Reply
 
Thread Tools Search this Thread
 
Old 02 May 2008, 17:55   #1
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
RIBase
Possible to convert 40HP to 50HP?

Hi

Is it possible to convert a 3 cylinder 2-stroke Yamaha 40hp Autolube (model 6H4 40V 1995) to a 50hp just by switching to a set of 50hp carbs?

Seems too simple to be true. I would have thought the CDI ignition would need to be changed regards sparks and what about autolube ratio?

Any thoughts?
__________________

__________________
spartacus is offline   Reply With Quote
Old 02 May 2008, 22:57   #2
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: WhiteNoise/Dominator
Make: Ballistic 7.8/SR5.4
Length: 7m +
Engine: Opti 225/Yam 85
MMSI: 235090687/235055163
Join Date: Jul 2005
Posts: 12,645
RIBase
You'll need a parts microfiche for it to check.
If the part numbers for the ECU,main engine block and liners are the same but the carbs/reeds have lots of different parts then you'll get your answer.

Same deal for the autolube-if it's the same pump then you'll be OK, just make sure it's properly adjusted.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 03 May 2008, 05:02   #3
RIBnet supporter
 
Jizm's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Hissing Sid
Make: Ross Smith Cobra
Length: 6m +
Engine: 200HP Optimax
MMSI: 235038046
Join Date: Jun 2002
Posts: 3,803
I thought the 30-40hp shared the same block and then the 50-60hp were the same motor with difrent carbs?
Jizm is offline   Reply With Quote
Old 03 May 2008, 05:49   #4
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: WhiteNoise/Dominator
Make: Ballistic 7.8/SR5.4
Length: 7m +
Engine: Opti 225/Yam 85
MMSI: 235090687/235055163
Join Date: Jul 2005
Posts: 12,645
RIBase
I'll have a look at the microfiche later but I thought the 30 was an uprated 25.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 03 May 2008, 06:46   #5
RIBnet supporter
 
Jizm's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Hissing Sid
Make: Ross Smith Cobra
Length: 6m +
Engine: 200HP Optimax
MMSI: 235038046
Join Date: Jun 2002
Posts: 3,803
Maybe it depends on year, but my 1996 50hp is 849cc as is the 60hp, the 40hp is listed as 698cc same as the 30hp of that year, all are 3 cylinder.
The current yam 2 strokes are different sizes tho'.
make sense to you nos?
Jizm is offline   Reply With Quote
Old 03 May 2008, 07:29   #6
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: WhiteNoise/Dominator
Make: Ballistic 7.8/SR5.4
Length: 7m +
Engine: Opti 225/Yam 85
MMSI: 235090687/235055163
Join Date: Jul 2005
Posts: 12,645
RIBase
Quote:
Originally Posted by Jizm View Post
Maybe it depends on year, but my 1996 50hp is 849cc as is the 60hp, the 40hp is listed as 698cc same as the 30hp of that year, all are 3 cylinder.
The current yam 2 strokes are different sizes tho'.
make sense to you nos?
Yeah, perfect sense-I was thinking of the earlier 2 cylinder 25hp.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 04 May 2008, 05:01   #7
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
RIBase
I read a similar post on another site - that the (1995) 40/50 share the same powerblock (693cc). The 50hp carbs are a 1/4" larger as is the exhaust manifold. Swapping over both in theory should increase capacity, albeit with some tinkering and fine adjustment.

I don't want to wreck a practically mint 40hp, however that extra 10hp sure does sound tempting. For the record - my transom will take a maximum 50hp.
__________________

__________________
spartacus 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 14:19.


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