Throttle linkage slop how much is normal.

[Taxus812]

Johnson Outboard 48 1991 J48ESLEIM

I have a question on how much play at the bolt holes is acceptable on the three cam levers that make up the throttle and spark advance. Is there a bit of wiggle

I was working through solving an inconsistent idol when I noticed that the cam lever at the carbs was flopping all around, side to side. It probably won't help fix my issue since the cam pickup roller doesn't make contact when idling. However, the bolt hole had been egged out over 35 years and it needed replacing. I replaced it and, as I hoped, can see very little slop at the link.

Now, I am looking at the last two cam levers for play. The spark lever assembly is of interest since it could possibly influence an inconsistent idol if egged out.

I would fire up the parts cannon and replace them due to age, but they are no longer available. The eBay market has marked them up ten times their original cost.

I would really like to know what is a normal, acceptable amount of play in that linkage before wasting time and money. Any reference for what is good and what is way out of spec ?

SHIFT & THROTTLE LINKAGE - 1991 Outboard 48 J48ESLEIM | Crowley Marine

View parts diagrams and shop online for SHIFT & THROTTLE LINKAGE parts, 1991 Outboard 48 J48ESLEIM. Offering discount prices on OEM parts for over 50 years. FAST $4.95 shipping available.

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[racerone]

What trouble shooting have you done for the bad idle condition?

 

[Taxus812]

Hi, Thanks for the reply. It seems like a lot of little things are compounding the issue. I'm picking through them slowly and have made a lot of progress. I have no known issues much past idol, lots of power, and can run at WOT all day. Just idol is up and down and stalls. The constant stalling drove me nuts. It made it hard to trailer on the river where we live.

OK, here is what we have done so far.
New plugs, gapped and fresh premixed fuel (no VRO)

Both cam rollers are new, and the "link and sync" was completed per the service manual. I could idol it, but it seemed to load up, stall and ran seemly rich (a bit of a sputter when accelerating).

We checked a few items (compression and spark) to allow us to focus on what we suspected (fuel system). I checked compression when warmed up. I forgot the exact number, but both cylinders were almost the same, around 130ish (well within 10%). Validated that we had a good spark using a spark checker before we chased other things. It has a nice, unmistakable bright spark, so back to carbs and tuning. (tool used )

I checked that the primer was not leaking and was functioning. I rebuilt both carbs (non-OEM kits, unfortunately). That made some improvements in Idol. . Unfortunately, it still loaded up and stalled. I suspected the idol screws were mucked with, so I tried adjusting them. No real change when adjusting (like turning the screw did little) per the service manual. That peaked my interest, and I decided to check for air leaks.

We found an intake leak at the primer port nipple, where it had apparently backed out. So I rebuilt the carbs again (this time using OEM kits). I pressed the nipple back into place, installed it, and checked for air leaks by spraying carb cleaner on the carb around the nipple and the manifold gasket area while running, listening for a change in RPM. I found another leak at the gasket (I just needed to tighten the bolt a bit).

That made perhaps the most significant improvement in the idol. It still seems rich but is much more consistent with an idol. It still seems to drop to 600- 650 randomly and is rough, but it didn't stall (perhaps once).

When doing all that. I discovered my dashboard tachometer also doesn't match my portable tachometer gauge. The portable says s 700, and my dash gauge says 1000. If I set 750 using the dash tachometer. It will stall. I suspect the portable is correct. (they will both agree with each other at about 1200RPM)

I also found the slop in the cam lever I mentioned, and it was rattling all over the place. So I replaced it. I installed a new one and redid the "link and sync." I figured I would do it before I retested. If the others needed replacement, I would replace them, too.

To do:
Check indexing and timing to see if anything is jumping around. I ordered a test light (2-cycle capable) that has a tachometer. I will check that against the other tachs to see who I trust.

I must get it into the water and adjust the carbs and idol again. Then, I can test the idol timing.

 

[Taxus812]

Got the test light\tachometer. It agrees with the portable tach perfectly. I will have to muck with the dash-mounted tachometer (it is old and the leads are likely corroded so I will start there).

I will have to get it on the water but my idle floats between 850 - 1050 out of the water and in neutral on muffs. I will have to see if that calms down in water and in gear.

 

[Taxus812]

So, if anyone is interested, I finally got it sorted. I redid the "link and sync", validating the gap at the cam roller for the carbs. Using a 2-cycle timing light with a tach, I checked the idol timing and indexing. Indexing was perfect, but I was 4 deg ATDC at Idol out of the water. this is within the 1-5 deg range, the manual states. I decided to go ahead and adjust it to 3deg, as the book states, as a starting point. The motor idol smoothed out of the water, and in the water, in gear, the idol was spot on. No adjustments were needed.
I can't quite get my head around why that would work since the idol is just advancing or retiring the timing. I would think I could have achieved the same results by adjusting the idol set screw and then the cam roller gap (per the book).