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Engine Failure: Camshaft and Piston damage - Rebuild in progress

914 Views 24 Replies 6 Participants Last post by  Tamir
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Hi all,
Hopefully Hello @Tamir as well, the one with the knowledge and kindness to reply the majority of threads!

My bike went in to mechanic for a new battery and fork seal maintenance as the right side was leaking.
Attached is the quote I got afterwards.

I noticed the black plastic (Can be seen on video, it's the black plastic round thing) is damaged, drove the bike home (5km) and there was a hard "klunk" sound on the front sprocket.

  • Drove slowly home after the sound and there is a definite something gripping or slipping whilst the shaft is turning.
  • Got stuck in second gear, after a kilometer or so my gears came loose again and was able to shift up to third and then back to 2nd and 1st. Now able to shift through them whilst testing parked.
  • I parked the bike and left town for a week.
  • Returned back to bike shop and showed them the attached video, they said bike needs to be loaded on trailer and brought in to shop.
  • Removed the front sprocket guard and took video, all teeth seem fine no chips or breaks.

My Question:
1. Redacted*

2. What is the possible cause to this issue?

3. Is it possibly just a loose sprocket?

Thank you for the time you take to read and respond to my issue.
Exmoz greatly appreciates your input!

Video:

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I noticed the black plastic (Can be seen on video, it's the black plastic round thing) is damaged, drove the bike home (5km) and there was a hard "klunk" sound on the front sprocket.
  • There is no connection between the battery treatment area, and the areas related to the treatment of the front forks. The front sprocket area is also a separate area and independent of the other two areas. That's why I don't see a connection between the repairs that was recently carried out in the garage and the problem you claim appeared after that repairs. The front sprocket problem It seems to me not related to the last mechanic's work.
  • As it can be seen in the video, your chain is very rusty, the front sprocket is already quite worn, I understand that both require replacement, and then it is customary to replace everything as a set, meaning also the rear sprocket.
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  • I'm not sure I understand what the round black plastic part is. The electric wire that reaches the neutral gear sensor passes in front or the front sprocket, this wire should sit inside his rail/slot. Maybe the front sprocket cover was tightened over the wire when the wire was not in his slot, so it damaged the wire?
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bike needs to be loaded on trailer and brought in to shop.
Yes
Removed the front sprocket guard and took video, all teeth seem fine no chips or breaks.
In the video it was hard to see because the camera was constantly moving, but you can download a stills image here, zoom in on the front sprocket and I'll try to see again. From the video I got the impression that the sprocket and the chain both look damaged to me.
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Thank you for your response @Tamir

I've cleaned up the sprocket area, correctly placed the cable (thank you for that) and upload a new video:

Please let me know if you need a longer one and I'll ask the wife to take whilst I push.

Uploaded a few still images of sprocket as well.
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If I understood correctly. your problem is that the chain jumps on the front sprocket.
If so, in the first video you can't see it well, you can see that there is a kind of jump.
In the second video you hardly turn the chain so you can't see the problem.

You have to be really careful when you are turning the chain, you can catch hairs and fingers and then it ends in really serious injuries:eek:💀☠

In my opinion, and this is how I get the impression(Rust + worn + jumping), go to a mechanic to change the set: two sprocket + chain.

For routine maintenance, I lubricate the chain with SAE90 transmission oil every 500 kilometers or les.
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Chain and sprocket set ordered, thanks @Tamir

Got the DiD Xring which lasts longer I see, also went with stock 14T front and back stock 38T.

Cleaner up the area some more now, if you can't ride may as well clean her.
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Yes, if you know that the motorcycle is going to stay with you for a long time, it is worth investing in a quality chain. If you keep the lubrication on time, it lasts at least 30,000 km.

Pay attention to the link, today you have a Spring Link that can be assembled and disassembled easily, if you do not have a special device(WEMOTO) for assembling a chain, then check that your order is for a Spring Link like the one you have now.
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If you intend to do the replacement yourself, then my tips are:
1. Be careful not to get seriously injured by catching fingers or hair in the sprockets.
2. Replacing the rear sprocket requires disassembling the rear wheel axle, pay close attention to the order of the parts, who is on the right or left and in terms of rotation what is up or down, and before you put them back in place look at the parts diagram and you will see that everything is back in its place - link to Partzilla.
3. When you clean, in the motor-shaft-seal area work really gently, because otherwise you can destroy that seal(link).
4. Finally, adjust the chain tension, and repeat the test after 200-500 km.
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I agree with Tamir that the sprockets do look worn
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Thanks for input Toby
Currently waiting for the mechanic to get back to me.
Seems to be internal issue as the new sprocket is doing the same thing.

Told them to open her up.
Thanks for input Toby
Currently waiting for the mechanic to get back to me.
Seems to be internal issue as the new sprocket is doing the same thing.

Told them to open her up.
Good luck!
Update:
Mechanic says, "main bed on crankshaft root cause, bearing failed, it disintegrated, jammed the engine, jammed gears, Some gears got damaged."
Good news: A couple of the parts can be saved and reused in the engine.
- Awaiting a quote, hoping I do not need a whole new crankshaft as I see they are over 300usd.

