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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc. |
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#1
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EC 300 cylinder pressure
Anyone know what the minimum cylinder compression pressure in psi for an ec 300 is, going to measure it next week after looking into exhaust port there is small amount black/brown build up 10mm below bottom ring, is this normal?
Thanks in advance! |
#2
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My 2008 250ec runs about 190psi. Build up below the bottom ring seems strange. A little oil wouldn't be awful, but if it sticks the ring, that's bad.
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Mike Sheetz OMRA #21AA What will I be riding next? Christini GG 300? '15 KTM 300 XC-W '08 EC 250 (Gone to new happy owner) Gran Prix Cycle LTR Suspension RB-Designs |
#3
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It starts and runs ok, but dont know if this build up is normal
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I think engine compression is something better monitored rather than just take a reading when something seems wrong. I don't know how people get these high readings, my gauge must be off or something, because I get around 125 in both my EC250 and 300. Aren't these pistons like 10:1, 14 psi atmospheric pressure, so the max it could be is 140? I never understood that.
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2006 EC300, 2000 XR650R, 2003 EC250, 2001 EC200 (OK, the last two are really my sons). |
#5
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I thought these bikes were 14:1.
Anyway, to get a consistent reading, put a couple drops of oil down the sparking plug hole. The 300 I had before consistently read 180-185psi. My 200 before that read similarly. Ron @ RB Designs did the squish band mod on my 250. He requested that I perform a compression test before sending him the head. He was not surprised by the reading. Bottom line, if you get consistent readings you're probably fine, as long as it runs fine.
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Mike Sheetz OMRA #21AA What will I be riding next? Christini GG 300? '15 KTM 300 XC-W '08 EC 250 (Gone to new happy owner) Gran Prix Cycle LTR Suspension RB-Designs |
#6
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Quote:
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2006 EC300, 2000 XR650R, 2003 EC250, 2001 EC200 (OK, the last two are really my sons). |
#7
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Compression ratio on a 2 stroke is always much lower than 4 stroke and I am never sure if they quote some virtual ratio using the stroke or the real ratio from when the exhaust port is closed. Additionally the working compression is hugely effected by the pipe and rpm although I don't suppose this has any effect when you're kicking it to get a test reading. That's why I assume the advice is test when it's known to be good so you have a reference with your own guage and speed of kick.
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#8
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Compression test pressure is measured by kicking the bike fast with the throttle open until the reading tops out and stops rising. A good 250 will be around 185 - 200, 300s a bit less, more like 175 - 185. You have to kick fast enough to make normal leakage through the rings and in the case of the 300 the bleed hole not a factor. Compression ratio is the volume of the cylinder from the top of the exhaust port plus the volume of the head divided by the volume of the head. No way 14:1, usually around 7-8:1.
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#9
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Quote:
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2006 EC300, 2000 XR650R, 2003 EC250, 2001 EC200 (OK, the last two are really my sons). |
#10
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Quote:
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