merc. 400 EL 45hp 1960speed control adjustment

[kelwendee]

merc 400 EL 45hp 1960 trying to adjust speed control linkage.<br />ok I have Old Outboard Motor rapir manuel from the library.<br />it says to "with engine not running move the speed control lever toward the "FAST" position until magneto advance stop just touches the crankcase. refer to fig M7-6. Loosen the screws securing the throttle actuator assembly to economizer collar, then move the actuator plate until 0.015 clerance exists between follower and throttle cluster lever. tighten the attaching screws. Move the speed control lever to "FAST position and adjust the full throttle stop screw to allow 1/64 inch travel to full open position. <br />then it gose on about slow idle adjustment.<br /><br />my problem is I dont see or understand the frist part about "slowly move the speed control lever toward "FAST" position until magneto advance stop just touches the crankcase". Nothing on the mag. actually touches the crankcase in any position that I can see..and I cant see from the only figure M7-6 what they are talking about, it only refrences 1, cluster lever 2,pick up pin 3, adjusting cap screw 4, full throttle stop screw A. adjustment clerance.<br />where is the magneto advance stop? and where dose it touch the crankcase. nothing on the mag touches the crankcase at all.it is the right section for my motor figure is the same and all just not enough info. I see the attaching screws and the actuator everything in the figure M7-6<br />just not where it starts to touch crankcase?<br />baffled Ben.

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Hi Ben, I too was mystified by that verbeage in the book. Only thing I can figure is that the bracket in the picture (that touches the crankcase) was an old design. I've seen several Mk35A, Mk58A and Merc400 motors and none I've seen have that bracket, but instead all have the throttle and timing stops on phillips screws with stop nuts. These screws are the left-most 2 screws on the stop bracket, while the right-most screw on the stop bracket is the low-idle speed stop. Good luck with it...

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

Thanks Marty,<br />ok, but it appears that everything in the picture is on my motor, however I still dont see in the figure or on my mag. where it is soppose to touch the crankcase. in fact it dose not and cannot touch the crankcase<br />Then, if they are using the stop adjustment screws instead, and the spark advance and throttle stop screws are backed out, how are they to be used as or what would be the refrence point to put the mag at to adjust the actuator plate?<br />put it into gear and as soon as the mag starts to move adjust the spark advance (bottom left screw) to just touch and then continue on to the actuator plate.<br />no it cant work that way cause that puts the spark advance stop screw all the way in and still dosent touch. <br />still stumped.

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

OK,let me put it another way can someone tell me or give me refrence to understanding how to adjust the speed control linkage for this 1960 400EL. which, as near as I can tell is a 58A 45 hp with altanator and long shaft thats what makes it 400el.<br />how do I figure out how to set the speed control linkade starting with the spark advance setting.<br />this 45 hp merc has a 3 screw adjustment plate with philps screw and stop nuts on the upper face of the magneto mounting bracket. Upper left says throttle below it is spark advance and the right says Idle. as stated above this dose not have any thing that touches the crankcase as stated in old outboard manuel so its got to be this spark advance screw as marty decribed also. but it is no where near the crankcase. cant seem to figure out this magnato advance setting?<br />thanks in advance Ben

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Hi Ben, No your mag will never touch the crankcase. That was meant to be my point, but sorry I didn't explain it well enough.<br /><br />The way that mag works to control power is: At idle speed the front of the mag is all the way inward toward the center of the motor. This is a clockwise movement of the mag, and so the thing that stops that clockwise motion is the right hand stop screw, so that right most stop screw is the low-idle setting screw. As your throttle lever is advanced to go faster, the mag rotates counter-clockwise with the front of the mag going toward the outside of the motor. This throttle travel stops when the mag rotates far enough to allow the throttle stop ledge on the mag to contact the throttle stop screw on the left side of the plate. Then you'll notice that the throttle pressure increases but the throttle can still be advanced further. This further movement of the throttle causes the top collar of the mag to continue it's counter-clockwise movement (further advancing the spark) until the spark-advance ledge on the mag collar contacts the spark-advance stop screw.<br /><br />So, that's why I said that the bracket contacting the crankcase doesn't exist on your motor. Nothing touches the crankcase anymore. Those stop screws on the later motors (Mk58A, Merc400, etc) are the things that stop the mag movement in both directions, with the clockwise direction being the low-speed idle stop, and the counter-clockwise direction being the high-speed throttle and high-speed spark-advance stops.<br /><br />You can follow the remainder of the procedure in the book, as long as you know what really stops the mag for all three functions, idle, throttle and spark advance.<br /><br />Best of luck with it,<br /> Marty

