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When to change Reed Valves
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| Bilito |
Posted on 02/17/17 - 8:43 AM
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I am looking for a silky smooth idle and slow speed operation more then hi speed on my 1997 Merc 4 cylinder 2 stroke
It is on a 13 foot GLI Whaler
I have rebuilt the 2 carbs several times
my compression is 120 on all 4 cylinders
I have new CDI stator that makes a spark that will knock you on your keister
New plugs
rebuilt the fuel pump and changed all the fuel lines and a new fuel filter
put in fresh fuel
And it still idles like crap and quits half the time when I put it in gear
every time when I leave the dock or return to is an adventure because it might quit at the worst possible moment
last year I took all the rear and side panel off and cleaned out crud and other debris that was blocking water flow making it run too warm and now it does run cooler. By too warm I meant it was hard to keep your hand in the flow out the pee tube because it was so hot, now it just very very warm, much cooler
Can my reed valves be worn out after 20 year of use?? Will new ones give me that nice reliable smooth idle??
Edited by Bilito on 02/17/17 - 8:44 AM |
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| tedious |
Posted on 02/17/17 - 9:50 AM
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Reed valves don't really wear out. Take a look at them - if the are not cracked or bent, and are sealing OK, then that's not your problem.
Do you have the factory service manual, and have you used it to perform a link'n'sync?
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| Bilito |
Posted on 02/17/17 - 10:52 AM
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tedious wrote:
Reed valves don't really wear out. Take a look at them - if the are not cracked or bent, and are sealing OK, then that's not your problem.
Do you have the factory service manual, and have you used it to perform a link'n'sync?
I have the manual, but I have not seen anything called link'n'sync, I have made all the adjustments that are in the manual.
How does one tell if the reeds are sealing OK??????
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| tedious |
Posted on 02/17/17 - 11:59 AM
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Yeah, they might have called it a carb sync procedure or something like that - it's basically aligning the carb butterflies with the timing. If you did all the recommended adjustments you're probably there.
I don't know of a direct way to check for the reeds sealing properly - just look for any damage such as bending or cracks, or particularly for any damage to or buildup of gunk on the sealing surface, either of the reed itself or the part of the manifold it seals against. Also, if they are not sealing properly, you may see fuel mix blowing back through the carb venturi - may need to run with the airbox off to see that.
Playing a hunch, since you were running hot, maybe you have an overly lean condition? Does your motor have an adjustable idle mixture? If so, you could richen it up a bit. If it's not adjustable, you could change the jets. As I recall, some motors of that vintage were really leaned out in an effort to reduce emissions.
Tim
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| Bilito |
Posted on 02/17/17 - 1:01 PM
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tedious wrote:
Yeah, they might have called it a carb sync procedure or something like that - it's basically aligning the carb butterflies with the timing. If you did all the recommended adjustments you're probably there.
I don't know of a direct way to check for the reeds sealing properly - just look for any damage such as bending or cracks, or particularly for any damage to or buildup of gunk on the sealing surface, either of the reed itself or the part of the manifold it seals against. Also, if they are not sealing properly, you may see fuel mix blowing back through the carb venturi - may need to run with the airbox off to see that.
Playing a hunch, since you were running hot, maybe you have an overly lean condition? Does your motor have an adjustable idle mixture? If so, you could richen it up a bit. If it's not adjustable, you could change the jets. As I recall, some motors of that vintage were really leaned out in an effort to reduce emissions.
Tim
It's a quandary. It's 4 cylinders with two carbs, one carb for two cylinders, cannot see see the reeds when you remove the carbs since the carb is located between the two cylinder intakes. The carbs have an idle mixture screw and believe me I have tried everything to make it run smooth at idle, it is probably set on the rich side.
My neighbor has a 3 cylinder motor, a johnson with 3 cylinders and 3 carbs and it just purrs smoothly at idle and at low speed, I would think mine should be even smoother running since it is a 4 cylinder.
The Merc manual call the adjustments a timing procedure.
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| ursaminor |
Posted on 02/17/17 - 1:25 PM
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We had the 1973 version of that engine (rated at 50 HP then.) It's one of the smoothest and most reliable 2 stroke outboards I've ever run. This particular one had the benefit of running in fresh water, it outlived one boat and as recently as two years ago was still going strong on a second hull with the original reed valves.
I know you mentioned that you've rebuilt the carbs and adjusted the idle mixture multiple times. I remember we used to adjust the idle mixtures with the engine in gear tied to the dock. If you have a tachometer, I seem to remember looking to get around 800 RPM in gear under these conditions but it's been quite a while. That method seemed to work to get enough fuel at idle so the engine wouldn't stall going into gear.
