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Evinrude 1972 25201r throttle linkage adjustment

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Rjybilcom

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I bought this motor a few weeks ago. I think it had been in this man's barn for a few years, but once I got a fuel tank hooked up and a good battery, I have it cranked and running. I think maybe the throttle linkage is out of adjustment, when I twist the tiller handle it doesn't seem to be WOT. So, I'm not a boat mechanic but...I see where there are two marks on the flywheel and how the cam roller starts to move when the tiller handle is twisted all the way to fast. That roller is nowhere near the two marks. I would appreciate any advice so I can get this adjusted properly.
 
It has to be in gear to go full throttle.------If it has no power it is likely running on one cylinder.-----Do not start adjusting linkages if you are unsure.
 
I went back and shifted it to forward and now when handle is twisted all the way fast the cam roller is at the second of the two marks. Is that where it should be at WOT?
 
The 2 vertical marks on the magneto plate have to do with timing of the magneto breaker points.------How does your motor run on a boat ?----Make no adjustments unless you are sure of what you are adjusting !
 
Rjybilcom said:
I went back and shifted it to forward and now when handle is twisted all the way fast the cam roller is at the second of the two marks. Is that where it should be at WOT?
Click to expand...

NO. The two marks are where the carb throttle butterfly should just barely start to open when the roller is aligned with them. At WOT, the two marks should have moved way, way past the roller
 
Good luck with your project.----But motor must be in gear to go full throttle.----The nylon pin at the bottom of the vertical shaft ( port side ) broken or missing ?
 
Let's all get on the same page here. I don't think we are all talking about the same two marks. I read it to say the two marks on the cam. Others are thinking two marks on the armature plate, others thinking the two marks on the flywheel. ​So, which two marks???


BTW, if your picture won't post, it probably is too big.
 

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I think if I could get my hands on a service manual I could probably figure it out without taking it to a shop. Of course I will if I have to, I just like to fix things myself if I xan.
 
The 2 vertical lines ( 3/8" apart ) are on the magneto plate and have to do with setting the breaker points.----And yes you should order a service manual.
 
You are not going to wide open position. At WOT, the cam will have moved to the right till the roller has climbed up onto the hump on the cam. Find out why it won't go that far. (Not in gear, tiller gears out of whack or ????) We can't see the problem from here.
 

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Thank you. That's what I suspected, that I was not actually WOT and in that photo it was in forward gear. I will try to find a service manual on eBay or Amazon and If it still can't get it right, I know someone who can, just have to pay him. It would probably be worth the $200. And I won't do any fishing until March anyway.
 
????-----When the motor is running the flywheel spins at about 4000 RPM.-----There seems to be some confusion about what you are looking at !!!
 
Agreed.----Do not attempt to adjust anything.---Find a friend who can help you.----Not sure if I would visit the $200 guy.
 
Found a diagram, cam is mounted on the armature plate. So are the tiller gears what determines where the cam is in relation to the follower?
 
It's like anything else, training experience and having the right service documentation. I have been doing it 24 years but I didn't learn it all overnight. I think once I find a service manual for this outboard and see how everything works, I'll figure it out.
 
Well-----2 contributors with near 99 1/2 years experience have tried to assist.-----Read your manual before making any adjustments.
 
If I may be so bold as to say so, I think you are going to be disappointed with what you find in a service manual. Factory service manuals are written primarily for the tech in a dealer's service shop, and assume he has at least some kind of background & experience. Except for what we've already told you, you won't find much additional information in the manual. You can learn much more by simple observation of what happens when you turn the throttle twist grip on the steering tiller. Lemme spell it out for you:

When you turn the twist grip, motion is transferred through a series of shafts and gears to rotate the armature plate beneath the flywheel. Rotate the armature plate against the rotational direction of the flywheel advances the spark for high-speed operation. Rotate the armature plate in the same direction as the flywheel retards the spark for smooth low speed running. At the same time, the cam attached to the bottom of the armature plate opens or closes the throttle valve in the carburetor and does it with the proper spark/carburetor synchronization. Finally, the amount of rotation of the armature plate is limited by an interlock bar actuated by the gearshift lever. This limits engine speed to a low setting for running in neutral gear, a bit more engine speed for running in reverse gear, and WOT for running in forward gear.

That's it. Just go through the motions and look, and observe what is keeping it from happening, if anything.

I might emphasize gearshift position. You might have to rotate the propeller to get it to slide into forward or reverse gear on a non-running motor. And twist grip must be in a "Slow" position to shift back to neutral.

Good Luck. I've never written this much detail for anyone else.
 
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