I would assume the 40 may have slightly more, depending on gears, prop size and hulls. However I beleive the 30hp 2 stroke would have better response.

Im Calm FED Just making my point clear.

Do you think that if there was water in the fuel tank that it would make a differance? ;)

This post has been edited by Rum Dust N Ruckus: Aug 27 2007, 01:09 PM

i got this reply on the poly oners sight and i think itcovers it very well
As RBF noted, I have a 4.1/40 honda. The 4.1 carries my honda on the back no worries and I have 2x25litre fuel tanks, a heavy duty battery, extra decking and 15kg of foam filler, plus me sitting down the back.

Go the 40 yamaha (or whatever brand of 4st you have available) as your boat will be lighter than mine and will be quite nimble. I played with props, engine height and foils to get the max performance out of my boat and ended up with an 11pitch solas SS prop and permatrim - which runs out at 5900RPM with 2x85kg fishermen on board (plus all gear).

The permatrim is a no-brainer, bolt one on from new - they make a big difference.

Also think about a stainless prop. The SS significantly reduces cavitation and allows engine height to be increased at least one hole, which gives better lift.

I would say that 30hp is a bit light on for power.

Send me an email or phone call and I can try to answer any other questions.
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yep . like I said pol even a 50 yamy would suit a bit more there if you want.

yours prob should have had a 40 on from start. and you might even have said . Iwouldn't mind a fifty just for that bit extra. and like i said you wouldn't be straining motor. whitch in turn last a lot longer

Judge Judy would not be impressed with this little gem.

What are you really trying to achieve from this upgrade Poly?


This guy has too much weight in the back of his boat, if it was set up properly he wouldn't need one.


Just because you read it on the net don't take it as gospel Poly, these guys weave their own web and convince themselves of lies.
Think about it, how does lifting the motor 1 hole give you better lift?
Smoke, mirrors and voodoo.

personally id say at around that size , id go for a 2 stroke,

FED i don't wont to get into a big discussion over this the idea about the permatrim is not to give better lift,there is a problem with the 4.1s as the horse power is increased towards maximum the boats have a tendency to porpoise and the permatrim solves this problem as i only posted 1 of the replies i received on the poly boat owners site all those running 40 horse power and above have recommended strongly that one should be fitted.
as for lifting the motor one hole i really don't know if this can be done or not.i will just have to wait and see how she performs with the standard 12inch prop.thanks for your input mate its very much appreciated.
HUSTLER 57 as i said in a earlier post the hole shot is not very important to me as i place a greater emphasis on our fishing,the additional stealth i will achieve with a 4stroke motor for me far out ways everything else

Stealth If you didn't go dancing around trying catch fish and have a more sensible aproach there's your stealth Iv'e seen you dance poly it aint pretty

STEVE i can only dance as well as the teacher can teach just ask SUMO

Orrrrr grasshoper , but you need more lessons

:drop the daks:

poly it's JG

Honestly I think you've been listenting to to much BULLSH*T from that guy on the poly site

He knows Sierra Foxtrot Alpha about motors or boat performance & he cares to debate me about the crap he's been telling ewe tell him to come aboard & I'll sort him out

ps ] SUMO & I R having a good laugh @ what he's told you

Stealth sounds like a plan to me Poly have you got a leccie?

The other guys are probably lifting their motors up to reduce drag and get more top end speed but the trade off is porpoising because lifting the motor starts to reduce the effect of the cavitation plate and they're putting permatrims on to counteract this.
Could these guys be Yankee revheads?

If I was buying a new motor I'd be looking for... quiet (4 St), smooth (4 Cyl) and power trim but I don't know if that configuration is available in the range you're looking at.

hear are the specks for the yammy motor i am buying i believe it will do the job nicely

