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Thread: fzr pistons

  1. #1
    tealgreen2000's Avatar
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    fzr pistons

    anyone ideas whats the cause of this made was do a few passes today had wideband connected afr never passed 12.0 motor just died out an started to run bad so towed it back an the took it apart an this is what i found # 2 and 3 cylinders other two are perfect thanks for any input
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  2. #2
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    What ecu? What kind of pistons? How many hrs on this set up?

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  4. #3
    Carbonic's Avatar
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    Running lean, debris, poor lubrication, etc.

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    tealgreen2000's Avatar
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    Quote Originally Posted by Rocketman View Post
    What ecu? What kind of pistons? How many hrs on this set up?
    its with the athena ecu, riva pistons about 4hrs

  6. #5
    formerly Gold06RXP Turbo Nick's Avatar
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    Detonation for sure! I've seen my piston look just like this befor on my turbo RXP. To much boost for the fuel your using, to lean or to much ignition advance. Or any combination of the 3. Your IATs could have been to high also. Your IC in good condition?

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  8. #6
    big john's Avatar
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    what was your piston to cylinder wall clearance ?????? looks like a classic seize from too tight a piston, should have been at least .0035 to .004

  9. #7
    Kristian Keppel Waterholics's Avatar
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    It looks like you need to add some extra fuel to cylinder #2 and 3 from your Athena. Those two cylinders run the leanest.Also what does your block look like ?

  10. #8
    formerly Gold06RXP Turbo Nick's Avatar
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    What's the electrodes in your plugs look like? In my experience with deto it starts pounding away and melting the edges of the piston towards the exhaust side. The molton AL then is smeared like peanut butter up and down the squirt of the piston and cylinder wall. Clean the ring land area if all the baked on oil in a solvent tank real good. Then inspect the edges of the crown and ring land area. If its deto you will see melted areas that recess into the piston some. Sometimes it's hard to tell when there dirty so clean them up real good. If u don't see any recession like I described above I'd agree with John about the clearence being tight and when the piston expanded on your runs it rubbed the cyl wall

  11. #9
    big john's Avatar
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    did you have the bores honed for clearance or just install them in the stock bores ???? the stock yamaha pistons are cast and require little clearance, with good bores you can have the bores honed for the proper clearance. i was hoping to do the same thing, but my cylinders were gut fucked and its going to toke a .020 oversize piston to be right. i also recommend more clearance than spec'd if your racing or high boost, the specs given are generic for replacing stock pistons with forged slugs,
    Last edited by big john; 04-28-2013 at 08:07 AM.

  12. #10
    ksalles's Avatar
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    http://www.greenhulk.net/forums/show...=1#post1743157

    A very informative post by desperado, as well as his efforts to correct the issue.

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