Can't Slow rpms Down 1975 85 hp Johnson

[jiju1943]

My 1975 85 hp johnson is running way way too fast, it is running about 3500 rpm or there abouts and I can not slow it down. I have rebuilt two sets of carbs so I know it has nothing to do with the carbs. I have adjusted the throttle cable back and even disconnected it and still no good. There is a gap between the cam and roller on the carb feed. It was stated that the Johnson rpm is controlled by the timing, I don't have a clue how to even check that. I could give you some history of what all I have done to get this engine ready for fishing but I am sure it would take too long. I will just say between this engine and another I have been on it for the last three months almost everyday. Any suggestion what I should check next?

 

[Bosunsmate]

the timing base is the thing that swivels under the flywheel when the throttle is moved, if it is stuck it wont go back to its stop and the revs will be high. If the balljoint linkage falls out this happens too.
Other than that you may have an airleak somewhere

 

[jiju1943]

the timing base is the thing that swivels under the flywheel when the throttle is moved, if it is stuck it wont go back to its stop and the revs will be high. If the balljoint linkage falls out this happens too.
Other than that you may have an airleak somewhere

Thanks for replying Bosun, the trigger rotates ok and the link is still in the ball thing on the arm. I am going to pull the flywheel again just to be sure all is ok under there. I can't imagine where there could be an air leak, this is the second set of carbs on there, same thing.

By the way, you aren't an ole swabby are you, I was an aviation bosunsmate, hook runner on an aircraft carrier.

 

[Bosunsmate]

Nope not a swabby unfortunately but i have salt n the blood, im just a new zealand farmer, hook runner sounds an interesting job. The stress that catch cable must be under would have me on edge.
While you have the flywheel off check the flywheel key hasnt sheared as if so that will ruin timing and make it speed up

 

[jiju1943]

Man that is too cool, I have always wanted to visit your country, my favorite boxer was from New Zealand, James Thunder, that was one heck of a boxer. Another thing I really like is you are a farmer, I grew up so far out in the sticks we had a possum for a watch dog. LOL I love the country life, there is none better.

I did take the flywheel off the motor and the key was still in good shape, I will pick up another one though. While under there I changed out the timer base and took all the linkage off the timer arm and gave it a really good cleaning. When I fired it up it ran at a good idle, it did not run away like before. I am one happy ole boy, now if I can just get the missing out I will be really happy. I have spent three months on this boat and motor, we really need a fishing trip bad. lol

Buddy I would sure love to know more about your country. Thanks again for writing back, have a fantastic day and week end.

Jim

 

[Bosunsmate]

Just looked up James Thunder, fastest knock out in history. Theres one reason why you dont fight Samoans here in NZ, especially in rugby games, you try and have them on your side.
Yes NZ is a nice spot, temperate climate here in the north, a couple of frosts a year and probly 70 fareinheit for 70% of the year. Gets colder as you head south but not North America type cold.
The flywheel must be torqued down to around the correct spec as too loose and it will break lose and get out of time, too tight and the taper gets damaged and the wheels off balance causing big trouble.
Too isolate the miss, post a video as its easier to tell if its electrical or fuel related by listening to it, also put a couple of fingers in a carb and if that fixes it then you know which carb has an issue.

 

[jiju1943]

Man you must be a young fellow not to remember James Thunder. I remember that fight, I was all ready to watch the fight, thunder walked out and popped the guy, one punch, all over. I was really disappointed, I love to watch him box, he was about as good as they come in my book. That is strange, here the further south you go the hotter it gets.
Man I may have messed up tightening my flywheel down. I sheared one woodruff key and was afraid I would do it again, when I put the nut on this time, I poured the coal to it, I know I torqued it to about 250 ft pounds, I was afraid it would shear again. I have another flywheel but the key way is wollowed out pretty bad.

I did try the fingers in the carbs deal, it didn't change anything at all, I even tried to smother each carb by putting my hand over it, still didn't change anything. It was suggested that the reed valves may be bad, I did the test where you hold a business card in front of the carbs, no blow back at all so it isn't the reed valves. I will try to post a video if I can figure it out. Thanks again for your time, I really do appreciate it.

 

[Bosunsmate]

Im nearing 40, so not sure if thats young. I honestly hadnt heard of Thunder, which is surprising considering that knock out .David Tua was the big boxer here lately but Lennox Lewis showed him how to eat humble pie. Tua had a mean left hook. He would drive around in a car with tuaman on the licence plate, seemed like he didnt do much else between bouts apart from eat and get even larger. So much so he had to go around in a samoan traditional dress. Yes south here means cold, its the talking in fareinheit which still gets me not to mention the inches you use there in US. We are metric measurements.

