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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc. |
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Thread Tools | Display Modes |
#1
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New oem piston problem!!!
So at 70 hours I decided to clean the power valve and check my cylinder.While I am doing this on my own I thought instead of just rings I should take a new A piston and get done.
When the new piston came from GG I took a look at it and the first difference was that mine was A 71.93 but the new one A 71.94. Second difference is that in the opposite side from the arrow are the pins which hold the rings.... Now in the old one the pins are one to the left side and one to the right side and in that way inside the cylinder move without passing any port as it seems. On the new one the pins are almost to the center of the back side of the piston with only a tiny difference amongst them and it looks like while moving they will pass from the back central port of the cylinder. (when I get my hands at the photos with the pistons I will post them because they are on a friends phone which is Spain for the presentation). After mailing GG about this (by the dealer here in Athens) they answered that regarding the size the new A's are 71.94 and not 71.93 and about the ring pins they said that the new pistons are like this and that there is no functional issues but I am not convinced about that. Both pistons are made from vertex and S3 is engraved on top. Has anyone in here encounter anything like this.?
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Gas Gas EC 300 2006 Gas Gas EC 300 R 2015 Gas Gas EC 250 GP 2018 |
#2
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The piston may have been packaged wrong.
The ring locating pins should not line up with any ports. |
#3
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My thoughts exactly but I think it's more of a quality control issue or something has seriously changed because I forgot to mention that when I went to the dealer I bought it from (which happens to be the importer for Greece) he brought two size B's he had in stock for the 300 and he was surprised to find out when he opened them that the same thing happened with both of them.
No1 B was marked 71.94 with the pins further apart like my original A and No2 B 71.95 and the pins almost aligned at the rear side of the piston (from where the arrow points). Also both A's shared the same product number as did both B's (A1 with A2 and so on) I am a little concerned about this and I don't want to take their word for it saying there is no problem with it.
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Gas Gas EC 300 2006 Gas Gas EC 300 R 2015 Gas Gas EC 250 GP 2018 |
#4
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Measure the piston and the bore before you make your decision.
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#5
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What is the clearance between the piston and the cylinder?
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#6
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I will take measurements next time I take it apart and see about the ring pins as for the clearance I didn't measure it because I needed the bike fast for an event and used the old piston with new rings, piston pin and rod bearing.
The cylinder didn't have any oval and the old piston inside with no rings on was almost tight so I don't think the bigger A they send me was needed. 30 more hours and will see.
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Gas Gas EC 300 2006 Gas Gas EC 300 R 2015 Gas Gas EC 250 GP 2018 |
#7
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0.01mm is a mere gnats cock. Be more concerned about the ring pins being in the right location.
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2006 EC300 Enduro - Ignitech CDI - 38/NECW#2/165 FMF gnarly, FMF shorty, .50 front 5.7 rear 2016 RM-Z450 |
#8
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Exactly. Don't lose sleep over the size.
It is entirely feasible for the ring ends over the rear boost port. Rotax have done it for years but you really want to have it symmetrical as the front of the ring bulges into the large ex port. Twisting could be bad. I've only done it on single ring pistons. But even on soft steel bores no damage occurred. Plated are much harder. The one pin over the other probably isn't anything. I mean single ring pistons are fine and the pressure that may leak into that area is gas not a physical object. Poke a balloon and the balloon deforms.
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'07 EC300 GG '14 TXT250 GG '? 496 CPI Cheetah RZ/RGV hybrid '22 765 Street Triple RS '21 XTrainer '69 Stinger T125 Suzuki '23 TRS 250RR (it's a Trials thing) |
#9
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It's probably nothing to worry about, after all GG wouldn't insist that there is nothing wrong to it except the design change. Anyway when I get my hands on the photos I will post them just for reference.
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Gas Gas EC 300 2006 Gas Gas EC 300 R 2015 Gas Gas EC 250 GP 2018 |
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