Top End Rust?



9 replies to this topic
  • F0Xryder61

Posted March 07, 2016 - 07:31 PM

#1

    Got a small issue on my 2011 YZ 450. Has 50 hours on it. Took it out last Saturday for about 30 min and ran good. Right when I was almost done riding It died at idle. No big deal. Started it up and ran it for a minute. It died again under 1/4 throttle while riding it. Started it up again, all the times it died it took about 10 kicks to get her going. Did this no matter what I did for about 10 times. The last time it did it it wouldn't start back up for anything. 

 

    I brought it into my garage at that moment. Pulled the spark plug. The spark plug is about 2 hours old. Iridium NGK spark plug. It had rust on it. It would kind of wipe off. I looked down at the piston with a light. It had rust on it also. Never seen anything like ti before. Decided to pull the top end apart and found this...

 

Please tell me what you think. Gonna take my head to the local moto bike shop. Have them check the head out and valves.

 

EDIT: That one valve that is black should have rust on it origionally but I wiped it off.

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Edited by F0Xryder61, March 07, 2016 - 07:34 PM.


  • grayracer513

Posted March 07, 2016 - 09:09 PM

#2

Well, it's not rust.  For one thing, there isn't a single steel or iron part visible in the pictures; none of the stuff you can see is capable of rusting.  The red/brown color is carbon from whatever fuel you're running.  May have been hot. 



  • NW Briff

Posted March 07, 2016 - 10:57 PM

#3

Wow too bad you thought it was rust and tore into it. Ive heard 50 hours is a good time to change the cam chain anyway although my friends bike (a gen2) went 126 hours before his skipped time.. he also had to replace his cams/crank and rebuild the head as a result.

I saw what appears to be white deposits in the picture of your cylinder head. Or is that bare aluminum where the brown soot flaked off? This makes me Curious as to what your spark plug looks like. Its always the best indicator of how the engine is running anyway. Was the tip of the plug covered in white/gray deposits or specs of aluminum (looks like silver sparkles)? That would indicate the fuel mixture in the combustion chamber has become too lean for some reason or another.
The bike was full of coolant right?

Also, you said you just replaced the plug. Is it the same heat range as factory?

Edited by NW Briff, March 07, 2016 - 11:44 PM.


  • F0Xryder61

Posted March 08, 2016 - 02:45 PM

#4

Well, it's not rust. For one thing, there isn't a single steel or iron part visible in the pictures; none of the stuff you can see is capable of rusting. The red/brown color is carbon from whatever fuel you're running. May have been hot.

I did just start running Targon MX race fuel. Its 90 octane. I also am running an iridiom ngk spark plug.

  • F0Xryder61

Posted March 08, 2016 - 02:48 PM

#5

Wow too bad you thought it was rust and tore into it. Ive heard 50 hours is a good time to change the cam chain anyway although my friends bike (a gen2) went 126 hours before his skipped time.. he also had to replace his cams/crank and rebuild the head as a result.

I saw what appears to be white deposits in the picture of your cylinder head. Or is that bare aluminum where the brown soot flaked off? This makes me Curious as to what your spark plug looks like. Its always the best indicator of how the engine is running anyway. Was the tip of the plug covered in white/gray deposits or specs of aluminum (looks like silver sparkles)? That would indicate the fuel mixture in the combustion chamber has become too lean for some reason or another.
The bike was full of coolant right?

Also, you said you just replaced the plug. Is it the same heat range as factory?

Bike is full of coolant. Sparkplug is same brown/red as everything else. The aluminum is showing because i scraped it off.

Edited by F0Xryder61, March 08, 2016 - 02:49 PM.


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  • F0Xryder61

Posted March 09, 2016 - 06:42 PM

#6

UPDATE: I ordered a piston kit from wiseco, rings, timing chain, spark plug, gasket kit and shim kit. Gonna put it back together this weekend then diagnose what the problem is and not tear it apart right away again like an idiot... Any other suggestions? What to look for? What to look at when i put it back together?

  • F0Xryder61

Posted March 14, 2016 - 07:30 AM

#7

Another Update:

Put the new stuff in from the post above. Started in 10 kicks or so. Runs great. Not gonna put race fuel in anymore and just run premium and also put a stock spark plug rating in besides a hotter spark plug that I was running. Hope it doesn't do what it did again.  Any reason why it did what it did?



  • grayracer513

Posted March 14, 2016 - 08:30 AM

#8

You should be running an "8" in an NGK plug, preferably a CR8EIX iridium, or a CR8E.  Nothing hotter, or for that matter, colder. 



  • F0Xryder61

Posted March 15, 2016 - 07:23 AM

#9

You should be running an "8" in an NGK plug, preferably a CR8EIX iridium, or a CR8E.  Nothing hotter, or for that matter, colder. 

I went on Rocky MTN's website and went to oem parts. Selected my bike and clicked on the spark plug and ordered that one. It shows the CR9EIX. 



  • grayracer513

Posted March 15, 2016 - 08:33 AM

#10

Yamaha disagrees with RMATV then.  The manual calls for an 8, not a 9.   The 9 will be too hard to keep from fouling.







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