Mercury 75 engine running. Opinions / advice wanted.

BenbowJ

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Aug 26, 2013
Messages
5

Hi. I am hopeing that someone with knowlege of these engines can tell me if this engine sounds like it's running OK. It's not a great Video but hopefully someone with a good ear may be able to comment.
I bought it in unknown condition and, whilst it did run on collection, it wasn't entirely happy about it. I have replaced the carb linkage, cleaned the carbs, compression check and did a link & synch. As a result it is running a lot cleaner and is a lot easier to start. I have yet to put in the water to test it yet.
I don't have a lot of experience with 2 stroke triples but I do know that they sound a little lumpy on tickover. To me it seems to pick up the revs quite well and pumps water well.
Any feedback and advice would be appreciated.

Thanks in advance
John
 
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hsi111

Seaman
Joined
Jul 25, 2013
Messages
51
Re: Mercury 75 engine running. Opinions / advice wanted.

We'll, I am no mechanic so take this with a grain of salt but it sounds a little rough to me especially when you give it gas. I take it you have not put it in the water? I am anxious to see what the mechanics think. Rick
 

BenbowJ

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Aug 26, 2013
Messages
5
Re: Mercury 75 engine running. Opinions / advice wanted.

Thanks Rick.
Whilst it's a massive improvement from when I first fired it up. I did have to re set the timing although I had to use a vernier as I don't have a dial guage. Was awkward to do on my own. Next step is to put it on the water. I'm keen to know what the experts think aswell.
John
 

oldman570

Lieutenant Commander
Joined
Mar 25, 2011
Messages
1,615
Re: Mercury 75 engine running. Opinions / advice wanted.

To get a better idea as to the running of the motor, you need to place the motor in a barrel of water with the water at least 5 inches over the cavitation plate so the motor has backpressure on the exhaust. Doing this will change the running of the motor and you will find that the idle will be somewhat lower. I believe that the motor RPM should be 650-750 in FWD gear at idle and the WOT should be 4750-5250RPM. Running the motor on muffs should never be reved more than 1500 RPM. The freewheeling of the motor on muffs will cause the motor to sound as though something is wrong. JMO
Oldman570
 

BenbowJ

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Joined
Aug 26, 2013
Messages
5
Re: Mercury 75 engine running. Opinions / advice wanted.

Thanks Oldman
Ideally I would have set it up in the water, but I am unable to launch at the moment. I may get it launched next week though. To be honest I was surprised it started so easily, even though it was on muffs. The yard where its at doesn't have a tank big enough for this motor.
I guess I posted this because I was hoping that someone with a trained ear my be able to identify any issues.
As I said before I bought this cheap in unknown condition so I am perhaps being a little cautious. I don't want to throw money at a lost cause. I'm pretty sure that with a proper tuneup it will probably be a good engine. I will post another video when I'm able to get it in the water.
Thanks again
John
 
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