oily plugs
 

Anyone else have or had this problem? I have a 2008 yamaha 70 2 stroke oil injected . motor runs fine . I just get this oil buildup around the plugs. Plugs are clean around the gap and inside. I never see excessive smoke . Maybe its not fully burning the oil so its not smoking, i don't know. Its like automobile engine oil after it turns black. During the winter it seems to be worse , then the inner part of the plug will get dirty and it will miss different cylinders till about half throttle and after its cleared up it will run fine the rest of the day.

I have seen that caused by excess gas dissolving the unburned oil sludge and carbon left in the cylinders from over mixing the oil in the gas.

try keeping better track of the oil/gas ratio you are using but the simple solution is get plugs one setting hotter and it should burn that gunk off before you see that.

if the mix is right the plugs should be coffee with cream colored light brown.

if this is just a sudden new thing that wasn't there before then maybe you have built in tanks and your oil isn't mixing well and its pulling slugs of unmixed oil from the tank.

also, I know people like to add the gas first so they know how much oil to add but always add the oil before the gas so the gas stirs and mixes the oil well. just don't feel the need to fully top off the tank so you can add x gallons of gas to the oil you added and if its not totally full stop there. rarely do you need a full tank to that extent of accuracy so if your a few gallons shy of full is not a big deal

I have a 2008 70 hp. 2 stroke oil injected........no pre mix......I had a neighbor put a set of hotter plugs in a 25.....Made the prettiest lil melted hole in the center of the piston you would ever want to see.....

Ring Free
 

Might want to run a tank or 2 treated with Ring Free. It should help with the build up.

Tried ring free for about 10 gallons and made no difference. Ran it for 6 months with it , no difference. I can shine a light in cyl. and there is very little carbon on pistons and cyl. walls shine like a mirror where i can see. During cold weather is the main problem. I runs rough till about half throttle then smoothes out and no problems rest of day. I run 56-5700 at wot but keep it at 51-5200. Its been running like this a few years now and I'm running out of ideas how to correct it. I thought about disconnecting oil injection and pre mixing but don't want to mess it up worse.

pre-mix might be the ticket to solve this but I would look into the things that control the mixture as its putting too much oil in so you might have a dirty or faulty sensor somewhere.

I don't know much about the oil injection systems so whatever is used to tell it how much oil you need is where I think your problem is.

you should make a regular habit of running it wide open for 5 or 10 minutes on the way in to burn the cylinders clean because the problem may just be that you aren't opening it up enough to burn the oil.

as to the hotter plug, yes if you just grab any plug that has a hotter rating you can cause issues but if you get the dealer or qualified outboard mechanic to recommend a plug that will only run "slightly" hotter then stock, and you monitor your plug condition it will tell you if you have the correct one or not. you cant just put a hotter plug with no thought to checking it to make sure its running correctly.

inj
 

are you using the right 2cycle oil? has to be tcw3!!! doesn't have to be yamalube!!!! is the boat sitting up for periods of time? how often do you run the boat? are the plugs like that right after you run it? or before?

if it is sitting up and you are finding this, it could be the simple fact that the gas in the cylinders is evaporating leaving the oil behind, nothing to worry about

the best thing you could do is remove that oil injection system and mix your oil in yourself

I've run yamalube,,,,evinrude,,,,merc. all tcw3....lately been running at least twice a week....before at least 4 times week. during winter mostly 5 days week....It doesn't seem to be hurting the motor but is just aggravating that something just ain't rite... My boat never sits more than 4 days.