Major Piston Problem......help!
- Thread starter StooL
- Start date
littleredrooster
Registered user
Hell's teeth!! That must have been giving signs and symptoms for several miles before it let loose!
Tentative diagnosis (diagnoses?)
1. Detonation (pinking) caused by incorrect timing, poor petrol (wasn't the first run after standing through the winter, was it?) or air-leak on the inlet side of that cylinder.
2. No valve clearance on the exhaust valve nearest the damage causing the valve to glow red-hot and cause detonation in that area.
3. Incorrect grade (heat range) of spark plug being used.
4. Errrmm... can't think of anything else at this time of night. Will sleep on it. Almost certainly related to detonation, though.
Sorry - life is a bitch sometimes.
Tentative diagnosis (diagnoses?)
1. Detonation (pinking) caused by incorrect timing, poor petrol (wasn't the first run after standing through the winter, was it?) or air-leak on the inlet side of that cylinder.
2. No valve clearance on the exhaust valve nearest the damage causing the valve to glow red-hot and cause detonation in that area.
3. Incorrect grade (heat range) of spark plug being used.
4. Errrmm... can't think of anything else at this time of night. Will sleep on it. Almost certainly related to detonation, though.
Sorry - life is a bitch sometimes.
Fanum
Toubab
I'm totally no engine expert or anything but my first reaction to those pics is friction, heat, gas flow...
lots of scoring, melted alloy....mind you, there does appear to be some mechanical damage on that side of the crown from the exhaust valve hitting the top of the piston......that might be from when it finally failed though.....
Very ugly damage, whatever caused it!
G|ood luck chap!
lots of scoring, melted alloy....mind you, there does appear to be some mechanical damage on that side of the crown from the exhaust valve hitting the top of the piston......that might be from when it finally failed though.....
Very ugly damage, whatever caused it!
G|ood luck chap!
PB
The marks that you see on the exhaust valve cutout are caused by localised detonation at an inapropriate time on the pistons travel (pinking).
Small uncontroled explosions not initiated by the spark plug but by by some other catalyst.
I did not see the head and valves personally but the mechanic who was rebuilding said they were all in good condition with no signs of damage or over heating.
Also no signs of any problems on the other cylinder.
The marks that you see on the exhaust valve cutout are caused by localised detonation at an inapropriate time on the pistons travel (pinking).
Small uncontroled explosions not initiated by the spark plug but by by some other catalyst.
I did not see the head and valves personally but the mechanic who was rebuilding said they were all in good condition with no signs of damage or over heating.
Also no signs of any problems on the other cylinder.
StooL
Registered user
Thanks Kenny
Many thanks Kenny for coming over last night with the repair manual disk and for taking those fine photos. We will no doubt get lots more suggestions for what may have caused my bike to blow up!
My bike is now back on the road and running like it did before. I'm going to get it Dyno'd and mixture tested as soon as possible and will also fill it up with some decent fuel. I'm also going to ride around without my ear plugs in for a bit to see if I can detect any strange noises.
I'm still saying I got no detectable signs of trouble before she blew. I know this is hard to believe and I am starting to doubt it myself but I am at least a little mechanically minded and I've got experience of hearing/feeling the signs of impending doom with a couple of old cars I've owned in the past.
Anyway, I'm back on two wheels.....for now!
Many thanks Kenny for coming over last night with the repair manual disk and for taking those fine photos. We will no doubt get lots more suggestions for what may have caused my bike to blow up!
My bike is now back on the road and running like it did before. I'm going to get it Dyno'd and mixture tested as soon as possible and will also fill it up with some decent fuel. I'm also going to ride around without my ear plugs in for a bit to see if I can detect any strange noises.
I'm still saying I got no detectable signs of trouble before she blew. I know this is hard to believe and I am starting to doubt it myself but I am at least a little mechanically minded and I've got experience of hearing/feeling the signs of impending doom with a couple of old cars I've owned in the past.
Anyway, I'm back on two wheels.....for now!
PB
No probs.
Mind and have the heads re torqued after a few hundred miles and also make sure the valve clearances are OK, before the dyno run preferably.
No probs.
Mind and have the heads re torqued after a few hundred miles and also make sure the valve clearances are OK, before the dyno run preferably.
Re: Thanks Kenny
Let's hope not...
Mike
StooL said:
Let's hope not...
Mike
The Mechanic
Guest
Like I said and many others after....
DETONATION>>>>or in laymans terms 'pinking'. As I said earlier.
Very worried to hear that you've experience of mechanical mayhem with cars as well!
DETONATION>>>>or in laymans terms 'pinking'. As I said earlier.
Very worried to hear that you've experience of mechanical mayhem with cars as well!
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