15 hp Johnson no power

[AlTn]

Re: 15 hp Johnson no power

try leeroysramblings.com, 9.9/15 hp articles for info and pics

 

[oldman570]

Re: 15 hp Johnson no power

As AlTn states; going to Leeroys ramblings will get you some of the best advise and tricks to setting the points and timming, along with carb info, on the older OMC motors that size. Had to use it myself more that once.
Oldman570

 

[kfa4303]

Re: 15 hp Johnson no power

Here you go....

http://www.leeroysramblings.com/Johnson 9.9_15.htm

 

[Johnson209]

Re: 15 hp Johnson no power

Here you go....

http://www.leeroysramblings.com/Johnson 9.9_15.htm

Thks for all the help guys. I'll really appreciated it. I went ahead an clean my points and set them at spec...
I now have stronger sparks. I will post up details how it runs.
Thks a mill

 

[Johnson209]

Re: 15 hp Johnson no power

Hey OptsyEagle, I took off the flywheel and look for the screws to adjust the throttle cam and i didnt see any except the one I have on the picture. Are these the correct screws to adjust. Even though I loosen those two screws it still wont budge or move.It's only giving me a little play. I dont see any other screws but those two. Does the motor needs to be in neutral or in gear? Also am I suppose to take off the whole plate where the coils and points are surface on just so I can adjust it? Leeroyramblings web site doesn't show the adjusting screw on my motor, it only shows the newer model. If anybody knows can one Point them out.

thanks

 

[oldman570]

Re: 15 hp Johnson no power

It dose not appear to have the adjustable plate as some motors have. There might be a clip with a screw in it on the rod from the roller to the carb that will let the roller be adjusted for the correct setting. JMO
Oldman570

 

[OptsyEagle]

Re: 15 hp Johnson no power

Those are the two screws that should allow that plate to move forward or backwards or at least pivot. Perhaps there is some corrosion holding it down, but it should move. You shouldn't even need to take off the flywheel if you can find a wrench that will fit under there. If you can't get it to move you could look at removing the armature plate completely and trying to see why it can't move. It is an important setting for fine turning your motor's performance.

 

[kbait]

Re: 15 hp Johnson no power

I have found that you cannot adjust the cam on that model. I use 2-3 wraps of 3M electrical tape around the 'cleaned' roller. Just put on enough so it starts moving the throttle butterfly when at the cam mark. Good luck!

 

[OptsyEagle]

Re: 15 hp Johnson no power

I have a 1975 9.9Hp where the cam is adjustable. His throttle cam looks identical to mine.

I have to admit that I always wondered why it is adjustable at all since it is in very rare occurances that I would adjust it so the roller hit before or after the arrow. I would think that it is something that could have been hardset into the motors design, but in my motors it is adjustable.

 

[Johnson209]

Re: 15 hp Johnson no power

Those are the two screws that should allow that plate to move forward or backwards or at least pivot. Perhaps there is some corrosion holding it down, but it should move. You shouldn't even need to take off the flywheel if you can find a wrench that will fit under there. If you can't get it to move you could look at removing the armature plate completely and trying to see why it can't move. It is an important setting for fine turning your motor's performance.

Thks optsyeagle, I'll take the armature plate off and see what I can do. If it cant move still, then I guess mine isn't adjustable also. I'll just have to improvise and place 3m tape on the roller. Thanks guys for getting back at me so quick. Time to get my hands dirty again.

 

[OptsyEagle]

Re: 15 hp Johnson no power

It would seem to me that something would need to be done with that cam or roller. Since the roller is hitting the cam "after" the arrow, it not only means your timing advance is off but also that you would not be giving it as much gas as you should, at start up, making it very hard to start. The second issue I would check is to turn the throttle grip full on to WOT. Then with your fingers (motor is not running here but must be in fwd.gear) try to pull back on the carb roller and see if the throttle butterfly opens even more. I would think that with your throttle cam set where it is, the carbs butterfly will not fully open when you limit out on the throttle grip, causing you a limit to your top end power. This test should confirm it. Maybe I am wrong.

 

[Johnson209]

Re: 15 hp Johnson no power

It would seem to me that something would need to be done with that cam or roller. Since the roller is hitting the cam "after" the arrow, it not only means your timing advance is off but also that you would not be giving it as much gas as you should, at start up, making it very hard to start. The second issue I would check is to turn the throttle grip full on to WOT. Then with your fingers (motor is not running here but must be in fwd.gear) try to pull back on the carb roller and see if the throttle butterfly opens even more. I would think that with your throttle cam set where it is, the carbs butterfly will not fully open when you limit out on the throttle grip, causing you a limit to your top end power. This test should confirm it. Maybe I am wrong.

