1988 XR4 Timing

[red95gtcoupe]

1988 XR4 150 s/n 0B363520

I just pulled the timing module on my XR4 and want to check/set the timing. I am familiar with setting timing on cars, but have never done so on an outboard. From what I gather, they are set by adjustment screws. I plan on setting the WOT timing to 22* static (=24* running WOT in water?) and the idle timing to ~8-9*, figuring I may have to adjust it in the water to get a great idle. When I set the timing, I will pull/ground the plugs, hook up the timing light and remote starter, and disconnect the throttle cable. When cranking the motor over, I will move the throttle arm to WOT and adjust the WOT stop so I get 22*, then back to idle and set the idle stop at 8-9*. There are 4 stops on the arm that I can see, and am unsure which need adjusted. In the picture below, are # 2 or 4 the idle stop, and are #1 or 3 the WOT. What are the 2 stops that are not for timing? Do they have their own settings? Also, I have read about adding a jumper when removing the timing module, but others make no mention of it. Other than removing the white/black, red/black, and black wire for the module, is there anything else I need to do (other than set timing)?

Thanks,
Brian

 

[red95gtcoupe]

I used my dial indicator to confirm TDC on the pointer and checked the timing. I figured #1 in the picture is WOT timing and #2 is idle timing. The idle timing ended up being ~10 ATDC and WOT was only 18 BTDC. Is WOT usually set this low? I did notice when moving the timing lever/arm that it was gritty (maybe from a mud dauber nest) under the flywheel where the trigger moves so I tried to flush it. Sometimes it seemed like due to the grit that the timing arm wouldn't move through its full range if moving just the lower throttle arm. I also noticed when I put the control box lever to WOT the WOT timing stop was not quite touching. Not sure if this makes sense, but I am wondering if this prevented the timing from advancing when at WOT (described in post #7 of this thread http://forums.iboats.com/forum/engi...1-1988-xr4-150-s-n-0b363520-several-questions)

 

[racerone]

You only set the maximum timing advance.-----Now folks are often confused by " idle timing " on outboards.-----It is the point where the throttle plates start to open and thus it is a " linkage / carburetor adjustment " on these motors.

 

[Dukedog]

when ya had tha dial indicator out did ya set tha pointer? .462?...tha 10/32 screw IS tha idle timin'...idle timin' is best set on tha water, in gear ta whatever tha motor wants...that screw is tha ONLY thing used for idle speed/rpm...tha 2 1/4 20 screws (3 & 4) have nothing to do with changing speed/timin'..they are just "stops"...there should be a slight "gap" between tha roller on tha carb and tha throttle arm...idle is controlled strickly by carb idle circuit and timin'....

 

[red95gtcoupe]

I haven't changed anything yet. I have a manual on the way and should have it next week. I just wanted to get a feel for where it is at and get a better understanding before I start changing anything. I was confused at first by all the stops, but once I fired it up it made more sense. I have a slight gap between the carb linkage roller and the arm. I also pulled the air cover to make sure the butterflies were not under or over travelling when at WOT and that they were closed at idle. I did not set the pointer since I didn't plan on changing anything. I just checked to see if TDC lined up with the timing pointer. What is the .462 setting? Is that past TDC?

Thanks,
Brian

 

[Dukedog]

tha .462 is a mark on tha flywheel that you set tha pointer too after ya get tdc "before ya set any timing"... it will be in tha manual on how to do it...might get a little confusin' tryin' ta explain ona key board...

 

[red95gtcoupe]

The manual came in today and I just finished the link and sync. Overall it was pretty easy. I wish I had a manual this detailed for everything I own. It puts the Haynes and Seloc manuals to shame. TDC ended up being slightly off (1 dot on the flywheel, so maybe ~1*). I checked it a couple times before I changed anything to make sure it was correct. I then checked/set all clearances and timing in the order the manual went. If the weather cooperates and the wife lets me, I plan on testing it on the water this weekend. I will take the manual and adjust the idle timing as well.

 

[red95gtcoupe]

Took the boat out today and it ran great. There was no need to adjust the idle and it ran strong at WOT. It went 47mph @ 5000 rpm (WOT) and I'm not sure I would want to go any faster. This is on an 18" lund deep V.

Thanks,
Brian