FUEL ADDITIVES FOR OLDER BIKES ?

[wiseman]

Was wondering if any of you guys out there put fuel additives in your gas tank.
What i am referring to is, in Australia, we no longer have "leaded" fuel,   only Unleaded (ULP), which is equivalent to standard, 92 octane or premium, 95 octane.                              This has not been available and was banned since about late 80's, so all vehicles made after this were made to run on unleaded fuel.
The lead in our leaded fuel was for top end, valve stem lubrication, so now if we run unleaded fuel in a leaded fuel motor, your valve stem seals wear out much quicker, then you start to blow smoke.  One solution is to have any old engine head converted to run on ULP, by having the standard valves and stem seals replaced with hardened ones.  Same as a car if converted to run on LPG gas.  I know you can buy lead replacement additives, but i think these are just a waste of money, cause it's not lead you are adding.
My solution when running an older engine that requires leaded fuel, is just to add a bit of 2 stroke oil to the fuel, much cheaper, and does the same job.
I had an old Triumph 650, used to BP 100 in it, racing fuel with an octane of 100, and contained lead. Best fuel i ever used! no pinging in the motor.
What fuel you guys have in the States, and what octane rating, leaded or unleaded?

[shinyribs]

You got us beat on octane for sure. We have 87 standard,89 mid-grade and 91 premium.Some places'  premium may be 92 or 93 octane instead. In the States they started phasing out leaded gas in '73. But it wasn't officially banned until 1996,and then only in pump gas,or on-road gas.Off-road fuels could still be produced with lead-race fuel,aircraft fuel and even some marinas sold leaded gas still for boat owners. But for the most part,since the early 70's leaded gas has been scarce,or more or less nonexistent.

[TOOLS1]

Also the gas here in the states also has ethanol alcohol in it. This causes a lot of problems as it will attract water, and eat older rubber parts. I always add octane booster to my gas. If I don't it will ping, and knock. I have been told that adding diesel fuel will increase octane, and and add lead.
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[Re-run]

Actually they do not have us beat on octane. The rest of the world uses a different system. They use RON for the measurement. The US does it different but ultimately they even out.
Also, for these bikes, Japan knew this was happening, our valve seats are hardened so unleaded gas is no big deal.

[sgtslag]

I read somewhere that adding oil to a four-stroke engine's gas is bad because the oil will not compress (it may not atomize as easily as gasoline?).  I don't know enough to say more than that I would recommend discussing it with a trusted mechanic.  I would also recommend you discuss your unleaded gas concerns with said mechanic.  Cheers!

[shinyribs]

Oil in the combustion chamber can be bad. Y'all know I am no motorcycle mechanic as this is all still fairly new to me,but I do know a fair amount about V8's. Especially high performance ones. I consider the motor of a CB750 to be a high performance engine.The HP per cu. in. of these bikes is phenomenal IMO. Roughly 1.5 HP/cu.in. Thats pretty impressive!

With the nitrous and blown motors we have run in the past there were two number one killers of pistons,and therefore engines. And that was oil in the combustion chamber. The oil deposits dont want to burn off as quickly as the gasoline does.When it does decide to ignite it would either cause preignition or it would pop the top of the pistons off. The preigniton is a result of the oil firing,basically at random.The out of sequence firing will try to drive the piston down (as it should) but while the piston is trying to go up since it was out of sequence. Hammered out rod bearings and cracked piston heads are the result. Oil puddling around the top compression ring trying to ignite will cause that ring land to pop off.

Of course all of that is worst case scenario,but it is the result of oil in the combustion chamber. I have seen engine run on oil alone.A buddy had one puke out an intake gasket under high boost and the oil it started sucking in thru the lifter valley wouldn't let the motor die even after he killed the ignition. Compression firing like a diesel engine.

We've all seen or owned an engine that burns oil from worn rings.So it is obviously not a time bomb exactly,but not really a good thing either.

[TOOLS1]

Why aren't all those two stroke engines blowing up? They put oil in the gas, don't they?
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[shinyribs]

Hey man,I said I wasn't a bike mechanic!!

That was running through my mind while is was typing.Good question

[cdaiscool]

You never want to let oil get into the combustion chamber of a 4-stroke motor. Just because they're both motors, doesn't mean one is compatible with the other. Here's a nice link about each:   http://www.deepscience.com/articles/engines.html

[seestheday]

Ethanol is our gas really pisses me off.  We have it in Canada too.

Worse for the environment, worse for our engines, worse performance, costs more money after you account for the subsidies..  Seems to be the only reason we do it is to find a way to somehow burn through the massive subsidized corn stockpile that gets bigger every year.

[wiseman]

Hi Guys, and thanks for the many replies. I have ridden the bike on unleaded and there is no difference in performance, compared to leaded fuel with the same octane rating.
I guess my choices are to buy lead replacement to add to the fuel, this is sold as a "valve stem lubricant".
Octane booster is not really necessary, as we already can get 95, or i think i have even seen premium at 98 octane.  We also have E10, Ethanol fuel, it is cheaper, but i stay away from that, even in my car!  Aviation fuel would be the best, if we could afford it !  The last time i purchased a 20 liter drum, i think it worked out  about  $2.50 Au a liter. The price of our premium here now (95) octane is about $1.60 a liter,  with a 20 liter gas tank, works out at $32 to fill my bike.  I have only had one test ride on it so far, (15 miles), and don't really plan to keep this one long term.
Looking to go back to an old Triumph in the future, this CB750 is just way to heavy for me to maneuver around.  (300KG) with fairing and panniers, dry weight, then add another 20KG of fuel, and engine oil, plus anything you have stored in the panniers. If it fell over, i could never pick this bike back up alone, (i am nearly 50!)
I have had other bikes that require leaded, and i have run them on unleaded without problems,  i heard it would take around 30,000 miles before any major wear starts to occur.
When i talk about adding two stoke oil to the fuel, (synthetic), im talking only a very small amount, maybe a tea spoon or two per full tank.  Cars add these "lead replacement" additives at about 50ml to a full tank (50 to 70 liters of gas).
Very interesting to read your comments about the different fuels in different countries.  Here we can still go to the local airport and buy avgas, (aviation fuel), 100 octane, and i think it still contains the lead, or a lead substitute.
Buy adding a spoon full of two stroke oil to the fuel, the only difference i have noticed over the years, on many old bikes,  is,  you blow a tiny bit of blue smoke, but it smells great too!
Cheers to all from Australia
thanks for the replies so far!
Sorry about the liters and Kilograms, but i don't know the conversions for gallons in fuel and pounds in weight.