Reply
 
Thread Tools Search this Thread
 
Old 27 May 2007, 06:12   #1
Member
 
Country: UK - England
Town: Liverpool
Make: Humber
Length: 5m +
Engine: Mariner 60 4/s
Join Date: Aug 2006
Posts: 18
strange topping out

my club rib is a 5.3m aircraft rib with a a 4 year old yamaha 50 2/stroke.
it tops out at about 4,300 revs at WOT but then backs down quite quickly to 3,900 then creeps up again to 4,300, this continues unless you cut the throttle back a bit.
The out of the hole performance is good but the top speed is quite poor.
I would have thought it was overpropped heavily but due to the way the engine 'hits a wall and backs off' i'm wondering if there is a porblem,
but when we first got the rib it was great and did 5,600 WOT.

It's been holding back as it has done for most of it's lifetime, just wondering if there is an easy fix?
__________________

__________________
Jack h is offline   Reply With Quote
Old 27 May 2007, 06:22   #2
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,855
If hole shot is good then it's not the prop as a good holeshot will mean higher revs. Sounds like a problem with the over rev limiter. That'll drop your revs quickly to a "safe" level.
__________________

__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 27 May 2007, 06:40   #3
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,112
Fuel supply problem? Perhaps blocked filter or carbs? Or even tank breather...
__________________
Poly is offline   Reply With Quote
Old 29 May 2007, 04:48   #4
Member
 
Country: UK - England
Town: Liverpool
Make: Humber
Length: 5m +
Engine: Mariner 60 4/s
Join Date: Aug 2006
Posts: 18
thanks for the help sp far, the first answer sounds more likely, anyone else got an idea?
__________________
Jack h is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 22:23.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.