61 Fastwin 18hp fuel consumption

[bwkre]

I have a 18hp Fastwin that I replaced the coils, condensers and points in. I took it for a run today on a 14' aluminum wide / shallow boat. With 2 occupants, trolling motor and battery it seems a rough calculation showed about 7.1 mi/gal ( imp) or 2.5 km/l . Does this sound reasonable or do I need to do a more precise calculation? I basically ran at wot up and down the river to test the motor. I was the first time I put it in the water since I purchased it. I have not had a chance to pull the plugs and look at them as it was getting dark. Any & all input appreciated.

 

[Daviet]

Re: 61 Fastwin 18hp fuel consumption

Older outboards are not very fuel effient, there is no specs on fuel burn that I know of. The old rule of thumb is 10% of the horsepower (1.8) gallon per hour at WOT. I have seen that work out as true, and I have seen it not anywhere near correct.

 

[bwkre]

Re: 61 Fastwin 18hp fuel consumption

Thanks Daviet, there is a high speed knob on the front but I did not adjust it. Need to find out how to adjust it first. I imagine it is a lean / rich control.

 

[Daviet]

Re: 61 Fastwin 18hp fuel consumption

Yes it is, at high speed turn it in until the slows slightly, then open it up until you achieve maximum RPM, turn in small increments, 1/8 of a turn and give the engine a 5-10 seconds to respond. After you get it set just right, open it up another 1/8 turn. Sometimes you have to play with it a little to get it just right.

 

[bwkre]

Re: 61 Fastwin 18hp fuel consumption

Thanks again. I have no idea where it is set but hope to get out Saturday for a longer run. So far I love this motor, a big step from the 74 9.9 hp. Unfortunately I'll be switching back & forth as my favorite spot has a max 10 hp restriction.

 

[kfa4303]

Re: 61 Fastwin 18hp fuel consumption

Hi bwkre. I have a '66 20 hp on my 14' semi-v hull tinny which is virtually identical to your motor and I can run around all day, from idle to WOT on about 3-4 gallons. Of course, if you have a larger load, or are battling wind, tide, or both then it can change quite a bit. There are lots of variables that can influence your performance, everything from motor height, the motor's trim/tilt to the weight distribution inside the hull. I can get about +/- 20 mph and she hops right up on plane. However, I do have my motor on a transom riser and I also use a tiller extender and grab bar which allow me to sit/stand amidship while underway. They've all made a huge improvement over my old set up where I sat on the rear bench and used the stock tiller. Here are some handy links to help keep your motor running another 50 years.

http://www.leeroysramblings.com/johnson_E-FD_15_18hp.html
http://www.marineengine.com/parts/v...evinrude-johnson/ITEM_2514/ITEM_251400001.htm
http://www.duckworksmagazine.com/06/columns/max/index6.htm
http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm
http://www.outboard-boat-motor-repa...hnson 5.5 HP 1954-1964 Carburetor Tune-UP.htm

 

[steelespike]

Re: 61 Fastwin 18hp fuel consumption

Yes it is, at high speed turn it in until the slows slightly, then open it up until you achieve maximum RPM, turn in small increments, 1/8 of a turn and give the engine a 5-10 seconds to respond. After you get it set just right, open it up another 1/8 turn. Sometimes you have to play with it a little to get it just right.

When adjusting the high speed end up just slightly on the rich side not enough to change the performance just enough to be sure of enough fuel to lube properly.

 

[kfa4303]

Re: 61 Fastwin 18hp fuel consumption

This may help too.

http://forums.iboats.com/showthread.php?t=167352

 

[Chinewalker]

Re: 61 Fastwin 18hp fuel consumption

I think most folks here on iboats would LOVE to get 7 mpg in their boat!

 

[bwkre]

Re: 61 Fastwin 18hp fuel consumption

I think most folks here on iboats would LOVE to get 7 mpg in their boat!

Really, shows you what I know about old motors. I thought 7 mpg sucked!
Thanks for all the input. I never got a chance to get out today to fine tune with the high speed adjustment. Maybe next week.

 

[bwkre]

Re: 61 Fastwin 18hp fuel consumption

I was finally able to get the 18hp back in the water on the weekend, and do some fishin. Motor good, fishin bad. I adjusted the high speed jet/knob as suggested, same load, same boat and we topped out at 31.4 km/hr or 20 mph. It ran great. Thanks for all the help & suggestions. Hopefully I can return the favours here some day.

 

[Daviet]

Re: 61 Fastwin 18hp fuel consumption

Glad you got it figured out, now go have some fun.