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Old 11-26-2008, 06:23 AM   #1
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XR650R engine rebuild advice please

Long story short: Ran it low on oil, started making a hell of a racket. Knocking noise that screamed "bearing" to me. Right?

So, I've torn down the top end and everything is fine, save for a kind of gnarly looking camshaft with some ridges and grooves in the lobes. I'm replacing that anyway because the auto decomp mechanism was taking a poop.

The piston pin is in spec, rod small end OK, piston OK, ring grooves OK, cylinder in spec, etc. Cam chain looks OK, tensioner works fine, chain guide checks out.

I've checked out the crank as much as possible without splitting the case. Side clearance between the rod and crank is in spec, and there is no noticeable radial end play, though that can't really be measure accurately until the crank comes out.

My question: What's most likely to be the issue here? By my way of thinking the options are down to crank roller bearings or connecting rod big end bearing. I sure as shit hope it's not the latter as that means replacing the crank, or taking it to a shop for a rebuild if that's possible (pressed-together crank).

Anyone with more experience with the mighty XRR want to chime in?
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Scribe screwed with this post 11-26-2008 at 06:35 AM
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Old 11-27-2008, 02:27 PM   #2
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Not only the crank, valves and piston you have to worry about.. you also have to check the transmission bearings.

my first thought is "how bad" or low as the oil? did any come out when you drained the oil?

color of parts in the filters? all silver or is there a little bronze/gold specs in it..

.. you could replace the cam and everything on top but that might just be a bandaid as other parts my fail afterwards.

I've taken the BRP engine down to the case for a rebuild..

I'd be suspect of your motor and would want to mic everthing during tear down to determine the wear of items.

It sucks.. I know.. but I rather replace worn parts at time of rebuild than have a failure in the middle of BFE.

best of luck..

I would look at it this way.. no time like now to build the engine to your dreams. it's going to cost money no matter which way.
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Old 11-27-2008, 05:09 PM   #3
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In a situation like this, it might be cheaper to just buy a replacement engine.
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Old 11-27-2008, 09:06 PM   #4
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Quote:
Originally Posted by ADVJake
In a situation like this, it might be cheaper to just buy a replacement engine.
I see them on ebay all the time.
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Old 11-28-2008, 08:19 AM   #5
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Did you re-fill the oil and run it? If so did it make a bunch of noise then?

In general, the first thing to go will be any plain bearings (I don't know the 650R motor well, but big end bearings are usually plain in most modern four strokes), roller or ball bearings will survive with minimal oil for a little while.

The gearbox will generally long outlast the crank and top end in the event of oil starvation.

If it were me I'd rebuild it rather than buy a used motor as you never know what you'll get with a used motor and rebuilding is a good excuse to make everything in there just as you like it

If you do need a new crank, they are surprisingly affordable straight from honda. Service Honda usually has the best prices, but most anywhere should have one for under $400.

I believe Carillo does rods and of course the HRC top end kit is quite nice. There are also the 680cc kits to think about and Falicon cranks....
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Old 11-28-2008, 02:59 PM   #6
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Quote:
Originally Posted by kenaroo
Not only the crank, valves and piston you have to worry about.. you also have to check the transmission bearings.

my first thought is "how bad" or low as the oil? did any come out when you drained the oil?

color of parts in the filters? all silver or is there a little bronze/gold specs in it..

.. you could replace the cam and everything on top but that might just be a bandaid as other parts my fail afterwards.

I've taken the BRP engine down to the case for a rebuild..

I'd be suspect of your motor and would want to mic everthing during tear down to determine the wear of items.

It sucks.. I know.. but I rather replace worn parts at time of rebuild than have a failure in the middle of BFE.

best of luck..

I would look at it this way.. no time like now to build the engine to your dreams. it's going to cost money no matter which way.

I filled the oil again after the "incident" and rode for about 20 miles, mostly because I had to get out of Mexico. The bike shifted fine, did not smoke, did not over heat. It just sounded like a coffee can full of rocks. When I finally drained it, the oil was dirty, but not full of metal of any kind. Neither was the filter.

