Gday Glen,
Not being an expert on outboards, and if i am wrong in any of the points i make below please tell me so i can adjust my brain accordingly <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt=':th' /> , i was given a few pointers by my mechanic when i went secondhand boat hunting last time.
First off some general comments, i'd look at the general condition of the outboard and make an assessment as to whether or not it has been looked after.
Look under the cover and in particular at the powerhead and be wary of paint discolouration (burnt paint) or paint peeling from cylinder heads (indicating cylinder is too hot when running, because it is running lean i believe).
Ask to see the sparkplugs, if they are new then they wont tell you much and i would be wary but not put off. The plugs should be blackish in colour and have a bit of oil on them but nothing excessive. If they are dry and light grey in colour the cylinder is running too hot.
#1 Check compression in the cylinders. They should all be above 100psi and all within 5~10psi (10psi may be too much) of each other.
What i mean by that is if the engine has 4 cylinders then the following would be acceptable: #1@105psi, #2@106psi, #3@110psi, #4@115psi.
Whereas: #1@105psi, #2@106psi, #3@110psi, #4@120psi would not because difference between #1 and #4 = 20psi
#2 Engine noise/vibration Just make sure the motor sounds like it is running properly with no wierd rattles/grinding noises, and when running it isnt vibrating excessively.
#3 Check gear selecting Make sure forward and reverse gears can be selected for a start <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/whistling.gif' class='bbc_emoticon' alt=':lol' /> , and that there are no crunches or "sick" noises as you move the throttle and select gear. I have found that you can get a bit of a "rattling" sound while you move the throttle to selest gear which is sometimes due to adjustments required in the cables.
Those are my humble tips Glen, there is nothing more frustrating than finding the right hull but with a dud donk on the back <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='
' />
Good luck <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/xyxthumbs.gif' class='bbc_emoticon' alt='' />
AK
Not being an expert on outboards, and if i am wrong in any of the points i make below please tell me so i can adjust my brain accordingly <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt=':th' /> , i was given a few pointers by my mechanic when i went secondhand boat hunting last time.
First off some general comments, i'd look at the general condition of the outboard and make an assessment as to whether or not it has been looked after.
Look under the cover and in particular at the powerhead and be wary of paint discolouration (burnt paint) or paint peeling from cylinder heads (indicating cylinder is too hot when running, because it is running lean i believe).
Ask to see the sparkplugs, if they are new then they wont tell you much and i would be wary but not put off. The plugs should be blackish in colour and have a bit of oil on them but nothing excessive. If they are dry and light grey in colour the cylinder is running too hot.
#1 Check compression in the cylinders. They should all be above 100psi and all within 5~10psi (10psi may be too much) of each other.
What i mean by that is if the engine has 4 cylinders then the following would be acceptable: #1@105psi, #2@106psi, #3@110psi, #4@115psi.
Whereas: #1@105psi, #2@106psi, #3@110psi, #4@120psi would not because difference between #1 and #4 = 20psi
#2 Engine noise/vibration Just make sure the motor sounds like it is running properly with no wierd rattles/grinding noises, and when running it isnt vibrating excessively.
#3 Check gear selecting Make sure forward and reverse gears can be selected for a start <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/whistling.gif' class='bbc_emoticon' alt=':lol' /> , and that there are no crunches or "sick" noises as you move the throttle and select gear. I have found that you can get a bit of a "rattling" sound while you move the throttle to selest gear which is sometimes due to adjustments required in the cables.
Those are my humble tips Glen, there is nothing more frustrating than finding the right hull but with a dud donk on the back <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='
' /> Good luck <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/xyxthumbs.gif' class='bbc_emoticon' alt='
' /> AK