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

marty;<br />thanks again very much appreciated. <br />there is just one thing though, I do understand what you are saying and you said it well, however I still dont see how or where to start the spark advance adjustment screw from?. If the mag did touch the crankcase it gives you that reference point to start the rest of adjustments from, the actuator plate on. but sence these dont touch the crankcase and rely on the adjustment screws instead, where would or how do you find the adjustment setting for the spark advance screw to start with? <br />where do I start from, on the spark advance setting screw its self? <br />so there has to be a starting point to put the spark advance screw in place of touching the crankcase so as to continue on with the adjustments.. <br />I know its simple but it still slips me<br />thanks again Ben

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Hi Ben, I’m not sure which service manual you’re using, but the ones I’ve used are pretty much the same since they’re copied from the Merc manuals. I have the original Merc “1965 and Prior” manual and a couple of copies by others.<br /><br />But, here’s the way to set the advance. There’s no setting for the minimum advance. For that you just set the points as close as you can to .009 and all is well. Merc says minimum .008 and max .010 for the points.<br /><br />You should be able to find the max setting procedure in the book, and I can’t remember the verbeage exactly, but it’s something like this:<br /><br />Unfortunately, you need a special tool. The deal is, you remove the #1 (top) spark plug and then rotate the flywheel clockwise until the #1 piston is (on the up-stroke) 0.235 inches below TDC. That’s what the special tool does, it let's you know when you exactly hit .235" BTDC. Most folks these days use a dial indicator fitted into an adapter which will thread into the spark plug hole. Once you’re at 0.235" BTDC, you (with throttle linkage disconnected) start with mag at idle position and then slowly rotate the mag to the full open position (with spark adv stop screw backed all the way out). If you have a good ohmmeter with one lead connected to the grounding lug on the mag and the other lead connected to a good ground, you will see a slight drop in the meter when you get the mag way outboard. This is the points breaking, and you hold the mag real still and set the stop screw at that position. You can re-check your setting by moving the mag back and forth with the stop screw set and you should see the break as you hit the stop. All this works, but the #1 piston MUST be at 0.235 Inches BTDC for you to do it…

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

Marty, thank you sir,<br />thanks very much. All I had was that old outboard motor for refernce, and it talks about how to set the timing in the timing paragraph just like you described just never mentions the advance spark screw or crankcase at all until they have passed it, and on to the actuator plate in setting the speed control linkage section.<br />it did say in the timing section that some, but few models have the advance timing mark on the flywheel. TA DA my flywheel has both marks and i had the ohmmeter also to double check. but I could not put the two togather to set the spark advance screw. <br /> whew, so simple enough thanks to you.<br />1 ether use the ohm meter or if you got'em the advance timing mark <br />2 set the spark advance screw,while at the advance setting on flywheel 0235 btdc <br />3 set actuator plate for for clerance 0.015 between follower and throttle cluster lever<br />4 speed control lever to fast and adjust the full throttle lever 1/64-inch travel to full open throttle position<br />5 move the control to slow position and adjust the slow idle screw to 525 rpm.<br />and thats it???????<br />thanks marty <br />Ben

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

OK so thats that. Seems to be alot better.<br />Now all I have to do is put her in the water under load and adjust the low idle jets on carbs. the high speed jets are fixed.<br />seems to run smoother in the can, a few pops and sputters but that was while trying to adjust low idle jets. so I have her running as smooth as possible in the can. but im not so sure that that is the same as under load on the water, actualy pushing my arse around. <br />thanks alot Marty, Iboats and everyone else that at least thought about it. if I have forgotten anything please let me know.<br />thanks again,Ben

