Upgrading 2 stroke to 4 stroke?

[Flex]

Hi all. I currently own a 4.55m seajay running a 50hp 2 stroke yamaha. Im really happy with its performance and speed. planes very easy and goes fairly quick.

But Im hating the fuel consumption. I recently started fishing a bit differently than I did 18months ago, I drift/troll etc alot more these days, and My poor 2 stroke doesn't like it very much. I go through 4-5l per hour trolling and at wot 22l per hour.

So im seriously considering upgrading to a 4 stroke. but my major concern is spending $9000 and having my boat perform like a piece of crap. Obviously the 4 stroke wont up and plane as easy and top speed wont be as fast. But its very hard to tell how much of a difference compared to a 2 stroke. I can handle a small drop im performance, but I'd hate to get one and have my boat take 50m to get on the plane!.. i have thought of an e-tec but im not sold on em yet.

I dont want another 2v4 debate. but as you can understand its alot of money to spend and not be happy. I run a 70l underfloor tank+3 blokes in my boat usually+gear so it needs to have a bit of oomph!

I've never been in a mid sized tinny with a 4 stroke on the back so its very hard to tell.

anyone out there gone from using a 40-50hp 2 stroke to a 4 stroke on the same boat? how did you find the difference?

[Dan5]

Flex i have a 4.5 mtr bluefin with a 60hp yam 4 banger,top speed is just over 31kt's getting on the plane is not an issue with 3 up proberbly not as quick as a 60 2strk but not a 50mtr run up thats for sure.

Normal fishing with 2 up is a breeze,fuel consumption is very good easy 70nm for 30 odd ltr's,troll all day for bugger all and idle for hour's and hour's while casting.

This is all with the standard prop 11 3/8 x 13, cruising speed is about 24kt's weather permitting ofcourse.

The weight of the e-tec is very comparable in the 60hp range to the 4 banger same with the 2strk yammie there's not a lot in it to be really significant.IMO

The engine is very queit for sneaking around casting etc but not as quiet as my old 70suzi.

Cheer's Dan

[Outsider1]

Hi Flex,

what is the maximum weight and horsepower on the Builder's plate on your Seajay?

Your Yammy is probably basically the same motor as the current Yammy 2s 50hp, and it weighs 88kgs, so there is a base line.

As Dan says there is no great weight advantage to the E-Tec at this horsepower rating, but the Tohatsu DI 2s is very light (93.5kgs), and also very cheap in comparison!. Most of the 50hp 4 strokes weigh the same, about 110kg, and all bar the Honda are EFI. The Honda 50hp is lighter (93kgs) but is has Carbs, not EFI.

My initial thought is if the budget can handle it , go a 60hp. Nearly all the 60hp motors are the same as the 50hp ie basically same motor, same displacement, same weight etc.

Cheers

Dave

[ashleyhj74]

22ltrs a hour flat out seems pretty good for a 2-stroke to me. My 200hp uses 36+ltrs a hour at cruise :) I've been tossing up the whole 2/4 stroke thing myself of late, but for me to get a 200/225hp 4-stroke for my boat, its gonna cost me a extra $50+ dollars a week for repayments on the loan. Thats every single week for 5 years (or whatever it would be). I dont use that much in fuel for my 2-stroke every week. Thats the conclusion i've basically come to, its just not worth the extra money for me. I realise we have two different boats/engines etc, but i guess its still somethin to think about. You can buy alot of fuel for the difference.

[honda900]

Flex,

On making this change myself on a bigger boat, from a yam 130 to a suzi 140 I have found, after much prop testing, My need was to reduce fuel consumption to increase the range of the boat as I only have a 150ltr tank.


The four stroke needs to be run higher in the rev range to achieve the same speeds.
Fuel consumption even running higher in the rev range was in the vicintity of 10 litres an hour better.
I lost 10k's per hour throughout the rev range.
I have not lost anything from the hole shot, although had to prop the engine correctly.
The 4- is definately better in a heavy swell, does not seem to lose rev's as as badly as the 2- did and from that fuel consumption is considerably better.by the way the yam was traded with 93 hours on it and was mine from new and fitted to the same yalta 555HC hull.

Regards
Honda.

[FNQCairns]

Flex don't think you will be disappointed in performance with any of the 4cyl 4st 60hp engines compared to your 50 3cyl yam 2st which shares the same block as the 40hp.

You could even go to a 50hp 4st 4cyl and be ok with it but only if it shares it's block with the size engine above.

cheers fnq

[Flex]

Unfortunately my boat is only rated to 50hp.. So im not really allowed by law to get the 60hp:(

Max transom weight is only 115kg.