I was able to adjust the cam. Now it's sits almost perfect with the arrow when touching the roller. I had to tied a wire to see when the throttle starts to opens and it's lining up exactly on the arrow. I hope this does the trick along with setting the points because one of my points gap were set at 18 so i had to reset it at . 20
Crossing my fingers hope this works. Taking the boat out tommorow and see if it works. Thks

 

[OptsyEagle]

Re: 15 hp Johnson no power

I hope the carb. synchronization helps. Any idea if the carb butterfly opened fully the way it was before? I doubt the point gap at 0.018" would have caused a noticiable reduction in top end power, but a carb throttle that does not open fully, surely would have.

I would imagine your motor should be a lot easier to start as well, now that the cam is set properly.

 

[Johnson209]

Re: 15 hp Johnson no power

I hope the carb. synchronization helps. Any idea if the carb butterfly opened fully the way it was before? I doubt the point gap at 0.018" would have caused a noticiable reduction in top end power, but a carb throttle that does not open fully, surely would have.

I would imagine your motor should be a lot easier to start as well, now that the cam is set properly.

The carb butterfly seems to be opening fully as it did before when its wot and in gear. I double check it and it seems ok. I haven't start the motor yet but I'm confident it will start better

Thks

 

[oldman570]

Re: 15 hp Johnson no power

You can check the point settings by using a timming light to check the timming with the motor running if the flywheel has marks for both cyclenders. Hook the light to each plug wire and see if the marks are at or near the same spot on the mag plate as they should be when the plugs fire. I have had to set used, and new, points at diffrent gaps inorder to get them both to fire at the same spot and time on the timming marks. If both plugs fire at the same spot on the timming marks, then the motor should be at its best performance when all is done. I belive Leeroys ramblings tells just how to do this the best. It will give you an inducation of just how bad the ware ring for the stator plate is also.JMO
Oldman570

 

[Johnson209]

Re: 15 hp Johnson no power

You can check the point settings by using a timming light to check the timming with the motor running if the flywheel has marks for both cyclenders. Hook the light to each plug wire and see if the marks are at or near the same spot on the mag plate as they should be when the plugs fire. I have had to set used, and new, points at diffrent gaps inorder to get them both to fire at the same spot and time on the timming marks. If both plugs fire at the same spot on the timming marks, then the motor should be at its best performance when all is done. I belive Leeroys ramblings tells just how to do this the best. It will give you an inducation of just how bad the ware ring for the stator plate is also.JMO
Oldman570

I don't have a timing light so I'm out luck. I 'll just have to wait and see If the motor runs at top end and if it doesnt the next step would be replacing the crack coil.
Thks

 

[Johnson209]

Re: 15 hp Johnson no power

It's been raining non stop and I hadn't have the chance to take the boat out on the river yet. At the moment I went ahead and order new spark plugs because the ngk plugs doesnt work on my motor. It takes 5 to six pulls sometimes more to get it started. I reuse my old plugs and it starts right up on first pull. My question is that my old plug that was in my motor was a champion uL81c and the new plug I bought is also uL81c but the numbers that is on the plug is different. The box does says 835 uL81c. The old plug has # 605 and the new one has# 878 on it. Did I bought the wrong plugs? On the Johnson spark plugs chart, it just says Just to use uL81c.
Both plugs do say champion uL81c on it so I'm kind of lost? Any suggestion ?

Thks

 

[OptsyEagle]

Re: 15 hp Johnson no power

The Champion number of UL81C is the main determinant. Did you try to start it with the NGK plugs AFTER you re-set the cam? The way it was before, I would imagine you would be pulling the starter rope quite a few times with any spark plug. It just wouldn't have been getting the proper gas for start up the way it was set before, in my opinion.

In any event, if it worked fine for you with UL81C plugs then use them. Good luck and I hope it stops raining for you soon.

 

[Johnson209]

Re: 15 hp Johnson no power

The Champion number of UL81C is the main determinant. Did you try to start it with the NGK plugs AFTER you re-set the cam? The way it was before, I would imagine you would be pulling the starter rope quite a few times with any spark plug. It just wouldn't have been getting the proper gas for start up the way it was set before, in my opinion.

In any event, if it worked fine for you with UL81C plugs then use them. Good luck and I hope it stops raining for you soon.

Before I had set the cam, it only took me 2 pulls to start the engine cold and 1 pull when the engine got warm with old spark plugs. I decided to replace the plugs with the NGK plugs when I reset the gap. It took me 6 or seven pulls just to get the engine started. I then decided to put the old spark plugs back on and the motor started easily as it did before. Now the engine sounds louder and is idling better with the gap set. I just need to test it in water after the rain settles.


And if the number of the uL81c is the main determinant how do I know which number is the correct one to used or It shoudn't matter, just as long as its A uL81c plug.

Thks again Opts

 

[OptsyEagle]

Re: 15 hp Johnson no power

I can't say what the other numbers that you listed indicate. Probably a batch number or something like that. The UL81C are numbers where each letter and number has specific meaning. I forget which are which but the 81 indicates the heat range, the others help sort out thread size, whether it is a resistor plug or not, the thread reach and sometimes even the gap and electrode type. Those are the numbers/letters the designer will need to look at when figuring out the best spark plug for a given motor.