2021 255xd LOW COMPRESSION

[Aug91]

So I decided to do a compression test on my boat with 208h

S-111,87,86,86
P-107,78,78,78

FYI these are low compression engines for anyone thinking otherwise.

What gives? I had valve clearance check done. Valves are in spec, the variation in cylinders is really concerning. The boat runs and pulls the same way it did when new. Does 56mph. Gets up on plane within seconds. Doesn't burn a drop of oil. Nothing

Service manual shows minimum compression 71.1

I still have YES warranty but yamaha said if it's anything related to valves I'd have to pay since it's a wear/maintenance item? That's really dumb honestly

 

[Neutron]

So I decided to do a compression test on my boat with 208h

S-111,87,86,86
P-107,78,78,78

FYI these are low compression engines for anyone thinking otherwise.

What gives? I had valve clearance check done. Valves are in spec, the variation in cylinders is really concerning. The boat runs and pulls the same way it did when new. Does 56mph. Gets up on plane within seconds. Doesn't burn a drop of oil. Nothing

Service manual shows minimum compression 71.1

I still have YES warranty but yamaha said if it's anything related to valves I'd have to pay since it's a wear/maintenance item? That's really dumb honestly

I would try another gauge if possible. But i would like to see 120psi on a supercharged motor.
The other thing is are you pinning the throttle body fully open when cranking. If not that will lower your reading

 

[Aug91]

I would try another gauge if possible. But i would like to see 120psi on a supercharged motor.
The other thing is are you pinning the throttle body fully open when cranking. If not that will lower your reading

Well dealership had compresion readings in the 60s lol for both engines 2,3,4 and 105 for cyl 1

On these you're not suppose to open throttle as per service manual. Just take out plugs, unplug injectors and crank. But I did try to put the lever all the way forward the boat would not even crank.

There's a guy at the marina with the same boat I'll ask him if he wants a free compresion test skeptical he'll agree to it but worth a shot

 

[Neutron]

Throttles forward wont crank on any boat unless there is a neutral lockout button.

 

[Aug91]

So

Throttles forward wont crank on any boat unless there is a neutral lockout button.

are you saying throttles forward and I disconnect the safety lanyard or what? Curious

 

[Neutron]

Nope, you disconnect the harness to the throttle body and hold open the butterfly with something then crank. It will most likely set a code but it wont damage the throttle body.
I do this every time i do a compression test on a ln electronic throttle body system.
Then reconnect the throttle body

 

[Aug91]

Nope, you disconnect the harness to the throttle body and hold open the butterfly with something then crank. It will most likely set a code but it wont damage the throttle body.
I do this every time i do a compression test on a ln electronic throttle body system.
Then reconnect the throttle body

Thank you

 

[Neutron]

Thank you

You bet