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cylinder pics and question. dings and scoring.. how much is too much?


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picked up a 2010 crf 450 for 1000$.  the bottom end was seized when we got it.   brought it home, put it in 5th, rocked it back and forth, and she started up!!!  def had a bit of a knock though so we took it apart.  filter was filled with copper too.  crank bearing is destroyed.

 

anyways, the cylinder has 2 tiny little dents in it, as well as a few small score marks.  should I get a new cylinder?  should I get it honed?  or should I just run it as it and not worry about it?

 

thanks.

 

e8vqc4.jpg

 

you can see the 2 tiny little dents in there, as well as the scoring.

 

 

I am looking into buying this rebuild kit... any opinions about it? anything else I might need?   is hotrods or wiseco better than OEM?

 

http://www.ebay.com/itm/Top-Bottom-End-Rebuild-Kit-2010-2013-Honda-CRF250R-Crankshaft-13-2-1-Piston-/131104830061?pt=Motorcycles_Parts_Accessories&hash=item1e8674f26d

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i have had lots of stuff in my oil filter when a crank started to go. Didn't break, but big time up/down play in the rod, and the shavings stripped off the nickasil in some places of the cylinder. nasty mess. how did the piston look ? was it obvious shavings went through the oil passages prior to hitting the filter ? you often get some marks on the exhaust side of the cyl that clean up nicely with scotchbrite, or an aluminum oxyde ball hone.. as he posted above, it's kind of hard to tell, especially without looking at the piston skirt.

Edited by MELK-MAN
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ill give it a wash with scotchbride and see if its left behind aluminum, its also got a divot or 2 in the cylinder.

 

the piston sides looked fine, but the buttom was chipped and dinged up...what would cause that?

 

there were 1 or 2 shavings in the top end, but I believe the filter caught most of them.

 

how about those 2 little dings beside the scratches?    there is almost more dings like that at the bottom 1/2" of the cylinder.... but I believe the piston (the rings at least) doesnt go quite that low in the stroke so I dont think those are anything to worry about.

 

how come avoid wiseco? 

Edited by coryf89
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ps: melk man, remember me??? youre the guy with like 800 hours on your crf with no hour meter right 😛    been a few years eh!!!!!

 

not really.. but my 08 that i got a few years back, has 490 hours, and the 04 hour meter broke, and the one on there now has almost 500.. 😉 (and conservatively has well over 1000 hrs).   Oh, and the 2014 350xcf that i got six months ago, has 120 hours 🙂

Edited by MELK-MAN
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that piston skirt is toast, from metal shavings that were squirted on the cylinder. The oil ring kept it below the combustion chamber though.  Nickasil  is mega hard though, so as some have suggested clean it up and see how it looks and feels.. then measure for round/spec. But, not sure i would risk it at this point, especially since you have very little in the bike.

Edited by MELK-MAN
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ok, I got another one here for you guys.... we noticed that there is a piece broken in the case... no idea where it went.  its right beside the flywheel, and below the cam tensioner guide, just the corner is busted off.   what does that little flat piece even do?

 

should we be worried?  I wouldnt think this is a very critical piece but ya never know.. any advice would be great

 

thanks

dpjmgi.jpg

Edited by coryf89
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There should have been a screen fitted in the slotted space at the bottom of the case. Which is missing in the picture.

If the piece recently broke it would either be sitting in the screen or in the stator cover.

It would be broken off from someone forcing the motor to turn with the cam chain disconnected or some other similar act.

The motor appears to have suffered from dumb-ass-ness,  and abuse.

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yeah.... we might or might not have tried finding TDC via the hole on the clutch side while the cam chain was loose.... causing it to double back on itself. oops!!!

 

the screen was taken out for cleaning....  

 

the piece isnt in the stator cover.

 

what is the point of that piece?   will it be fine to run it with the corner chipped off like that?

 

thanks

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I had a cylinder bored +.06 inches and replated and it exposed a significant number of casting pores towards the bottom of the bore.  A few of them were about .04 inches in diameter and half as deep.  I was extremely upset I paid so much and they never even called (it was a 4 cylinder and quite expensive).  I contacted the company and they blew me off so without mentioning names I contacted their biggest competitor and asked if they recommended I have them repair it.  They also said it would be fine.  Next I read a crap load of reports and the consensus was for the most part slightly more oil consumption and higher emissions but no real loss of performance.

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I had a cylinder bored +.06 inches and replated and it exposed a significant number of casting pores towards the bottom of the bore.  A few of them were about .04 inches in diameter and half as deep.  I was extremely upset I paid so much and they never even called (it was a 4 cylinder and quite expensive).  I contacted the company and they blew me off so without mentioning names I contacted their biggest competitor and asked if they recommended I have them repair it.  They also said it would be fine.  Next I read a crap load of reports and the consensus was for the most part slightly more oil consumption and higher emissions but no real loss of performance.

 

If its below the ring travel as in the pictures above there will be no effect on oil consumption

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we honed it and got the cylinder fixed... not bad for guys that are in over their head eh?

 

I am not sure if we broke the piece, or if it was broken before.... we def cant find it anywhere and we really didnt reef on the crank that hard to break something. we woulda heard or found it. thats besides the point.

 

just wondering if itsok to use that case still or not, im pretty sure its fine but wanted a 2nd opinion.

 

 

what does that little broken piece even do?? 

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I went through this myself, except when I bought mine I was told it was cherry!... ya ok...

 

This crank swap is real easy on this bike...  As for that piece, I'd be willing to bet at some point the previous owner has the cover off and removed the broken piece as it was probably laying on the filter screen that's on the bottom.  Who know how it broke though... 

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