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Year 2011 70 2 stroke Yamaha's
Vamizi Island	#1  Posted on 04/11/15 - 12:51 AM
Member Posts: 3 Comments: 0 Joined: 04/11/15	Hi I have a 21 foot cat hull with 2x 70 2 strokes and I am battling to get more than 2200rpm at WOT where should I start looking ? Thanks Stephen
mtown	#2  Posted on 04/11/15 - 4:47 AM
Member Personal Page Posts: 613 Comments: 5 Joined: 07/06/08	Sounds like fuel issue. Are both motors on same tank, filter, supply line.
Vamizi Island	#3  Posted on 04/12/15 - 12:28 AM
Member Posts: 3 Comments: 0 Joined: 04/11/15	Hi each motor has its own tank which goes through a water separator Have taken the carbs off and clean throughly I have 13 1/4 x 17 -k props aluminuim 3 blade regards Stephen
wing15601	#4  Posted on 04/12/15 - 6:47 AM
Member Posts: 699 Comments: 0 Joined: 07/14/12	Is this a problem that's always been there or a first ride of the year problem? What kind of props do you have on them? If it's both engines then it's something in common with them both. Have you checked that the throttle linkage actually opens the throttle all the way on the engines? Edited by wing15601 on 04/12/15 - 6:50 AM I winter in Ft. Myers and summer in St. Joseph, Michigan. It’s now about 12 years since I’ve joined this group. I gave my 1972 whaler to my daughter and sold the 17’. Bought an O’Day 28 sailboat and sailed on Lake Michigan. Yesterday I bought a 2005 130 Sport.
Vamizi Island	#5  Posted on 04/12/15 - 7:05 AM
Member Posts: 3 Comments: 0 Joined: 04/11/15	Thanks will check that the boat is always in the water we opperate a dive centre on an island in Northern Mozambique somto answer your question no its not the first time using the boat for a long time but since I have been here this has been the case the motors only have 250 hours on them Please keep sending me idea's Thanks Stephen
Binkie	#6  Posted on 04/21/15 - 10:05 AM
Member Personal Page Posts: 2012 Comments: 0 Joined: 12/19/05	If you have a non planning displacement hull cat boat you need props with less pitch. I would try 13 or 14 pitch top start with. rich Rich
Binkie	#7  Posted on 04/21/15 - 10:09 AM
Member Personal Page Posts: 2012 Comments: 0 Joined: 12/19/05	Woops, didn't read your post. You are already using props like that. Maybe 4 blades would help. Is the bottom of the boat full of marine growth. Rich
Finnegan	#8  Posted on 04/21/15 - 11:19 AM
Member Posts: 1926 Comments: 16 Joined: 05/02/08	Yamaha modle year 2011 2-strokes couild not be sold in this country. Where did you get them?
mtown	#9  Posted on 04/21/15 - 2:11 PM
Member Personal Page Posts: 613 Comments: 5 Joined: 07/06/08	Try a remote tank for one motor with fresh gas and no filter or separator in line. Is the motor able to make proper RPM with less load? If you tie to fixed pier ect. is the motor under load able to exceed the 2200? If so I would guess it is bottom growth or a prop problem. The cheapest and simple way to eliminate prop and other complicated fixes or problems is to first make sure of two things fuel and spark. Speaking of which, what plug are you using? From memory B8HS-10 is what I used for 1985 and 2007 2-stroke Yamaha 70 Hp motors I owned.