[Jeff L]

this is out of the middle cylinder of my Rocket3.The other two look new.Can I sand down the area where its pitted to make it somewhat smooth?Will this area be prone to hot spots?

 

[bobscogin]

Clean up the damaged area and post another pic.

Bob

 

[La Dolce]

I can't say if you should run it or not but you will want to polish it after sanding to keep away hot spots and carbon build up.

 

[Dr. Benway]

Do you have huge thumbs, or is that a teeny little piston?

 

[hogster]

how did it get that way to begin with? ufo in the chamber or something...I would clean it off with a fine file or emory and run it but would not feel confident till I found the cause of the condition first.

 

[Guest]

Don't look like the ring land has any damage done to it...
File off any points or high spots so as pre-ignition doesn't occur...

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[bandit]

how much is a new one ?

 

[Old Codger]

No.

 

[bandit]

you might want to check out that oil cooler,not much air running around the middle barrel.

 

[Jeff L]

I cleaned it up some.That's about as far as I want to go.I cannt remember,I dont think it had an oil cooler on it.Could that of been the cause?When I took the engine apart,other than that one piston, it looked real clean.Crosshatch pattern still in the cylinders & all.No other part shows any wear at all.

 

[bandit]

yea,i was thinking trident (had a t160v new in 77)
i,d get another piston (and an oil cooler).

http://tr3oc.co.uk/wp-content/uploads/2012/07/hurricane-1-150x150.jpg

 

[bandit]

http://tr3oc.co.uk/

 

[el diablo]

i would replace it !!

 

[Larrydawg]

the rings are what makes the seal.. if there is no damage to the ring lands, hone the cylinder and run it....ive ran worse and had them last for years.. you do need oil cooler and check and make sure middle carb is not running lean..... my 2 cents
LarryDawg

 

[bandit]

what color was the middle spark plug when you took it out ?
...a tan color is about right.

 

[bandit]

Do you have huge thumbs, or is that a teeny little piston?

piston is 250cc or 15.25 cubic inches. gotta love online calculators .

 

[BigWilly]

how much is a new one ?

+1
Not sure what it cost, but can guarantee it will cost much more if it lets go once it's all back together. I've done that before. Spend the money so you know its correct. There will always be other shit to worry about.

 

[weaselpyker]

spend a bit now or a lot latter!

 

[Jeff L]

Thanks for all the feed back.I think Ill probably replace it.

 

[Glider]

Looks like classic signs of detonation starting to eat away at the piston. Detonation usually takes place near the exhaust valve at the edge of the combustion chamber (hottest place in chamber and poorest-quality fuel/air mix). You may have been on the verge of disaster there.

That piston looks like a hi-comp piston. Better check to make sure. Hi-comp Triumph engines running on pump gas with their old-fashioned combustion chambers are prone to detonation — especially on the triple's center cylinder. On a street triple that you want to get a lot of use out of, I'd recommend using the stock compression ratio.

You definitely want to run an oil cooler. Although they are called "air-cooled" engines, the oil does a huge amount of cooling as well.

And of course, make sure the timing is exactly what the manual calls for.

As far as reusing the piston, better not to. Detonation is a real piston killer.