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Discussion Starter #1
Ok, so I buy a used 150R, it makes a knock sound when kickstarted cold. Once it is running I hear nothing (maybe just to faint) and once it is warmed up I don't hear the noise when I kick it over.



Potentially a topend rebuild?



If so, what is the recommended path...:confused:

hi-compression piston?

big bore?

stock piston w/cam?

Not sure what you regulars are doing....



This is my first 150R, moving from a 150F to a 150R for blasting around with my kids and messing around with other guys on 150's on pitbike tracks and trails etc....



From the 20 minutes I rode the bike it seems like a blast and I cannot wait to ride it with the confidence that it will not explode on me.



Thanks in advance for any advice!
 

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then u should not need to rebuild it. I would check the valve lash, do these engines have an auto decomp on the cam? I would start by looking at the valvetrain.
 

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If it's a little metal clink, then it's the little auto-decompression arm thing. You can hear it when the bike cuts off, especially when it's kicked over and fires, but doesn't quite start.
 

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Discussion Starter #7
Yes you hear it when you kick it over and when it shuts of you hear it as well. Thanks, I will investigate further this week.
 

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Discussion Starter #8
turns out it is the decompression thing on the cam. weird! never expeirienced (sp) that before.
 

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Discussion Starter #9
So how do I fix the decompression knocking sound? Is it just a spring or something? I want to sell the bike and I would rather it did not make that sound...



Thanks In Advance!
 
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