'87 yam 20 jumps into forward gear

[daleburt]

my 1987 yam 20hp 2 stroke jumps into forward gear if you give it a rev in neutral. It doesn't have to be wild revving,1500 revs and it'll jump into forward. The gear selector doesn't move when it does it.
It's also really hard to get in reverse and jumps out of gear when given some revs.
I've opened up the gearbox and checked the dog clutch and the gears,all seems in good condition and working properly.The gear selector is sliding as it should and there's no damage to the clutch spring,pin or plunger

Any ideas?

 

[pine island fred]

Re: '87 yam 20 jumps into forward gear

Sound like your shift cable is mis rigged in the control. If the control is a 703 or 704, the plastic eye end should be screwed on to the cable end 10 MM. Just about coming out of the hole. That will fix your difficulty going into rev. also. FRED

 

[daleburt]

Re: '87 yam 20 jumps into forward gear

It's manual shift so it's not rigged with a control.
It will go into reverse if I holt the gearshift back but wont stay there.I've adjusted the gearshifter shaft till it's on the last of it's travel but makes no difference.it still jumps into forward and wont stay in reverse.

 

[pine island fred]

Re: '87 yam 20 jumps into forward gear

I can only guess now as it has been a long time since I have dropped any leg. I believe but am not sure that the YAMAHA shift shaft is splined and does not have a master spline that would prevent the shafts from mating in any position. Is there a possibility that the leg was dropped and the shafts mated wrong when it was reassembled? Maybe some one here will come along who has done this recently and knows better than I do. My memory is not as good as it use to be.
Strange but I can remember everything about a CHEVY stove bolt 6 from 50 years ago. regards FRED