MSTA Forums
Main Forums => The Garage => Topic started by: NinjaBob on May 20, 2017, 08:15:09 AM
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Noting my last post in Garage can it be a coincidence???
I was accelerating hard, in 4th gear I think, on a back road about 30 miles from home when my 09 Concours 14 just died. My first
thought was that I had hit the rev limiter and quickly upshifted but the oil light was on and the engine was dead and I was coasting. I downshifted to match my speed and let out the clutch to bumps start it but nothing. I coasted to a stop and tried the starter which spun at higher than normal speed. I immediately sensed that I had a major problem.
A couple of pickup trucks passed before a good samaritan came along on his Honda Shadow with is young son on pillion. They lived nearby and went and got their truck and trailer and took me and the bike home 30 miles.
I sought help on two Concours forums, posting an audio recording of a starting attempt. All the knowledgeable subscribers, including three pro mechanics agreed there was no compression. I first removed the timing cover to access the crank bolt to turn the engine. There was a tooth broken off the timing rotor. Removing the valve cover I discovered both exhaust cam sprocket bolts sheared of. Ex valve buckets for 3 & 4 were abnormally low, suggesting bent valves. 1 and 2 buckets were way high and removing them revealed both valve had dropped.
What caused it? The obvious first culprit in my mind is the valve adjustment work, but it ran great for 500 miles after that. The evidence seems to me to suggest over-revving. In half a million miles of biking this is the first engine I ever blew up.
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That just sucks. I would lean toward the valve adjustment process too. Something either didn't get torqued right and backed off or failed when torqued and gave way later. I'm no expert but I did stay at Holiday Inn all week. ::) How many miles? Only engine issues I've ever had or heard of out of the Concours was in 2000 when they had that soft cam lobe issue. That was fixed under the warranty. Any chance you have a warranty recourse?
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Trouble shooting on the web is really shakey. The theme title of blowing an engine is not something I would bet on. IMO opinion blowing engines are pretty noisy affairs and engine parts tend to put holes in things like engine casings. My bet is something electrical. ECU, or some other engine control component. Although there are sharp guys on Connie forums, I would try a dealer first.
If it were valve job related you would have known it immediately. BUT, if you disconnected some plug and it came loose later, that could do it.
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Just under 30,000 miles. It is an 09, no warranty. I have removed the valve cover post mortem and clearly have valve damage.
I assume when the cam stopped turning the pistons hit the valves, at least in 3 & 4.
There is no sign of damage to the cam bearing surfaces so does not appear the cam seized. But something major had to happen to shear the cam sprocket bolts. I am amazed I did not feel anything, except the motor die. I fished around in the sump with a magnet looking for the timing rotor tooth and found one of the sheared off bolt heads.
To remove the valve cover for the post mortem I had to go through all the same steps for the valve check and did not find anything out of order.
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I first removed the timing cover to access the crank bolt to turn the engine. There was a tooth broken off the timing rotor. Removing the valve cover I discovered both exhaust cam sprocket bolts sheared of. Ex valve buckets for 3 & 4 were abnormally low, suggesting bent valves. 1 and 2 buckets were way high and removing them revealed both valve had dropped.
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Bummer. Pretty sure that ^^^ rules out electrical issues.
Of course this should not have happened, particularly not at only 30K miles. I know many of these bikes seem to go on forever.
My personal experience with Kaws has not been great. I not owned many Kaws however on 2 of the 3 or 4 that I've owned they failed catastrophically. They didn't just quit running - they broke a lot of internal parts making for very expensive repairs. i.e they "blew up".
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I have had no major troubles with the 7 other kaws stacie and I have owned. My 08 Concours is still running fine at 170000. Ran at track day like a champ.
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Sorry, I missed the part about the exhaust valves. More familiar with FJR's. If you have just done on valve clearance check on FJR's the one thing that is easy to screw up is skip a tooth on the timing chain. Normally that would be immediately made apparent and the engine would not just stop. If the cam timing was off, the cams would not necessarily be damaged. That engine just stopping is the part that doesn't make sense to me on a purely mechanical failure.
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Diagnosis, based on what's been presented here:
Important facts- Valve gear problem + Valves adjusted 500 mi ago= Related.
Bent/broken valves means camshaft went out of time. (Over revving could theoretically cause this, but the ECU has a rev limiter that cuts ignition well before the mechanical limit is reached.)
Cam sprocket bolt heads are sheared off. That is a key fact here, but is it the cause or the effect?
There are several ways this could have happened.
1. Sprocket bolts could have been overtightened when they were assembled after the clearance check, weakening them. Not very likely.
2. The camshaft bearings could have seized, locking the camshaft and causing the sprocket bolts to shear. The camshaft bearing caps are numbered and have to be reassembled in the original positions on he head. If two of them got switched, the bearing surfaces do not mate correctly, making the camshaft much harder to turn. A camshaft bearing could overheat and seize, shearing the bolts.
3. A valve stem broke and the head of the broken valve jammed between the piston and the other valve as it was opening at the end of the exhaust stroke. This would prevent the valve from opening and lock the camshaft. That would shear the sprocket bolts at the surface where the sprocket mates with the camshaft hub.
Collateral damage:
One of the falling boltheads got the tine on the timing rotor while the crankshaft was still turning.
In addition to damage to valves, there will be damage to pistons, possibly bent connecting rods. Broken valve heads getting crunched in the cylinder can damage the cylinder head and cylinder walls as well. Since the cylinder block is part of the upper crankcase casting, you may find it best to find a used motor and do a swap, rather than fix this one.
