What Fuel ?

[lurch]

Hi all

Ive just got a second hand motor for my boat , its a 90HP Jono '86 model .

What fuel do you recomend / use for mixing with 2st oil in these motors
Unleaded
Premium Unleaded
or Lead Replacement Fuel

What fuel / octane rating were they originally made to use as these motors were made when super was the fuel of the day and there wasnt the push for unleaded at that stage.

And is there any prefered oil to use ??

thanks
Peter

[fnq_tinnie]

unlead fuel is ok for your motor.
in 1985 new reg came into force.
i use premium unlead 500ml on every fith tank as a additive to stop plugs flowing.

[Kerry]

Being a low compression motor, Unleaded and ALWAYS fresh Unleaded especially considering it has oil mixed.

Cheers, Kerry.

[Daintreeboy]

Most TCW3 2 stroke outboard oils are ok. I use the BP brand followed by the Caltex one when not available.
Cheers, Mark.

[NQCairns]

Hi lurch, consider the idea of useing Fict ram oil, I hear that it is miles ahead to the point of a grade higher than TCW3, too expensive for my blood though, I pretty much do what Daintree does.

Good idea FNQ I will have to remember to do that.

Hi Daintree i liked your gulf report, you got the important stuff in life down solid it seems. Top spot that. Any updates on you motor problems?
Nq

[Daintreeboy]

Oh yeah the flippin motor. It's in getting fixed for the price quoted which I gave hereabouts. You wouldn't believe it but I went fishing with my dad after his was serviced at the same time and the bloody thing nearly caught fire just as we were getting to the reef. There was nothing wrong with it before the service so I reckon the mechanic, as good as he has been for us over the years, has moved some wires or something and caused the relay to short circuit and burn all the wiring out. Normally they open circuit but this one shorted so we got towed in by the other boat with us. They towed us to 3 bommies before leaving and we still managed 11 trout. They got 14. Would have been more if not for the sharks, they got all the big ones :'(

[lurch]

OK
When I picked up My boat I was told to use LRP ( Lead Replacement Petrol ) with the oil ( Type not stated ) and told to use unleaded only if I had to that LRP should be the fuel of choice.

As i use unleaded fuel in all my other 2 stroke machinery i assumed it would be the same for the outboard ?? Maybe not !!

NQ Cairns - is fict oil a synthetic oil ? Apart from less smoke from synthetic oils do they claim any other advantages or are they only really for the new outboards ? What brands are there in synthetic or normal and which are the prefered brands
( 1. BP 2. Caltex )

Peter

[NQCairns]

Hi lurch yes i think the ram is synthetic or blended synthetic, i have not even seen the bottle. I understand it has greatly superior sheer, film and wear properties also it is almost smokeless/ashless and can be mixed with any other o/b oil as is normal these days. With properties like those beyond the other o/b mineral oils and if true it is actually of far more benefit for the older o/bs. Real solid info is hard to come by these days, if it was really so superior why is not Bom yelling it from the highest branch, I would be?
LRP IS premium unleaded it just has some oil added to look after 4 stroke valves.
Lots of people run low grade unleaded (LGU)in those things and have no problems I even did once upon a time, just keep it fresh or do what FNQ does, it's just with LGU you have nowhere but down to go in quality for whatever reason, at least with LRP or premium there is LGU below. That is how I justify it myself rightly or wrongly. Nq

[NQCairns]

Hey Daintee, thats it! when I get the reef boat finished and need a buddy boat for the shakedown cruise/fishing trip. Your not invited. ;D Dont these things come in 3s :-X Good luck with the rebuild. nq

[fnq_tinnie]

hi lurch lead replacment fuel is 50/50 mix of leaded and unlead fuel. premium unleaded fuel has octane 96 unlead octane 86 lead replacment fuel has octane 85.many years ago lead was used in engines to help lubricate the inside of engine,s.lead would melt thus lubricate inside of engines. oil could only be pick up from the sump to lubricate piston chamber. fuel lubricate the head,top part chamber hes leaded fuel.
i dont think would do any marjor damage to the engine.by using lead replacment fuel would fowl the plug faster to much lubricate.use 500ml premium unleaded fuel on every fivth tank of fuel to keep plug clean. to use premium unleaded fuel all the time on a old motor could burn a hole in the top the piston octane of 96 burns alot hotter than of octane of 86

[NQCairns]

Hi FNQ, this might be of some interest to you, there is a lot of misinformation around with fuels. I have been guilty before of this more than once. Here are the octane ratings of our fuels by method of measurement.

MON
85.0 PULP
81.0 ULP
82.0 LRP

RON
91.0 ULP
95.0 PULP
96.0 LRP

You are right that combustion temp can run high with pulp but it can also restrict detonation etc so it is a damned if you do damned if you dont situation, but a standard 85 V4 compession ratio falls where either can be used, and not be doing anything strictly wrong or right by the motor in my opinion, i guess if it were my motor and I could remember or be bothered a 50/50 mix of ULP and PULP/LRP would be the best of both worlds. I might start doing that in my motor now.

There is no leaded fuel sold in Australia anymore except for some aeroplane fuels. LRP is premium with upper cylinder lubricant added it looks like they add a token amount of an octane booster as well judging by the numbers for the old high comp 4 strokes. There is heaps of info around I just then used Yahoo australia with this exact string +LRP +RON +octane and got those numbers from the a Government site. cheers nq