I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and timin

[Massey]

My '76 Mercury 1150 115 hp is a 2 stroke - 6 cylinder, electric start, manual tilt and trim. It's on the back of a '76 Ranger 18 and a 1/2 foot, 185A. I bought the boat several months ago, and it ran decent, but not hot when I first got it. But, over the past 3 months it's performance has been going down. It is bogging really heavily out of the hole, and is not running hot at all. I've noticed at first that if I had a passenger go to the front of the boat, it would accelerate better, but now that's not helping. I removed the spark plugs and they're all moist with fuel and oil, and they have no electrode on them??? Anyway, I believe my timing is off, and I think the plugs are bad. But, I don't want to put the same kind of plugs back in, and I can't find a manual that I can afford to find out which plugs to put in them.<br /> What I really need, I need to know what plugs I should be putting in the engine, brand and number...how can I accurately measure my fuel oil mixture since it's a 2 stroke, and, what speed should I be experiencing with this boat? I think my prop might be a problem cause it's chewed up pretty good, and I think it might have a little to high of a pitch, but I don't know where to find the numbers on it. Please help????

 

[JB]

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

What tachometer readings go with original performance and declining performance? <br /><br />Fuel mix. 50:1 is one pint of oil per six gallons of gas, or close enough. I don't understand what the problem might be with that.<br /><br />Your prop certainly isn't helping your performance. Repair or replace it.<br /><br />Let us know.

 

[wjones]

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Those plugs are probably surface gap plugs. I have a 1970 135HP and it uses the same plugs.

 

[mrm]

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

AC-V40FFM or Champion L76V, OR NGK BUHW<br />Gap is not adjustable<br />Don't mess with timing until you find a manual and study it. Stock prop. is 19 pitch. I run a 21 S.Steel. RPM should be between 5000 and 5500.<br />You need a working tach. and a manual.<br /> MRM

 

[Massey]

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Hey, thanks everyone for the quick and helpful info! I didn't know what mixture to target for my oil, but I'll start with that 50:1. Also, I found today, perma gap plugs from a local place that cross matched them for me. I don't remember the brand or number, but they're working great. The timing specs are actually listed right on my manifold on the inside, so I went off of that. Out of the water with the water muffs on, the boat reallllllllyyyyyy smoothed out. Purrs like a kitten instead of the rough rider sound before. My timing was at 16 degrees btdc, and was supposed to be 23. I think the next step is my prop, but caint afford it right now. Thanks to everyone who posted, any additional info would be appreciated too! Thanks, Major

 

[ShafferNY]

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

Re: I have a '76 Mercury 115 and I need help! Bogging, dirty spark plugs, and t

I use a regular, house hold, measuring cup to mix oil with my gas. <br /><br />2.6oz. of oil to every gallon of gas. If it comes out to be some odd number(like 7.8oz), I round up(to 8oz.), better more oil than less.