New Piston?


9 replies to this topic
  • rmcr250r

Posted December 10, 2010 - 03:32 PM

#1

My 09yz450 has around 60hrs on it. However, during that use I had some airfilter/intake boot issues which allowed a considerable amount of dirt in the carb. As a result this caused the left and center intake valves and one of the exhaust valves to go out of spec. So i was wondering should I put a new piston in it for preventative maintenance. It doesn't burn oil or anything and it starts up and runs normal. Heres a pick of top of the carb above the slide just to give an idea of how much dirt was in there. Posted Image

Edited by rmcr250r, December 10, 2010 - 06:31 PM.


  • Steel Panther

Posted December 10, 2010 - 05:46 PM

#2

what exactly were your intake issues?

  • rmcr250r

Posted December 10, 2010 - 06:01 PM

#3

what exactly were your intake issues?


the guide, holder (as yamaha calls it) was not sealed properly to the intake boot.
Posted Image

  • Johnny_On_The_Spot

Posted December 10, 2010 - 06:12 PM

#4

I wouldn't blindly buy anything without inspecting it first. If you're that worried, just tear it down and see how everything looks, who knows it might not cost you anything but some gaskets:thumbsup:

Either that or run 'er till she blows up

  • husky390or

Posted December 10, 2010 - 06:57 PM

#5

If I'm not mistaken, I think I've seen other pictures on this forum of the same amount of dirt in the same place. You may just need to adjust your valves and make sure your air boot is fixed.

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  • rmcr250r

Posted December 10, 2010 - 07:06 PM

#6

If I'm not mistaken, I think I've seen other pictures on this forum of the same amount of dirt in the same place. You may just need to adjust your valves and make sure your air boot is fixed.


That was probably me. I posted it to see if people could help me figure out where it came from.

Valves have already been adjusted and so far they haven't retightend.

  • Charlie755

Posted December 10, 2010 - 10:25 PM

#7

I am suprised the valves havent moved again. Once the coating is worn off the ti valves they tend to keep moving until you either replace them or it drops a valve into the piston. Personally I would replace all of the valves and have the seats recut. Install a new piston and timing chain while your there. If you drop a valve it will be a lot more expensive. Then your looking at possibly a trashed head and cylinder along with the crank. As for the carb if you havent already take it apart and clean it really good.

  • rmcr250r

Posted December 11, 2010 - 09:05 AM

#8

I am suprised the valves havent moved again. Once the coating is worn off the ti valves they tend to keep moving until you either replace them or it drops a valve into the piston. Personally I would replace all of the valves and have the seats recut. Install a new piston and timing chain while your there. If you drop a valve it will be a lot more expensive. Then your looking at possibly a trashed head and cylinder along with the crank. As for the carb if you havent already take it apart and clean it really good.


Ya people suggested that to me but the valves haven't moved yet after two track days and i rode it hard and hit the limiter a few times. I check the valves often. I am gonna tear it down after i clean it up nice. That seems like the only way to answer my question.

  • brentn

Posted December 11, 2010 - 12:20 PM

#9

Looks like you might need filters on the breather lines for the carb, all that dirt in the bottom of the bowl there is probably from the breathers and not the intake.

  • rmcr250r

Posted December 11, 2010 - 04:43 PM

#10

Thats not the float bowl. But i plan on purchasing one of those filters.





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