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Hi Ben, You’re most welcome. I know you’re frustration. Setting the max timing was the last thing I did on my Mk58A after building it. I read 3 different procedures from 3 different manuals over and over for several months and also asked questions from others who had done it. I finally got the idea and was lucky enough to find a dial-indicaor with adaptor. Only then did I finally have the nerve to actually set the max timing and it was a breeze after all the prep/study, but the last thing I wanted to do was to fry the motor I’d spent months building. And I’d previously set max timing on later model 44ci 4-cyl Mercs, but with the degrees labeled on the flywheel and with electronic ignition it was no problem at all on those newer motors.<br /><br />A few comments about things I bumped into along the way and about your procedure:<br /><br />Old pros I spoke with wouldn’t trust the .235 line on the flywheel. I was told that this line was found to be un-reliable multiple times by one former outboard tech. After hearing this I looked and looked until I could find a dial indicator. Months later, after I got the dial indicator and performed the procedure, however, I found (by using the dial indicator) that the .235” BTDC line on my Mk58A flywheel was exactly on the money. So hopefully your .235” BTDC flywheel line is correct also.<br /><br />I have to admit that I’m not familiar with the #3 and #4 steps of you’re procedure.<br /><br />Instead of your #3 and #4 steps, what I do is what I’ve done with other similar 4-cyl Mercs of this vintage. Probably not as technically correct as your steps, but just what I’ve found always works well for me on these motors, and that is to slowly advance the throttle while watching to make sure the carb butterflys are brought to the full open (parallel to inward air flow) position. This just makes sure that full throttle will be stopped by the stop nut while the carb shafts still have some travel so the shafts won’t be damaged (the shafts will open beyond the “parallel” position before the shafts hit the end of their travel). If the follower needs any adjustment, I just tweak it to allow the “parallel” butterfly position at full throttle. Hopefully your “0.015” setting will accomplish the same thing. But still, you might want to “eyeball” the butterflys as you slowly advance the throttle to make sure the butterflies are fully open but not so far as to bend shafts. By doing this you’ll also see if both butterflies are parallel with each other and if not you can tweak that also. And for idle speed, I just set the idle stop screw so that when in fwd gear it sounds about right. Real technical huh... <br /><br />On the carb idle mixtures, I don't know if your manuals stressed this or not, but I was warned to get the idle as rich as possible and then back the idle adjustments off about 1/8 turn when the motor is heard to begin to "load up", and this adjustment is done in fwd gear. Even though the motor will idle great with leaner settings, I was warned that the richer settings are a must to be sure the cylinders receive adaquate oiling, etc.<br /><br />Good luck with it,<br /> Marty

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

RIGHT ON! Marty, <br />you know shes an old girl but dosent know it or run like it either. they take these blocks out and put them these little river racers here on the North coastal rivers. and they go like hell. I loaned my little boat to a friend a couple years ago and he's a good shade tree mech. so I dident mind when he came back and said he had adjusted my carbs for me. however I dident know what all he had done and I dont think he did either, as it never ran well sence he favored me. no harm done I hope.<br />we'll definatly heed your advice and go check things out better. <br />and ill be saving this to disk for refrence<br />thanks again, Ben

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

OK so the lower butterfly was lagging a little so had to "tweak" that. by the way there is an adjustment in the linkage from top carb to bottom on this model loosen the little boldt and slider around.<br />I made all the settings as suggested, double checked, turned her over and she was running the smoothest id ever heard. set the low idel mixture screw backed her down to 550 rpm was running pretty smooth but hear a slight miss, fiddle with the low mixture again, started to stall some? got her back to smooth. shut her down, turn the key again and now sounds like the timing has moved. real hard starting. not sure what ive done all i did was further adjust the low idel jet?<br />I guess just to make sure ill start over and recheck all my setting again. it seemed like it dident start running bad until it had ran for quite a while in the can could be to much carb adjustments or i was thinking maybe the condenser may be getting alittle weak. <br />more than likley its my carb adjustment.<br />I didnot rebuild this crankcase. rebuilt the lower unit and replaced the wire harnes inside the outboard, points checked cleaned,set. rebuilt the carbs. new plugs ,cleaned and went over the mag,rotor and cap.<br />its got to be the low idel jets. good fuel fresh with 50 to 1.<br />whats tough is a hour drive to put it in the water to finish checking settings then not running when you get there. been there a few times.

