hey

toonin22

Petty Officer 3rd Class
Joined
Oct 28, 2008
Messages
87
working on a 5hp 4stroke tohatsu 2005. is the compression low on all of these motors or do i need a rebuild. compression was 70. i have heard of some motors running on a low compression just dont know it is one of these. if you have any knowledge of these motors your knowledge would be appreciated.
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,500
Re: hey

That motor has a decompression feature to make it easier to pull start. Check the specs in your Factory service manual (shows figures for both decompression activated and not activated), and you will probably find that you are OK.
 

toonin22

Petty Officer 3rd Class
Joined
Oct 28, 2008
Messages
87
Re: hey

question for you. If you were to squirt some oil in the cylinder and then recheck would that show any signs of a problem?
could that be a quick way to check if you do not have manual.
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,500
Re: hey

That would be standard compression testing technique to determine whether the rings are worn. Yes, you might expect a slightly higher compression with a little oil.
 
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