Mercury 200 HP Compression

[Duke01]

Launched my V20 cuddy today on Lake Erie which gave me a chance to check compression on my 1980 Mercury 200 HP. She is hard to start, but runs well. 1570 hours. Compression is as follows: 130, 135, 120, 125, 125, 115. I tested hot. My understand is that the overall range should be within 10%. I am close to 15%. Any thoughts regarding these numbers?

Thanks, Duke

[phatdaddy]

Actually for a 40 year old motor, that s not too bad. If it runs ok, I d just run it. When u checked compression, did you have the other 5 plugs out and the throttles open?

As far as hard cold starts, does that motor have a choke or an fuel enricher system? Could be something not working in that.

[Duke01]

All plugs were removed, but the throttle was not wide open.

The only choke that I am aware of is with the key, push in as you turn the key to crank the engine.

Carbs were all cleaned good last year.

As you say Phat, my plan is to run it this year and forget about it. She never stalls, just needs a little starter fluid and off to the races. I have a new Tohatsu 9.8 for insurance and trolling.

The other starting issue is that the starter only engages the flywheel about 50% of the time. Not sure to do about that.

[phatdaddy]

When u press the key in to start, it actually spritzes s little gas in the throat of the carbs not sure if all three or just middle one. It s not a choke butterfly in the normal sense of the word. I would verify that all of that system is working.

I had a 84 & 94 carbed merc 150, they were both a little finicky when cold. What i would do is pump ball till hard, turn key on and press in 3 times, advance throttle lever about 1/3 up and then spin starter. After they were warm, just bump the key.

I d be careful with the starting fluid, usually not a friend of 2 strokes.

Maybe some of the really smart guys will come along and chime in

[spareparts]

hit the cylinders with a can of power tune decarb spray. Let it set over night, cranks it up, blow all the power tune out and recheck your numbers. If the carbs are set up correctly, it should start from cold by just holding the key in while spinning the motor over, once it hits, it will stall, then try to restart, momentarily holding the key switch in, it will start, but try to die out, when it stumbles, bump the key switch in for a sec, it should pick right back up, after about 30 secs it should idle on its own. Let it warm up a bit before putting it under load

[Duke01]

Thanks for the tips regarding the starting sequence. I will try what you have both described. I don't think that I have used a consistent approach regarding pushing the key in while cranking thus far.

I was not aware of Quicksilver Power Tune. Just placed an order.

Thanks again, Duke