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Engine Knock in a 2003 XR 650 L

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New to this site, but love all the info. I bought a 2003 XR 650L discounted due to a knock in the engine. It sounds like it is an upper issue. The local shop says they want to start by removing the top and they think it might be a chain related issue. The knock gets faster as you rev it up. The local Honda dealer said it could be a crank shaft issue but would not know until they took it apart. It is 5,000 miles and starts, runs fine. Any insight or thoughts would be appreciated. Thanks in advance !!!!! :p

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If it is a fairly solid knock, it could be the rod small end is wallowed out. The only way to fix that is to either have a shop split the crank and replace the rod or to replace the whole crank/rod assembly to the tune of $600. It could also be a timing chain rattle or loose valve clearances; I can't tell without hearing it.

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My guess is that the piston has worn out its bearing surfaces (front and rear) and your piston to cylinder clearance is a few thousands too much. If that is the case, a new piston and rings will be in order. Most likely, there has been dirt in there causing the wear and has also scored your cylinder walls. In that event, an oversize piston (.25mm bigger) and a cylinder bore to match will be necessary.

Without question, you should also replace the timing chain and do a cylinder head cleanup while you are in there.

You should do the tear down and inspection and rebuild yourself if at all possible. It would probably be under $300 for everything assuming it's not crankshaft related. Rebuilding these things is really straightforward and there is a LOT of help already in the forum here if you do a search.

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Thanks for the input, the Honda dealer tech. said he would just " ride it " as is. Kinda wierd advise I think. What does anyone think about chances of engine failure ? The knock is fairly solid ... not a clicking, a knock with each stroke. I am going to have a shop perform the work it needs eventually, but I would like to wait until mid summer. I don't want to risk additional damage ... the prior owner stated he drive it over 1000 miles since he bought it with the knock. Any more advise ???? Thanks a lot ..... :)

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You can decide for yourself, but here is what will happen...

If that piston (or anything else) breaks, you will have to completely tear town the motor to zero. That means, split the cases, take everything out, inspect everything, clean everything, replace worn items, and just hope you found all the little fragments of aluminum and/or steel. It's a long, hard job. There are a few threads in here about broken pistons. Read them - it's not good.

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It does not sound good ...... Thanks again ...

Where in MN. are you?

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Thanks for the input, the Honda dealer tech. said he would just " ride it " as is. Kinda wierd advise I think. :

thats cuz he wants it to come back completely blown up and he can charge you more for total rebuild LOL

Id have the head removed and start looking at it, its a KNOCK KNOCK and not a TICK TICK TICK noise???

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I've not heard all the possibilities, but like was said there is a big difference between the tick (valve clearance), klack(piston slap, rod small end), and knock (rod big end and rod small end).

The downside of doing nothing is if the piston skirt or rod breaks it could completely trash the engine.

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My Xr had a cracked piston (hairline) If I had of kept on riding it would have been Bad, Real Bad...If your not going to be riding it get yourself a clymer or factory service manual and tear it down to see what happened..Post lots o pictures so we all can help..

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Thanks guys ..... I am going to let the dealer fix this one. They estimate $750.00 to $1,000.00 worst case scenario as I have a good used crankshaft I got on e-bay for $90.00 if it needs to go that far on the re build. That will save $500.00 +/- on that part alone. I will post and let you all know the extent of damage. It really makes me question the prior owners and what kind of abuse this bike got to cause this damage. As I stated, it only has 5,000 miles on it and it is a clean bike overall. Any thoughts on what could cause major internal damage with so few miles ? I suppose, lack of oil changes, low oil or sustained over revving. Thanks, :)

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It's anyone's guess. Oil starvation usually burns up the cam and rockers before anything and excessive high revving will take out the rod small end, but poor maintenance(like 5000mi oil change intervals) takes its toll on everything.

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The shop took off the top of the engine and stated it got real hot at one point and some areas actually melted. The estimate was $2,200. I am just having them clean it up and put it back together. Hopefully I can get a couple of years out of it with frequent oil changes. Bummer ....

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$2200!!!! I bet you could buy a whole engine from Service Honda for that much.

I don't quite know what to make of what they are saying about the engine. Find out what melted. Usually if a piston gets even close to melting it's done. The pressure from the burning fuel in the combustion chamber blows a hole right through.

If it's a rod knock then I doubt that you will get much use out of the bike. Consider stripping the thing down to it's smallest parts and selling it all on ebay. I bet you could get at least $1500 if not $2000 or more. For example just the front and rear wheels will get about $500. If you wait until the engine blows you will have less to sell. Take the cash and get a better bike.

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I just bought a complete 650L engine without the head for $250. Look around for one and just swap it. Paying them to disassemble then reassemble the engine is a complete waste of money.

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very sorry to hijack, but with all these descriptions of engine noise, i would love to hear your diagnosis of mine.

http://s107.photobucket.com/albums/m297/bcjcgnar/?action=view&current=2009_0314board0006.flv

here is a lnk to the thread i started in the xr250/400 forum. please respond there as to keep this hijack to a minimum.

http://www.thumpertalk.com/forum/showthread.php?t=757456

thanks, and again apologize.

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The shop took off the top of the engine and stated it got real hot at one point and some areas actually melted.

Sounds like the center cam bearing in the head went dry and piled up and/or the rockers and cam burned up. That is more an indicator of oil starvation and not so much overheating. Overheating usually scuffs the piston if there is adequate oil flow to the head.

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Seriously Dude tell the dealer to stop smoking crack.Ask them to leave it unassembled.Get a good service manual and get to work on it yourself.Ebay is your friend. That bike wont last riding it the way it is.You might as well do the work yourself. Im willing to bet you could find a used motor for it for wayy less than that..

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