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Anything I say from here on is from my personal experiences and fiddling and not necessarily how/what someone else would do/recommend.<br /><br />First, I’d for sure replace that condenser. I’ve always done that whenever I go into the mag since they can really cause headaches, and they’re cheap and easy to replace. Consistant hot spark is key.<br /><br />Next, when I said I set the low idle where it “sounds about right” for these motors. Here’s why I do that. I ran these motors for many years (at the recommended 24:1 ratio) back before they (and me) were considered antiques and running them as slow as 550 rpm just seemed to always cause me problems. Maybe it's because I wasn't ever able to have the carbs and spark "perfect". I’ve just been better able to keep the plugs from fouling at a little hotter rpm, say 700’ish or so, and with these motors keeping the plugs from fouling has always been the main key for me to keep em running. In my early days I changed plugs many times at the lake due to plugs fouling from slow idle combined with weak spark and carb mixtures, and as a result, I still always carry an extra set today. Many newer Mercs, even with strong electronic ignition call for 725-750 rpm at idle in gear and that’s at 50:1, so I just think that 550 is too slow. But that's just my opinion. When your motor started missing a bit, did you clean the plugs so you could start clean again?<br /><br />Next, when you said 50:1, these motors were originally run at 24:1. There’s been so much discussion about this that it is definitely a personal preference for whatever mixture you desire, since these Mercs were built with roller bearings and can easily tolerate the 50:1. Many run them that way (this is the same block and internals as the later Merc500). When I built my “new” Mk58A last year, I thought about this and asked a lot of other folks about this, and I ended up running mine at 24:1. I want to protect the old motor as much as possible, and so to me, “smoke is good”. One thing that got me to go 24:1 was talking with several guys who raced these old Mercs (and some still do). I was surprised to hear that racers run hotter oil mixtures, with many running 20:1, 16:1 and even 12:1. One thing that surprised me about this is that an ignition system must deliver a hot consistant spark to burn that much oil, but the racers say the point of the heavier oil mix is 2-fold, one being better lubrication at the higher rpm's, and the other being better crankcase seal which spells better compression and more power, etc. <br /><br />I know many of the Merc fellows will probably disagree with a lot of this, and I respect that. I just included what has worked well for me and what I've stumbled into along the way to keep these old motors going (and going, and going)...<br /><br />Best of luck with it

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

thanks again very good info <br />well, to start the 50:1 is what I had read the most consistantly so thats that, <br />the plugs, no I dident recheck. however today i went out this morning and without touching the fuel pumper I hit the choke and started to turn her over while she dident fire right up she did fire, let warm for a minute and tried to adjust lower idle jet better at idle, out of gear, to get closeer. popped into gear, stalled. turned the low idle screw in to raise the idle up to about 650 or, turned the motor over no pop. hit choke turn over again and gas started to flow out the carbs? drop the choke turned over again and started.????????????<br />Im going to start from scratch again. I belive that I have the actuator plate out of whack a littel. next time I get to town IM gonna get another condenser just to be sure.<br /> Marty, I have a another problem with this little bugger. I rebuilt the lower unit and I cant seem to get it to seal properly. I put speeded sleves on the drive shaft, both seals on both sides of impeler housing, put a little gasket sealer on o ring below the impeller housing. new seals all around. really popped the shaft down to get a good seat on the impeler housing as I have taken it out several times now. and when I popped that bugger down good the last time and fired it up, no oil.good. used her once in the bay. fine, no resdue on water. get home flush her out. and dicded to rebuild the carbs. ect, get almost done with that, thanks to Marty. <br />fill up the can and fire her up. here comes that film again. day later nice film in can water. <br />I cranked the collar down real good last time, but still have a little oil on top of water after setting and slight yellowing of the oil in gear box. I put new seal on the shift rod.and put SAE 80w-90 MAG-1 {brand} gear oil. it says recommened for limited slip. one of the merc dealers said any old 8o-90 oil will work in these lower units. However a rearend has a breather for expansion and of course this dosent. I filled it from the bottom up like it states in the book. any hints on sealing this little bugger up. Mr. Marty my motor savior.<br />Ben