This whole thing has me scratching my head.

Everything has been measured, remeasured and measured again. That's how I know what's good and what ain't. If you could see the internals of this engine you'd understand why replacing it with a new one would be foolish. Something went bad, and that something needs to be replaced. I just can't find out what the hell it is.

BTW, this engine has roller bearings on the crank, not plane bearings.
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Old 11-28-2008, 04:21 PM   #7
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Some guy ran his BMW out of oil and the connecting rod and the crank shaft were all scratched up.
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Old 11-29-2008, 05:45 AM   #8
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The big end is still my guess, I'm pretty sure its a plain bearing:)
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Old 11-29-2008, 06:05 AM   #9
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Quote:
Originally Posted by BikePilot
The big end is still my guess, I'm pretty sure its a plain bearing:)
Yes, correct on that. The bearings in the case are roller bearings.

I think the big end is highly suspect as well, but wouldn't excess play show up as sloppiness in the radial end measurement? Like I said above, there is no play between the rod big end and crank, and the side clearance between the rod and crank is in spec.

I know I should just tear it down but that requires some tools I don't have.

Oh, and one more clue I just remembered: While I was riding it noisy, it would get quieter under load (up a small hill) and louder at light load (coasting) or at idle.
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Old 11-29-2008, 01:54 PM   #10
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Contact Rob Barnum - he knows the XRR engines! And how to get power without loosing reliability.

Good luck in building a great engine
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Old 11-29-2008, 03:04 PM   #11
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It might be important to know how the engine got low on oil and if you remember exactly how much oil you had to add to get to proper level.
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Old 11-29-2008, 03:11 PM   #12
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Hmm, a big end would normally be louder under a load, not quieter. Also it would normally show up when measuring the play, but such measurements are quite hard to do with sufficient accuracy to determine much (at least hard for me to do).

Are you positive the noise was coming from the motor? I've seen maladies with a drive chain make all sorts of weird noises. I even worked on a bike once that had an ever so slightly bent shifter such that it just contacted the chain around the countershaft sprocket. I'd have sworn a gear had gone in the transmission from the way it wouldn't stay in gear and the way the shifter vibrated when shifting...

As someone earlier asked, any clues from the color of junk in the oil? A big end will usually leave a little bit of copper powder in the oil while main bearings will tend to leave chrome chips.

Good luck!
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Summer 2009 Ride Report http://advrider.com/forums/showthrea...1509c&t=507038
Summer 2008 RR. http://www.advrider.com/forums/showthread.php?t=367703
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Old 12-02-2008, 05:37 AM   #13
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Quote:
Originally Posted by Scribe
I know I should just tear it down but that requires some tools I don't have.
On a shop tricks thread someone mentioned that motorcycle dealers have been known to lend or rent tools. If it is not motorcycle specific, the auto parts stores are lending tools too.
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Old 12-02-2008, 07:03 AM   #14
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I feel you pain. I recently was having a problem with my low mileage xrr. It was running great, but was also pumping oil into the air box. I went to find the shop manual for it then realized I had inclued it when I sold my other xr. I think found cyclepedia.com on ebay. I think it is pretty cool. The idea is you pay $20 the first year for a "membership" to their online manual. And it is their property, not pirated. You get instant access and saves on paper and they can easily up-date and correct or add info. I recomend it.

Oh and the problem?? The oem piston had cracked the ring landing between the compressin rings. A new Wiesco kit was $160 and took 3 days to get it and an evening in the garage. It runs great, and no more oil in the airbox.
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Old 12-02-2008, 07:04 AM   #15
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Quote:
Originally Posted by Fast55
It might be important to know how the engine got low on oil and if you remember exactly how much oil you had to add to get to proper level.
My XR has always used oil, which I understand isn't unusual for these bikes. When I measured the end gap on the oil rings, they were one of the few things out of spec on the engine. I'm putting in new rings when I button it back up.
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