Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Year 2011 70 2 stroke Yamaha's
Posted by Vamizi Island on 04/11/15 - 12:51 AM
#1
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
Posted by mtown on 04/11/15 - 4:47 AM
#2
Sounds like fuel issue. Are both motors on same tank, filter, supply line.
Posted by Vamizi Island on 04/12/15 - 12:28 AM
#3
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
Posted by wing15601 on 04/12/15 - 6:47 AM
#4
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
Posted by Vamizi Island on 04/12/15 - 7:05 AM
#5
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
Posted by Binkie on 04/21/15 - 10:05 AM
#6
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
Posted by Binkie on 04/21/15 - 10:09 AM
#7
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.
Posted by Finnegan on 04/21/15 - 11:19 AM
#8
Yamaha modle year 2011 2-strokes couild not be sold in this country. Where did you get them?
Posted by mtown on 04/21/15 - 2:11 PM
#9
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.