lenten
Well-Known Member
15 hp 4 stroke---run it dry by disconnecting the fuel line at the tank end-----no stale fuel in the line
Outboard. Running the carb dry.
- Thread starter wombat88
- Start date
lw395
Well-Known Member
The line should stay full of fuel, the connector is supposed to seal when you disconnect.
I guess 15hp is small enough to still have a carb these days?
Heckler
Well-Known Member
Overthinking it, think two stroke motorbikes going downhill with the throttle closed, no fuel, no oil. So advice on a long descent is to blip the throttle occasionally. Note the word "long"
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richardabeattie
Well-Known Member
Amazing that such a simple question about fairly simple technology does not generate any kind of unanimity. I've always turned off the tap and let it run itself out but now I'm not so sure! I've got a Malta and must now start looking for the drain plug.
TSB240
Well-Known Member
To drain or not to drain.
All two stroke single carb engines used to be fine if you just ran the carb dry at tickover. They will only run lean for a very short time indicated by a slight increase in revs just before they stop. If you notice this its handy just to pull the choke and you will stop it dead with a virtually empty carb but the engine will have a nice coating of fuel left on its bores and bearings. There is no risk of damage to bearings or bore on a water cooled engine.
Please note single carb 2Ts...... dont risk it on a multi carb tower of power...
I have noticed the occasional problem of sticky vapourised fuel residue from new biofuels that sometimes still cause issues with 2Ts even if running empty. So long term storage is best to drain the bowl.
The hated honda 4T suffers more from corrosion of its poorly plated mild steel float bowl than anything else. Always drain this as if it is left for any length of time the total lack of oil in the fuel and any water or moisture in the fuel drains to the bottom and creates a lovely rust soup that will soon clog up the main jet. Honda's worst product ever IMHO.
The other top tip is to always shut off the air tap on the tank, make sure the cap is well sealed and have an engine cover if you store your engine on the rail. If you leave it open then after a hot day the fuel tank cools down and will draw in moist air or even rain that is on or near the cap into the tank. This will then cause water to block the fuel line and carb bowl. This can in turn cause fuel starvation,difficult starting and running with possible piston damage to boot.
All two stroke single carb engines used to be fine if you just ran the carb dry at tickover. They will only run lean for a very short time indicated by a slight increase in revs just before they stop. If you notice this its handy just to pull the choke and you will stop it dead with a virtually empty carb but the engine will have a nice coating of fuel left on its bores and bearings. There is no risk of damage to bearings or bore on a water cooled engine.
Please note single carb 2Ts...... dont risk it on a multi carb tower of power...
I have noticed the occasional problem of sticky vapourised fuel residue from new biofuels that sometimes still cause issues with 2Ts even if running empty. So long term storage is best to drain the bowl.
The hated honda 4T suffers more from corrosion of its poorly plated mild steel float bowl than anything else. Always drain this as if it is left for any length of time the total lack of oil in the fuel and any water or moisture in the fuel drains to the bottom and creates a lovely rust soup that will soon clog up the main jet. Honda's worst product ever IMHO.
The other top tip is to always shut off the air tap on the tank, make sure the cap is well sealed and have an engine cover if you store your engine on the rail. If you leave it open then after a hot day the fuel tank cools down and will draw in moist air or even rain that is on or near the cap into the tank. This will then cause water to block the fuel line and carb bowl. This can in turn cause fuel starvation,difficult starting and running with possible piston damage to boot.
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macd
Well-Known Member
Except most road-going stinkwheels have had oil pumps for the last half century, so they did get some oil. And decades ago some racing two-strokes (Bultaco particularly spring to mind, but there were others) were notorious for nipping up when the throttle was shut at the end of long straights.
But with modern oils and a very mild state of tune, you're right that no jobbing outboard is going to have a problem. The only time I've stripped a stroker and not found a beautifully veneer of clean oil was when I could inspect the bottom end through the hole in a piston
Heckler
Well-Known Member
Except most road-going stinkwheels have had oil pumps for the last half century, so they did get some oil. And decades ago some racing two-strokes (Bultaco particularly spring to mind, but there were others) were notorious for nipping up when the throttle was shut at the end of long straights.
But with modern oils and a very mild state of tune, you're right that no jobbing outboard is going to have a problem. The only time I've stripped a stroker and not found a beautifully veneer of clean oil was when I could inspect the bottom end through the hole in a piston
Am aware that modern 2t have pumps BUT said pumps are connected to the throttle cable so that oil injected is proportional to throttle opening
macd
Well-Known Member
Am aware that modern 2t have pumps BUT said pumps are connected to the throttle cable so that oil injected is proportional to throttle opening
Not directly proportional (and not actually very modern, as I mentioned). The pump still delivers oil even with a closed throttle, but not so much.
Heckler
Well-Known Member
Except most road-going stinkwheels have had oil pumps for the last half century, so they did get some oil. And decades ago some racing two-strokes (Bultaco particularly spring to mind, but there were others) were notorious for nipping up when the throttle was shut at the end of long straights.
