HonkyRigged
Recruit
- Joined
- May 20, 2009
- Messages
- 3
I had to mess with a good thing. 
Last year I bought a 1975 9.9 hp Evinrude short shaft. It ran wicked good. I wanted a little more horse power though and it sounded like no big deal for anyone who is mechanicly inclined to change from a 9.9 to a 15hp carb.
Well I figured while I was at it I might as well do some maintenance.
I added the shims for the reed valves to go with the 15 hp carb.
I changed the thermostat. (Old one was frozen - in open position luckily)
I did a carb. rebuild kit on the 15 hp carb. (It had the old cork type float)
I added an overboard water indicator. (motor is a 75 - they didnt put these on till a few years later)
I did a water pump rebuild kit.
I replaced the very worn manual start rope.
I replaced the old and fouled spark plugs. New plug gaps set to .030.
I noticed the cam roller wasnt hitting the cam arm like the book said it was supposed to so I adjusted the arm.
I used all new gaskets for every old gasket I exposed.
Well after it was all done I got it running on the second pull.
The problem is that after hours of messing with it on two seperate occasions the motor wont run on SLOW. It is idleing nicely at about half way between START and SHIFT. If I turn it to slow it dies.
Ive re-adjusted the cam arm to roller position to every posible combo and now have it back where the book says it should be.
Ive adjusted the LEAN to RICH nob to where it needs to be.
Ive checked the tiller arm to see if the teeth are out of mesh and they arent.
I am definetely running on both cylinders.
Overboard water indicator is working flawlessly indicating impeller is mint.
I did find a chewed up rubber gasket in the water outlet holes before I started all this work that I have no idea where it came from.
I did notice (with a small LED flash light throught the spark plug holes) that there is a lot of carbon build up in the head.
One of my ignition coils has a pretty good size crack from top to bottom.
Although I consider myself mechanically inclined Im not a mechanic and have no experience other than this with two stroke motors. I dont know if I have good compression or what would cause bad compression/how to check it.
Im leaning towards some type of exaust gas leak/and/or compression issue although it ran fine last summer.
Any help would be greatly appreciated - if I dont get some type of answer from this post my plan is to just try it out on the boat this weekend and maybe it will be fine for this summer and I can tear into it as a winter project.
Thanks For reading this really long post.
Last year I bought a 1975 9.9 hp Evinrude short shaft. It ran wicked good. I wanted a little more horse power though and it sounded like no big deal for anyone who is mechanicly inclined to change from a 9.9 to a 15hp carb.
Well I figured while I was at it I might as well do some maintenance.
I added the shims for the reed valves to go with the 15 hp carb.
I changed the thermostat. (Old one was frozen - in open position luckily)
I did a carb. rebuild kit on the 15 hp carb. (It had the old cork type float)
I added an overboard water indicator. (motor is a 75 - they didnt put these on till a few years later)
I did a water pump rebuild kit.
I replaced the very worn manual start rope.
I replaced the old and fouled spark plugs. New plug gaps set to .030.
I noticed the cam roller wasnt hitting the cam arm like the book said it was supposed to so I adjusted the arm.
I used all new gaskets for every old gasket I exposed.
Well after it was all done I got it running on the second pull.
The problem is that after hours of messing with it on two seperate occasions the motor wont run on SLOW. It is idleing nicely at about half way between START and SHIFT. If I turn it to slow it dies.
Ive re-adjusted the cam arm to roller position to every posible combo and now have it back where the book says it should be.
Ive adjusted the LEAN to RICH nob to where it needs to be.
Ive checked the tiller arm to see if the teeth are out of mesh and they arent.
I am definetely running on both cylinders.
Overboard water indicator is working flawlessly indicating impeller is mint.
I did find a chewed up rubber gasket in the water outlet holes before I started all this work that I have no idea where it came from.
I did notice (with a small LED flash light throught the spark plug holes) that there is a lot of carbon build up in the head.
One of my ignition coils has a pretty good size crack from top to bottom.
Although I consider myself mechanically inclined Im not a mechanic and have no experience other than this with two stroke motors. I dont know if I have good compression or what would cause bad compression/how to check it.
Im leaning towards some type of exaust gas leak/and/or compression issue although it ran fine last summer.
Any help would be greatly appreciated - if I dont get some type of answer from this post my plan is to just try it out on the boat this weekend and maybe it will be fine for this summer and I can tear into it as a winter project.
Thanks For reading this really long post.
