Hi everyone,

I have a 2000 Honda CBR 600 F4 with 8900 miles. I bought it used just over a week ago. This week, I was driving down the highway when the bike made a grinding / clanking noise and then I lost the response to the throttle. I pulled over and had to get my bike towed to a shop. They told me that cylinder #1 had no compression and cylinders #2, #3, and #4 all had low compression. I picked up my bike from the shop this morning and brought it home. I checked the oil and coolant and both levels were full when the bike stopped working. Any ideas what might be wrong? What should I do? Thanks

-Ernie

 

Could be CCT or Cam chain broke. That would cause low or no compression in the cylinders and would sound like you explained.

 

Thanks! I checked the Cam Chain and CCT... how can you tell if it's bad?

I opened up the "Cylinder head cover" and "timing hole cap" and i rotated the cam chain through the timing hole.

What I found was that the cam shaft did not fully rotate. The cam shaft at cylinder #1 did not rotate at all. And was not lubricated either. The cam shafts at cylinders #2, #3, and #4 were all lubricated and rotating, however, it was still kind of loud. Is this noise normal??

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Here is a slightly better pic. Please Help!



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That 4th journal looks pretty dark, if i had to guess going on the fact that you said its not rotating with the rest of the shaft that it seized from heat and lack of lube and snapped the cam. Pull the cap off and inspect the bearing and cam at that point. You may be able to do it without releasing the pressure on the chain, or you might have to remove the tensioner. I havent torn one of these down personally yet. Let us know what you find.

 

I drained the oil and removed the oil pan. There wasn't really any shavings in there, you think the engine might be ok once I get the new cam shaft? Pic of oil attached

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I guess you got my pm? I got to thinking more about it last night, and maybe someone else can chime in. Arent these Interference engines? If they are as I think then you most likely have bent valves and will need a complete head. Thats homping the valves in #1 didnt stick open enough to knock a hole in the piston. Like I said, im not sure these are interference or not. Just a thought. I'll keep searching for a more definative answer.

 

I just took off the camshaft holder and there was a lot of burned and melted metal and a broken cam shaft. Here are some pics, looks like the cylinder head is completely shot. Is it even worth trying to salvage? I'm gonna go check the pistons now...


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I'm still curious to why it quit oiling and broke the cam. If the pistons are still good once you get the head off and everything else turns over fine, you can probably replace the head and be fine. It really depends on what you can get a used motor for and wheter you wanna drop it and replace it or bolt another head on.

 

My valves and pistons look like this....

The one valve was stuck open which you can see hit the top of the piston a little bit.

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