4 strokes

[Gilli]

Im just curious, do you have to run in 4-strokes the same as you have to run in some 2-strokes?
Been told by 1 person you do and another person that you dont.


Chris

[finga64]

Yep, you do Gilli.
There was a thread last week or the week before about that.
Have a gander through the last couple of weeks in the boating section. You may find some more ideas :)

[Kiktz]

Yep sure do Gilli,

i have been told that for the first 10hrs you hvae to vary the rpm
a lil high and lil med and a lil low, then after that shes your baby
AJ

[Gilli]

Thanks for that. Just my boat motor is playin up and they cant find the problem with it, and f i was to get a new motor i was wondering what would be the best to get. But they all sound pretty good.

Gilli

[seatime]

G'day Gilli

When you say 'they' can't find the problem with your motor, do you mean the mechanic at the service dept of a dealer, or an independant mechanic.
Be careful 'they' don't sell you a motor that may be unsuitable for your boat.
If your upgrading to a 4stroke from a 2 stroke, check out your boat's maximum allowable transom weight, this will determine the HP or even brand of 4 stroke you will be able to use.
There can be a bit of weight difference between brands and HP -
a 140hp Johnson/Suzuki is lighter than a 115hp Johnson/Suzuki, for example. There may be other examples in smaller HP, I'm not sure, but it's something to consider.

can you provide anymore details on boat and motor and problems, there could be someone here who can help.

regards
Steve.

[finga64]

That's a great idea Steve. Well done matey :)

[Kunnara1]

I had a 60 4stroke fitted last week and was told by the dealer to run it in the same way I intend to use it...ie..If I intend to run it flat out all the time then I should run it in that way...
Kunnara...

[Gilli]

yeah thanks mate. Well its my first boat and the motor has been kept in verry good condition and wen i got it off our mate he had only just taken it into the dealer (Angus Smith Marine, Townsville) to get the 12-monthly service. Anyway, it was a week after the service i took it out on the water and after about 20 minutes of running the motor seemed to just stop and miss a cylinder, and it has done it ever since i got it off him. We took it back into the dealer and he ran it for 2 hours, opening up the throttle and letting it idle and all, and it never played up on him. But when i got it back and put it in the water the next day it done it again. I've been told by a number of mates that it couldbe a fuel problem, over plaining. Cant seem to find the problem...Any help would be greatly appreciated.

The motor is a 25HP johnson 2ST, 1989 model. He hasnt used the boat much at all and was kept in verry good condition.

Gilli

[Kunnara1]

Did he put the boat in the water to test it???Sounds like your problem is only under load and he won't get the same load with muffs or in a water tank...
Kunnara...

[Spaniard_King]

Gilli,

Is your engine a UFI model (under flywheel ignition) these were a problem as the ufi module had a tendency to contact the flywheeel. UFI came out early 1990

If its not, you most likely have a coil problem and maybe a CDI problem as the stator will supply power for both plugs. it's usually a coil if one plug has a problem.

If its a missfire its unlikely to have a fuel issue due to both cylinders sharing the one carby.

Angus needs to spend more time diagnosing the problem under the same conditions you are having the problems

Garry

[Gilli]

he put it in the tank. I was thinking it might be a problem when underload. It seems to just start missing a cylinder straight away and i cant seem to find the problem. It seems to me that all the load causes 1 of the cylinders to overload and seize.

Gilli

[Gilli]

oh thanks for the advice mate. the Cdi's are on the left hand side of the motor but under the pull start compartment. could that be any problem?

[Spaniard_King]

Gilli,

If you have the cdi on the left side of the engine you are clear from the UFI dramas

You will have a primary coil and trigger coil under the flywheel these should be tested, also your service guy should have the ignition load adapter that along with a peak reading volt meter can measure peak volts going to each coil from the CDI unit whilst it is running. This would give the best indication of which cylinder is giving you the problem

Garry

[Gilli]

ok thanks for that mate, i will have to get it checked out as it is a real pain when you go out on a fishing trip and it does this. It wont do it on low revs though, only on half throttle and above and it only does it after it has warmed up.

Gilli

[Spaniard_King]

Gilli

will it run fine flat out when its cold.. as I am thinking its a carby issue :-/ from your last post


Garry

[Gilli]

it will run fine flat out for like 20 minutes then once it is warmed up it will start. The whole boat will stop as the power drops so suddenly.

[Spaniard_King]

Gilli,

Sounds like a painfull one.... best to replicate the problem and start testing. One thing you could do is whilst its happening squirt some fuel down the carby with a squirt bottle... if it takes off you have identified the problem

Garry

[Gilli]

ok mate thanks for the tip. Will be sure to try it. I will post up the results. I'm probly taking the boat out on sunday.

Gilli

[rotto]

I still reckon its electrical. Most likely an insulation breakdown between the windings in the coil. Coil failure on old motors happens all the time. :(

Just replace the coil, they arent that expensive! Alternatively a lot of outboard mechanics have spares, or another motor which is the same; lying around in the yard. You could borrow a coil for testing purposes :)

[Kendall249]

Hey gilli, try tony's mobile marine for a mechanic, he usually busy so book ahead. I've had some issues with ASM, PM if you want some details. Kendall

[WAfarmer]

Hi

Look for a fine crack in one of the coils

wafarmer

[Gilli]

thanks for all the replies. My old man is a sparky and he said something about it could be brokendown insulation on the leads or coils. Gonna take it back in soon to get checked again.

Gilli

[Hellmannn]

Just get an ETEC, you dont have to service it for 3 years I was told.

;)

[Gilli]

mate i would get an E-TEC but i aint got the money...lol. Will upgrade in a few years or if this motor packs it in.