piston help


8 replies to this topic
  • asxasxz

Posted May 14, 2008 - 01:14 PM

#1

I put in a new piston the other day but insted of using the clips that came with it I used the old ones because they are easier to put on but then I talked to my buddy who is a mechanic and he said that he ruined a bike that he was working on by doing that so i want to get yalls advice on the subject should I try and start it or should I take it apart again and put the other clips on btw it is a 03 yz450f and the piston i bought is a athiana oem piston :thumbsup: :rolleyes:

  • Berm-Saw

Posted May 14, 2008 - 01:30 PM

#2

well the safe thing to do would be to trear down again and put new ones in

in my manual (crf250r) it says NEVER to use used piston clips

  • grayracer513

Posted May 14, 2008 - 02:49 PM

#3

The grooves that are cut in the piston are machined to fit the clips that came with it. In some cases, there may not be a significant difference, but other times there is, so you should not mix the types. You should also never reuse the old ones, as was just pointed out.

Always install the clips with the opening toward the top.

  • todds924

Posted May 14, 2008 - 06:16 PM

#4

The grooves that are cut in the piston are machined to fit the clips that came with it. In some cases, there may not be a significant difference, but other times there is, so you should not mix the types. You should also never reuse the old ones, as was just pointed out.

Always install the clips with the opening toward the top.


+1 on never using an old circlip. Just tore down a crf 250 today that the guy re used old clips. It tossed one and trashed the cylinder and head. And good advice Gray on installing with the opening at the top. On the one circlip that didn't fail, the opening was at 9 o'clock so i would assume the one that failed could have been also.

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  • sirthumpalot

Posted May 15, 2008 - 02:31 AM

#5

Ditto the grayracer info. If it were my bike, I would replace the clips. If a clip comes out you're talking a big money fix. Also be sure to heed the advice to have the opening on the clip up (or down), basically pointing in the direction of motion. If the opening is not facing the direction of motion, then the G forces at high rpm can be enough to make the clip collapse and come out.

  • grayracer513

Posted May 15, 2008 - 05:51 AM

#6

The question of up vs down is a little bit about splitting hairs. The important thing is to put them in with the opening either up or down.

I prefer up because that makes the ends subject to the inertial forces that occur when the piston slows at BDC. Turning the clips over makes them subject to the forces from slowing at TDC. Since the piston accelerates/decelerates more quickly at TDC then at BDC, it's marginally better to have the opening up than down.

  • btray

Posted May 15, 2008 - 02:13 PM

#7

How many hours should one get on a 04 450 yzf topend...since we're talking about clips and things...bought bike use 20 hours on it in my stable...love this hot rod. What do you think Grey?

  • grayracer513

Posted May 15, 2008 - 02:54 PM

#8

Well, my '03 had a whole bunch more time on it then that when I sold it. and it still ran really well. No oil consumption, never a valve adjust, and more than 350 hours on the same rings.

  • btray

Posted May 15, 2008 - 03:25 PM

#9

By talking to the guy who bought it new...he weighed 250 and was probably pretty good for 45 was clearing some pretty big jumps at a local track here in Texas...he guessed around 225 hours or less...I've put 20 on it and thought well I pull it down put a new piston and rings in it and check valves, but now you make me feel like no big hurry...These things are amazing compared to the rest of the 450's out there...thanks again

Bill





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