings about that as I would - in your situation - probably feel the same.
If you don't believe me - I would suggest and recommend to have the components of the engine to be assessed by a third party.
I am happy to suggest but am also open to suggestions. Please do not send the parts to the component replacers at the "appointed & approved agents" as we all know that they are rather useless. I am happy to either use any of the knowledgeable & skilled local WD forum members (your choice) like Gavin (Bradleys Classics), Andy (Hunday Services), Justin (Superbike Solutions), or Wolf (ex.and ret. Bo Kaap Honda) or any reputable and knowledgeable mechanics shop or any relevantly qualified RMI asssessor recommended and trusted by you.
Please feel free to see me or contact me at yor earliest convenience.
Kind regards
Jürgen
Le Cap
"end of quote
I decided to take the first step as this will most probably - according to the customer threatening me repeatedly - escalate into a mud slinging contest here on the forum.
Have fun! :happy1:
typos edited
![N[]vA](https://secure.gravatar.com/avatar/39fc70600d70a0afa40b682c3a695dc0?s=96){kind=avatar}