@Tamir Have you ever had a bearing fail on the crankshaft causing similar issues?
Update:
Mechanic says, "main bed on crankshaft root cause, bearing failed, it disintegrated, jammed the engine, jammed gears, Some gears got damaged."
Good news: A couple of the parts can be saved and reused in the engine.
- Awaiting a quote, hoping I do not need a whole new crankshaft as I see they are over 300usd.

@Tamir Have you ever had a bearing fail on the crankshaft causing similar issues?
Look, I haven't seen the problem, and I haven't heard it, so I guess I know less about the extent of your problem than your mechanic.

It happened to me that my aluminum chips broke off from the case (due to a manufacturing fault during the casting), and these chips destroyed the bearings that started beeping, and when I heard the characteristic beeping, like crickets, I stopped, and prevented major damage to the rest of the engine. When I opened the engine I took the opportunity to replace all the bearings, even the ones that were probably not damaged.

If your crankshaft main bearing broke and "jammed the engine", in that case you don't hear crickets chirping, you hear metal clicking on metal, and that cliking loud, and they increase according to the rpm. And this may not fit a little with the beginning of your story, which is why I ask:
When your engine was running, and yuor motorcycle did not move and stands still, have you heard loud metallic knocks from your engine?
UPDATE:
Crankshaft and Piston rebuild kit is required.
With all the needed gaskets.
Local mechanic asking 1500usd to repair.

Sourcing parts from an alternative supplier to see if I can save costs.

It is a dark time, this cbr is costing me the same price as what I paid now.
But in all honesty, it's saves so much fuel and drives so **** good I have to restore it.

@Tamir unfortunately I did not notice any engine noise, but my hearing is not good.
The mechanic noted that the engine noise is odd on the picture of quote I attached about fork seals that were done.
That's crazy money, Exmoz. I think that's even more than the Blue Book value of my 2011.
I don't know your situation in Singapore, but you should consider putting that $1500 towards another used bike.
Don't "throw good money after bad" as they say. A rebuilt engine will never be as reliable as stock.
Thanks for the condolences and advice.
Went with the risky route and ordered the parts from abroad and importing them Myself.

In South Africa there is a massive boom going on with motorcycles due to grocery delivery becoming a very big job market.
The odds of finding a 250cc engine is close to nothing, the delivery guys all buy them the second they are online.

Another point is this bike saves me roughly R2000 in fuel a month, so everyday I drive it, it saves me money.

Searched the bike market and could not find any other bikes below R70k.

I'm rebuilding her, and hoping to get another 60k km done on her.
A rebuilt engine will never be as reliable as stock.
YES:sneaky: Of course it doesn't have to be that way,
but at the level of practice you are unfortunately completely right.

I have repaired engines two times, and it wasn't a perfect repairs.
All the faults I have was from one type: Spare parts availability problem.

You see that there is a part that needs to be replaced, but you didn't order it in advance, because you didn't know it was needed, and you already want to return the motorcycle to active service, and the problem you were running away from appears after a relatively short time.

From time to time I improve, part of the payment for the DIY hobby is the cost of your mistakes.
The sad part in that story is that even in "professional" workshops they take similar decisions, give a warranty of barely six months, and hope that the repair will last at least six months.

I hope my next big repair should be at the "Honda factory" level.
Maybe next winter I will open the top engine to improve my compression(Which is probably the problem that is causing my cold engine starting issue.
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I'm rebuilding her, and hoping to get another 60k km done on her.
Your goal is absolutely possible, a lot depends on the quality of the repair.
I can understand the type of yuor "risky route ", sounds reasonable to me.
I wish for you that you succeed above expectations!
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I'm rebuilding her, and hoping to get another 60k km done on her.
You seem committed to reviving your engine, so good luck and please let us know how it goes.
My apologies for mistaking the flag of the Republic of South Africa with Singapore's. I'm sure it's a lot harder to get parts in RSA than Asia.
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Parts has been ordered from direct India Source, will share the details once parts arrive safely.
Seller is very responsive and quick, DHL waybill done this morning, parcel on the way.

Received some photos from the mechanic as well, hoping they can assist someone in the future!
Let me know what you think of the damage and what else may be good to replace.

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Thanks for the photos(y)

It's hard to see from the pictures, I can say what I would considering to do:
  • I would inspect the parts closely and looking for cracks or unusual wear, then replace them.
  • For axles and other precise parts, you will find minimum dimensions in the manual, and if necessary, replace them as well.
  • I would replace all the seals, O-Rings &' gaskets, and all the bearings, also those of the coolant pump.
  • What is the condition of the timing chain, so maybe it is worth replacing it and the components related to it?
  • What is the condition of the valves? So maybe it's worth polishing?
  • What is the condition of the piston? Maybe it's worth replacing, including rings, and polishing the cylinder?

Bottom line, if you're already doing the big job, then it's worth not saving on spare parts, use compatible work tools, and try to do it as good as possible.
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1. Could the damage caused to the black plastic be related to the issues I am facing?
(The mechanic claims he did not cause that damage, but I have photos of before I took in the bike in and after, as they damaged my front break fluid glass thing in December).
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