Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Twin Yamaha 250's out of sync
Posted by Josey Whaler on 06/25/08 - 5:06 PM
#1
I have twin Yamaha 250 OX66 EFI's. I recently switched out props from 23P SWS II's to some 22P Bravo I's. The engines both run fine, but are now out of sync about 300 RPM's-Port motor is lagging. No outward signs of poor performance, just lagging behind the starboard motor 300 RPM or so. I plan to switch back to the SWS props to see if the proplem may lie with the props (perhaps the pitch's are not identical-they were not bought new) but thought I would ask if there are other likley culprits. Had a similar problem at the start of the season with the starboard motor, but that was determined to be a bad plug leftover from last year.
Posted by John Fyke on 06/25/08 - 5:58 PM
#2
Switching back will definitely help you, the pitch might have to be tweaked on one or both of them. Are you running counter rotation?
Edited by John Fyke on 06/25/08 - 6:01 PM
Posted by ioptfm on 06/25/08 - 6:40 PM
#3
Without a doubt, the pitch has got to be the same or they will remain out of sync
Posted by Josey Whaler on 06/25/08 - 6:53 PM
#4
Yes, they are counter-rotation. I think before I look elsewhere, I will switch back to see if they sync-up and have my prop guy check the pitch on the Bravo I's. Too coincidental that the sync issue started about the same time as the prop switch. If not, I'll be back with another post.
JW
Edited by Josey Whaler on 12/08/09 - 2:00 PM
Posted by Tom W Clark on 06/25/08 - 8:53 PM
#5
This happens all the time. It has happened to me with a pair of new Rev4s.
Most folks do not realize how much variation there can be in even brand new propellers.
Have the props checked out and adjusted if necessarly.
Posted by Binkie on 06/26/08 - 1:27 PM
#6
If both motors weren`t trimmed the same, wouldn`t that also make a difference? Its been a long time since I had twins, but I used to even up the RPMs with the trim, but they were never off by much anyway, as I can remember.
rich
Posted by Josey Whaler on 07/06/08 - 6:15 AM
#7
Switched back to my 23P Yamaha Saltwater Series Props over the weekend and problem solved. The 22P Bravo I's did not preform well at all. They were 2-7 MPH slower than my SWS props all through the RPM range (2 MPH @ 3,500, 7 MPH @ WOT). Also lost about 300 RPM @ WOT-a bit strange because the pitch on the Bravo I's was 22 vs 23 on SWS. I think the Bravo I's would preform better on a hull designed primarily for speed (i.e. less weight and more aerodynamic). Gonna try some Mirage Plus and Rev 4's next.