Your post said you had redone the fuel pump as well, that might be worth another look as well. I don't think that rebuild kit is a whole lot of money and I remember getting the diaphragms and springs set in place correctly could be a little tricky. Again, ours was a lot older, your engine could be much different under the cowling. Good luck!
1989 Montauk 17 / 2012 90 HP Evinrude E-TEC |
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| Bilito |
Posted on 02/17/17 - 2:03 PM
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ursaminor wrote:
We had the 1973 version of that engine (rated at 50 HP then.) It's one of the smoothest and most reliable 2 stroke outboards I've ever run. This particular one had the benefit of running in fresh water, it outlived one boat and as recently as two years ago was still going strong on a second hull with the original reed valves.
I know you mentioned that you've rebuilt the carbs and adjusted the idle mixture multiple times. I remember we used to adjust the idle mixtures with the engine in gear tied to the dock. If you have a tachometer, I seem to remember looking to get around 800 RPM in gear under these conditions but it's been quite a while. That method seemed to work to get enough fuel at idle so the engine wouldn't stall going into gear.
Your post said you had redone the fuel pump as well, that might be worth another look as well. I don't think that rebuild kit is a whole lot of money and I remember getting the diaphragms and springs set in place correctly could be a little tricky. Again, ours was a lot older, your engine could be much different under the cowling. Good luck!
I have not tried adjusting the carbs with the boat in the water tied to the dock, that might be a good thing to try, thanks for the suggestion
last year I came across another boater with a similar boat and the same engine and his just fired right off and ran as smooth and quiet as a new motor. I asked him what he had dne and he said he recently bought it and it always ran good. And there I was with mine sputtering and trying stay running with the idle handle reving it up above idle and when I had to reduce the rpm the get it in gear it was all arms and elbows to get in gear and revved back up before it quit.
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| Old Bay |
Posted on 02/17/17 - 6:43 PM
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I just had a similar issue with my 1993 Johnson 88spl. I had even rebuilt the carbs, but missed a tiny blockage in the idle jets of one of tne carbs (also a twin carb setup). I found which carb it was by disconnecting the spark plug wires one at a time. When disconnecting the plugs linked to the "good carb" the engine wouldn't run at all, whereas when the plugs linked to the "bad carb" where unplugged it ran (badly) as before.
Edited by Old Bay on 02/17/17 - 6:44 PM
1961 Nauset 16 |
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| Bilito |
Posted on 02/17/17 - 7:59 PM
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Mine will run fine for a few minutes and then start gasping and quit if I can't get at it fast enough, the worst part is shifting gears because it goes to idle to get into or out of gear and that is the exact time it will stall out. I have actually soaked the carbs in cleaner overnight the last time I rebult them. The kit is expensive and all it contains is a new bowl gasket and a new float valve. I blew out every passage I could find and removed every jet that could be removed and made sure all the passages in the jet were clear, spent an hour or two adjusting the linkage and still have the same issue, it sputters and stalls out at idle about half the time when I am either leaving or approaching the dock and have to switch gears. just when I think it is working perfectly is when it bites me in the butt.
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| mtown |
Posted on 02/18/17 - 4:55 AM
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I am betting a jet has an obstruction. Some are awfully tiny.
If you can do this, try it.
With the cowl and air cleaner off, run the boat at 3000rpm take a clean rag and "choke" one carb at a time. See if one really affects the motor more than the other. The carb that has the least effect is the one with a problem.
This takes 2 people unless you have a lift. In that case keep the bow high enough to keep the boat in place.
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| Bilito |
Posted on 02/18/17 - 9:02 AM
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That would take some doing because the oil tank is in front of the carbs and there is an round opening thru the tank for each carb and about an inch space behind the tank and the carb throat, gonna be hard to get a rag in there.
I just started it up this morning and it fired right off on the muffs and after about a minute I reduced it to idle and it ran pretty smooth, so I let it run at idle and every couple of minutes it would rev up on it's own and then slow back down
also the tach was jumping all over the place and the amp gauge showed about 10 voltss and when I revved it up it went up to around 12 volts???? Got a charger on it now.
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| Phil T |
Posted on 02/18/17 - 9:24 AM
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Remember - Do NOT run an outboard on the muffs higher thank 1k rpm's.
If you need to, get a tub, garbage can.
1992 Outrage 17 I
2019 E-TEC 90, Viper 17 2+
2018 Load Rite Elite 18280096VT |
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| Old Bay |
Posted on 02/18/17 - 6:43 PM
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Does the engine ever cough or sniff? I ask because those happen sometimes when running lean, like a blocked jet. The change in revs could also be a change in mixture. Or a change in timing, but that would be odd to have timing change that fast.
