200 1987 Yamaha not pissing at WOT!

[diverjon123]

i have a 1978 Master angler that i restored recently with the journey documented on this site but...!


the issue i am having is with the 1987 200 Yamaha dinosaur on the back end, the motors pee stream trickles and stops at wide open throttle and over heat alarm sounds. This is around 5500 rpm and around 46 mph.

but for all the power band up to 4500 rpm the motor pees strong like its been sitting in car for 8 hours.

so far i have:
- taken water jacket and heads off the motors and cleaned them. replaced all gaskets.
- replaced both thermostats and gaskets
- installed yamaha impeller kit which included bottom water pump plate and seal, impeller, key, metal insert into top of water pump housing, new bolts.

after installing water pump kit the motor did pee harder but still looses prime at WOT.

the engine has a 25 inch lower unit and the anticavitation plate is about dead inline with the keel.

i do not believe the motor is cavitating at WOT as it does not loose power and sound great.

any ideas to fix this issues would be great.
thanks!

[DonV]

Poppet valve replaced?

[gofastsandman]

If memory serves, the water tube is not ss before `96???
I believe the PH has to come off for that joy.
Keep an eye on the tiller arm as well.

[Fr. Frank]

Originally Posted by DonV

Poppet valve replaced?

I agree here. Check the poppet valve.