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Link & Sync a bad idling 50hp 1991 Johnson ? *Pics*

M

mostwanted-lkpg

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I have a "new" motor, a 1991 50Hp, 2cyl Johnson. The problem is that I cannot get it to run on slow RPM´s . I took off the cover and tried to adjust the idling set screw and noticed that it didn´t even touch the stop.

So I believe I have to do a link and sync?

Here´s 2 pictures how it looks on "no throttle, no gear" and in WOT

Green ring; there is a big gap between the roller and the roller cam(?) maybe 0,30" gap, space. Shouldn´t it be tight? And the two arrows, they roller never lines up with them?!

Yellow ring, idling set screw? As you se , its hard to adjust when it dont evcen touches the stop?

Blue ring, how do I know where it should be?

Red ring, I have now adjusted so that the carbs are opening fully at WOT.


bild 1 (3).jpgbild 3 (3).jpg
 
Remove the carburetor face plate so that you can observe the throttle butterflies.

With the roller backed away from the cam... touching nothing.... make sure that the throttle linkage between the carburetors is such that the butterflies open and close at the same time. Open meaning full horizontal. Closed meaning absolutely both fully closed... you do not want one closed and one ever so slightly open.

Green Ring = You have no control over this one.

Blue Ring = Appears to be the full throttle advance setting. Disconnect the throttle cable temporarily. Advance the linkage manually at the engine via where the throttle cable normally attaches and observe the throttle butterflies. Set and lock that Blue Ring screw when the linkage has the butterflies fully open (horizontal). You do not want the butterflies to pass thru that horizontal setting to start to close again.

The lever that slides against the throttle roller has a scribe mark on it. Adjust the roller so that the butterflies just start to open when that scribe mark is dead center with the roller... not before or after.

Red Ring = To set this, the engine must be running and you need to know the engine's idle timing setting. Using a timing light, the idle timing must be set to whatever your engine's idle timing specification is when that scribe mark on the cam lever is dead centered with the throttle roller... adjusted one way or the other via the threaded connector within that Red Ring.

Now.... if you have proper compression and spark on all cylinders, that should do it. Let us know what you find.
 
Thanks for the info Joe!
I did your timing-setting and set the WOT -4 degrees to 15deg BTC (should be 19) on land with both sparkplugs off.
I tested it today with my buddy sitting with a strobe-lamp with me giving it WOT in gear :) the result was 15degrees and we had to screw the spark-Rod in again to 19deg.


about the idling , the manual says 4 degrees ATC , but with so much timing the engine went down to 500-600RPM and dies. i had to set the idling-timing to 4deg BTC to get it to rev about 1000RPM without missfiring.
but the idle-stop-screw dont go back to the stop when I pull back the throttle...? Should ot be a spring that pulls it back? I have alot of play in the incoming gaswire with the plastic hull around, can it be someting wrong there?


well the engine runs pretty fine anyway and sometimes the revs on idle dips a bit low and I have to give some gas.
 
There's a threaded portion of the cable with an adjustable trunion where the throttle cable is anchored in a clamp at the engine. You'll no doubt need to adjust that trunion so that the engine linkage returns to idle when you return the throttle lever to neutral/idle..
 
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