zytec
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causes of possible piston failure KH250Hi all, some help will be appreciated please, while "ringing its neck" along a local 2 mile straight at 8000rpm got to end of it and engine was missfiring and stalling and eventually not restarting. There was plenty of smoke being developed along straight indicating a decent oil supply, but cant confirm if from all cyls tho.
When got back removed plugs and left and centre plug colours where a darker "biscuit brown" but right cyl plug was blackish in colour, all plugs B9HS and not very old. Checked compression on right cyl and it seemed very poor, removed right head and found part of piston crown possibly melted or erroded at frontish side near to exhaust port. Barrel appears not to be damaged. Refited head and 3 new plugs but still fails to start on any cylinder.
Is damage caused to right cyl due to possible oil starvation, wrong grade of plug, timing, mixture or not enough cooling. Any thoughts or similar experiences anyone please?
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ja-moo
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detonation. Bad fuel, timing, air leak any or all.
I know things are different in Europe, but running WFO flat out for miles is asking for trouble.
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The Wolfman
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+1 for detonation.
If it were oil starvation then you'd have a seizure, plugs are correct for a triple.
So that leaves the other two, fuel mix and timing (the usual suspects).
since your plugs are looking like a good to slightly rich mix, I'm gonna opt for the timing, but check the carbs and look for air leaks as a matter of course.
We like a good thrash Moo, it's sort of an 'up yours' for the Nanny state we live in, BTW have you Mooooved house?
...and what's WFO?
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zytec
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Thanks for the replies so far, a few things for me to look at then.
Regarding the air leaks for the mixture problem I assume that it is at connection where carb clamps to inlet flange and also where flange attaches to barell.
Also its running on K+N filters but i do not know what main jetting it has, if it has not been re-jetted by previous owner to suit K+N could this have contributed to failure, can understand why right cyl not firing but not why other 2 cyls wont start, when on first look they appear to be good(havent had heads off those yet)
Have posted different topic about piston identification, so I can get them, but I do assume ID is a matter of measuring it.
Well said Wolfman about the nanny state and I was also wondering what WFO is.
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180kid
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WFO = wide f*ckin open ?, usually said WOT = wide open throttle,... :P
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180kid
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Wide Full Open...?
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ja-moo
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| The Wolfman wrote: |
We like a good thrash Moo, it's sort of an 'up yours' for the Nanny state we live in, BTW have you Mooooved house?
...and what's WFO? |
We all like a good thrash! :lol: I was referring to "miles" at WFO. I will find a back road and run through the gears and go for a top speed run, usually less than a 1/2 mile. Running WFO for miles needs really good jetting, it heat soaks the motors and bad things happen to them. Usually deto or siezure and ruined undies..... :shock: )
And no, I haven't MOOOved, why do you ask?
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The Wolfman
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You used to live '2000 miles to our left'.
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ja-moo
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| The Wolfman wrote: | | You used to live '2000 miles to our left'. |
AHHHHHH :lol: Been forever since I even looked at that.....LOL
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simonh
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| zytec wrote: |
Also its running on K+N filters but i do not know what main jetting it has, if it has not been re-jetted by previous owner to suit K+N could this have contributed to failure, can understand why right cyl not firing but not why other 2 cyls wont start, when on first look they appear to be good(havent had heads off those yet)
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almost certainly your problem, if jetted at 67.5 or 75, too small with k&n's, just lucky that only one let go.
its also the solution to your present problem, not starting, the rh cylinder was best set up, thats why it died first and why the motor wont start, it was pulling the other two up.
reset everything correctly, run at least 82.5's and bump start
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180kid
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Moo, what happened at Roswell? sure been asked before just ya' live there, New Mexico, did ya' grab a piece,... :lol:
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ja-moo
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| 180kid wrote: | | Moo, what happened at Roswell? sure been asked before just ya' live there, New Mexico, did ya' grab a piece,... :lol: |
I went there for a turbo school years ago, The instructor was a very short gray guy, Man was he smart.
And I didn't grab a piece untill I got home to my GF...... :lol:
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husson73
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10500 RPM!
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zytec
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update to my piston probs, striped top end of all 3 down and rh piston was knackered other 2 ok.
Simonh right in his assumption about the main jets on the K + N s being wrong size, striped carbs down and jets were 75.5 so i suspect that was my problem for the piston failure.
bought the bits off simon, rebuilt it and been out earlier for 100 miles and it seems good. Jets now 82.5
might have slight timing prob as thought it was pinking at times, so thats next to look at in next day or so.
thannks for help at begining all
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simonh
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nice one 8) 82.5's normally right but keep an eye/ear on it
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