Tune up on old motor?

[gpfishingdude]

I called a Mercury dealer and asked to speak to the service manager. The guy on the phone asked me what I needed and said that he might be able to help me. I told him that my old outboard didn't perform up to it's maximum when I had it on the big lake last week so I wanted to get it tuned up. He told me that he didn't know who works on old outboards like that anymore and that they wouldn't be able to even look at it until December because everybody is bringing theirs in for winterizing right now. He said that his uncle who works on motors part time might be able to look at it for me. I asked for his uncles phone number but he said he didn't like giving it out and he would call me back. He called back and said his uncle was too busy to do anything for me and suggested another marina up the road. I told him I would find a dealer closer to where I live to work on it for me. Are you guys having problems getting tune ups done on your old motors or was this guy just trying to drum up work for his uncle? This guy was such a fast talker that I had a hard time asking about his uncles qualifications but he claims he works for the dealer at times. I think I did a fantastic job getting this old outboard starting, running and idling as well as it does but I just don't have the gauges and tools to get the motor running at it's peak, to set the carbs- the linkage- etc. properly.

 

[nwcove]

Re: Tune up on old motor?

ok....what is this old outboard??

 

[gpfishingdude]

Re: Tune up on old motor?

The outboard I was talking about is a 1985 Mercury 50 horse four cylinder two stroke motor. I know that all that is wrong with it is just minor adjustments because it still has good compression and it starts and idles good. I plan on calling some other Mercury dealers tomorrow and see if they will still do tune ups on old motors.

 

[Scott Danforth]

Re: Tune up on old motor?

Most marinas will not work on anything more than a few years old. the price of the repair can quickly become more than the worth of the motor. you have a 30 year old motor. The guy you actually find that works on old motors will probably not be a dealer, however most likely an independent.

 

[gpfishingdude]

Re: Tune up on old motor?

The service manager for the first dealer that I called today said "SURE, bring it on in and we can tune it up for you". I asked what it costs for a tune up and she said $90 an hour plus parts and usually only takes an hour or two. Parts are usually spark plugs. This sounds like it is about in line with what I expected. What a difference in attitudes from the first place I called.

 

[TD_Maker]

Re: Tune up on old motor?

Few dealers want to trouble shoot the old motors either. If they can't link up with the computer on the motor, they don't want any part of it. I took a tour of the Marine Mechanics Institute, and everything they were working on, and training on was new technology.

This is why websites (Like this one) is especially handy for guys like us. Doing it yourself gives you a great satisfaction, and personally I find it very relaxing knowing that if something goes wrong, AT LEAST I know where to start looking.

 

[jbjennings]

Re: Tune up on old motor?

The service manager for the first dealer that I called today said "SURE, bring it on in and we can tune it up for you". I asked what it costs for a tune up and she said $90 an hour plus parts and usually only takes an hour or two. Parts are usually spark plugs. This sounds like it is about in line with what I expected. What a difference in attitudes from the first place I called.

I hope she's not overly optimistic about the number of hours of labor....... There always seems to be more needed than a link and sync, a carb cleaning, and new fuel lines and spark plugs on a 30 year old motor that's sat for several years. I sure wouldn't tell someone I could likely do it in 2 hours.
Good luck either way,
JBJ

 

[gpfishingdude]

Re: Tune up on old motor?

I didn't say that this motor had sat unused for 30 years although I am kind of amazed at how well it ran with the number of things that I found that needed fixing on it. I replaced the stator and trigger because the wiring coming down from the top was all corroded and I had the carburetors rebuilt because it was flooding easily when I bought the boat and motor last year. Then I did a spark test and found one bad coil that was keeping it from idling properly. A new rectifier started it charging properly. When I had the carburetors rebuilt I took them off myself and took them in and the dealer rebuilt them and I reinstalled them. I adjusted the idle and the air mixture as best I could but I have to admit that I may be lacking the ability to fine tune the carburetors. Therefore it ran rough during acceleration last week and only topped out at 4500 rpm and 15mph on Table Rock Lake. I just want it to perform at it's peak for a change. I'm sure there are a few mechanics around who are pretty good at working on old motors yet and can still tune a carburetor. Thanks for all the suggestions though.

 

[jbjennings]

Re: Tune up on old motor?

Check and make sure the timing is getting full advance. I'm thinking it should reach full advance and hit the stop screws at about 3/4 throttle. If the carbs are indeed clean, then tuning them shouldn't affect high speed operation as far as full rpm. Maybe something is sticking from corrosion on your spark advance.
Just some ideas---sounds like you've done a lot of the time consuming stuff. Didn't know you'd done all that..
Got new fuel lines??? There's a how-to tune a carb/carbs by expert Joe Reeves in the top secret files on the Johnson/evinrude forum that should help you on fine-tuning your carbs, BTW. Handy stuff....extremely easy to do. Also, you might try giving it full throttle and checking to see the throttle plates are fully opened in the back of the carbs. I would NOT adjust the timing stop screws----without a timing tool it's something a dealer might be best to take it to. THey rarely need adjusting, however....
Good luck,
JBJ

 

[gpfishingdude]

Re: Tune up on old motor?

