Engine Compression Test Question...

[oonighttrain]

LONG STORY SHORT..

i have this no good, pile of chit fawkin yamaha 4 stroke 50 h.p. outboard.. i would have thought it would be virtually indestructable but, its proven otherwise...

anyway, when you do a compression test on it, it shows virtually NO compression in #1 cylinder.. when i put a few squirts of oil in the same cylinder, it jumps up to about 100 psi.. i tried to tell my buddy that this means there is a problem in the cylinder.. he finds it hard to believe because we just honed the cylinders and put new rings in it..

whats the deal???

 

[swampwater]

Did you forget to put the rings in? Swampy

 

[ripperd]

If the new rings are not broken in at all, I could see this happening.

 

[oonighttrain]

i forgot to mention that THE COMPRESSION HAS NOT CHANGED from before the rings were put in and cylinders were honed...

 

[TWISTER]

Did you guys check to see if the valves needed to be set. It is a 4 stroke

Rob

 

[oonighttrain]

Did you guys check to see if the valves needed to be set. It is a 4 stroke

Rob

yup.. i have had the head on and off so many times i could do it with my eyes closed.. valves have been adjusted and re-adjusted about 18 times..

even had the valves out of the head to inspect them...

 

[SNOW JW]

Sounds like it's not broke in or the Cly are glazed if that is possible on that motor?? Have seen a few motors do this.

 

[Estevahn]

What was the ring end gap on the new rings?

 

[To The Pipe]

Did you gage the cylinders with a good bore gage? It sounds like you are just a little over spec on your bore.