Seloc book makes no sense....please help if you know....

[ssportsmfg]

I have been trying to solve a rough idle problem and tune this motor up.

OK all you knowledgeable mechanics on here.....I have a Johnson 2001 50 2 cyl, 2 cycle. Model J50PL SIB

The Seloc book on tuning up this motor and syncing the spark advance and carb states the following.

For ALL models 1994 and later the spark advance rod length is determined only by the charging system that if it is 12 amp length should be 2.5" and 4 amp length should be 2"

Mine is currently set at 2 5/8" exactly.....which is listed as the length in the paragraph above but does not list my model or year.

I also looked up my motor and it is listed as 6 amp, which matches neither of the settings the book says the charging system will be. What am I missing here?

If I set the rod to 2.5 inches will that not advance the spark more than a 2 5/8" length and possibly damage the motor from to far advanced spark? Or does it matter? What is the reason for these exact lengths?

I have to admit I don't understand the setup's on these outboards at all. I have already figured out that the idle is set not with the carbs buy by the spark advance setting.

So far on this motor I have de-carboned, checked compression 145 and 140 top and bottom, checked the plug wires 000.1 resistance on both, and my sperry digital meter bounces between 000.0 and 000.1 with probes touching so my plug wires seem to be fine, no cuts or bleeding (watched at night) Strong spark.

Help with the correct spark advance rod length would be greatly appreciated, trying to do this myself, but with conflicting info that I am finding, I am not sure how to proceed.

Thanks!

 

[daselbee]

That's the problem with Seloc and Clymer. They try to cover a wide range of motors in one book.

But that doesn't help you with your problem, does it?
I have to admit....the link and sync process for this family of engine design is tricky.
I understand the concept and process of the link and sync very well, but I have trouble getting all the various rods, stop screws, cam follower marks, etc lined up as the books say. They are never exactly right for some reason when the engine is running to my satisfaction.

First off, use your head. The rod you speak of will not even adjust out to 4" right? So it has to be the 2.5" spec. Secondly, when the rod is adjusted to 2.5" basically it is in the middle of the full range of adjustment, right? This gives you leeway on both sides of the adjustment...either in or out. If you get it where one adjustment is way off toward the full range of the adjustment...you got something wrong. Think about it.

The rod you are referring to is the rod that rotates the timerbase around as throttle is applied. The length of that rod basically sets the range of spark advance that the engine will experience. Say for example, the rod is set at 2.5". If your idle timing works out to be 2* ATDC (example) where it idles smooth and at the right speed, well then as throttle is applied, the 2.5" length of that rod sets the full travel AWAY from 2*ATDC toward the max advance of 20* BTDC (example figure). It is a physical limitation that the rod imposes on the advance mechanism. You can see that if the rod was shorter, starting at 2*, it would not push the timerbase as far around.
Similarly, if it was longer, again starting at 2*, it would push the timer base farther, and advancing the timing more.

So, you have to give and take, adjust and re-adjust that rod, the idle stop screw, and the throttle push rod to try to get them all adjusted in such a way that the marks align, the pickup point is correct, the throttles are all closed at idle, and YOU DO NOT EXCEED THE MAX TIMING SPEC. That would be set by slight adjustments of the 2.5" rod you speak of.

Problem is, when you change that rod, you also change the idle timing, which changes the idle speed.....vicious circle.

Seloc manuals do specify how to do the adjustments. They start at the carbs, and work backwards toward the finishing point of throttle cable adjustment and connection.
I think that is a good approach. Once you get it in the ball park, then small slight adjustments have to be made to get it running exactly right.

Last step, and this is crucial, is get it on the water, attach a timing light, and make absolutely sure you are not exceeding the max timing spec. (Don't know what it is for your motor.).

But, start with that 2.5" measurement and go from there. Even tho your specific motor is not mentioned in the text of the book, 2.5" is the right length to start with.

It is a very complicated link and sync process for that motor.

Those ball joint connectors are very easy to break....careful.

 

[daselbee]

I went back and re-read your posting....I see where I mis-read some of it, particularly the 4" length I referred to. I should have read.... 2" length OR 2.5" length.... is specified, not 4".
So, I apologize for the mistake in my posting. The concepts I speak of above are correct, regardless.

I would start with the 2.5" setting, and see how it goes.

If you PM me with your phone number, I can call you when you are in front of the motor to discuss real time.
I have a 2001 40 horse in the shop right now, and just went thru this whole thing.

 

[ssportsmfg]

Daselbee Thanks so much. The Seloc book is saying that the length of that rod is dependent on the AMPS of the particular motor either 12 AMPS or 4 AMPS but when I looked my motor up on the internet I first had a hard time finding how many AMPS it was and when I finally found it, it was lised as 6 AMPS which did not match the description in the Seloc book.

 

[gm280]

ssportsmfg, seems daselbee has you covered for you question. So all I will post is, buy yourself the manufacture motor specific, horse power and year specific shop manual you only your year engine and I guarantee you it will cover everything to the letter. Those after market manuals try to cover a general range of engines and in doing so, cover only the basics and never the particular things folks really need to know. I can tell you the original manufacture motor and year and HP specific shop manual is the best...

 

[ssportsmfg]

Daselbee,

Thanks so much for the call, info was invaluable, will look for a motor specific book. Thanks to all. Got it all put back together, still running the same rough on idle, but I am sure it is carbs now. Everything is synced. Has to be carb or fuel pump. Electrical all checks out OK.

 

[ssportsmfg]

Well just as it got dark last night I hooked up my timing light and fired it up. The sticker on the air box says 17 degrees BTDC. It is on the mark exactly. Also per Daselbee's suggestion I shot some carb cleaner into the top air hole beneath the fuel intake cover on the carbs. It killed the motor immetiately. I sprayed them both and left it sit all night. Fired up really hard. (didn't like that liquid in the air passages) but once it fired up it is running some smoother. Not as smooth as I think it should or can, but did smooth out some.

Guess that carb cleaner got some gunk out of those micro holes in the top plate. Thanks again Daselbee! End of the year I will take the carbs off and clean them out and put kits in each one. It is only rough idle so am just going to run it this summer and do it next fall. Have new prop on the way to get the RPM's up.