Thanks! For the help about checking the timing and the throttle plate positions. I might have the secondary pick up screw out of adjustment because I started adjusting it, at one time, thinking that it was an idle adjustment. After finding out how to make idle adjustments, I could only guess at where the secondary screw adjustment was set at. I am hoping that I will be able to discuss some of these ideas with the service department when I take the boat in. I am waiting to get my truck back from the body shop so I can take the boat in. I am getting a quarter panel replaced that got damaged during a blow out while pulling a fifth wheel trailer last winter. I will try to find the article by Joe Reeves. I thought that a good mechanic uses a vacuum gauge to get the carbs. set properly.

 

[jbjennings]

Re: Tune up on old motor?

Carb adjustment procedure:
http://forums.iboats.com/engine-fre...sorted-carb-variations-joe-reeves-167352.html
I've never used a vacuum gauge to set my 2-stroke carbs and honestly would have no idea how to do it. They're really simple carbs compared to a truck carb.

I would suspect that your carbs only have a low-speed fuel circuit adjustment screw, a throttle valve stop screw, and an idle timing and high speed timing stop screw. The only thing that usually needs adjustment after carb overhaul on your motor would be the low speed fuel circuit screw (idle jet), since you don't have to remove any idle timing stops or throttle stop screws as far as I know.
If you're taking it to a shop, it should indeed not take them long to set the timing stops and idle jets.
If the high speed timing stop is not right, you could get detonation and melt a piston. I guess it's not a bad idea to have an expert finish tune the motor after all--- you may be wiser than I, to have planned on doing that!
Good luck,
JBJ

 

[gpfishingdude]

Re: Tune up on old motor?

It is taking a lot longer than expected to get my truck back from the body shop so I decided to try and tune the carbs myself. The Mercury book pretty much explains how to make the adjustments. I filled a garbage can full of water and dropped the motor leg down into it and left the water running in the can. I think I should have removed the prop because it blew so much water out of the can that it wasn't picking up enough to stay cool. The Mercury book says to tune the carbs. in a tank of water while in forward gear. Do you tune them with the prop off or do you need it on to get the proper load or something? Right now I'm thinking in a tank of water and with the muffs on.

 

[wired247]

Re: Tune up on old motor?

Mercury uses a test prop which i s just a low drag impeller. You can make one out of an old prop and cut the blades back quite a bit.

 

[gpfishingdude]

Re: Tune up on old motor?

I think they use a lot bigger test tank at the dealers for tuning them up. I really doubt that the pros get their feet and legs wet trying to tune theirs. At the end of the day I still don't know if I really accomplished much of anything. The Mercury book says basically to start at 2 turns out and then adjust IN until it runs rough and then back out 1 1/2 -1 3/4 turns. That seems like it is way past the peak on mine. Mine seems to idle the fastest at between 1/2 and 1 turn back from rough idle. The bottom carb adjustment seems to effect it more than the top one does. As a matter of fact the top one doesn't ever really peak out like the bottom one does at any adjustment.

 

[wired247]

Re: Tune up on old motor?

Don't fall into the trap of adjusting the carb for best idle. It will fall flat on its face in the water transitioning to the main circuit.

 

[gpfishingdude]

Re: Tune up on old motor?

Don't fall into the trap of adjusting the carb for best idle. It will fall flat on its face in the water transitioning to the main circuit.

Thanks! That might just be what I have been doing because of the rumble I got when I accelerated on the lake the last time out and the lack of top end performance. I will try getting it in the range that the book suggests and see if it will perform better the next time out.

 

[CharlieB]

Re: Tune up on old motor?

Idle mixture needs to be perfected ON the water and IN Forward gear. This provides the correct exhaust back-pressure and load on the motor.

Each carb is initially adjusted to 'Best Idle', from there each must be adjusted richer to provide the additional fuel necessary for crisp acceleration, often almost another 1/8 turn out.

From "best Idle' back each idle screw out just the width of the screwdriver blade slot, then test acceleration. Any hesitation, lean cough, bog, indicates a need for more idle fuel.

Make another slot width adjustment and retest acceleration.

Repeat to perfection.

Adjustment of the distributor and throttle pick-up points is well spelled out in the 'stickies', find the write up done by Clams. Last name ??????? tinino ?? or close to that.

 

[gpfishingdude]

Re: Tune up on old motor?

I finally got the boat in the water yesterday after adjusting the carbs. a couple of weeks ago. It was cold and windy and the water temperature was down to 46*. I didn't spend a lot of time out there but I did open it up enough to see that it sounded a lot better accelerating and I managed to get 5200 rpm out of it at wot. That is about 700rpm better than what it did before. Then it started dying at idle and I had a hard time keeping it running at the dock to get the trailer in the water. I think I am going to winterize it today and give up until it is a lot warmer outside.