Rotax FR125 EVO Senior - poor compression?

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iancwalker
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Joined: Sat Apr 21, 2018 2:52 pm
First Name: Ian
Last Name: Walker
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Rotax FR125 EVO Senior - poor compression?

Post by iancwalker » Sat Apr 21, 2018 3:01 pm

Based on an EVO.

Running flat out, suddenly engine felt like it had an engine brake, turned it off real fast.

Still cranks, albeit sounds a little off.

Checked the following:
~ Top of piston appears good
~ Plug clean (no metal shavings lol)
~ Thumb on plug hole, crank and can feel pressure (not sure how much there should be)
~ Pulled carb off
~ Pulled reed out and it appears fine
~ Cranked while reed out and piston wall looks great, no visible wear and/or scuffs etc.

Any suggestions for next steps of trouble shooting, cranks, sounds slightly off (maybe a lack of full compression) and will not fire.

Thanks,
Ian.

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John Kwong
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Re: Rotax FR125 EVO Senior - poor compression?

Post by John Kwong » Sat Apr 21, 2018 6:17 pm

Rebuild the fuel pump. If you already did that and now have this problem, certain pump diaphragm gasket kits are troublemakers. The kit with the black gaskets is the good one. The beige gasket kits will tend to give the symptoms you describe.

John K
John Kwong___CIR Realty___403-294-1500
www.johnkwong.ca
http://kartopractor.weebly.com/

iancwalker
Posts: 2
Joined: Sat Apr 21, 2018 2:52 pm
First Name: Ian
Last Name: Walker
City/Town: Victoria
CKRC Member ?: No

Re: Rotax FR125 EVO Senior - poor compression?

Post by iancwalker » Sun Apr 22, 2018 2:45 am

Thanks, I will try a new pump tomorrow, along with the solenoid for the power valve and also take the power valve apart, confirmed spark this afternoon too... :(

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