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I'm curious if anybody else is experiencing engine noise on their C50. I have 1,800 miles on my bike and for about the last 4 weeks began noticing a rattle noise which is rythmic with the rear cylinder and becoming more prominent. It is especially noticeable when the engine is cold and under a load. I took it to the dealer and they said everything is normal, the technician did not notice any abnormal noises. I have let friends listen to it and also ride the bike and they too agree there is a noise in the engine that is not normal. I guess the best thing I can do is make sure it is documented more than once at the dealer in case I experience an engine failure. I was thinking it may be piston slap or possibly a cam chain tensioner. Otherwise, the engine runs fine. Anybody have a thought on the subject.

Dan
 

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Dan
I had similar concerns and was advised the same as you by the dealer, although my mates did not notice any noises, yours do and that would suggest you try another dealer. Mine sounds more like valve lash though whereas yours sounds like a cam chain issue.
 

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Hey RCflier15,

I am new to this site, but I have what you have. I have worked on engines both cars and motorcycles for the past 40 years.

Here is what mine started doing:

At about 800 miles I started getting a little knock in the bottom end when I would first start the bike and give it a little gas. But after it warmed up for about three minutes it would go away. I had just changed the oil at 600 when I checked the valves and did the service.

At 2K miles when I did the next service, it was taking about 5 to 6 miles of real easy riding to get rid of the knocking sound. So I changed from 10w40 motorcycle oil to Kendall 20W50 motorcycle oil. Once I did this, it went back going away after about three to five minutes of warm up.

But by the time I had 4K miles on the engine it was taking me up to 6 miles before it would go away. Also I have found out that even if hot the knock will come back after it sets for about 15 to 20 minutes.

None of this is normal by any means. What this means is that there is to much play in a bearing for bearing surface.

If you want to get ahold of me please email me at [email protected].
 

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Valve train noise is not unusual with these bikes - even with the valves adjusted correctly.

Did you have your valves adjusted?
 

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It isn't, by chance, a "chirping" noise (kinda like a cricket), is it? If that's it, try squeezing your knees on the tank when it happens. Does it change sounds or go away completely? If so, it's the bushings at the front of the tank. I imagine putting some sort of lubrication on them would help... I've just been too lazy to do that on mine..
 

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a little less then 2k on mine ... mine sounds good to me. (and I have not changed the oil since the 600mile change in Sept. 05). there is a "ticking" that just sounds like valves to me, I'm not worried about it.
 

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Ticking is normal, but a rattle or knock is not. I know mine is a knock, because using a mechanics stethoscope, it is loudest between the cylinders on top of the case.
 

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A knock is usually pre-detonation, right? (gas igniting due to compression or over lean condition)
 

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92Notch said:
A knock is usually pre-detonation, right? (gas igniting due to compression or over lean condition)
No, it can be a few other things also.

Piston to wrist pin clearance to much
Wrist pin to rod clearance
Rod bearing clearance on the crankshaft
Broken gear

You have to listen to the sound to better isocilate it.
 

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Try running 87 octane. 91 octane could be a little too hot causing the engine to detonate before the piston reaches the top of the head. The two pressures working against each other could cause a pinging sound. Like a hammer tapping on something metal. I'v listen to this sound on a harley 883 once. Seems that a change of gas solved the problem. When the engine is cold it takes a few for the oil to make it to the top end of the valve compartment. The valves will tap a little louder untill the oil reaches it's destination. Always give your bike time to warm up before a load on the engine. good luck
 

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Yaker_24301 said:
Try running 87 octane. 91 octane could be a little too hot causing the engine to detonate before the piston reaches the top of the head. The two pressures working against each other could cause a pinging sound. Like a hammer tapping on something metal. I'v listen to this sound on a harley 883 once. Seems that a change of gas solved the problem. When the engine is cold it takes a few for the oil to make it to the top end of the valve compartment. The valves will tap a little louder untill the oil reaches it's destination. Always give your bike time to warm up before a load on the engine. good luck
In actuality, the higher the octane number the slower it burns. When you have a high heat problem causing detonation, you want to run a higher octane. This is why higher compression engines run the higher octane. Another thing that can cause early detonation is timing off (firing to early).
 

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Blade said:
No, it can be a few other things also.

Piston to wrist pin clearance to much
Wrist pin to rod clearance
Rod bearing clearance on the crankshaft
Broken gear

You have to listen to the sound to better isocilate it.
Gotchya!
 

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Moderators note:
I have deleted this post because it duplicates another one you left in another thread.

Please post your questions or comments only ONCE so that the discussion doesn't get scattered all over the place.

Thanks.
 
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