mercury 70 hp 2 stroke outboard rebuild advice

rammed wx

Cadet
Joined
Jun 11, 2012
Messages
6
hi guys
just looking for a bit of information and advice.
i am new to the site so hopefully this makes sence haha.

ok i have just bought my first boat which has a old 70 hp 2 stroke 3 cylinder outboard.
i am looking to rebuild it or at least get a bit of information.(just engine at this stage)

i am an engine builder by trade but have had very little to do with outboards especially 2 strokes.

so what i was wondering is firstly does anybody have engine specifications (with full tensions,piston over sizes,crankshaft sizes etc) or does anybody know where i could find them. even engine diagrams

and also could anybody direct me with gasket kits,bearings or just anything you could suggest i would need.

or just generally any advice.

any help would be greatly appreciated

thanks in advance

clint
 

carholme

Rear Admiral
Joined
Sep 4, 2010
Messages
4,845
Re: mercury 70 hp 2 stroke outboard rebuild advice

Clint;

Do you have the s/n of the engine?

Gerry
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: mercury 70 hp 2 stroke outboard rebuild advice

so what i was wondering is firstly does anybody have engine specifications (with full tensions,piston over sizes,crankshaft sizes etc) or does anybody know where i could find them. even engine diagrams
Piston over sizes are .015 and .030 other sizes are available but it don't suggest that brand. What crank speck ya looking for? Check cylinders for taper as all inlines wear around the ports.
 

captainredbeard

Recruit
Joined
Jun 11, 2012
Messages
1
Re: mercury 70 hp 2 stroke outboard rebuild advice

hi guys
just looking for a bit of information and advice.
i am new to the site so hopefully this makes sence haha.

ok i have just bought my first boat which has a old 70 hp 2 stroke 3 cylinder outboard.
i am looking to rebuild it or at least get a bit of information.(just engine at this stage)

i am an engine builder by trade but have had very little to do with outboards especially 2 strokes.

so what i was wondering is firstly does anybody have engine specifications (with full tensions,piston over sizes,crankshaft sizes etc) or does anybody know where i could find them. even engine diagrams

and also could anybody direct me with gasket kits,bearings or just anything you could suggest i would need.

or just generally any advice.

any help would be greatly appreciated

thanks in advance

clint

Hi guys i also have an mercury 70 hp 2 stroke 3 cylinder outboard and was looking for engine spec and any other information or maunals

thanks :)
 

rammed wx

Cadet
Joined
Jun 11, 2012
Messages
6
Re: mercury 70 hp 2 stroke outboard rebuild advice

Piston over sizes are .015 and .030 other sizes are available but it don't suggest that brand. What crank speck ya looking for? Check cylinders for taper as all inlines wear around the ports.

ok great news. so it is possible for a bore and hone with out sleeve replacement.
crank specs i am looking for are standars sizes for big ends and mains and if you can grind them if worn for undersize bearings.
basically thats why i need specifications and sizes to measure and inspect everything to see what is reconditionable and avaliability of pistons bearings etc.

thanks alot
 

carholme

Rear Admiral
Joined
Sep 4, 2010
Messages
4,845
Re: mercury 70 hp 2 stroke outboard rebuild advice

Clint;

Your s/n comes up as:

70 70 3-cyl 4571652 4825848 1977 USA

From here:

http://www.marinshopen.se/Motorer/O...Mercury2takt3cyl6090hp/tabid/486/Default.aspx

Parts Listing:

http://www.crowleymarine.com/mercury-outboard/479.cfm

Service Manual P/N: 90-86135--5

http://www.ebay.com/itm/USED-93-Mercury-Outboard-45-50-4-Cyl-Service-Manual-/270801861441

In the interim until you get a Merc manual, here is a link to the condensed version of the Clymer manual. Let the page load for several seconds and then download soonest to your computer as the link is short lived.

http://web.ebscohost.com/serrc/pdf?...c-9565-ebced3a5b401@sessionmgr14&vid=4&hid=11

Gerry
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: mercury 70 hp 2 stroke outboard rebuild advice

i am looking for are standars sizes for big ends and mains and if you can grind them if worn for undersize bearings.
Nope..... bearings only come in one size and in over 40+years of wrenching never see a worn out crank as everything internal is roller/needle bearings.
 

rammed wx

Cadet
Joined
Jun 11, 2012
Messages
6
Re: mercury 70 hp 2 stroke outboard rebuild advice

Clint;

Your s/n comes up as:

70 70 3-cyl 4571652 4825848 1977 USA

From here:

http://www.marinshopen.se/Motorer/O...Mercury2takt3cyl6090hp/tabid/486/Default.aspx

Parts Listing:

http://www.crowleymarine.com/mercury-outboard/479.cfm

Service Manual P/N: 90-86135--5

http://www.ebay.com/itm/USED-93-Mercury-Outboard-45-50-4-Cyl-Service-Manual-/270801861441

In the interim until you get a Merc manual, here is a link to the condensed version of the Clymer manual. Let the page load for several seconds and then download soonest to your computer as the link is short lived.

http://web.ebscohost.com/serrc/pdf?...c-9565-ebced3a5b401@sessionmgr14&vid=4&hid=11

Gerry

thanks gerry
 

rammed wx

Cadet
Joined
Jun 11, 2012
Messages
6
Re: mercury 70 hp 2 stroke outboard rebuild advice

Has anybody built one of these engines before as I would be interested to know what they have done in terms of performance modifications
 
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