BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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Last year I bought a new Suzuki DF 9.9hp outboard. I noticed at the time that the 9.9hp and the 15hp models are very similar, same cubic capacity etc.
I am damn sure that the 9.9 must be a restricted version of the 15hp but I am buggered if I can see how Suzuki have done it. I had hoped that there might be a restriction in between the carb and the inlet manifold but having looked this doesn't seem to be the case.
I contacted a Suzuki dealer who passed me over to the Suzuki UK Technical Department. The Tech dept said that they 'do not recommend modifying the engine in the nature you have described'.
Not knowing how the engine is restricted is driving me mad. Can anyone shed any light or point me in the direction of someone who might be in the know and willing to share the big secret!
Cheers
Billy
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"He is not only dull himself, he is the cause of dullness in others."
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alrob
regular
Reged: 19/07/2005
Posts: 825
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not sure if its the same scenario but the 2.5 HP & 3.3hp mercs are the same engine but the gearing is different. also been told that in big outboards the jets can be altered to give more output
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misterg
regular
Reged: 31/10/2003
Posts: 1544
Loc: N. Wales
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Quote:
not sure if its the same scenario but the 2.5 HP & 3.3hp mercs are the same engine but the gearing is different....
2.5 & 3.3 Mariners are the same engine, but the 2.5 is restricted by the throttle slide not opening fully - it is physically to long to do so. (I suspect this applies to Mercuries, etc. too.) Number of gear teeth is different because the 3.3 has a F-N gearshift, but the 2.5 doesn't. Overall gear ratio is nearly the same though (from memory).
May be worth checking the Suzuki for the same thing on the throttle slide. Is the part number of the carb for both engines the same? Is there a 'changeable' venturi in the carb? I suppose there could possibly be a restrictor in the exhaust or air 'filter'?
Andy
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spannerman
regular
Reged: 30/11/2002
Posts: 1072
Loc: Stavanger, Norway
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If I remember correctly ypu have to change the carb on Suzukis and maybe adjust the stop on the reed valve which determines how much they open.
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jfm
regular
Reged: 16/05/2001
Posts: 7818
Loc: London/Antibes
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I dont know that particular model but it's normally done by restricting the diameter of the carb jet(s) to restrict the fuel flow. It is not normally done by restricting the throttle opening (which restricts the air flow, not the fuel flow). So, just taking the carb to bits and fitting the 15hp jets should do it. Quite simple job if you are ok with carbs. or your local motorbike shop could do it
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MVP
regular
Reged: 05/09/2007
Posts: 67
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Messing about with modern engines is going to be a high risk game and will invalidate any warantee.
If you wanted a 15hp engine why didn't you buy one?
MVP
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itsonlymoney
regular
Reged: 21/06/2003
Posts: 4501
Loc: UK
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Quote:
2.5 & 3.3 Mariners are the same engine, but the 2.5 is restricted by the throttle slide not opening fully - it is physically to long to do so. (I suspect this applies to Mercuries, etc. too.)
So how would one get round this and make the slide open fully ?
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jfm
regular
Reged: 16/05/2001
Posts: 7818
Loc: London/Antibes
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Oh come on, be more adventurous! Changing a few carb jets is a piece of cake. And why worry about warranty? The thing only cost a thousand quid anyway so what's the worst that can happen?
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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Quote:
Messing about with modern engines is going to be a high risk game and will invalidate any warantee.
If you wanted a 15hp engine why didn't you buy one?
The 9.9 was on special offer. I couldn't muster enough points with SWMBO to get hold of the extra £200 for the 15hp
The idea about the throttle cable / slide being limited is well worth looking at.
