2 stroke Timing problem

[12bravo]

I have a 1999 Mercury 2 stroke 150 that I just had the power head re-built. After installing I am having trouble checking the timing. I had a mechanic help with the instatalition. We started the motor and put it in the water. The motor started easy and ran fair but because we had not checked the timing, I ask him to do so to make sure it was right. Cover says 4 degrees BTDC for idle and 20 degrees at high speed. When he hooked up his light, we could not see the marks anywhere close the the timing mark on the flywheel cover. They were showing up around 4" to the right of the mark and could not get it to change, they were not even in the opening in the cover. I thought maybe the marks were off for some reason, but when the #1 piston is at TDC the mark shows that. I can not believe that the motor would even run that much out of time. It would start as soon as you hit the key. When he checked the timing, he took all plugs out, used #1 plugs wire but did not ground any of the plug wires. Could this have made a difference? Can anyone help on this. I have invested quite a bit of money in this but hate to run it if it is this bad out of time for fear of damage. Thanks for any replies.

 

[ondarvr]

The reading will be different doing it that way when compared to running it in the water under a load. So check it on the water and see what you get.

​Also the idle timing isn't important, so don't worry about what it is, you just adjust it so it idles correctly.

 

[12bravo]

Thanks for the reply. Do you agree that if it starts very quick, then the timing must be close even though it is showing off? Would not grounding the plugs when checking make a difference?

 

[ondarvr]

Well, it's close enough to run, other than that it's hard to say.

​Grounding the plug wires is a safety measure, and possibly prevents damage to the ignition system, but it won't influence the timing reading.