But with modern oils and a very mild state of tune, you're right that no jobbing outboard is going to have a problem. The only time I've stripped a stroker and not found a beautifully veneer of clean oil was when I could inspect the bottom end through the hole in a piston
Remember selling one of those Suzuki 125 singles to a lad. He brought it back seized. I stripped it, the piston top was spotless as was the combustion chambet and one of the rings was broken with half of it jammed in between the piston and exhaust port. I told him to get on his bike and by the way you owe me £20 for stripping and diagnosing that he had had the head and barrel off, polished/decoked the piston and had not put the ring back in the right position and it had broken causing his woes. He then took me to the Small Claims Court. I hired a specialist engine expert to accompany me. Miladdo lied through his teeth, my expert made him look stupid backing my story. The lay judge didnt even hesitate, case dismissed. I then said, can I say something olease? He said yes. So I said, this lad has cone here, lied through his teeth and it has cost me £50 for the expert (it was 30 years ago) I know that costs arent awarded but it doesnt seem fair that people can do this with impunity (I was that ticked off that I paid a solicitor as well to make sure that we won!) The Judge said, Mr Davies you are quite correct, I cant award costs as such but I am in agreement with you and so I order that miladdo does pay you £50! His face was a picture! He paid me there and then! Then it was time for the bike which was still in my shop. He came to collect it. I was still ticked off so I said storage at x amount per day, plus cost of stripping it etc. I gave him the difference between what he had paid and my bill. He didnt walk away with much!
TSB240
Well-Known Member
Not decades ago son, daughter and self were racing 100cc 2T air cooled kart engines. Typically we could be pulling up to or even in excess of 20,000 RPM depending on the direct gearing set up and the length of the longest straight!
I had to teach my teenagers the art of tweaking the high jet to lean the mixture to the point that the engines started ringing(pinking) as they were racing. You would not have known they were running two stroke engines in the latter stage of a race as there was hardly any smoke from the exhaust.
Karts have a large intake air box just to the right of the steering wheel so that the driver can put a gloved hand over the intake and choke the engine at the point that it might be going to seize usually just at the same time as they brake at the end of a long straight and turn in. This would dump large amounts of fuel into the engine and rapidly cool the piston aand barrel down and prevent seizure until the next lap round.
It also had the effect of stuffing the exhaust and crank case with fuel so that the kart had instant pick up as soon as you pressed the throttle. Instant oversteer on the exit of a corner was guaranteed.
It is no wonder the best F1 drivers learned and still hone their skills with a bit of kart racing.
macd
Well-Known Member
I know little about kart racing, TSB (except that the grip is unbelievable), but think that the hand-choking is for exactly the reasons I mentioned re Bultaco a few posts ago: the extra shot of oil mitigates end-of-straight siezures. I think it lingered particularly in the 100cc class with air-cooled, pre-mix engines, which were especially vulnerable. But I could be very wrong.
Glenlivet
Well-Known Member
Off topic but I have a feeling Barry Sheen came to grief on his flying kettle due to not blipping his throttle on the overrun. Modern 2ts are rather more civilised I think!
macd
Well-Known Member
Very much not. The rear tyre disintegrated at about 180mph during practice at Daytona. The only blipping was performed by his sphincter.
A chastening experience unlikely to befall anyone with a Tohatsu 3.5.
chewi
Well-Known Member
BP told me their Ultimate was ethanol free.
I have heard since of another but I can't remember who it was. If I find out I'll post back to here.
lw395
Well-Known Member
I'm told it's more about cooling, the heat build up due to a long fast section, followed by a slow corner, pushes the limits of an air-cooled stroker. A shot of fuel evaporating cools the piston.
Logically, when the throttle is closed, there's no airflow through the engine removing the oil.
lenten
Well-Known Member
lw395----you could be right but i was given this advice by an out board engineer before that i always disconnected the fuel line from the engine
CLB
Well-Known Member
That's interesting. About 8 or more years ago, BP were quite vocal about having no ethanol in their ultimate fuel. Now there is no mention whatsoever about it. I suspect there probably is now some in the mix. I hope I am wrong because I would buy it like a shot for all my small use petrol motors, as I am fed up with dealing with fuel problems that I think are methonal related. Mower, strimmer, motorcycle, numerous outboards etc etc.
chewi
Well-Known Member
just googled ethanol free petrol...
got this site https://www.esso.co.uk/fuels-faqs
which says:
What is the ethanol content of your fuels?
The majority of unleaded 95 Octane petrol sold in the UK contains up to 5% ethanol as required under the Government’s Renewable Transport Fuels Obligation (RTFO).
There is currently no requirement for renewable fuel (such as ethanol) to be present in super unleaded (97 grade petrol).
Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland). We would therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in Devon or Cornwall, the Teesside area or Scotland.
also found this
https://www.bp.com/content/dam/bp-country/en_au/media/fuel-news/fuel-octane-power.pdf
which says:
BP ULTIMATEBP Ultimate is the highest octane retail fuel that BP has on the market. It has an octanerating between 98 and 100 and does not contain ethanol. It is suitable for all cars but pre1986 vehicles designed for leaded fuel may need to add an additive to prevent valve seatrecession if they do not have hardened valve seats. BP Ultimate also contains a high dose ofadditive to protect the fuel system and to remove deposits that foul intake valves and thecombustion chamber causing poor combustion and knock.
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Praxinoscope
Well-Known Member
If like me you still occasionally use an old Seagull 2stroke, then drain the carb otherwise you have a carb full of two stroke over everything when you tilt it or lift it off to carry it. Don’t know about other 2stroke engines and have never had a 4 stroke.
macd
Well-Known Member
At the foot of that document is information which suggests that it might never have been relevant in the EU, or may not even in its home country anymore:
Document: PET0609.doc Page 1 of 2
Issued: 15TH January 2010
Supercedes: 1st May 2006
BP Australia Limited
That said, my understanding is that ethanol-free fuels are still legal for road use in the EU. The specific legal requirement is for x% ethanol across their share of the applicable market, not in any particular product or tank-full sold.
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