1971 50hp Lark HydroShift Electric Fault

[expertsetup]

Hello everyone,<br />I have to say that this web site has been quite a resource for me already. This friday I purchased a secondhand 1959 P-17 16'2" Motorboat Distributing Co. deep V hull fishing boat with a 1971 50hp Evinrude Lark. This is my first boat and I can't tell you how excited I am about this project.<br /><br />After getting the boat home I tried to fire her up. No luck so I started some basic diag. here is what I came up with:<br />Comp: #1 125 psi #2 110 psi<br />Spark on both up to 1/2" blue arc both coils<br />about 4 gears on the fly wheel have damadge where the starter contacts.<br />Fuel lines hard and clamps wire-spring type<br /><br />I replaced all the fule lines and all the spring hose clips with hose clamps. pulled the carbs and B-12 Chemtooled them and reassembled.<br />Motor now starts and runs strong with the muffs but idles high and wont go very far below start on the remote.<br /><br />Since I had it running and the battery ran low I also recharged my battery and took a read before and after the motor was running. no rise in voltage at all. At this point I am not sure where the fault lies but suspect it may be the rectifier. <br /><br />With a unknown fault in the ignition/charging system I am a bit reluctant to run the boat in the water. I am also a bit reluctant to shell out $$$ if I dont have to. I have purchased a parts manual and have ordered the oem manual for this unit. I should be able to determin the fault with the data in the manual (wish me luck). The boat has no Tach and the Speedo looks like it will not function. I can order a tac from TinyTach but will that be O.K? If I have my nice battery for the lights etc. and a starter battery with a good sized solar battery minder would it be safe to run like this? <br /><br />Also for the people who keep stats on this 50hp HydroShif unit. This unit is shifting forward, nutral and reverse. Yes the unit seems to be at rest in forward gear but when cranking it shifts fine.<br /><br />I hope everyone can feel the glow of my gratitude. The FAQ was a huge help and the search function was a big help.<br /><br />Any input welcome.

 

[expertsetup]

Re: 1971 50hp Lark HydroShift Electric Fault

Update:<br />Well I tested the Rectifier with my meter, Infinity one way and ~150-300KOhms the other on all the leads.<br /> Since the rectifier seems to be out I thought it might be a good idea to qualify the Stator while I was at it. A close look into the gap where the flywheel meets the case showed that the stator wire routing tube/sleeve had sliped out from the fastner and was rubbing just a touch. Very light damage to the sleeve only the wires seem to have been unaffected. A quick test showed 1.2 Ohms from each stator wire which seems quite low to me.<br /><br />Also the compression test I performed was while it was cold with the throtle wide open. I noticed the compression in the #2 tube was showing about 100PSI before I set her WOT and then she went to 110.<br /><br />I also have a new question about this situation, would a slight imperfection on one reed be responsible for a reduction in compression? I would guess that it could. If so what level of improvement could I expect by replacing the reeds? It seems to me the least invasive replacement that could have a real gain in compression. I thought there might be a slight problem with one of the reeds that looked like a few sand size pices may have been missing from the edge. I didnt use good light to verify the problem so would have to tear the carbs off again to take another look.

 

[ledgefinder]

Re: 1971 50hp Lark HydroShift Electric Fault

A leaky reed would mess up the idle, but shouldn't affect the compression. <br /><br />That motor has a self-energized ignition, so it shouldn't drain the battery very quickly. You can rope start it in an emergency.<br /><br />Try eBay for parts, or a parts motor. Lots of those around, & not too expensive. TinyTach will work fine. Those 50 twins produce their power up high, so prop it so it can rev.