I have looked at the schematic for the 9.9 and the 15, both share the same drawing. Any ideas:
MVP
REF# PART #REQ YOUR PRICE
1-1 CARBURETOR ASSY
13200-94J20 1 $263.09
1-2 CARBURETOR ASSY
13200-94J30 1 $290.78
1-3 CARBURETOR ASSY
13200-94J60 1 $263.09
2-1 NOZZLE,MAIN
13236-94J10 1 $13.41
2-2 NOZZLE,MAIN
13236-94J00 1 $13.41
3-1 .JET, MAIN (70)
09491-70017 1 $7.94
3-2 JET,MAIN 115
09491-23029 1 $7.07
4-1 .JET, PILOT (38)
09492-38009 1 $8.21
4-2 JET,PILOT 40
09492-40029 1 $7.07
5 CAP,RUBBER
13239-94J00 1 $3.86
6 FLOAT
13250-94J00 1 $19.24
7 VALVE COMP,FLOA
13370-94J00 1 $12.60
8 SCREW
13247-94J00 4 $4.80
9 .CLIP
13375-26E00 1 $3.09
10 PIN,ARM
13254-94J00 1 $1.68
11 SCREW
13802-94J00 1 $1.76
12 SCREW,STOP
13534-94J00 1 $4.15
13 SPRING
13268-94J00 1 $2.34
14 GASKET,FLOAT CH
13251-94J00 1 $6.12
15-1 CHAMBER,FLOAT
13245-94J00 1 $34.99
15-2 CHAMBER,FLOAT
13245-94J10 1 $34.99
15-3 CHAMBER,FLOAT
13245-94J20 1 $34.99
16 SCREW,DRAIN
13279-94J00 1 $2.85
17 O RING
13523-94J00 1 $2.34
18 U RING
13345-94J00 1 $3.86
19-1 COVER
13346-94J00 1 $11.47
19-2 COVER
13346-94J10 1 $10.78
19-3 COVER
13346-94J20 1 $11.47
20 SCREW
13247-94J00 4 $4.80
21 HOLDER,CABLE
13361-94J00 1 $7.68
22 GUIDE,CABLE
13362-94J00 1 $6.90
23 CAP,CABLE SEALI
13363-94J00 1 $6.12
24 VALVE,STARTER
13364-94J00 1 $8.46
25 SPRING
13365-94J00 1 $2.34
26 .O RING
13295-14G00 (replaces 13366-94J00) 1 $1.81
27 PIPE
13684-94J00 1 $5.22
28 .CLIP
09401-05402 1 $0.68
29 .PLATE
13428-06F30 1 $2.90
30 SCREW
13367-94J00 1 $2.34
31 STARTER ASSY
13368-94J00 1 $114.73
32 CLIP
13494-94J00 1 $3.47
33 CAP,RUBBER
13495-94J00 1 $5.22
34 PLUNGER
13493-94J00 1 $11.44
35 SPRING
13441-94J00 1 $2.34
36 BOLT
09103-06276 2 $1.85
37 GASKET,CARBURET
13125-94J00 1 $2.47
38 INSULATOR,CARBU
13124-94J00 1 $5.77
39 GASKET,INSULATO
13127-94J00 1 $2.63
40 KNOB ASSY,START
13640-94J00 1 $15.29
41 PROTECTOR,START
18498-94J00 1 $2.05
42 CLAMP
09403-12318 1 $1.51
43 PLUG,STARTER KN
59252-94J00 1 $4.24
Cheers
Billy
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"He is not only dull himself, he is the cause of dullness in others."
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jfm
regular
Reged: 16/05/2001
Posts: 7818
Loc: London/Antibes
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The HP restriction is VERY unlikely to be done by restricting the airflow (throttle). I repeat, it is done by the carb jet sizing. So just change the jets. Parts 2, 3, 4. Quite cheap, less than a £fiver per item. Note, each one of these 3 parts is listed twice, with a different dimension code. One set will be for the 9.9, t'other for the 15hp. Which kinda proves my point
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itsonlymoney
regular
Reged: 21/06/2003
Posts: 4501
Loc: UK
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So were do I find a parts diagram for a mercury 2.5/3.3. One assumes its the same script for my 2.5 ie. change a jet ????
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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Quote:
So were do I find a parts diagram for a mercury 2.5/3.3. One assumes its the same script for my 2.5 ie. change a jet ????
try here
http://www.usboatsupply.com/outboardparts.php
Cheers
Billy
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"He is not only dull himself, he is the cause of dullness in others."
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misterg
regular
Reged: 31/10/2003
Posts: 1544
Loc: N. Wales
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Quote:
Quote:
2.5 & 3.3 Mariners are the same engine, but the 2.5 is restricted by the throttle slide not opening fully - it is physically to long to do so. (I suspect this applies to Mercuries, etc. too.)
So how would one get round this and make the slide open fully ?
One could presumably buy a replacement throttle slide for a 3.3, or if one is impecunious, one can carefully cut about 6mm off the top of ones existing throttle slide (look into the throat, and hold the slide so it is flush with the top of the venturi and mark where it needs to be cut). One then needs to bend the throttle linkage to give full travel of the modified slide. One's done it, and it works, but is of limited benefit on a heavy rubber dink (more noise, but not really any faster - I've since acquired a mercury 3.3 and it's just the same).
N.B. this engine has a carb with a slide, so both petrol and air are controlled by slide opening (petrol via the needle valve attached to the air slide). Looks like the engine in the original question has a butterfly valve for the throttle, so not the same.
Not wishing to get into an argument, but I don't think the jets are the whole answer, because these could only give you more fuel, not more air, and you need both. I still suspect there is a restriction elsewhere (either on the throttle opening, or somewhere in the air intake, or exhaust system). Maybe the alternative jets are for high altitude use, or something ?
Andy
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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Quote:
The HP restriction is VERY unlikely to be done by restricting the airflow (throttle). I repeat, it is done by the carb jet sizing. So just change the jets. Parts 2, 3, 4. Quite cheap, less than a £fiver per item. Note, each one of these 3 parts is listed twice, with a different dimension code. One set will be for the 9.9, t'other for the 15hp. Which kinda proves my point
I agree that the jets apear to be different but if I increase the jet size only, the engine would run rich wouldn't it.
i.e the same volume of air but more fuel !