So im kinda limited by wight and hp. I dont expect super fast performance, but i do expect it to perform adequately.

[Dan5]

Unfortunately my boat is only rated to 50hp.. So im not really allowed by law to get the 60hp:(

Max transom weight is only 115kg.

So im kinda limited by wight and hp. I dont expect super fast performance, but i do expect it to perform adequately.

Well that sux:P ,maybe have a look at the 50 honda? just hang out for the new efi jobbie that's heading our way.

The 50/60 yam are the same engine and are 4 cyl apposed to the honda's 3cyl and the suzi 50 3cyl which would make them have more torque.

You could also look into the mariner/merc engine which is also 4cyl.

Just make sure you are happy with your local dealer no matter what type engine they sell.

Dan..

[Splash]

Sorry - see post below

[Splash]

Flex - take heed of what Ashley stated here...very real.

Ask yourself how many acutal boat hours (with engine running on water) you plan on using each year for next 5 years - than add 20% for buffer.

If your'e like me and work your but off during week and can only get out during weekends ONLY - that's 52 outings max.

Take into account weather, family commitments, etc, take off say 10 weekends at least.

42 occassions at say 8 boat hours in total for each occasion.
Of these 8 hours for event occacion, maybe 3 hours at WOT and 5 hours trolling.

Example calculations to consider...

Existing 2-stroke :
A - WOT - 22L/hour x 3 hours x 42 x $1.60/L = ...........
B - Trolling - 5L/hour x 5 hours x 42 x $1.60/L = ...........
C - Buffer (20% of (A+B))
TOTAL (A+B+C) = ...................

New 4-stroke :
Monthly Repayments, depreciation, warranty service :TOTAL =.................

If total cost of running existing 2 stroke donk is much less that interest, etc, it may be worth keeping it for as long as you can....8-)

Remeber, in 5 years time, your new donk will lose at least half it's value and be out of warranty..

Good luck!

Splash............

[disorderly]

Flex - take heed of what Ashley stated here...very real.

Ask yourself how many acutal boat hours (with engine running on water) you plan on using each year for next 5 years - than add 20% for buffer.

If your'e like me and work your but off during week and can only get out during weekends ONLY - that's 52 outings max.

Take into account weather, family commitments, etc, take off say 10 weekends at least.

42 occassions at say 3 boat hours at WOT/trolling on each occasion (126 boat hours).

Existing 2-stroke : $22L/hour (max) x 126 hours x $1.60/L = ...........
New 4-stroke : Monthly Repayments and depreciation =.................

If cost of running existing 2 stroke donk is much less that interest, etc, it may be worth keeping it for as long as you can....8-)

Good luck!

Splash

Without wanting to sound like your mother,flex,on the financial side of things, splash makes perfect sense.
I only upgraded to a DI 2 stroke because I was in need of a new motor anyway.
As long as the motor remains reliable you will have a lot more money in your pocket if you keep the current one.
I also wonder if you might be disappointed with the performance of an equivalent 4 stroke given your stated requirements.

Scott

[Tangles]

Flex,
I have a Seajay 4.55 territory with a 50 ammie 4stroke, im at viccie point so if you want to come out and see how it goes pm me and arrange a time.. no problems

cheers
Mike

[Splash]

Flex,

You also need to ask yourself of these 42 outings, how many litres of fuel LESS would you may be gaining when a 4-stroke is used...over the 2-stroke...

[stabi430]

Hi Flex, late last year I repowered my Stabicraft 430 with a new Honda 50hp, previous motor was a Yamaha 50 2 stroke, so I can give you an exact comparison
Here’s what I’ve found:
Honda has much more low down torque than the Yamaha
It gets off the mark much better, loaded or unloaded
Much quieter and is much more economical
The Yamaha would to 62 kph and the Honda will do 56 kph
Yamaha had a 10 1/8 x 13 3 blade prop, Honda has a 10 ½ x 13 4 blade prop
At the end of the day the Honda is a far more pleasant motor to be around
I did try a lot of different props but I can’t get the extra 4 kph back that the Yamaha had, but it is only 4 kph and who cares
The Honda 50 EFI is out now in NZ, and it’s $700.00 cheaper than the out going model
This would be the one to go for, I’m sure you won’t be disappointed

[Flex]

Thanks for all your replies.

