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seanus100

Beta 300 4 Stroke Tapping Noice

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I noticed over the last few rides out that there seams to be a tapping voice coming from the engine, some were near the cylinder head, any one any ideas or suggestions please.. Thanks

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Have you compared it with another similar bike? Is it the same frequency as the engine rotation? Did it start suddenly? Is it there hot and cold?

It is normal to be able to hear the piston rocking in a four stroke at some RPMs if the exhaust is quiet enough. Also possible to be noise from the valve train.

Knock knock at engine speed - piston noise. Tap tap at engine speed - valve train noise. Ticking or clicking noise that happens irregularly may be cam chain noise

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I don't know how loud the "tapping voice" is you have, but here is my experiance with a tapping noise I had with my 2010 300 4t. The tapping noise was quite severe, so I did not dare ride it. I took the whole top end apart and checked all specs trying to find and fix where the noise was coming from...many, many hours. The tapping noise ended up coming from the decompressor release arm hitting the surrounding housing. For me to fix this I replaced the small, thin guage coil spring that holds the decompressor weight in place (#18 in parts diagram manual). This involves removing the cylinder/valve head and dropping or a good engine tilt to access. Refer to the bikes service manual for this because you have to be careful to insure your timing stays in place and/or is set correctly. Second, actually try this first...Remove your cam chain tensioner and inspect for proper funtion and wear. If all looks good as it did with my bike, I added a .25 - .35 inch (6.35 - 8.9 mm) piece of heavier guage spring to the existing spring to increase the tension on the cam chain guide. Like I said, try the mod to the cam chain tensioner first as this could be the quick fix. These recommendations are from my experience with many hours into tying to figure it out. Bikes been running great ever since (about 1 year).

Edited by JimG
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I had same problem ?? if the tapping increases with the revs mine turned out to be one of the bolts holding the chain pulley wheel had worked loose because the factory hadnt put any thread lock on ?? once you get the engine dropped a bit so you can get the top off its a quick 5 min fix its dropping and replacing engine thats the issue ??? i just took sump guard off and undid the frame brackets next to radiator this allowed the engine to drop forward to create enough room to get in and sort all in all about 1.5 hours work ??? good luck

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Just going through this now. Trying to find the problem. Dropped the motor but not had it on the bench yet. Will report back my findings 

7F5A2EDC-53B8-46F8-B776-271234C64EF3.jpeg

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Here was my tapping noise issue about 5 years ago.  Bushings bad.

 

Click Link 

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My 2010 Evo quickly developed an ominous tapping sound like the one you describe in the video. Any more info on the rocker bushings? 

Edited by crustybill

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Valves within spec. No discernible signs of wear despite 100+ hours. 

Hoping this spring stops the tapping. 

538A05C2-0BC0-40A0-89F7-1100FB27BEB3.jpeg

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50 minutes ago, madmostin said:

Valves within spec. No discernible signs of wear despite 100+ hours. 

Hoping this spring stops the tapping. 

538A05C2-0BC0-40A0-89F7-1100FB27BEB3.jpeg

It might stop the tapping.

Edited by oni nou

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