Outboards

[adzzy]

Hi all

Do i need to remove all spark plugs to do a compression test or just the one that i am testing

any help would be good

cheers

[pelican]

motor cold

Remove them all - gives best possible result and is easier on starter motor or your shoulder

throttle butterfly's open ( if it has them)

Strong battery

turn over 6 times on elictric starter or a couple of pulls.

Apart from the base number it is all about having even compressions ( within 5-8 psi ). Every tester unless calibrated will give a different reading so just check they are even and near enough to original spec. Below 110psi i'd start to ask big questions.

Is it a 2stroke or 4 stroke and how new as some extra care may need to be taken with motors with newer electrics

Plugs tell you a lot about ow motor is running but an on water test to check it revs out will tell you a lot as well if you have been in comparable boats.

Pel

Edit

Just saw in your other post that it is a Yammi 2 stroke. 115psi I would want but ask a mechanic for numbers for that motor.

Edited November 26, 2008 by pelican

[adzzy]

Thanks heaps for your info pelican

that was my thoughts and i have done the same thing on other boats i have bought in the past

and never had a problem or bad reading

except for the throttle butterflies didnt know that

now i can rub my mates face in it cause i'm right

it is approx an 86-88 model 2 stroke

thanks once again

Adzzy