midas69er Posted June 27, 2013 Report Share Posted June 27, 2013 Hey All, Took the kids out for some blue gills in the creek, landed a tone, lots of fun for sure! When I got back I was talking to a guy at the dock, he said that my 87 merc outboard would run better if I used higher octane gas. It runs fine, however its not the first time I had heard this. Anyone have experience with this? sorry 1987 45 hp merc 2 stroke, with oil injection Link to comment Share on other sites More sharing options...
fishkid Posted June 27, 2013 Report Share Posted June 27, 2013 The only real difference is the lower levels of ethanol in high octane gas. Since the motor is so old it's not built to deal with it. You may gain slightly more power but it would be marginal at best. What size is the motor? Link to comment Share on other sites More sharing options...
ron4blues Posted June 27, 2013 Report Share Posted June 27, 2013 Higher octane gasoline is more resistant to pre-ignition than lower rated fuel. It enables an engine to run at higher temperatures and compression ratios, which is why you'll see higher ratings for racing or aviation fuel. I don't think there'd be any real advantage in a two-stroke engine unless you run it hard for long periods. Link to comment Share on other sites More sharing options...
Ainsley Posted June 27, 2013 Report Share Posted June 27, 2013 I recently rebuilt a 69 merc 1000ss (100hp) and after only two years started to have problems with the cork gaskets on the fuel pumps. I believe the ethanol was causing it to degrade and pieces of cork were jamming up the check valves. This year I'm running only premium fuel, not for the higher octane but for the lack of ethanol. Link to comment Share on other sites More sharing options...
scapulataf Posted June 28, 2013 Report Share Posted June 28, 2013 You will go faster with high octane gas. Because your wallet will be lighter. Link to comment Share on other sites More sharing options...
nwillz Posted June 28, 2013 Report Share Posted June 28, 2013 High octane usually has no ethanol. Ethanol is not good for your carb. That is why on most small 2 stroke engines, ie chainsaw, gas auger, atv, anything that is carb it is always better to run high octane. Ethanol is more corrosive and burns at higher temp. Also it can leave carbon deposits and cause rust. The ethanol also can cause the fuel to ignite at the wrong time in the combustion process. To each's own, I always run high octane in my small engines and amsoil. Whatever you feel comfortable with. Link to comment Share on other sites More sharing options...
captnn Posted June 28, 2013 Report Share Posted June 28, 2013 If it ain't broke don't fix it. Link to comment Share on other sites More sharing options...
Bic4d Posted June 28, 2013 Report Share Posted June 28, 2013 If you want to cut the Ethanol in the regular gas, buy the (Star brite) Star Tron Enzyme Fuel Treatment. It cuts the Ethanol in gas and diesel fuel giving you a cleaner burn, increasing power and will eliminate carb gumming and varnish deposits as well as prevent carbon build up.. 1 8 fl. oz bottle will treat 128 gallons, I put it in my tank and gerry cans before topping up the boat...... Check out there web site, you can buy it just about anywhere, Wal-Mart, CT or your local marine.... I buy mine at Wal-Mart in the U.S, it's about 1/2 the price....... Good luck....... Link to comment Share on other sites More sharing options...
bucketmouthjohnny Posted June 28, 2013 Report Share Posted June 28, 2013 totally agree with Bic4d !!! most motors are rated for 87 octane...putting richer octane can hurt your engine...get yourself a couple bottles of star tron enzyme fuel treatment and add accordingly...you can err on using slightly more.. also, this makes running stabilizer for 10 minutes obsolete according to star tron as this also acts as a stabilizer , I still fog my engine and plugs though! sorry meant to mention , two bottles should last you a season, they are like $8 and change per bottle at walmart, US... Link to comment Share on other sites More sharing options...
midas69er Posted June 28, 2013 Author Report Share Posted June 28, 2013 Thanks everybody, your feedback is welcomed and fishkidthe engine is a 1987 mercury 45 hp (classic 50) I like the idea of the fuel treatment and will try that for sure. I am concerned of increase presure built up from the higher octane. Link to comment Share on other sites More sharing options...
smerchly Posted June 28, 2013 Report Share Posted June 28, 2013 I have been using the blue Star Tron since last spring . The guy I take my small engines to swears by the stuff . It has fixed up many a weed wacker by cleaning out the carb ., then adding a new filter & fresh gas ! I saw it at CT last winter for $11 + tax($10.9999) lol , but haven't seen it since . Link to comment Share on other sites More sharing options...
fishkid Posted June 28, 2013 Report Share Posted June 28, 2013 Another thing that is definately worth doing on an older engine is having all the lines from the fuel tank to the carb (including the fuel pump diaphragm) changed out to ethanol compatible fuel lines. Ethanol will eat the rubber and send debris into your system, clogging carb jets and what not. The enzyme treatment in low octane is the best treatment, but the big misunderstanding is that it does not get rid of the ethanol. The ethanol will always be in there, but the treatment will help prevent phase seperation and give you a more consistent burn and help prevent everything from gumming up. Link to comment Share on other sites More sharing options...
ron4blues Posted June 29, 2013 Report Share Posted June 29, 2013 Octane used to be regulated in part by lead content. I'd say ethanol is a more palatable alternative. But it does have drawbacks. Updating your system with new gaskets and hoses will help. Link to comment Share on other sites More sharing options...
smerchly Posted June 29, 2013 Report Share Posted June 29, 2013 Octane used to be regulated in part by lead content. I'd say ethanol is a more palatable alternative. But it does have drawbacks. Updating your system with new gaskets and hoses will help. For true Coachman .....my neighbour had trouble with his older 2 stroke Merc & they found the draw tube inside the gas tank had disintegrated into little pieces from ethanol . Link to comment Share on other sites More sharing options...
ROB MCINTOSH Posted June 29, 2013 Report Share Posted June 29, 2013 I run a 225 merc and can't afford to replace another motor.Johnny is right for 8 or 9 $ two or three times a year will cover your butt. I also mix a 1/2 tank of high test 2 times a year just to clean out any crap that may build up. Link to comment Share on other sites More sharing options...
pudge Posted June 29, 2013 Report Share Posted June 29, 2013 is the star brite stuff the same as seafoam? Link to comment Share on other sites More sharing options...
bucketmouthjohnny Posted June 29, 2013 Report Share Posted June 29, 2013 no, similar but as far as I know, seafoam helps stop the build up of carbon but doesn't stop the phase separation of ethanol and doesn't stabilize like startron or biobor eb...I have a can or two kicking around my garage as I had used this on my 150 carbed engine to help prevent carbon buildup while idling long no wake zones like chippawa creek...now all I use is startron and haven't had carbon build up and have the peace of mind that the startron is helping with the ethanol as well as acting as a stabilizer... ps , I use startron in my gas weed whacker (like papa smerch mentioned) and will use it in new lawn mower when I get one...this ethanol really can do a number on smaller engines from what I read.... Link to comment Share on other sites More sharing options...
pudge Posted June 29, 2013 Report Share Posted June 29, 2013 thanks...i will look into the startron.... Link to comment Share on other sites More sharing options...
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