1990 Johnson 90hp throttle cable binding after Joe Reeves timing procedure

[sregdorr]

Hello All! Long time site stalker, first time poster.
I recently purchased a 1990 Nitro Tracker with a Johnson 90hp (TJ90TLESB). The boat had been sitting a while so I rebuilt the carbs which made a world of difference. I checked the timing with the Joe Reeves method and it was quite far off. The manual calls for 28° @ WOT. With the JR Method, I was seeing about 15° BTDC. I moved the spark advance to achieve 24° BTDC, performed a link and sync, started her up, and idle sounded great at around 700rpm with muffs. Everything seemed to go as planned but as I went to hook back up the throttle linkage, I found it to be in a nasty bind at the idle position. I realize this is due to the fact that the linkage arm is now in a more counter-clockwise position per the new timing setting and the throttle cable connection is closer to the anchor postion at the air silencer base plate. Part of the problem is that the cam roller that connects the primary linkage to the spark advance lever is quite worn which means that the first linkage arm has to come back farther for the spark advance arm to reach idle position. I've ordered a new part, but the slop is a only few 16ths, and shouldn't account for the amount of binding I'm seeing. The binding is significant to the point that I can't pull the control lever back to the idle position for fear of breaking something with the force required. Has anyone run into this before? Any ideas on how to fix? The control lever is integrated into the boat and it appears that they control assembly and cables came with the boat. I thought at first I may have placed the cables backwards (I had it with the throttle on bottom and shift on top), but when I tried to switch them the shift cable was no where near close.

Thanks in advance for the insight and help!

 

[jimmbo]

Did you adjust the throttle cable length before reconnecting it?

 

[sregdorr]

Yes sir, I matched the length at WOT by screwing in the barrel adjustment (I basically had to bring it in until it was out of threads) and then attached it. From there when I tried to bring the control lever back to idle is when I noticed the binding. I pushed the lever back to WOT, disconnected the throttle cable, brought everything back to idle position, and then tried to attach the cable and I couldn't even get it on by hand due to the position of the linkage end relative to the cable anchor position.

I apologize that the pic is hazy (my phone camera lens cover is busted), but hopefully this will help describe what I'm seeing. This is at WOT. You might notice that I had to move the spark advance lever quite a ways to reach 24° BTDC, as well as the pick up timing adjustment respectively. At idle position the black plastic end of the throttle cable is almost touching the barrel adjustment.

 

[Joe Reeves]

If you ran out of threads with the trunion on the throttle control cable, you're doing something wrong!

Also, the starting point of that method pertains to the full spark advance screw that has a rubber bumper cap on the head end of screw..... your 1990 90hp doesn't have that stop screw. Without it, it becomes possible to make an expensive error.

If it were me, whenever the water might be calm, I'd have that engine's timing checked and set at full throttle, running on the water.

 

[sregdorr]

Thanks for the response, Mr Reeves! 10-4! I'm certainly not interested in melting a piston, so I will definitely take your advice. Now that I've tampered with the timing (and wasn't bright enough to mark the original position...) do you have any guidance for where to set a baseline before checking it on the water?

 

[Joe Reeves]

Thanks for the response, Mr Reeves! 10-4! I'm certainly not interested in melting a piston, so I will definitely take your advice. Now that I've tampered with the timing (and wasn't bright enough to mark the original position...) do you have any guidance for where to set a baseline before checking it on the water?

No, but since you know that the full spark advance setting is 28 degrees, if it were me, I would start my timing check at a low rpm so as not to allow it to get over that 28 degree mark and as the rpms increase, adjust as needed.

Keep in mind that the full spark advance will hit that 28 degrees via the turning of the timer base under the flywheel "before" the throttle butterflies open to full.... so you'll have a little time to fool with it before actually hitting the full spark advance, full throttle position.... a little lower speed situation. But do check it (the timing) at the full rpm range before calling it a night.

 

[sregdorr]

Got it! Will do. Thanks again!