DOEL FIN Stabilizers

jbett98 · Feb 8, 2016

I have a Honda 7.5 outboard on my 14' aluminum boat.
I use an older 9.9 Game Fisher 2 stroke for salt water crabbing and the 7.5 Honda 4 stoke for Willamette River Springer fishing.
There is a noticeable difference between the two outboards when trying to get the boat up to plane and I was thinking of adding a pair of those Doel Fin stabilizers to compensate for the lesser hp Honda outboard.
The Honda is great when trolling. Quiet and vibration free, it's just that the run up river from the Basin Ave dock seems to take forever.
Anybody use these plastic trim fins on smaller hp motors?

Mikej · Feb 9, 2016

I had a pair of those, coincidentally, on a Honda 7.5. They served the purpose well, well until I hit some little piece of wood and broke one of the cavitation plates off.

YMMV

jbett98 · Feb 9, 2016

Thanks for the info.
I didn't think about the downfalls of bolting one on to those thin aluminum fins.

Mikej · Feb 9, 2016

Maybe look at some of the 1-piece models?
http://www.boatersland.com/thmhyd1d...UgYaIcmiTdRYmYU87siB4R6IDC9-QABjYBxoCXgTw_wcB

Heck, for that kind of money, (not much) as long as it fit the lower end properly you could always grind on it, (customize?) to make it just right.

jbett98 · Feb 9, 2016

There is a boat junk yard near me and I stopped by to see if they had any Doel Fin's laying around. They had buckets of them.
I found a really nice set with ss bolts for only $15.00.
The owner also told me how to increase the horse power a bit, so I'm now looking for an outboard motor rpm gauge.
Cheapest I've found is $8.99 on eBay.

Mikej · Feb 10, 2016

You've got that throttle limiter screw on there don't you? I had that on my 9.9. It came right off after I bought it and gave me closer to 15hp. I never worried about over revving. Being I was in the biz of wrenching on Honda motor cycles for a good bit I just trusted my ear.

If that's the case I'm not sure why Honda would have a limiter on a 7.5? I know they had it on the 9.9 because they had to keep the HP under 10 for the feds, state where ever under 10 was a requirement. Honda 10hp and 15hp were the same engine, 10 with the limiter, and maybe a smaller carb.

jbett98 · Feb 10, 2016

No limiter on the 7.5. The guy at the boat junk yard told me that I could increase rpm's by enlarging the primary carb jet.
The motor performs perfectly at trolling speeds and I'm reluctant to mess with it.

Mikej · Feb 10, 2016

jbett98 said:
No limiter on the 7.5. The guy at the boat junk yard told me that I could increase rpm's by enlarging the primary carb jet.
The motor performs perfectly at trolling speeds and I'm reluctant to mess with it.

??
Eh. If it runs good, enlarging the main jet won't make it run better. If you really wanted to know, get the thing warm then run it like you stole for a minute or three, shut 'er down and pull the plugs. If they've got a light tan color you don't want to do anything, that's the perfect color after a hot run. If they're white-white then a richening would be in order. You'd do that with fresh plugs because the ones you have in it would most likely be dark all ready from all the trolling. There's most likely an idle jet and a high speed jet, so changing one a bit wouldn't affect the other. Besides you probably have a low speed mixture screw also.

I wrenched on cycles in Utah. All the Hondas we sold came in jetted for sea lever so proper jetting for the 4300 altitude was something we did a LOT of. Fascinating work, figuring low, mid and high range lean/rich mixture jetting, using plug color, sound ,smell, performance. We didn't have no fancy exhaust analyzers or dynos!