1985 Mercury 25xd starting issues

[ct1762@gmail.com]

Rebuilt the carb (ultasonically cleaned) with a new OEM quicksilver kit. Looked flawless after I was done. New coils and plugs/wires. The motor takes about 5 or 6 pulls to start when cold, and idles at about 1800rpm. initially on starup, it idles ok around 1100 rpm (on hose no backpressure), but once its done loading up from the extra startup fuel, it creeps up higher. the idle timing is set about even with the block half (trigger), and the carb is closed at idle. compression 125psi on both, and CCMS reeds installed (obviously all new intake manifold gaskets too). I left my shop manual back at my house, but does anyone have the correct linkage lenght adjustments for this motor (trigger and throttle cam)? One thing: I did a DVA test on the trigger, and was consistently getting cranking voltage of 18v when the cdi website says its supposed to be 25v minimum. Is that my hard starting issue? thanks in advance here. oh... low speed needle was set correctly. I believe it wouldn't start with anything less than 3 turns out.

 

[flyingscott]

Have you done a link and sync? Why was the timing linkage touched? Is thios a tiller or remote model?

 

[ct1762@gmail.com]

No because I don't have my shop manual. its a tiller rope start. Previous owner made a mess of the linkages. got it in on trade kinda deal. i have a 1981 18hp and roughly copied the setting for that one. As long as the throttle plate is closed, and it has adequate timing it should just fire right up correct? it does start up when warm half a pull. the primer is correctly clean and installed with the spring and check ball. I'm an OMC guy... has me stumped here.

 

[flyingscott]

Is the primer working? When the square Knob is pulled out all the way does the wire pull on the magneto? Is the idle screw set correctly? That Is on the recoil safety.

 

[ct1762@gmail.com]

primer working, yes timing gets pulled forward when the knob is pulled. i can push the primer down with a flat screwdriver without the primer knob and can hear and feel resistance/fuel going through the carb. as mentioned idle screw had to be about 3 turns out... wouldnt idle anything under that. maybe these just take 5-6 pulls to start when cold? my 18hp starts on half as many. possibly the idle timing is a tad too high, but that wouldnt stop it from starting well would it?

 

[flyingscott]

The idle screw is up by the recoil safety. Sounds like you need to do a link and sync> Did you verify fuel is squirting out of the primer hole in the carb?

 

[ct1762@gmail.com]

excuse me yes the idle screw is about halfway in. I asked if anyone has the correct linkage adjustments to get everything set up properly. ill wait till next week to get my manual. will need to take off the carb and confirm the primer is working as well.

 

[flyingscott]

Good idea maybe the book will tell you something you want to hear.

 

[ct1762@gmail.com]

i am taking your advice here... checking to make sure the primer is functioning and the linkages are in the correct place. I had asked if anyone knew the correct settings, but I cannot see that that question was answered unless you happen to know what they are.

 

[Lobbij]

I need these "link-n-sync" numbers too. ct1762, any luck finding the info?
I also have a 1985 25XD I'm trying to tune.

 

[ct1762@gmail.com]

I need these "link-n-sync" numbers too. ct1762, any luck finding the info?
I also have a 1985 25XD I'm trying to tune.

oh boy no not really. that block was a nightmare for me as it was swapped onto the more modern ignition (1994 on up). was a side project for a friend of mine, and he eventually made me give up haha. if your motor has its original non-computer ignition, it will be WAY easier to set up. throttle plate closed, trigger around block half line, low speed needle 1.5 turns out to get you started.

 

[Lobbij]

I got it started - just don't think linkages are adjusted properly. Idle/air screw is 1.5 out. The banana curve slot that moves the Throttle Plate shaft has two slash marks on it - I THINK the throttle should be centered there at Idle - I'll add a picture of where it needs to be to idle for me.

 

[Lobbij]

You can see by the coloration on the linkage rod threads how much I had to adjust that out.
A little history- got this engine 3 weeks ago- nonrunning- compression is 120 psi on both- cleaned the carburetor and installed new carb kit. Installed New Reeds and reed block gasket and center seal. New NGK plugs. New impeller and housing.

 

[ct1762@gmail.com]

i believe the throttle plates need to just start to open when the cam roller hits the center of those 2 lines on the throttle cam. now, it could also be your starting point and throttle plates closed aka just start to open immediately PAST the marks but consult your service manual to find out the correct procedure as i am an OMC mechanic. Looks like you will need to shorten your spark advance rod 1/3 inch or so to get it set up. if the dashpot is not applying enough spring tension to it, adjust it so it does. it stops the linkage from vibrating at idle, throwing things off from what i can gather.

 

[Lobbij]

Yeah where my cam roller is located currently is where it just starts to move the throttle plate, like the cam roller diameter might be worn down or that cam slot maybe too big?

 

[flyingscott]

That link and sync is not good. buy a manual or continue to struggle with it.

 

[Lobbij]

Yeah, I need a manual anyway