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Compression ratio?

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Could some one tell me the compression on a 05 Sx 125 + the procedure (how to check it).

Please and thanks!

Led.:banana::ride:

Edited by Led_rocks54

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typically KTM 2st are in the 180lb range when running well, maybe a little higher right after a rebuild. Also high elevation will give a lower number. Each compression tester will give a little different reading too so its a good idea to test with the one you have right after a fresh rebuild so you know what the reading can be at the best possible time.

The way to do it is to kick the bike several times with the throttle wide open.

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Warm is best.

If you are buying a compression tester, look for a plug insert no longer than a plug or it will interfere with the frame and look for a fairly flexible hose. With a suitable tester, you can fish it down the tank vent next to the rad with the tank on.

Readings on testers vary widely, some good advice given above here.

Mine reads 175 on my 300 but I can barely kick it over.

My 125 reads 90 and still starts every time, runs and idles (but really does need a ring).

Low compression mainly affects low rpm torque.

It is most valuable as a tool to track wear over time.

Like said, record compression after rebuild and chart values over time.

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