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Discussion Starter · #1 ·
so i just put a new 686 namura piston and rings in my raptor, got the brake in procedure finished, then i start to do a few high revs. CLUNK! so i finish the weekend on my bike and i got home, took it apart and my cam snapped where the cam gear goes, all the decompression things were cracked and bent in every which way, and the chain was snapped in a couple places. now, i knew the chain was already stretched out, and the tensioner was in all the way. Do you think i should buy a new cam, chain, and all those goodies and make sure i put it back correctly? again, thanks in advance everybody.
 

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Yeah....there could be a lot more than just a broken cam chain.
 

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so i just put a new 686 namura piston and rings in my raptor, got the brake in procedure finished, then i start to do a few high revs. CLUNK! so i finish the weekend on my bike and i got home, took it apart and my cam snapped where the cam gear goes, all the decompression things were cracked and bent in every which way, and the chain was snapped in a couple places. now, i knew the chain was already stretched out, and the tensioner was in all the way. Do you think i should buy a new cam, chain, and all those goodies and make sure i put it back correctly? again, thanks in advance everybody.
If you have all those broken and bent parts, your most likely cause for the chain breaking was the broken parts getting caught in the chain, and most likely you have also bent valves........and possible piston damage and maybe you may have bent the connecting rod if the valves broke........
 

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New OEM Cam chain is 20-30 bucks. I swap them out when I do a top end. It is a replacement item for me. Cheap insurance.

I also wouldnt build a High RPM screamer with a Namura piston. The piston should be a good forged one not a crappy cast one.
 

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New OEM Cam chain is 20-30 bucks. I swap them out when I do a top end. It is a replacement item for me. Cheap insurance.

I also wouldnt build a High RPM screamer with a Namura piston. The piston should be a good forged one not a crappy cast one.
Just built a Rhino 660 into a 686, 3 plugger, with some decent porting and dual FCR 35mm carbs, the timing chain on a Rhino is about 2/3 the size of a Raptor in width, so I installed the whole setup from a Raptor, bigger chain and gears............
 

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Discussion Starter · #8 ·
the vavles were adjusted before i did the piston job, i did not check them after i put the new piston in, and the piston still moves up and down freely, same with the valves,there was no damage to the spark plug either.
 

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the vavles were adjusted before i did the piston job, i did not check them after i put the new piston in, and the piston still moves up and down freely, same with the valves,there was no damage to the spark plug either.
that really doesnt mean something isnt still wrong
 

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I would deffinetly take her apart & see what needs replacing. I no it sucks, ive been thear before & im thear now...Thats just the nature of the beast. & Id listen to Willy & everyone elce & check your connecting rod , valves , piston. & everything in between fore damage.
 

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I would deffinetly take her apart & see what needs replacing. I no it sucks, ive been thear before & im thear now...Thats just the nature of the beast. & Id listen to Willy & everyone elce & check your connecting rod , valves , piston. & everything in between fore damage.
+1
I am in the same situation right now too. I would tear the entire top end down and look over EVERYTHING and check the oil for metal. When my chain broke it bent all of the valves, but didn't damage anything else. It defanatly sucks but if you ride them you are going to break them.
 

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Discussion Starter · #12 ·
im gonna tear that S.O.B. down tomarrow night, not gonna be fun, all the timing chain is jammed behind the flywheel. Why did i get into 4 strokes? my good ol 2 smoker runs like a champ, oh well. thanks to all for input, and will keep you guys updated on the damage.
 
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