Thats not so good about the flywheel. I have read that people have used grinding compound to straighten them up again- more research needed there.
If the flywheel isnt wobbling then i would definitely leave it as is, if it wobbles off the plane you will need to fix it asap.
Yes video would be good, you can upload a video to youtube and link it over. You can also try grounding each cylinder in turn and seeing if you can isolate the missing down.

 

[jiju1943]

Im nearing 40, so not sure if thats young. I honestly hadnt heard of Thunder, which is surprising considering that knock out .David Tua was the big boxer here lately but Lennox Lewis showed him how to eat humble pie. Tua had a mean left hook. He would drive around in a car with tuaman on the licence plate, seemed like he didnt do much else between bouts apart from eat and get even larger. So much so he had to go around in a samoan traditional dress. Yes south here means cold, its the talking in fareinheit which still gets me not to mention the inches you use there in US. We are metric measurements.

Thats not so good about the flywheel. I have read that people have used grinding compound to straighten them up again- more research needed there.
If the flywheel isnt wobbling then i would definitely leave it as is, if it wobbles off the plane you will need to fix it asap.
Yes video would be good, you can upload a video to youtube and link it over. You can also try grounding each cylinder in turn and seeing if you can isolate the missing down.

Well, compaired to me you are pretty young, my youngest daughter is older than you. LOL I know Lennox Lewis, he must be getting on up in age now days. I haven't heard of Tua, I don't watch much boxin now days.

I am going to pick up a spark tester to see how the spark is in each cylinder, and hopefully a DVA adapter to check the high voltage from the stator and if I can find an inductive tach I will pick one of those up. The first thing I will do is unhook the yellow wires from the rectifier to see it that does anything. I will give it a shot posting a video. Thanks again for all your help I really do appreciate it.

Jim

 

[Bosunsmate]

Ha yes comparably so i suppose. Id hate to think what shape Lennox Lewis is in now, punch drunk syndrome probably, his reach was legendary. I remember him in that bout with tua just keeping him out of his danger zone by fending him off with repeated long jabs eventually opening a cut above tuas eye which started bleeding in to it and that just made Tua go beserko with his swing as he couldnt see- unaminous win to Lewis.

If you can check spark jumps a 7/16 gap then for me that often rules out stator and saves buying a dva as a bad stator will normally not put out enough to ever make regular healthy spark.

 

[Bosunsmate]

Check your tach is working if you have one as if thats acting weird it can indicate electrical issues on some motors

 

[jiju1943]

Hey Bosuns, I think I finally got it running right, I unhooked the yellow wires on the rectifier and it didn't seem to make any difference. I checked the plugs and only one looked like it wasn't firing so changed the coil, on that one. I did pick up a spark tester. good spark on all but that one just kept missing but I decided to change out the power pack also. Once I changed the power pack and the coil, I decided to change out the plugs also. Fired it up, it ran so slow I had to keep giving it gas to keep it running.

I forgot, before I changed out the coil and power pack, the strangest thing I have never seen an engine do before, while trying to crank the engine it ran like it was hitting on two cylinders, I looked up and the flywheel was going back and forth, it was not going around and around but back and forth and it ran like that for about 15 seconds. Never seen one do that before.

I did adjust the cable so it would stay running and I am very happy to say it sounds really good now. One thing I am concerned about is the mark on the cam roller is not in the right place and the roller is touching the cam. I was so excited to get it that close that I quit for the day. We may take it out on the water tomorrow and see how it runs. I will let you know how it goes. Thank you so much for your help.

Jim

 

[Bosunsmate]

You might of had the plugs hooked up to the wrong cylinders when it was going back and forth, easy to do on these.
Before you take it out on the water be sure no cylinders are running lean. You should do a drop test on each cylinder to make sure each one is pulling some weight.
The roller and cam thing is a bit of a spanner in the works though. At idle it shouldnt be touching which means that something is carrying more load than it should. perhaps your timing is too low and hence the butterflys are open more than they should.
I always do my adjustments by first checking butterflys are closed, making sure the cam roller is only just not touching and then bringing up the timing until the engine just keeps going in gear and in the water (and the motor has to be warm).
Post a video of on the water action if you can. And any photos./videos of the link and sync if you cant get that as it should be.

 

[Bosunsmate]

You may want to do a compression test if its still not able to be adjusted right, good luck

 

[jiju1943]

What is a drop test? When the motor was running forward and backwards, I hadn't changed anything yet, it was running but missing just moments before and it ran and missed after that also, it is weird.