SPECIFICATIONS



GENERAL
O/M Transom Height (mm/in) 533 (21.0)
Weight (kg) with prop. 96.9
Engine Type Inline 3 Cylinder
Displacement cm³ 747
Bore x Stroke (mm) 65 x 75
Output (hp/kw) 40 (29.4) @ 5500 rpm
Max. Operating Range (rpm) 5000~6000
Compression Ratio 9.87
Scavenging Single Overhead Camshaft
Ignition CDI microprocessor
Gear Ratio 2.0 (26/13)
Fuel Management 3 - Carb with Acceleration Pump
Oil Pan Capacity (litres) 2.0
Max. Fuel Consumption 15 l/h
Spark Plug DPR6EA-9
Steering 40° Each Direction
Gear Shift F-N-R
Exhaust system Through Propeller Hub (Jet)
Prop. Engagement Spline
FEATURES
Operation Method Tiller Handle
Lubrication Wet Sump
Starting System Electric
Tilt & Trim Method Wide Range Power Tilt & Trim
Prime Start™ Standard
Engine Stop Watch Lanyard Yes
Shallow Water Drive Standard
Alternator 12V-15A (M:6A (85W))
Rectifier Not Installed
Rectifier Regulator Standard
2 Pin Connector Not Installed
Start in Gear Prevention Standard
Overheat Warning Standard
Over Revolution Prevention Standard
Remote Control Box Not Installed
Speedometer Not Installed
Tachometer Not Installed
Trim Meter Not Installed
Propeller Standard
Fuel Tank Remote
Separate Fuel Tank Capacity (litres) 24 l
Emergency Start Rope Standard

CDI-E:CDI-Electronic Automatic
CDI-M: CDI-Mmicrocomputer
TCI: Transistor Controlled Ignition
Above specifications are subject to change without notice

J G as i said to FED the reason for the prematrim is to prevent porpoising and not to increase lift, however it will be a bonus i would think, as for the SS prop i will wait and see how she go's in stock trim before i start to change things

Poly, The Permatrim is a total waste of time and money, If the motor height is set correctly and the motor angle is correct, THERE IS NO way that the boat will Porpoise. I notice that you have Posted the Specifications for the 40HP four stroke. this motor has POWER TILT & TRIM so therefore you would not require a powertrim unit. and this motor would probably not perform much better than the 30Hp two Stroke you have. Have a Good look at all the engine specs you have listed there is NO MENTION of TORQUE Specs.

POLY, I forgot to mention, I noticed that your SPECIFICATIONS state that this engine is 3 carburetter, how far obsolete is this motor with CARBIES????

george my dearest friend,let us start with torque,none of the engine manufactors list figures for torque so i am assuming that the engine torque will be created somewhere between 2500r.p.m and 4500r.p.m placing them far higher in the rev range compared to a2stroke where torque would normally commence between 1500 and 1800r.p.m beginning to taper at somewhere between 2500 and 3000r.p.m where overall horse power takes over giving the engine the impression of been more powerful.however this is actually an illusion.at 5500r.p.m a 40 horse power engine regardless whether it is 2 stroke or 4 stroke if they are both turning a 12inch propellar on the same hull the top end speed has to be the same.the difference is the 2 stroke gets there quicker.
i do sincerely hope that u can see i do understand the difference between the 2.
carbs george this is a HARD ONE we run a high performance motorcycle well should i say our son does.it has been built to do one thing and that is for maximum performance over a 4 mile straight.in other words he is looking to go as fast as he can on a 2 cyclinder 750cc motorcycle.the only way this can be achieved is through the use of carbaraters as fuel injection cannot not supply enough fuel at any given point in the rev range to reach a maximum r.p.m with the given gearing of the bike.also carbs.are far simpler to work on then c.d.i lets face it if c.d.i shits itself midstream u will be paddling. if cards blocks up just blow out the jets keep going.okay i hope this answers your questions
thanks mate for all your suggestions much appreciated.

This post has been edited by poly: Aug 31 2007, 03:01 AM

Hey guy's been stay'n outta this as i don't have much experiance with large motors(6hp+ ),sure i've been in many but never owned any.


I'm just a bit dumbfounded by the above quote .


How does a certain material prop make a differance in cavitation??

Does'nt it have more to do with where the motor is placed and the pitch of the prop??


Poly i'm not trying to rrubbish your mate BTW,just curious.


SMELLY

It's due to the strength of SS Smelly, a SS prop being stronger can be made with thinner & sharper blades which makes them more efficient.
Imagine if you had a prop made of wood, the blades would have to be very thick so they wouldn't work as well at slicing through the water.
Nowdays there's not a great deal of difference between SS & Alloy as the alloy materials they are using are getting better all the time.

Poly, how much does your existing motor weigh, I hate to see you turn the boat into a dog.
Have you thought about holding out for a whole new rig, maybe one that has a steering wheel?

FED thank u for your concern, possum and i have given that a gr8 deal of thought in the past few months and have desided against it.
the 30 suzi weighs in at 68kg i think and the new motor will be 96.9kg well within the manufacturer's spec's, i could go up to a 50hp yammy if i wish as it is the same weight as the 40hp how ever it would make it a lot harder for me to work on the motor as they have E F I fuel injection.
thank u all so for explaining why ss props work better as it had me scratching my head to