You make some very good points splash. One of the main reasons for wanting good fuel consumption is I often go up far north QLD and we can only take 300l of fuel for us for 2 weeks fishing. so a 4 stroke would allow us to troll more and travel further. but thats only a once a year thing. otherwise your argument is very good. I'd be looking at $4000 to upgrade my outboard. I only get out fishing once a month somtimes 2. So thats say 15 outings a year+1 2week long trip up north.
Each trip I rekon I usually troll for a couple of hours and an hour running time so thats roughly 30l of fuel per trip x 15= 450l of fuel per year+300 each trip up north= 750l of fuel a year for boating x $1.30liter = a tad under $1000+ $100 for oil. over 5 years thats around $5000 or the cost of a 4 stroke upgrade(4 strokes cost more to service I know)

So its much of a muchness really, i could convince myself one way or the other I rekon:)

The other issue is transom weight, I'd be pushing the limit with a 50hp 4 stroke as my boats only rated at 115kg.

Aigutso (http://www.ausfish.com.au/vforum/member.php?u=35469): thanks very much for the offer mate, how do you find your boat performs? gets on the plane ok?

[FNQCairns]

Flex and don't forget by the end of the next 5 years if you did purchase the 4st soon, depreciation would have ran at near the same cost as the fuel you would have used in your current engine! and thats not counting the fuel the new 4st has got to use.

Your current engine depreciation has slowed right down I would assume (astute time for a secondhand O/B purchase)

So a net loss purchasing the 4st after 5 years??

"Oh what a feeling.....boating!" :)


cheers fnq

[Tangles]

Thanks for all your replies.

You make some very good points splash. One of the main reasons for wanting good fuel consumption is I often go up far north QLD and we can only take 300l of fuel for us for 2 weeks fishing. so a 4 stroke would allow us to troll more and travel further. but thats only a once a year thing. otherwise your argument is very good. I'd be looking at $4000 to upgrade my outboard. I only get out fishing once a month somtimes 2. So thats say 15 outings a year+1 2week long trip up north.
Each trip I rekon I usually troll for a couple of hours and an hour running time so thats roughly 30l of fuel per trip x 15= 450l of fuel per year+300 each trip up north= 750l of fuel a year for boating x $1.30liter = a tad under $1000+ $100 for oil. over 5 years thats around $5000 or the cost of a 4 stroke upgrade(4 strokes cost more to service I know)

So its much of a muchness really, i could convince myself one way or the other I rekon:)

The other issue is transom weight, I'd be pushing the limit with a 50hp 4 stroke as my boats only rated at 115kg.

Aigutso (http://www.ausfish.com.au/vforum/member.php?u=35469): thanks very much for the offer mate, how do you find your boat performs? gets on the plane ok?

Hi Flex,
Max on the Seajay 4.55 territory is rated to 115kg so the 50 4 stroke Yammie is ok. As to boat performance, i fish with usually 2, but sometimes three and haven't had an issue getting on the plane. Usually loaded up with Esky, extra fuel ( 24 litres) eyc plus it has a Minn Kota and Battery up front, it will by the GPS get 50kph WOT,, bit more or less depending, saying that I usually cruise at 36-40kph which seems the sweet spot.

Onto the plane, no problems, cant compare it to a 2 stroke as havent had one on the same hull, but with 2-3 blokes fully laden with all the gear and cab pots its been fine.

As for fuel economy, its a electric tiller steer, no gauges, so cant exactly say except to say from Viccie Pt to Peel ( top side) muck around around all day then down to McLay and back, I can do that twice out of a 24 ltr plus have third of a tank left...sorry for being so inexact..but basically im more than happy with the economy.;D

As for the 2-4 stroke thing, all ill say is im very happy with the 4 stroke and so is the wife with no fumes, a 50 4 stroke will push that hull along very well,,, like i said if your down my way, your more than free to take it out for a blast.

cheers

mike

[Gary Fooks]

In the 50 hp range you should check out Honda. The current 50hp is lighter than some 2 strokes. Its about to be replaced so you should get some good prices.


The new model has the same clever electronics as the 75/90. called "blast" it senses if you push the throttle hard, advances the timing and throws in fuel - giving 2 stroke like performance.

Electronics made the E-TEC a good, clean, economical 2 stroke. Now technology is making 4 strokes lighter and with better hole shot. Interesting stuff.

Gary

[ctwaddle]

I have a Seajay 4.55 excape sports with a 50hp 4 stroke on it and it gets up and out of the water with 3 adults in the boat with no worries at all. And best of all they are quiet. The 50 and 60HP Yamaha 4 stroke are Fuel Injected and the 40hp is carb fed i think...

[Flex]

Thankyou everyone for your replies. given my lots to think about and some very good opinions.

Much appreciated