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Re: Adjusting Throttle & Transmission Controls [Re: Rob Van Name] #19333
03/10/24 02:05 AM
03/10/24 02:05 AM
Joined: Jul 2004
Posts: 868
New Orleans, LA, USA
David Erwin Offline
David Erwin  Offline
Joined: Jul 2004
Posts: 868
New Orleans, LA, USA
Anyone know what would cause low horsepower when in reverse? Transmission in Forward mode is working well.

I have a Yanmar KM2A transmission,

Found this very nice film online.

Any ideas are welcome.


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Re: Adjusting Throttle & Transmission Controls [Re: Rob Van Name] #19334
03/10/24 08:25 AM
03/10/24 08:25 AM
Joined: May 2007
Posts: 2,669
Portsmouth, RI
Rhapsody #348 Offline
Past J/30 Class President
Rhapsody #348  Offline
Past J/30 Class President
Joined: May 2007
Posts: 2,669
Portsmouth, RI
Dave - it may be the clutch slipping due to glazed cone. See this old post and my old Rhapsody blog post. Hard to believe that was 14 years ago!
[Linked Image]

Re: Adjusting Throttle & Transmission Controls [Re: Rob Van Name] #19356
06/05/24 06:15 PM
06/05/24 06:15 PM
Joined: Oct 2009
Posts: 89
Belmont, MA
Georges Offline
Senior Member
Georges  Offline
Senior Member
Joined: Oct 2009
Posts: 89
Belmont, MA
When I had this issue with footloose:
  • I went through the same steps mentioned by Bill
  • I got this diagram from a mechanic - which really made me understand why you need to rev up initially when switching to reverse to get max torque over those diagonal groove which force the coupling - and then rev down to wherever you need...
  • I still ended up getting a new Martec (my prior one had already been refurbished too many time).

Both helped for 5-10 years or so... but to be fair I am a bit fed up by this inherent folding prop limitation.

I am considering switching to a feathering prop (e.g. https://www.pyiinc.com/max-prop-easy.html)... I saw in the forum that Ananda got one... and yes I read https://www.yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807 :-)
I would like to know if you really loose that significantly when racing... I still love speed...

Attached Files
KM2A-OUTPUT-SHAFT.jpg [86.44 KBytes] - (8 downloads)
Last edited by Georges; 06/05/24 06:17 PM.

-- Georges
Foot Loose #467 - CPYC - Winthrop
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