I recently purchased a 45 mag on an excel 1860 f86 with 11 hours on boat and motor. I took it out for the first time yesterday and at times even after the motor had ran for a while it bogged down when I lowered prop into water and died a few times. Prior to this I changed spark plugs, oil, and oil filter because it had set for a few years per the previous owner. I even almost got stuck in 4 inches of water and mud which from what I have heard should not be a problem. Motor pegged was over 4000 rpms and the exhaust was hot on both sides so I assume bother cylinders are working fine. Any ideas on what is the problem? This is my first mud motor and I am not a mechanic by no means. There are no dealers in Indiana or at least close to South Central Indiana as far as I know. Any advice would be appreciated. There is a briggs dealer close. Do you think they would be able to diagnose the problem?

Did you drain the old fuel and put fresh fuel in the tank? What type of fuel line do you have?
Id replace the fuel line also.
A motor, and gas sitting for that long is not a good thing.

Sounds like you're running some bad gas through there. Does that motor have a mikuni on it?
I would also imagine you may have a little gunk in the carb. Could be a collapsed fuel line also.
Lots of different things.


Also, that is a big boat you have it on.
You say you almost got stuck, were you on hard bottom?

Does this just happen at idle when you trim down to get going. Stock carb?

I failed to mention the prior owner used this boat with another outboard so the fuel didn't sit as long as the motor. When I took possession of the boat and motor I added sea foam and topped off the tank with about 9 gallons of high octane gas station fuel. It runs fine out of water and idles well from what I can tell. I do not know what exhaust it has, I assume the stock 45 mag exhaust. I also assume stock carb for a 45 mag. When I got stuck I trimmed the motor into the mud and had to work the tiller back and forth for what seemed like 20 minutes and inch after inch I finally got it into deep enough water for the boat to float. I do not know if one would say it was hard bottom or not but I was able to trim down into the mud. The boat did have 2-250lb guys, full tank of fuel, trolling motor, 4 batteries, poles with lite tackle, and it does have a rear drop deck. I also believe the weight was distributed evenly.

45 mag was rods, pistons, cam, stock heads, stock carb, and some type of performance exhaust. If its not bad fuel or fuel line or dirty carb, I would do a leakdown test. The 45 mags were very stout, I had one and it was mean on a big boat.

What will it rev out of the water? Mags should rev well past 4k.

Out of water rpms are 4400 full throttle, 1140-1180 idle out of water. Does this seem right for a 45 mag? Thanks for all the help. I also found a certified briggs dealer that will look at the carb and also check the valves. Any other ideas on what he should look at it? Anything he should need to know since this is not a stock engine?

I did just replace the in-line fuel filter as well and do not know what the rpms were be for that. I guess I should have checked. Is there a rev. Limiter on this model to make sure the rpms do not go to high?

Does the 45mag charge the battery while it's running? Was wanting to know if the accessories would draw it down? The only thing hooked up to the motor is front light, navigation lights, and bilge. My 24 volt trolling motor is hooked up to its own batteries in the front that I charge with a 2 bank charger of course.

45 mag with 4 in a 1751 runs 4200 or so. Best in water rpms I saw was 4500 or so, with 1 or 2 in the boat.

The brings dealer will be checking the valves and cleaning the carb so hopefully this will result in higher rpms. What should they be at?

Pretty sure out of water it was governed around 4650. Don't quote me on that.

Thanks for all the help. I have made an appointment with the brings dealer and they will be able to look at it in a couple weeks. On another note how fast should an F86 1860 with 45 mag and 700lbs of guys and gear run?

Should be an easy 25-26 or so.

OK, thanks for the help. I will check the GPS next time I am on the water but I do not think I am getting close to that. Maybe around 20.

I gave the briggs dealer what the valves should be set at per Glade with MB. The briggs mechanic said they were way out and couldn't believe that they were that far out. He adjusted them to specs and said it should run like a top. I will be taking it out this weekend to see how wot runs. Thanks again for all your guys' help.

How'd she run?