Low compression in bottom cylinder

[Pete]

Maybe the top is bit too high and the bottom a little low from carbon? Run the engine with the cleaner suggested and retest. Did you do the test cold with throttle full open? I do them cold that way so temp is about the same for test and not influencing results. Relative consistent results matter a lot and conditions should be consistent from test to test. Take a peek in the spark plug holes with a flash light and at least observe the top of the pistons and see if there is a lot of carbon rotate crank to put piston at bottom of stroke for a better view.

What oil are you using? If Mercury Premium Plus it has a lot of Moly Di sulfide and is a dirty oil with lots of build up, especially if you go slow a lot. I use to use it and had to add Mercury Quickleen #2 each fill up to the fuel to keep the carbon down. BTW 40:1 is not that rich since 50:1 is the usual mix.

https://www.mercurymarine.com/en/us/par … -products/

Although I have never used it the Mercury Powertune looks like a good start. Why don’t they list it on the Mercury Marine site?

Are you using E free fuel? You should be.

[shane-r13]

quote zul8tr:

Maybe the top is bit too high and the bottom a little low from carbon? Run the engine with the cleaner suggested and retest. Did you do the test cold with throttle full open? I do them cold that way so temp is about the same for test and not influencing results. Relative consistent results matter a lot and conditions should be consistent from test to test. Take a peek in the spark plug holes with a flash light and at least observe the top of the pistons and see if there is a lot of carbon rotate crank to put piston at bottom of stroke for a better view.

What oil are you using? If Mercury Premium Plus it has a lot of Moly Di sulfide and is a dirty oil with lots of build up, especially if you go slow a lot. I use to use it and had to add Mercury Quickleen #2 each fill up to the fuel to keep the carbon down. BTW 40:1 is not that rich since 50:1 is the usual mix.

https://www.mercurymarine.com/en/us/par … -products/

Although I have never used it the Mercury Powertune looks like a good start. Why don’t they list it on the Mercury Marine site?

Are you using E free fuel? You should be.

Top compression to high? Is that such a thing? I’m hoping its carbon. I ordered some cleaner and am waiting for it to arrive.
To perform the test it was cold, wide open throttle. I literally pulled it from storage put it in a barrel and tested it. I think maybe thats where it went wrong, maybe carbon or stuck ring etc, form sitting and since i didn’t run it to MAYBE free it up. Anyways i’ll run the cleaner through it when i can and report back what happens.
As for oil, I usually use just a shell brand outboard oil or mystic outboard synthetic. Honestly i’m not highly picky on oil, while i should likely be, as with the little use the motors get a year. And for gas, I have never found a reliable source that is E free in my area. I think i can buy it in 104 Octance at the race track and its E free haha. Seems like no matter the company or grade its there. A little birdy once said you basically cant get it E free in Canada but who knows.

[outbdnut2]

quote Shane.R13:

A little birdy once said you basically cant get it E free in Canada but who knows.

Hmmmm….maybe I can make a few bucks smuggeling ethanol-free gas into Canada from Minnesota!

On a more serious note, ethanol-free gas does exist in Canada. Every year I go with friends and rent a houseboat for a week on Lake of the Woods, out of Sioux Narrows, Ontario, and the houseboat business owner is very picky about fuel used and wants nobody dumping fuel brought across the border into the houseboats – he said he uses nothing but ethanol-free. Maybe you can get it if delivered by the truckload to a bulk tank like he does.
He will sell it to us if we need for the fishing boats we bring, even has a hand pump for pumping out of the houseboat tank if we need outboard gas during the week. We have towed up to 7 boats in two strings off the back of a 58 foot houseboat.
Dave

[crosbyman]

I think most high octane car fuel is ethanol free…see it all the time at stations in upper NY state (Massena) Samein Canada

Joining AOMCI has priviledges 🙂

[outbdnut2]

In Minnesota, the only reason we can get ethanol-free gas is because the Minn Street Rod Assn lobbied the state legislature to have ethanol free premium available, by showing the economic impact of the custom car/rod hobby (they have over 15,000 members) and told the legislature most of their cars can’t use ethanol. You have to seek out stations that have ethanol-free premium, but there are more all the time as more and more people want it for old cars, boats and small engines. A few years ago I had to drive 30 miles to get it, now I have 5 stations within 15 miles, which is about 20% of the stations.

OK – I guess if we want to continue this discussion, we should start a new post, as we have kind of hijacked the low compression on one cyl post – Sorry!

Dave

[Steve A W]

Puregas will list Efree gas stations.
https://www.pure-gas.org/

Member of the MOB chapter.
I live in Northwest Indiana

[shane-r13]

quote Steve A W:

Puregas will list Efree gas stations.
https://www.pure-gas.org/

Thanks for the site. I checked it out. 2 stations in my town sell premium ethanol free. I live on the US border and 2 stations over there have ethanol free too. I usually buy gas in the states. Its way cheaper than Canada.

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