 

[Bass Runner]

Re: 1971 50hp Lark HydroShift Electric Fault

I'm confused You said the motor is a 1971 model are you sure that's not a 1961 lark? sounds like you are talking about a motor like i have if so it dosn't have a charging sys. unless it has a generator on it, check the numbers on the motor against the title, is it electric shift? If so the motor is built in the 60's not the 70's they are the same basic powerhead but if somthing goes wrong with the lower unit woa is you. Parts are like finding hens teeth As far as the idle, i would put the boat in the water and run it a little then decarb it and see if that clears it up, could just be gummed up from setting, another little trick i use is put B-12 in the gas and run it

 

[expertsetup]

Re: 1971 50hp Lark HydroShift Electric Fault

Hi ledgefinder,<br />Thanks, if the idle doesn't clear up after first run and decarb I will take a closer look at the Reed. I guess the little notch hooks in the fly-wheel top are for the rope? <br /><br />Hi Bass Runner,<br />Here is the data I should have posted in the first place, sorry about that.<br /><br />Model#:50173S<br />Serial#:E07990 <br /><br />I looked up the year online and must admit thats not always the best source. I did check the powerhead over and noticed what looks like a waterjacket plug with the E07990 number so I guess this is the same powerhead. Yes, I am sure its an electric shift, dont they have two levers if there not? This unit has one throttle lever and three colored buttons.<br /><br />Should have the new rectifier tomorrow so I guess I will findout if that was the problem.

 

[Bass Runner]

Re: 1971 50hp Lark HydroShift Electric Fault

I'll be darned guess i learned something i thought they discontinued the elec. shift in the late 60's guess i was wrong (sorry) did you try the decarb on the idle problem, yes the notches on the flywheel are for a rope start. By the way welcome to the forum.

 

[Joe Reeves]

Re: 1971 50hp Lark HydroShift Electric Fault

Bass Runner.... You are correct about the straight "Electric Shift" engines.<br /><br />There came another version called the "Hydro Electric Shift" starting with the 55hp in 1968 and continuing through 1972.

 

[Paul Moir]

Re: 1971 50hp Lark HydroShift Electric Fault

ExpertSetup - don't call the rectifier dead yet. If you used a digital meter or a vtvm to test the rectifier, the ohms setting will not work. You must use the diode setting, which looks like this:

-|<-

Read infinity on direction, and probably south of 1v in the other.<br />Depending on the particular meter and rectifier, the test may also be inaccurate on an analog meter. <br />Testing rectifiers with an ohmmeter is a gross misuse of the range. Why they use that test in manuals is beyond me since it relies on an arbitrary design parameter, which cannot be considered reliable. Especially now that the old fashioned analog meters are becoming the rarity. Or testing resistance with a test voltage over 1v, since that may be destructive to modern electronic devices.

 

[expertsetup]

Re: 1971 50hp Lark HydroShift Electric Fault

Hi Paul,<br />I belive you are correct. I received the new rectifier today and put it on my meter to see if the digital meter was a problem. Well I discovered that the reading from the new rectifier is the same as the old.<br /><br />I went to the Diode tester and it showed a drop of about .5v I guess that is in step with the silicon drop. Looks like I threw some $$$ to the wind. I may put this new one in and keep the old one as a spare. It may be possible that this system has been modfied. I see that there is one wire that is not connected that has been taped off. This may have something to do with the charging problem. <br /><br />So now I am at a real loss as the stator test indicates there is not a problem there. Where in the heck could the fault be? I will take it to the water this weekend and run her a bit. That will answer my questions about the mechanical aspects of this motor.<br /><br />Thanks for your help.

 

[kd6nem]

Re: 1971 50hp Lark HydroShift Electric Fault

Paul Moir,<br />Did you mean to say that "Depending on the particular meter and rectifier, the test may also be inaccurate on an DIGITAL meter" ? My $350 Fluke 87 digital meter is absolutely wonderful and exquistely accurate for a field meter, but I do not trust its diode test near as much as I do an old Simpson analog. Just what I've noticed.

 

[Paul Moir]

Re: 1971 50hp Lark HydroShift Electric Fault

Bearcat Powered: No. If an analog meter tests resistance with below say 1v, as in the case of a VTVM, or a single 'AA' battery type analog meter with a low battery, or where the resitance test voltage is divided internally by a resistor pair or regulator, you cannot test a semiconductor with it. It's a misapplication of the resistance test. Just because it happens to work on an old Simpson meter, doesn't make the Simpson meter 'better'.<br />The diode test, not suprisingly, is the superior test for testing diodes and other semiconductors. It is far more trustworthy and telling than a 'resistance' test, since diodes and other semiconductors 'resistance' depends on the forward voltage. <br />I guess I'm just sick and tired of reading about people who needlessly replace their rectifiers because the manual publishers can't be bothered to edit a new revision.

