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Know a good machinist? (Piston Problems)

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Howdy yall, I finally got around to tearing into my bike and found out why it was acting a fool.

IMG_20171229_152959.thumb.jpg.172b921360f6e80644563dbda6a2f10c.jpg

IMG_20171229_152843.thumb.jpg.6f6adc7b108e444df37bc87f5f13093b.jpg

 

That's the bad side of the piston. The other side also had a couple scrapes but not like this. 

I need a bore job, piston, rings and gaskets me thinks. Is my cylinder even borable? Yes, no? 

cylinder jug diameter: top: 100.5mm

cylinder jug diameter bottom: 100.9mm

Piston diamter: 99.75mm

 

I'm assuming it had the stock piston in it so I need to go up in size, just not sure how bad my cylinder is. pictures couldn't get details of the scrapes but when you run a finger nail over it you can feel the grooves. This also helps explain the nonmetallic shavings i found in my oil filter previously. 

I think Mcma111 has a machine shop out there in cali. Ya'll want a job? lol

 

 

I'd also like to know what caused the piston to do this. I assume the rings and oil ring compressed too much and failed causing the piston to cant slightly to one side and scrape. 

I should have taken the jug off when I did the top end earlier this year. Live and learn though.

 

Edited by TxSamsquanch

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3 minutes ago, JoeRC51 said:

What's your cam and rocker arms look like. How much oil came out when you drained it ?

They're good, no marrs or scrapes on cam or rocker arms.

Didn't drain the oil this time, no need to until I get the piston and cylinder rebuilt. (It's got 2 quarts new oil in there. Ride prior to parking it: *Bike acts like it's seizing up* "Better check the oil,... SHIT... no oil.. Alright 2 quarts in! Vroom Vroom Grind Grind *dead* "Well... load it up in the truck... &%$#@!."

The bike had been burning oil since I bought it. Rebuilt the top end and still burnt oil. Didn't check the piston - rookie mistake.

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This was caused by lack of oil. Stock bore is 97 mm. yours has been overbored to 100 mm. The cylinder looks like it might be damaged to the point where resleeving is necessary. 100 mm is as far as you can go with the stock jug. I have a Wiseco 102.4 piston kit (resleeving necessary) available if you go that route. Take a hard look at the cam and rockers, they might be galled too. 

Edited by creeky

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I've already sent Engine Dynamics an Email. lol Bout how much am I looking at?

Hopefully it'll just be a rebore and not a re-sleeve. She'll be basically brand new after this. :p

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There has to be a machine shop in your area that does quality bike work. There is nothing unique or special about an XRL engine that requires sending it several states away for a simple overbore. Ask around locally. Take it to a machinist and he can measure it and let you know what piston to buy, then he can bore it to fit. 

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20 hours ago, TxSamsquanch said:

I've already sent Engine Dynamics an Email. lol Bout how much am I looking at?

Hopefully it'll just be a rebore and not a re-sleeve. She'll be basically brand new after this. :p

Engine Dynamics was closed this week.

 

If I recall correctly a bore job is about $90.00

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That is a severe failure, not just normal wear & tear.

Find out what's the cause and fix it, otherwise your new piston and cylinder may soon look the same.

 

Pics remind me of an old thread about a DRZ400 owner who simply replaced damaged parts,

without searching and fixing the cause of the failure (plugged up oil intake screen?)

His newly rebuilt engine lasted about 20 miles and failed in exactly the same way as it previously did.

Edited by mlatour
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On 12/30/2017 at 0:20 PM, JoeRC51 said:

What's your cam and rocker arms look like. How much oil came out when you drained it ?

So I misspoke, or did not inspect my arms diligently. I do have some damage to the rocker arms where they contact the cam shaft. I've got a new hot cams camshaft with maybe 4-10 hours ride time on it. Lobes on the shaft look decent. I'm gonna buy new rocker arms for this rebuild as well, and &%$#@!it, why not new valves.

New rocker arms, new cam shaft, new piston, new valves. Damn near gonna rebuild the entire thing. Not worth the $2800 I paid for it...  Last time I buy anything from a redneck or good ole boy.

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