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| blaster |
Posted on 02/19/17 - 5:09 AM
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Delete
Edited by blaster on 02/19/17 - 5:11 AM |
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| tedious |
Posted on 02/19/17 - 6:57 AM
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I think adjusting the carbs (both idle speed and mixture) with the boat in the water, in gear is going to be key. If you do it tied to a dock, it should create even more load than if you were out putting around, so I it works there, it should work fine in everyday usage.
That said, my 1989 Johnson 70 had symptoms such as you describe - it would run for a while at idle speed, but they you needed to fuss with it to keep it going. I did not have adjustable carbs, but I did everything else possible, and docking was still an adventure - you just got used to it.
I think some of these old-school two-strokes are just that way - some people get good ones, others not.
Tim
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| freeportd |
Posted on 02/19/17 - 7:01 AM
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Two quick thoughts. Rebuilding carbs means different things to different people. When doing carburetor cleaning - you need to remove all jets and assure that all holes are clear. You mention problems primarily at idle. That indicates issues with the idle circuit. Among other things, the transition ports come into play. They are cut into the carburetor bore - very close to where the throttle butterfly touches the bore. Make sure to use a wire to clean here as well. Soaking/ultrasonic cleaning of these orifices is also helpful.
Second. Mercury outboards were notorious for poor wiring - but mostly in the 80s. I don't know when they addressed this issue. It's possible that you have ignition issues - meaning that coil, stator and high tension (spark plug) wires all potentially at fault. Check the insulation closely. if it's cracked or cracks when bending, it needs replacement. Also, I had a 70s Evinrude that wouldn't idle - and it was a bad power pack.
Good luck
Edited by freeportd on 02/19/17 - 7:03 AM |
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| Bilito |
Posted on 02/19/17 - 8:12 AM
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One of my friends has a whaler with a Yamaha 3 cylinder engine. I have worked on that engine and have found it to be the easiest engine to do maint in, all the torque values and the torque sequence is stamped right onto the head, everything is simple to work on, nothing complicated, all the carbs have drain screws on them so you can drain any water or crud out of the bowls and those screws are easy to get at, I think My next boat will have to have a yamaha on it and I have been a merc, jonnyrude guy all my life, but once I was fooling around with that yamaha and saw how easy everything was and how smooth it runs, WOW
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| dauntless-n-miami |
Posted on 02/20/17 - 5:42 AM
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Hello Bilito,
A curious thought, by chance have you inspected your fuel primer bulb? You seem to have covered the majority of the mechanical maintenance with your Merc, have you considered checking for proper fuel delivery from your fuel tank? Check your fuel lines for a possible obstruction, I had an idle issue some time back and I was pretty certain it wasn't my carbs. It turned out my primer bulb had delaminated internally (darn ethanol fuel) and was restricting fuel when my outboard was in load (throttling up).
Food for thought...good luck with the diagnosis.
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| Bilito |
Posted on 02/20/17 - 7:13 AM
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dauntless-n-miami wrote:
Hello Bilito,
A curious thought, by chance have you inspected your fuel primer bulb? You seem to have covered the majority of the mechanical maintenance with your Merc, have you considered checking for proper fuel delivery from your fuel tank? Check your fuel lines for a possible obstruction, I had an idle issue some time back and I was pretty certain it wasn't my carbs. It turned out my primer bulb had delaminated internally (darn ethanol fuel) and was restricting fuel when my outboard was in load (throttling up).
Food for thought...good luck with the diagnosis.
Angel M.
I never thought about that , my bulb is getting a tad harder to pump
Someone on another forum suggested that I put the boat in the water and tied it to the dock and make all my idle adjustment while in gear both forward and rearward, any thoughts there.
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| VA Whaler |
Posted on 02/20/17 - 8:46 AM
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Blito, I worked at a marina for about 10 years and we never had to replace a set of reed valves unless something broke loose and damaged them.
I see where you said you rebuilt the fuel pump. If possible see if you can test a new one just to eliminate that from the list of possibilities.
Air seeping into the fuel system can cause all sorts of issues. You might make sure your connections are all good especially where the line connects at the tank and the engine. and try a new primer bulb. You could check for air by temporarily using a clear fuel hose.
If all else fails and you are at a total loss,2 cycle engines are notorious for building up carbon in the exhaust manifold. I remember one time we had to pull the powerhead to thoroughly clean the carbon out of the exhaust stack. Afterwards the engine ran like a champ.
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