How do they get the mixture back to being right?
Billy
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"He is not only dull himself, he is the cause of dullness in others."
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itsonlymoney
regular
Reged: 21/06/2003
Posts: 4501
Loc: UK
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So not worth the hassle then ?
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Nick_H
regular
Reged: 20/04/2004
Posts: 3002
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I bought a Suzuki 4 hp 4 stroke, and to turn that into a 5hp you just flip over the little moulding that the throttle cable attaches to, done. I don't think that's the case with yours though.
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Davy_S
regular
Reged: 31/01/2003
Posts: 792
Loc: Greece (Ionian)
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On the smaller engines it is pretty easy, increase jets, take out the restricter. I think you have worked out for yourself you need to increase RPM to increase power, ie, push more air through, In the bigger engines the CD ignition modules need to be changed to increase rpm, its a bit like changing the engine management system, it aint cheap! good luck.
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jfm
regular
Reged: 16/05/2001
Posts: 7818
Loc: London/Antibes
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Good point. Can you examine the carb a bit more. Maybe there is a restricter ring inserted to the air intake tube, that you can remove? I very much doubt it will be a case of making the butterfly open more fully, much more likely to be a restricter ring. There are lots of US outboard tinkering forums - have you googled them?
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misterg
regular
Reged: 31/10/2003
Posts: 1544
Loc: N. Wales
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Quote:
So not worth the hassle then ?
Not unless you're bored  - I'm sure my old rigid f/glass dinghy would have gone a bit faster, but a dead-loss on the flubber. F-N gearbox on the 3.3 is much more use than the extra HP.
Andy
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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I didn't see any sign of restriction either side of the carb. googling the US sites is a great idea, I will report back when, or if, I find the answer !!
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"He is not only dull himself, he is the cause of dullness in others."
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alrob
regular
Reged: 19/07/2005
Posts: 825
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F-N thats the reason I bought the 3.3 - great buy great engine very kid friendly
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MajorCatastrophe
regular
Reged: 31/05/2005
Posts: 17119
Loc: ust plague be upon you
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I'm warming to this thread. I have a Suzuki 6hp 4 stroke. What can I turn that into?
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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I have joined a US forum and asked for international help - lets see what response, if any, we get.
Billy
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"He is not only dull himself, he is the cause of dullness in others."
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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Quote:
I'm warming to this thread. I have a Suzuki 6hp 4 stroke. What can I turn that into?
Sods law means it would be a 4hp.... 
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"He is not only dull himself, he is the cause of dullness in others."
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MajorCatastrophe
regular
Reged: 31/05/2005
Posts: 17119
Loc: ust plague be upon you
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Quote:
Quote:
I'm warming to this thread. I have a Suzuki 6hp 4 stroke. What can I turn that into?
Sods law means it would be a 4hp....
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CalicoJack
regular
Reged: 05/01/2004
Posts: 79
Loc: Chatham, Kent
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Quote:
I bought a Suzuki 4 hp 4 stroke, and to turn that into a 5hp you just flip over the little moulding that the throttle cable attaches to, done. I don't think that's the case with yours though.
How do you turn a 5hp into a 6?
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Calico Jack
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Nick_H
regular
Reged: 20/04/2004
Posts: 3002
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That's a bit more complex, probably along the lines jfm is proposing above.
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MajorCatastrophe
regular
Reged: 31/05/2005
Posts: 17119
Loc: ust plague be upon you
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It is easier than you think.
Can't wait for the weekend.
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Kawasaki
regular
Reged: 21/06/2004
Posts: 4621
Loc: Anglesey Wales
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Davy you are on the right lines.
Just shoving more fuel in won't work.
OK on little two strokes.
As long as enough air is available too.
'Mixture' is important.
More revs are needed.
Ignition timing and valve timing (to get suck in and get rid of said mixture) and the Ig to adjust itself accordingly.
I think there is more to it than a jet change.
Just happened on the thread, not checked owt properly yet.
Will talk to contacts who deal with this stuff more regularly than Me Mr Bloater.
This kinda suff intersts Me!
Sad git that I am!
Major to turn Your 6 into 9 is much more easy.
Turn the Fekker upside down!
See the simple suggestions are always the Best 
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Jerk of all trades. Expert in none.
Plus Don,t do serious, lifes too short.
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BillyBloater
regular
Reged: 09/01/2006
Posts: 356
Loc: UK
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Thanks Mr Kawasaki,
This really is doing my head in!
Billy
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"He is not only dull himself, he is the cause of dullness in others."
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Kawasaki
regular
Reged: 21/06/2004
Posts: 4621
Loc: Anglesey Wales
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No sweat BB
Be be in touch!
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Jerk of all trades. Expert in none.
Plus Don,t do serious, lifes too short.
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