Can this damaged small end rod (XR600) be salvaged? With pics.


10 replies to this topic
  • cleonard

Posted January 20, 2008 - 01:01 PM

#1

I'm in the starting stages of putting together an engine to replace the very tired one that sits in my XR600. I picked up this 90 bottom end. It appears to have very low hours on it. There is very little sign of wear anywhere on any of the gears.

It did suffer a bad piston seizure and completely toasted the cam and rocker arms. Looks liek a classic case of oil starvation. I just took the wrist pin out and removed the piston. The wrist pin didn't just slide out, but I did have to press pretty hard and work it back and forth. I did not have to resort to tools to remove it.

Here is what I found in in the rod small end. It looks big in the photos, but it just lightly grabs a fingernail. A new wrist pin fits pretty well.

So can I clean out the center and still run it? My first reaction is to replace it, but I wish to avoid splitting the cases if at all possible. Not that it matters all that much, but the engine will be in the stock configuration with 9:1 compression and the Honda cam.


rod1.jpg rod2.jpg rod3.jpg

These are thumbnails. Click for a big version.

  • pwrpapa

Posted January 20, 2008 - 01:23 PM

#2

take a small brake cylinder hone an clean it up. check to see if your still in spec after your done honing it.( ckeck shop manual for spec)
I've ran them in worse condition then that. as long as the pin doesn't wobble in the rod I would give it a try.

  • ToXicD

Posted January 20, 2008 - 01:35 PM

#3

i agree with papa, smooth it out and if you still have pits it souldnt matter as long as you have no high spots from the metal gouging :cool:

  • XRMANU

Posted January 20, 2008 - 02:18 PM

#4

A good machine shop can machine out the bad small end and put a little bras piece in it instead,just like in the Hot Rod's. Works fine.:cool:

  • pwrpapa

Posted January 20, 2008 - 03:40 PM

#5

Honda had some major oiling problems on the 600 motor.
You might want to find out why it locked up.
The big end might be bad too.

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  • cleonard

Posted January 20, 2008 - 06:01 PM

#6

Honda had some major oiling problems on the 600 motor.
You might want to find out why it locked up.
The big end might be bad too.


So far in every other way it is looking good. The big end is as smooth as silk. The big is tighter than any other used crank that I had the opportunity to examine. I'm going to try the brake hone and see what it's like. I've done this before, but this one has more damage than the others. Everything else that I have looked at so far looks new. There are no wear marks on any of the gears and the clutch basket is pristine.

I will be taking the oil pump apart to check it. I have several and I'm sure that I can piece together a good one if it is screwed up. I'll be checking that all is good with the oil system before I start it. The main things that I am aware of is the oil into the end of the crank, the check valve, the orifices, and the external lines. I will be doing the "loosen the top oil tube bolt" oil pressure check when I first start it up.

  • Nailpounder

Posted January 21, 2008 - 01:10 AM

#7

I don't see why you couldn't hone that a tad. It's better to be a bit loose than to tight. Have you checked your pin and rod hole to see what they measure? Like pop's said if it doesn't wobble give it a try. What do you have to lose at this point? It beats spliting the cases. After you get it back together if it doesn't knock you're home free. Which it shouldn't if the pin doesn't wobble.
What do you think caused the oiling problem? Maybe he never changed the oil filter or???something else went wrong? I dunno:eek:

  • crmc33

Posted January 21, 2008 - 05:01 AM

#8

Youd be unlucky if the big end has suffered any significant damage as the roller bearing is less sensitive to lack of oil. It will also have been likely to have been getting some splash fed oil to it from the sump and gears etc

  • martinfan30

Posted January 21, 2008 - 08:08 AM

#9

I would try the hone idea then see what it feels like together. I'd hate to see you get it running and have a wrist pin knock...

  • Rockjockey

Posted January 21, 2008 - 08:34 AM

#10

If it were mine (and it's not) I would split the cases and replace it for longevity. I dont like to do things twice and with my luck when the problem resurfaces I would be miles and miles form nowhere. I would be of the mind to spend a little more now than alot more later, you know the old pay me now or pay me later strategy. Good luck with it whatever path you choose.

  • martinfan30

Posted January 21, 2008 - 08:56 AM

#11

If it were mine (and it's not) I would split the cases and replace it for longevity. I dont like to do things twice and with my luck when the problem resurfaces I would be miles and miles form nowhere. I would be of the mind to spend a little more now than alot more later, you know the old pay me now or pay me later strategy. Good luck with it whatever path you choose.


I'm with you 100%.

Don't like walking.





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