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Hopefully you're carbs are now down to fine tweaking. Your raised idle speed will help. While you're messing with the mixtures you'll probably get some flooding and need to clean the plugs now and then untill you've got it tweaked the way you like it.<br /><br />If you're motor is a 1960 Merc 400 it should have a prop that does NOT have exhaust coming thru the prop. Right? The old lower units (before exhaust thru prop) do NOT take oil, but instead they take a light white grease. The grease won't leak nearly as much as oil will, and it's also easier to let a little water out since the water won't mix as well with the grease. The grease you need is called "Lubriplate - 105". If you can't find it on iboats or somewhere near you, drop me an email at mwinn@genesco.com. That lower unit was not built to hold oil, so you're seals are probably fine and a little oil coating on them won't hurt anything...

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

damn marty, i need to buy a beer or doobie or something.<br />I started from scratch on the timing speed control linkage. went all the way through and I think the timing might be a little out. Ill need to heed your advice and check it with a dial indicator to be sure, as I still can hear a slight miss and slight hesatation at times on exceleration. But it fires right up. I did put the idle to about 700 rpm or so. it sounds like it might troll maybe alittle to fast. that was the reason for the carb rebuild. I thought I could bring the idle down some for a slower troll.<br />so im in the ball park, Ill try to dial it or launch and adjust in the next few days.<br />thank you<br /> GREASE,<br />The lower unit is NOT a exhaust thru prop.It drops down in the inner mid lower unit housing and out exhaust port.<br /> I had another lower unit that I striped down, and the oil was real real thick like a mild grease and coated the inside of that lower unit pretty thick. 1st clue, Doh.<br />this had oil in it for sure when I frist got it. that was the frist thing I changed and the reason it sat for the last 2 seasons.it acted like it was leaking out the top seals and had a film on the lake .parked it until now. now, talking with the now closed merc dealer in Weaverville Calif., Morris Hardware, that had a merc dealership in the basement. there salesmen sold me the oil and he was the one that told me about just using any old 80-90W. I had the boat and motor in his drive way, figures.<br />so the grease is at least thin enough to push up through the lower filler hole? do I use it like they told me to fill the oil? through the lower hole until it comes out the top little over fill screw whole on the lower unit.<br />These dealers around here will not hardly give me the time of day when they find the age of this unit. but this little bugger is like brand new, it's in great shape. one dealer in Arcata fliped out when I asked him if he had the puller for the impeller housing then he told me the impeller wasent even in the lower unit. even though I was holding the lower unit in my hands in his shop with the impeller housing exposed????????when I showed him further he just plain came uncorked, it was wild.<br />brought it home turned her over on a block of wood, couple of pops and out it came. and here I am.<br /> they killing me.

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Yes, you fill the lower unit with Lubriplate 105 exactly like you would fill it with oil, that is through the lower hole until it comes out the top vent screw hole. The Lubriplate can be purchased in 10 oz squeeze tubes, and you simply insert the tube nozzle into the lower hole and squeeze. It will take a bit over a tube to fill the unit so you'll need to get 2 tubes to fill it.<br /><br />When you replace that condenser check the points carefully and try to get close to .009 as possible. The combo of condenser+points might help your acceleration situation. <br /><br />If you want to troll you can keep an eye out for a lower pitch prop. The "standard" prop for those motors was a 12" pitch which ran 27-32 mph. If you check Ebay from time to time, you can find 9", 10", or 11" pitch props that come available, and those props aren't in that much demand so can be had for pretty cheap.<br /><br />Those are great motors but you'll probably need to forget taking it to your local ob mechanic. It's a totally different set of skills and tools to work on these things. These are great motors, so hang in there with it...

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

WOW that still blows me away. thanks for the lube info that was really putin me to the test.<br />the points I was pretty exact on the .009 but duley noted thanks.<br />there is a fella here in Hoopa Ca. that has sheds full of these buggers, stacks of them , the racers he's one, they only use the engines. everything else the scrap. he's got gobs of props as they use some other special type.he's got gobs of complete motors too. all I seen were mercs. I got a prop from him once, thats another story though, that we'll not get into. LOL<br />there is another fella in Klamath he's a merc dealer I think, buddy of the fellow from hoopa any way he's is soppose to have a whole shop yard full.<br />so ok another idot question, are the props ID stamped for there pitch in anyway?<br />Marty I feel dumber by the minute talking to you but im sure thankful.

