Thread Tools Search this Thread Display Modes
Old 05-23-2016, 10:03 AM   #1
Moderator Emeritus
dwhatty's Avatar
City: Home Port: Buck's Harbor, Maine
Vessel Name: "Emily Anne"
Vessel Model: 2001 Island Gypsy 32 Europa (Hull #146)
Join Date: Sep 2008
Posts: 2,845
Four stroke single cylinder outboards

Just bought a used Yamaha 4 stroke, single cyl outboard and a used Avon 9' RIB with the idea that this package would be less weight, easier to haul and shorter on our stern davits for our canal trip this year. (Our usual dinghy is an 11' 4" Achilles with a 15hp Yamaha 2 stroke 2 cyl that we customarily tow).

Had the local Yamaha dealer service it and check it over before we launched and he said all was in good condition.

I thought that 4 strokes were supposed to be quieter and have less vibration than 2 strokes, but boy this little motor is loud and vibrates to beat the band.

Is this usual for these little motors?

David Hawkins
Deer Isle, Maine
dwhatty is offline   Reply With Quote
Old 05-23-2016, 10:53 AM   #2
Mule's Avatar
City: Fort Pierce
Vessel Name: Florita Ann
Vessel Model: 1982 Present
Join Date: May 2014
Posts: 1,935
The single cylinder is the reason.

Mule is offline   Reply With Quote
Old 05-23-2016, 11:16 AM   #3
Senior Member
tallswede's Avatar
City: Baytown, Texas
Vessel Name: Islander
Vessel Model: Prairie 36
Join Date: May 2013
Posts: 287
Yes, those little single cylinder 4 stroke engines do vibrate a lot.

tallswede is offline   Reply With Quote
Old 05-23-2016, 11:47 AM   #4
Technical Guru
Ski in NC's Avatar
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,183
Four stroke single fires every other turn, or every 720deg of crank rotation. Two stroke twin fires twice per rev, or every 180deg of rotation. Huge difference. Four little hits compared to one big one. Small four stroke OB's are one of my favorite things to gripe about. Infernal beasts...

I would not want a four stroke with less than three cyl. Threes can be quite social, but not to be for a little dink.
Ski in NC is offline   Reply With Quote
Old 05-23-2016, 12:00 PM   #5
kchace's Avatar
City: Brookline, NH
Vessel Name: Blue Heaven
Vessel Model: Albin 43 classic double cabin, twin 135 Lehmans
Join Date: Sep 2013
Posts: 2,054
Until this year I had a 5hp Honda (one cylinder) on our dink and hated it. Don't get me wrong, it always RAN, but it was loud, hard to pull and vibrated like crazy.

Bought a 9.8 2 cylinder and its like going from a Hugo to a Cadillac. Actually, it was probably better than that. Did I say I hated the Honda?

kchace is offline   Reply With Quote
Old 05-23-2016, 12:54 PM   #6
Tad Roberts's Avatar
City: Flattop Islands
Vessel Name: Blackfish
Vessel Model: custom
Join Date: Dec 2012
Posts: 712
For some reason unknown to me, the small Yamaha 4-strokes have often impressed me as being extra noisy. I can always tell when one goes across the bay as they are so loud. Yet the big Yamaha's are wonderfully quiet. I too hated our little Honda, it always ran, but never properly and it was always hard starting. The best was a Mercury badged Nissan, smooth and quiet, easy starting, I wore it out. Now we have a Tohatsu 6hp, not really quiet but acceptable, hard starting when cold, perfect starting when warm.
Tad Roberts is offline   Reply With Quote
Old 05-23-2016, 02:21 PM   #7
Nomad Willy's Avatar
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,115
I've always disliked the four stroke twins and singles.

Had two of the old two cylinder two stroke OMC's "Light Twin" two cylinder engines. Water cooled w angled prop shaft lower unit. Very weedless props too but they seem to push boats fine.
The first two Evinrude's I had were too salted and would overheat. But I just bought a 4hp Light Twin (same engine w bigger carb I'm told) and it seems fine but I haven't ran a boat w it yet. Was pleased to get ot for $225. This one is a Johnson .. the others were Evinrude's.
Very light, smooth and quiet if not run near full throttle.
I think they are rebuildable and probably economically w the possible exception of the crankcase seal in the middle of the crankshaft. That's a weak link on all two stroke twins but rarely goes bad.
I think they are 33lbs. Many of these engines had folding lower units. They folded sideways so the prop ended up close to and perhaps a bit under the powerhead. In the day they came w an optional folding FG box that was much like a suitcase. Those are hard to find now though.

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 05-24-2016, 05:18 AM   #8
FF's Avatar
Join Date: Oct 2007
Posts: 21,948
As small one lung outboard does not make much thrust.

For no noise a simple DC trolling motor will have near the same thrust ,

and is never a problem with old fuel or starting for guests.
FF is offline   Reply With Quote
Old 05-24-2016, 05:37 AM   #9
Join Date: Jun 2014
Posts: 1,274
The bigger issue with small displacement 4 stroke outboards is their sensitivity to ethanol fuel issues...
The jets in the carburetor of typical small 4 stroke engine are so tiny that any exposure to water will cause then to hiccup when running ethanol fuel. Ever find that you have to fill up with fuel on a rainy day? Our last Yamaha 2.5 would always have difficulty after filling even on a damp day!
Then if you leave fuel in the carb for any length of time...its disassembly time to make it run.

I got so disgusted with the reality of the ethanol/small engine performance issues that I finally went out and found a like new 3 hp Yamaha 2 stroke that was 14 years old! I paid too much, brought it home and changed the impeller, fuel line and spark plug. Now we have a motor that always starts in a pull or two every time, ethanol or no ethanol! It sure does burn fuel though!
Bruce B is offline   Reply With Quote
Old 05-24-2016, 05:54 AM   #10
City: Sydney
Join Date: Jul 2015
Posts: 1,646
I love my Suzuki 2.5hp its quite little vibration and the lightest available starts second pull every time
gaston is offline   Reply With Quote
Old 05-24-2016, 06:00 AM   #11
O C Diver's Avatar
City: Fort Myers, FL... Summers in Crisfield, MD
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 10,122
Have a Lehr 9.9 with electric start. Easy to start, seems to be reasonably quite, and the fuel doesn't go bad. Have a 1986 Mercury 6 two stroke with electric start that still runs great and is a little noisier.

Both only require one push of the button to start.

Did I mention they were electric start.


I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
O C Diver is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program

All times are GMT -5. The time now is 07:04 PM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012