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S&S Swan General - Limited RPM...
25 May 2019 - 01:28
Join Date: 11 March 2007
Posts: 11

Limited RPM...

Hello Don Chisholm here from Zeevogel hull #49.


Question for the Professor...I've got a bit of a mystery with regards to my max RPM on my engine. 

Three seasons ago I bought a new MaxProp Easy 18" and the spec'd a 11" pitch adjustment. I have a Perkin's 4-108 with a Velvet Drive transmission at 2:1 ratio. When installed it worked crusinig RPM has been between 2200-2400RPM  at crusiing speed of 6.5 up to 7 in calm/no-wind conditions. I can run up to 2800/2900RPM if required however Perkins told me that 2200-2400RPM is the best. 

This season (Febuary I started) - I hired a mechanic to replace new injectors, adjust the fuel injector because I was getting white smoke on start up and when running, replaced the lift pump, new glow plug and adjusted the values...changed oil etc 

The smoke issue is gone and the engine is running nicely HOWEVER I'm not able to get more then 2300RPM - the trottle is pinned and its at 2300? The mechanic and I did a sea trail today and he's a bit stumped. He's saying my prop needs to be completely clean (I'm diving on her tomorrow to do so) however I just had a new bottom done and launched last spring and the 3 year old prop was cleaned, greased and anit-fouled at the same time...the prop doesn't look that bad from the waters edge.

Long background story...if it's not the you think the injectors (newly rebuilt) could be the issue? When in nuetral we get 3000RPM easy out of the engine.

I guess I needed to buy a new engine last year vs spending $40K on my bottom and other top deck items....


25 May 2019 - 19:31
Join Date: 02 January 2008
Posts: 1547

Dear Don
Suggest you check the following to start with:
-Throttle cable free to turn injection pump lever to maximum position
-Stop solenoid not set too tight so it restricts pump lever
-In neutral the engine should reach 3380 rpm
Kind regards

26 May 2019 - 07:09
Join Date: 02 February 2007
Posts: 202

Do not forget also to check the engine air filter !

Philippe 41/022


26 May 2019 - 15:32
Join Date: 30 January 2007
Posts: 461

Do not forget also to check the engine air filter !

Philippe 41/022


...and the fuel filter as well.  In particular the one with paper filter.

Daniel, Luna Menguante 411/004

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