Yamaha YDS // compression ???

[ttles714]

Can the YDS diagnostics determine compression ?? Or does it need to be done with a compression tester ??

[boscoe99]

YDIS can not provide compression. Compression tester is needed.

[ttles714]

Thanks for the reply ...... looking at a F225 and the owner is not to keen on me pulling out the plugs .... He is ok with scanning with the YDS. ... If there were a " bad" cylinder would the YDS pick up on any thing that would indicate that ?? Again, thank you for your time

[99yam40]

I would not buy a motor without compression or even better a leak down test to prove all cylinders were sealing properly

[fairdeal]

If there were a " bad" cylinder would the YDS pick up on any thing that would indicate that ?

Absolutely not;
the engine ECM "has no knowledge" of the physical condition of the engine,

and YDS would provide little useful information in assessing it;

merely the history of total operating hours within several rpm bands,
and records of alarm conditions / out-of-range inputs
(unless those were already cleared - which is easily done)

[robert graham]

What’s the owner got against removing the spark plugs?? …..maybe he’s hiding something?…

[brian3006]

What’s the owner got against removing the spark plugs?? …..maybe he’s hiding something?…

Yea that sounds a lil suspect. Any motor I ever sold I hooked up a compression gauge for the buyer just to show i'm not trying to offload a junker. andy I have bought have also been compression tested...