 

[kelwendee]

Re: merc. 400 EL 45hp 1960speed control adjustment

all right well, I took her to the lake to try the final in gear low idle and low idel jets adjustments. and while I went through everything as well as I possibly could prior to going out today. and it ran smooth in the can, fired right up. it ran like #@&$...on the lake, and seemed to have had to wait an extra long time on the warm up or it would stall on puting it in gear. (it was very warm out mid afternoon 90s) even though it went into gear just fine in the can, it dident seem to matter what I did to the low idle. couldent get that miss out and hesition in low throttle up. At first I only adjusted the low idle jets and low idle adjustment screw only. seemed to pick up from half throttle up and run like a raped ape but cut her back to troll speed and here comes that miss or stutter and hesation. the longer I trolled the longer the hesitation on throttle up. gonna double check that float spring measurement.another thing I noticed was, that at frist, at setting the low idel jets they seemed to have very little effect. I mean I could turn her in 3/4 or so and stall it alright but just not a great range beetwen extrems. so back to the shade tree. gonna have to get that dial indicator and double check that timing mark as well. Its close but not right. I fiddled with everything to try to get her dialed in after that I thought it was the actuator plate so I losended it and tried diffrent adjustment. wonder for a while if I was even gonna be able to fire it up again.but got it back to when I had arrived, but not much better. one other thing I noticed at times on turning it over it would hesitate, like timming, but fiddle with the both carb adjustment and it would turn over better again. but of course the low idel adjustment is turning the mag. <br /> Ill see about that dial indicator tomorrow.

 

[MartyTn]

Re: merc. 400 EL 45hp 1960speed control adjustment

Hi Ben,<br /><br />Here is a link to prop info for your motor. <br /><br /> http://www.maxrules.com/fixoldmercindex.html <br /><br />There is also carb data and other data for the older Mercs as well. The part# is stamped on the prop hub if it's an orig Merc part, but I've seen several that have a very readable p/n and others that don't, so hopefully you can find one with legible a p/n.<br /><br />On the dial-indicator, this is only necessary for max-timing, so it won't affect low speed performance in any way. It will just make sure at full speed that you get full safe advance but not too much as detonation can do damage pretty quick.<br /><br />One thing to check, if you haven't already, is to pull the cover from the mag pulley that holds the timing belt. There is a very small arrow on the pulley (ignore the lines on the pulley cover), and that little arrow on the pulley must be able to point exactly at the TDC line on the flywheel. If this is one tooth off on the pulley it could give you grief at low speed. You can slip the belt off the pulley, rotate the pulley to the correct tooth and slip the belt back down.<br /><br />And yes, another thing to check is the spring height on the top of the floats and needle/seat and float movement. When you rebuilt the carbs there should have been a new needle & seat for each carb and a little plastic piece to measure the spring height. So if the float is good with no holes, and if the float slides easily up and down in the bowl and the needle & seat are good, the fuel metering should be okay. If these components aren't correct the metering will be off and the idle adjustment screws won't have much effect. I've had some floats be "sticky" in the bowl, so I've taken very fine sandpaper to the plastic float burrs and inside of bowl surface to get a more friction-free float movement.<br /><br />Only other thing I can think of right off hand on the low speed problems is that in the can the water warms up quite a bit (at least mine does) so the engine is probably running significantly colder in the lake/ocean than in the can. These motors don't have a thermostat. Once those motors start running goofy at low speeds, in my experience (if everything else is correct) it's from plug fouling, I've found that many times no matter what I've done once this happens, the plugs are still fouled and won't recover without a manual cleaning. That ignition system is not nearly as strong as the modern ones that can burn anything off the plugs. After you get it running good in the can again, you might want to consider investing in a spare set of plugs (or 2) and when the goofiness starts and you can't recover, change the plugs and see if all's well again. That's been my experience in the past and that's why I carry an extra set of plugs with these motors. If you also have your plug cleaner tool with you, you can clean the old set and have them ready to rotate in when the 2nd set gets fouled, and you can repeat this on and on until your fiddlin is complete... Don't give up on it...