I know I need to do a compression test, I will do that tomorrow and see what the compression is. Before I take it out on the water how will I check to see no cylinders are running lean? Don't look like I am as close to being done as I thought. I have done a search on how to link and sync and so far haven't found anything. Man you know these engines, I wish I did.

I did do a couple of videos today before it started running smoother so I will practice to see if I can do post one. Thanks again for all your help.

Jim

 

[Bosunsmate]

What is a drop test? When the motor was running forward and backwards, I hadn't changed anything yet, it was running but missing just moments before and it ran and missed after that also, it is weird.

I know I need to do a compression test, I will do that tomorrow and see what the compression is. Before I take it out on the water how will I check to see no cylinders are running lean? Don't look like I am as close to being done as I thought. I have done a search on how to link and sync and so far haven't found anything. Man you know these engines, I wish I did.

I did do a couple of videos today before it started running smoother so I will practice to see if I can do post one. Thanks again for all your help.

Jim

Yes i got to know one after rebuilding it for my mate, i got a few things wrong on that rebuild but know them like an old mate now. I bought my motor off a chief mechanic who swore it had a gremlin and had given up on it, but i managed to get there in the end, you just got to persist with them as once they are sorted these Evin/Johnsons they are great. A drop test is grounding one cylinders HT lead and checking that there is a similar reduction in rpm. If the rpm doesnt drop then you know that cylinder isnt pulling. Its best done underload, and with insulated pliers. To check whether they are running lean you can also take out all the plugs and clean them and then put them back in and turn the motor over for about 5 seconds with the starter with the safety line disconnected so there is no spark. You then remove the sparkplugs and check they are all wet with fuel. If a seal has gone the upper or lower can be dry. And if its a dry carb it will show up in which cylinders are affected.

Link and sync are pretty easy on these. The low idle is what ive described and all you have to do for full throttle is to check that the butterflys are wide open and then with a timing light which im picking you dont have you just make sure that the timing advance isnt too advanced, its probably around 24 degs but an online search would clear that up

 

[jiju1943]

Thanks Bosun, I will get into it deeper tomorrow, it is about 1 AM here, I hope you have a great night/day.

Jim

 

[jiju1943]

Well this is not good, I just did a compression test on the Johnson, I have been putting that off because I was afraid it would be low and I was right, it is reading about 85-88 psi all cylinders. I guess this winter I will rebuild the other power head. I pulled the inspection plates on the Javelin (white motor) and the pistons and cylinder walls are smooth as a baby's bohunkus, but the rings are sharp as a razor which means they are shot or worn well. The compression in that motor is a little over 100 each cylinder.

I may change my mind when I see what a set of rings and complete gasket set costs. For now I am just going to run the fool out of the green motor (the one on the pontoon). It will eat gas like no tomorrow but there isn't much I can do about that for now. I will be looking into how to get the power head off so I will be ready come winter.

Any suggestions what I will experience with that low compression, I know a car will smoke it's butt off and not have much power. Probably will be the same on the boat motor.

 

[Bosunsmate]

Thats no good Jim, but no point dillydallying hoping its something its not. You could try running sea foam through it and seeing if that loosens up the rings and increases compression. They are relatively easy to rebuild so you have something at least to look forward to in winter. The hardest thing i found is undoing the bolts that hold the powerhead to the leg. The one i did was on a salty which hadnt being disturbed snce it left the factry so the bolts were really seized up. Whereas being inland in fresh water you probably wont have too much trouble, but who knows where a past owner had it.

I think you will find a complete gasket set for around $120 and rings about $20 a piston.
You would want to measure the bore too incase that has being worn out and you need to OverSize but id imagine its just a case of reringing. My 60hp is due for that too but i keep thinking one more season then il do it.

 

[jiju1943]

We finally got to try out the engine today, it fired up and ran great, it has plenty of power and runs smooth. We covered the same area we did when we had the 85 hp Javelin on the boat. The Javelin used 5 gallons of gas, this engine used about 1/2 gallon or so. I did notice it did cavitate at one point. I was going to do a video while it was running WOT but I was so surprised at how much water was spraying on top of the motor, that I was amazed that the engine didn't drown out from all the water.

I slowed down the rpms quite a bit and no water on top of the engine. The water however was almost over the top of the electric tilt and trim motor, good thing I water proofed it well. I think maybe the engine is down too far into the water. Since I did install a jack plate I can now raise the engine without too much trouble, I hope.

One more thing, I still can't get the motor into reverse, hopefully it is just an adjustment of the shifter cable. I will let you know how the engine runs after I raise it up some.