2001 25 hp Yamaha 2 stroke jumps out of gear

[bat119]

My motor *****s and runs perfect until you try to go faster then it "pops" out of gear

I thought it my be the prop changed to a new one does the same thing. Tried to adjust the linkage another failed attempt, solved the problem the old fashioned way I bought a new 4 stroke elec start should be here on Monday.

The old motor could be my winter project although I do have a few questions

What kind of special tools will I need ?
What parts, gears could I expect to replace?

[99yam40]

the service manual for that motor will have the steps and tools needed to take apart the lower unit.
clutch dog and forward gear would be my guess without opening up and looking to see what is wrong

[boscoe99]

While it could very well be a problem with the shift mechanism in the lower unit, it could also simply be a misadjustment of the shift mechanism. That particular lower unit can be a bit fiddly upon reinstallation. It has been known to whip many a mekanics arse.

The normal procedure is to shift the motor into reverse before removing the lower unit and ensuring that the lower unit shift mechanism does not move while the lower unit is not attached to the mid-section.

Before you reinstalled the lower unit was it verified that the lower unit was fully in reverse gear while at the same time ensuring that the shift handle was in reverse gear? Might be worth while to remove and reinstall the lower unit just to verify that it really does have a defect.

If I were you I would get both the genuine Yamaha service manual and a Chilton/Seloc type manual. The Yamaha book will have little to no words and music describing what needs to be done, and in what order. The non-OEM manuals have more descriptive test.

Below is an illustration of the shift cam showing its interface with the shift plunger. Perhaps the stepped profile of the shift cam is worn, preventing the lower unit from staying in gear, or maybe the forward edge of the plunger is worn.

[bat119]

While it could very well be a problem with the shift mechanism in the lower unit, it could also simply be a misadjustment of the shift mechanism. That particular lower unit can be a bit fiddly upon reinstallation. It has been known to whip many a mekanics arse.

Thanks for the advice and warning LOL

When the problem occurred the engine was running like normal for a couple of hours then it started jumping out of gear. I drained the bottom fluid over a piece of white cardboard the oil was clean no indication of any metal or shavings. I ordered the Chilton manual I'll do some research sounds like a good winter project.

[boscoe99]

Don't forget wear and tear on the shift mechanism that connects to the lower unit shift mechanism. Would be a shame to overhaul the lower unit only to find that the problem was in another part of the motor.

[rodbolt17]

as it is spring loaded for fwd gear and there are NO shift linkage adjustments my guess would be a shift clutch and most likely the fwd gear.

typically happens from slow shifting or excessive idle speed.