It's these nightmare scenarios that make me paranoid about doing valve adjustments on complex bikes. Sorry to have to be so negative, Bob. :-(
Norm Kern
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Thanks for the analysis Norm. I did not remove the sprocket during the valve adjustment, no need.
No sign of galling or scoring of the cam bearings, does not look like it seized. I verified that the cam caps were all in proper position.
Scenario # 3 sound very likely. No plans to try to fix. Used motors are available at at reasonable price but don't know what I will do at this point. Busy getting the 08 ready for STAR.
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Bob -
Have you checked the cam chain? I had what sounds like the same thing happen on my 2004 GSXR 1000 -- cam chain snapped - no jolt no nothing, bike just coasted to a stop. All 16 valves were bent. The key though is that the starter - ran very freely --
I was lucky in one respect the chain didn't bunch up and cause further damage - my guess is that your did.
Just my 2cents worth.
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Gregg, the chain seems fine, certainly still intact. Exhaust cam sprocket just sheared off. I will eventually open it up and see what the destruction is.
Is this scary or what?. Today I get an email from my favorite parts and tire vendor with this:
https://www.rockymountainatvmc.com/emailsales/deals/Top-End-Rebuild.html (https://www.rockymountainatvmc.com/emailsales/deals/Top-End-Rebuild.html)
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Gregg, the chain seems fine, certainly still intact. Exhaust cam sprocket just sheared off. I will eventually open it up and see what the destruction is.
Is this scary or what?. Today I get an email from my favorite parts and tire vendor with this:
https://www.rockymountainatvmc.com/emailsales/deals/Top-End-Rebuild.html (https://www.rockymountainatvmc.com/emailsales/deals/Top-End-Rebuild.html)
Now that is a coincidence - or had you already been looking into this? You know it seems like browsing and "cookies" and tracking, they target you within minutes of searching for something. Good luck with the rebuild, replacement or ........... whichever route you take.
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Gregg, the chain seems fine, certainly still intact. Exhaust cam sprocket just sheared off. I will eventually open it up and see what the destruction is.
Is this scary or what?. Today I get an email from my favorite parts and tire vendor with this:
https://www.rockymountainatvmc.com/emailsales/deals/Top-End-Rebuild.html (https://www.rockymountainatvmc.com/emailsales/deals/Top-End-Rebuild.html)
Now that is a coincidence - or had you already been looking into this? You know it seems like browsing and "cookies" and tracking, they target you within minutes of searching for something. Good luck with the rebuild, replacement or ........... whichever route you take.
No, the only search I've done was on Ebay for a used motor.
As for replacement, I know now why she blew up: to make room in my garage for the AFRICA TWIN! :clap:
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As for replacement, I know now why she blew up: to make room in my garage for the AFRICA TWIN! :clap:
Hopefully you can still attend STAR, even if you have to rent a bike in Colorado and then ride the AT home...
Don
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We will ride the 08 to Star. I have been busy transferring the touring stuff and getting the old girl ready. She's got 170,000 thousand on her but I am confident she will see 200k
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Well, if I were a bit more altruistic I'd be hoping the MSTA Africa Twin would be replacing it. But alas, I'm not. It's mine.
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As for replacement, I know now why she blew up: to make room in my garage for the AFRICA TWIN! :clap:
Hopefully you can still attend STAR, even if you have to rent a bike in Colorado and then ride the AT home...
Don
Having the raffle bike ridden home in 2 straight years, that would be pretty amazing ;)
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The first bad experience I had with a motor was the first used bike I bought. I had it a while when the engine made a big clunk and went silent, coasting to a stop. Luckily I was reaching for the clutch for a shift when it happened as the engine was completely locked up.
The bottom line is the cam chain tensioner gave out or was very worn. Cam jumps time, piston hits valve and your day/week/month is ruined.
I have had 3 more Nighthawk S's after that one and all were trouble free.
So that might be what happened to you, sorry about your luck. However, this is an example of why I say you should always have a back up. Multiple bikes rock!! :) TM
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Interesting, Tom! Was it an automatic tensioner? Since the 09 motor blew I have been busy getting the 08 ready for STAR, swapping the highway pegs, Zumo mount, etc. At 170,000 miles I am confident in the engine with the exception of the cam chain, I wonder how much it has stretched. There is nothing in the periodic maintenance schedule about checking it. I took a look at it and it seems ok. But since I already had the 09 tensioner out I thought I would put that in the 08 since it only has 30,000 on it. But as I was resetting it per manual instructions the thing fell apart - the piston and spring fell out of the body. It went back together with no problem and I can't see anything wrong with it but that has not happened the 4 times I did the same procedure on the 08 tensioner. (which I put back in the 08). It is a rather simple device and I have never heard of one failing but who knows? I am going to examine it with a magnifying lens and see if I can see anything abnormal.
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Yes, it was an automatic tensioner as many are. It's really a spring pushing on the shoe that squelches the slop in the chain. There is a ratchet mechanism that keeps it from returning as the pad wears some a little at a time. These have been known to act up but others are trouble free for about forever. Honda Superhawk 996's have been know to be prone to problems among others. Some riders replaced the mechanism with a simple bolt and lock nut adjuster and checked it from time to time manually. It's fairly out in the open especially on in-line 4's with cam chains on the end. Some say the '80's Nighthawks had problems too but I may have written off my experience to a bike not treated well.
In my case the piston hit a few valves and broke a rod, thus locking up the engine. I'm surprised yours didn't but it doesn't happen every time. TM
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Did you ever take this engine out and apart and determine the extent of damage or figure a probable cause?
yeah I know... it was about a year ago now
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No I have been busy riding my 4 bikes that still run! Thanks for asking. I will get to it some day.