blueband 50

[ab56452001]

hi, just picked up a mercury 50 hp blueband 4cyl around 1975-1980, what was the compresssion ratio new, and what should a reasonable one have now , thank's

 

[rickdb1boat]

Re: blueband 50

You should have at least 100PSI per cylinder and they should all be within 10% of each other. Might be slightly lower to to age, but should still be close together on the readings.

 

[andrewkafp]

Re: blueband 50

Welcome to the world's best Boating site...<br />What part of Oz are you from ?<br />If you supply your Serial No (7 digits starting with 4,5,6,9 or 8..) I can tell you the year.<br />I have an '81 Aussie made Merc 50 and the compression (psi) is not as important as the consistency of each cylinder.(As Rick said) Mine is @125 psi in all 4, but they can be down around 90 and the motor will still perform fine. Is your Blueband a 500 or a 50? Does it have light/Dark blue bands with silver or white text and a red "50" ? You can also get the year by the cowling markings and other engine components that were either discontinued or introduced in certain years.

 

[ab56452001]

Re: blueband 50

thank's for the info, i am from adelaide s.a.(salisbury). the motor serial no starts with an 8, dont know what year, it has 115-120 psi on allfour, thanks

 

[ab56452001]

Re: blueband 50

sorry forgot to say , on the cover it says 500 with a plain blue band, cam of a private houseboat and seems to run o'k',I have put in a new impeller kit and head gasket just incase

 

[andrewkafp]

Re: blueband 50

If you supply me with the rest of that 8 Number, I can give you the year. My '81 has a S/N of 8055958<br />Yours is an Aussie made Merc (Or probably just assembled here from parts made in USA). If it's a 500 it will be before 1979. Does it have a distributor or is it a 4 coil/trigger motor ?<br />Sounds like your compression is very good. Make sure you always use FRESH 50:1 fuel in it and I would advise adding some Fuelset or Petrolpower stabiliser to the tank in case there is any gum in the carbs. These multi carb 2 strokes are good motors, but if the carbs and fuel are not kept clean, they can run lean and burn up pistons.Best that you run it out of fuel before storage too.<br /><br />BTW ..If you follow my posts around this site.. you will find that I've got some good value from the great people on iboats. I've asked just about every question possible and got some good "Do's and don'ts.. Search on 20316 member.<br /><br />Cheers

 

[ab56452001]

Re: blueband 50

thanks for the help !, it has a dizzy and the serial no is-8023262

 

[andrewkafp]

Re: blueband 50

You can look here for some line ups..<br /> http://www.marinshopen.se/guide/mp/merc65.htm <br />It's in Swedish I think... and doesn't include Aussie numbers (Only USA and Euro)click on modelguide-merc then 35-65HK<br /><br /> http://www.dougrussell.com/partscat...x.cfm?fuseaction=serials&colid=01&coldesc=500 <br />Aussie Numbers are a bit hard to track, but based on your info, I'd say it would be 1974-75 due to <br />the fact that 8030090 lined up with USA 4357640 which is the last of the 1975's Your 802*** falls somewhere between 4357640 and 4141000 (1975)

 

[andrewkafp]

Re: blueband 50

Have a look here...<br />http://www.screamandfly.com/home/multimedia/brochures/mercury_ consumer/1975_outboards/1975_mercury_outboards.htm<br /><br />A rare 1975 link ..

 

[Troy_from _Oz]

Re: blueband 50

Unicorn - just a question about what you said earlier if you will all indulge me... Do you run the engine out of fuel to stop gumming or are there other reasons also? (i have a redband 650) -are there any downsides to doing this?<br /><br />Also - should you do this after every outing, or just after the summer when storing the boat?<br /><br />One final question, will the Fuelset or Petrolpower stabiliser dissolve gum or just stabilite the fuel?<br /><br />Many thanks<br />Troy (from Perth)

 

[andrewkafp]

Re: blueband 50

Troy<br /><br />Very debatable subject "Running out of fuel", but my motor's previous owners have always done it every time it's run.(20 year old Merc 50) This is to leave the minimum amount of 2 stroke oil and gum in the carbs.. so they tell me.<br />I have also read that some people leave the carby bowls full at all times and just give the bulb a squeeze now and then. Suppose the effect is similar (No evaporation)<br /> I use Petrolpower additive and run the motor until it starts to rev up and turn it off before it stalls upon advice from this site. Prevents dry starting next time.<br /> http://www.liquideng.com.au/fuelset.html <br />This product dissolves gum.. and has upper cylinder lubrication and cannot harm anything, so it seems to be a good addition for any fuel left sitting either in the carbs or in the tank.<br />You have a whitworths in Perth.<br /> http://www.whitworths.com.au/main_itemdetail.asp?item=38278&search123=power&intAbsolutePage=1 <br />Check here.

 

[Troy_from _Oz]

Re: blueband 50

Unicorn, <br /><br />Thanks for the info. I might try some of the petrol power. not sure exactly what you mean about running the engine up and then shutting it off before it stalls. Id be interested in talking off topic about this if you wouldnt mind? (hate to take up board space just because I dont understand something thats probably very simple). would it be possible to email? My address is t_f1@yahoo.com.<br /><br />thanks again<br />troy

 

[andrewkafp]

Re: blueband 50

Yeah, I should know better after 500 odd posts.<br />I'll drop you a line.<br />Apologies AB..