 

[kd6nem]

Re: 1971 50hp Lark HydroShift Electric Fault

Interesting. All I know is I tried the beefy old Simpson (not a cheap meter in its day) at the urging of an old tech and sure enough it gave me an honest reading of bad (virtually no resistance) where my trusty Fluke gave me false hope and said it was open where we wanted it to be. Can't remember what this was on or what sort of diode it was, just remeber it was sizeable. The Fluke's diode test didn't have enough oomph to show the breakdown in this case. Replaced the diode and was back in business. I don't disagree with you, just apparently found a rare situation where it worked better that way? The Fluke's diode test works fine on most diodes so far as I've noticed.

 

[Paul Moir]

Re: 1971 50hp Lark HydroShift Electric Fault

Yes, your right, your Fluke 87 cannot test high voltage diodes on the diode test setting because it's diode test voltage is 3v, and the forward voltage drop of multistage, HV (more than a couple KV) diodes often exceeds this. They work by putting a bunch of diodes in series, to multiply their PIV, but that also multiplies their total forward drop. A good example would be a TV tube HV rectifier.<br />Presumably, the Simpson tests resistance with it's 9v battery which turned out to be enough. So I suppose the moral really is, know your tests and your test equiptment.<br /><br />I feel bad for hijacking expertsetup's thread, especially since this isn't helping him any and his problems aren't yet resolved. ExpertSetup: I hope your test goes well this weekend!

 

[kd6nem]

Re: 1971 50hp Lark HydroShift Electric Fault

Ditto: If anyone was hijacking it was me. Hopefully we all gained from this dialogue, know I did. I didn't intend to get us off topic. Sorry. The important thing is hopefully expertsetup will have a grand time on his boat this weekend! Thanks for your explanation, Paul.<br />(Just got "promoted"! Will I get more in my paycheck now? An additional couple percent of ZERO? )

 

[expertsetup]

Re: 1971 50hp Lark HydroShift Electric Fault

Hello everyone,<br /> I made it to the harbor this Saturday. Launched the boat, tied off at the dock and parked the truck.<br /> All was well until we noticed the water. The rear plugs had not been installed and she was taking on water fast. Well no problem right? Just put the plugs in and run the pump. Right, no pump.<br />Since we were still at the dock and there wern't too many people waiting we loaded her back onto the trailer. all was fine, the plugs came out and so did the water.<br /> Plugs went back in and we launched her again. Made it out past the warf and noticed that she was pissing a little bit of water through the floor.<br /><br />Decided to head back to the harbor since we had no pump aboard and clearly were heading for trouble. Made it back to the dock without incident and loaded her onto the trailer again. This time it was clear that on the previous loading she was cockeyed and a pucture in the hull had resulted from an off center loading.<br /><br />While out on the water the motor did run stong, smooth idle out around the bouys. Had a good sound and I could feel her pushing with the throtle.<br /><br />I installed a Tach and figured out the problem with the charging circuit, I think. The tach was working great with no problems and was picking up the signal from the new rectifier. I set it to 6p and figured it was in the ball park. sounded to me like she was on the money.<br /><br />I have to say that I am still quite happy with the day. I have to say that there is a lot for me to learn. Lucky for me this is a starter boat and it's no tragedy to poke a hole. My friend works at a fiberglass shop and will hook me up with a pro patch for not that much $$$. He's a pro so Ill leave it to him to fix her.<br /><br />The hull needs it anyways. There is a spot where the roller had rotted and the hull was cracked. Also a spot in the rear looks as if it needs some work. While I have it off the trailer at his shop I guess I will get all three of theese problem spots taken care of.<br /><br />I will be sure to keep you posted but may start a new thread in another area. If I do I will link it here.<br /><br />Thanks for all the help and wish me better luck next time out.