Put Gasohol In My Two-Stroke!

[ClareQuilty]

The other day I got out my old Yamaha Tiara, a fine, good-running two-stroke, and while it started right away as usual, when I drove down the highway it was a bit rough and had a bad 'dead spot' at certain revs. It did OK just puttering around, and if I could get it just right and it started to rev high then it was great. But at middle revs it just coughed and lost all power, and almost died.

Well, I thought I'd go fill it up with gas just to see if that effected anything, and when I went to the station I very specifically asked for benzine - well it turns out they'd moved the benzine from the pump it used to be at to another one (so they said). Which means the previous visit I filled the poor thing up with gasohol! When I looked in the tank the fuel in there did look kind of weird - cloudy and greenish-grey rather than clear/amber. Is the gas color coded in some way?

Anyway I wonder if I might have done any damage? I immediately filled it up to the brim with good old benzine red 91, and it ran a little better the rest of the evening, but still far from its old self. Will one gas tank of gasohol ruin the fuel system and/or cause internal damage due to lack of lube in an old two stroke?

[cinbkk]

I hate two strokes, filthy machines that poison everyone around them...the sooner they are all off the road the better.

[SidFernwilter]

No problem running your 2 stroke bike on gasohol as long as it's not E85. Red gasoline has a color additive, gasoline is clear/yellowish in your tank it might even look a bit greyish...

[sirhollyBKK]

no motorcycle before year 2000 is gasohol compatible, some models even much later

in general all carburettor engines have plastic or foam floats which will be attacked by ethanol

ethanol and fuel are unmixable unless some kind of detergent like chemical is added, but the mixture isn't long term stable

after several weeks ethanol and water which ethanol always attracts from the environment collect at the tank bottom

when you use the bike again after a long parking period that's what enters the fuel system first and causes the problems you described

drain the fuel tank and the carburettor and refill with 91 gasoline

hopefully the carburettor float and other plastic and rubber parts are not damaged to much

[Travelmate]

Gasohol don't mix well with 2 strokes.

Besides you should be riding something cleaner and modern.

Thought the Government is trying to phase out 2 strokes. Since they are dirty, noisy, messy and downright polluting the very environment we all live in.

[thaicbr]

You should NOT use gasohol in a 2 stroke as the alcohol in the fuel washes the 2t oil off the bores to quickly. If it was 1 time then no problem. standard 91 is a red/pink colour (not clear)

[soundman]

standard 91 is a red/pink colour (not clear)

In-correct thaicbr.

Colours were changed & standardised nationwide at the end of February this year. 91 Benzene (no ethanol) is a clear (straw/faded yellow) colour. Red/pink fuel is B5 diesel oil.

[SidFernwilter]

Yamaha Tiara from -96 and forward will run on Gasohol 91. You will find the complete list from Shell here.

[thaicbr]

Yamaha Tiara from -96 and forward will run on Gasohol 91. You will find the complete list from Shell here.

And you believe that? Blimey that Shell list shows every bike ever produced and sold in Thailand. And yet they are ALL compatibly. WOW.

This is from other sources.

. Gasohol can be used in all car engines manufactured in Thailand since 1995. However, we do not recommend it be used in motorcycles. The reason for this is that cars made in Thailand in the past 10 years are all equipped with fuel injectors, not carburetors.

The Fuel Research Department of the Petroleum Authority of Thailand (PTT) researched the use of gasohol only in fuel-injected engines. We are therefore not sure whether the seals in carburetors - as in pre-1995 cars and as still fitted to most motorcycles - can handle the burning of ethanol. Carburetors contain plastic parts. If these are damaged and leak, an engine fire could result.

Carburetor-aspirated engines will work on gasohol but, for the reason stated, we cannot recommend its use in these engines.

( - Vichitpong Cheanthongsub, PTT Phuket Oil Depot Manager)

CONCERNS ON POTENTIAL RISKS OF GASOHOL

However, Dr Kanit Wattanavichien, head of the Internal Combustion Engine Laboratory, Faculty of Engineering, Chulalongkorn University, is concerned by potential problems caused by using gasohol.

"The guarantees are so vague," he said. "You can't guarantee [a car for use with gasohol] just by the year of manufacture as many consumers may have repaired their cars or changed parts, which may not be original parts and thus cannot sustain contact with alcohol. This can cause mechanical problems and who is going to be responsible for that?" he said. "Cars can run with gasohol, but they need specially-designed parts to support the fuel."

According to him all parts that come into contact with ethanol _ such as fuel filters, pipes, the fuel tank and the fuel injection system _ should be suitable for use with gasohol, otherwise, there may be problems such as rust, perishing rubber parts or clogging of the fuel injection system, reducing the car's performance.

"Very few talk about the potential long term affects. Each car manufacturer should come out to guarantee auto parts for use with gasohol and set standards for these parts to ensure quality and safety for consumers' cars," he said. "Manufacturers should also be ready to take responsibility if motorists report adverse effects caused by the use of gasohol," he suggested.

Ethanol/Gasohol Problems with 2 Cycle Engines

2 Cycle gasoline engines have new challenges when used with gas containing Ethanol.

A 2 cycle engine gets all of its internal lubrication from a special oil mixed with the gasoline. This premix of oil and gasoline can have serious problems when Ethanol is added to the gasoline. Lubricating oil normally creates a bond with the metal components of the engines. The oil molecules create a boundary layer that protects the metal and reduces friction.

When Ethanol is present it will actually get between the oil and the metal, preventing the boundary layer from forming. This results in little or no protection for the moving components, and little or no reduction in friction forcing the engine to work harder, run hotter, and often to destroy itself.

Also many small engines have plastic carburetors, fuel tanks, and other components that Ethanol can soften or dry out which will cause them to fail. Many rubber fuel lines, o-rings, gaskets, and other parts can be delaminated or turned to a gelatin like material often failing very quickly.

Storing this type of equipment with Gasohol (Ethanol blended fuel) can lead to catastrophic failure in a relatively short time.

There are a very small number of additives that can reduce the negative characteristics of Ethanol in the gas.

We recommend that everyone operating 2 cycle engines switch to a pure synthetic two cycle oil.

The synthetic oil will provide the boundary layer lubrication in spite of the Ethanol.

Edited June 11, 2010 by thaicbr

[ClareQuilty]

What's with all the two stroke hatred, guys?  I think if you'd ever driven one of those spritely old bikes you'd speak differently.  They make the new small bikes look like turtles.  Boring as can be.  I actively hated all my previous four strokes (Honda Wave, Suzuki Hayate), but when I got rid of them and started buying old Tenas and Tiaras I experienced the real fun of motorbiking for the first time.  For example when you find sudden unexpected kick-in-the-pants excelleration at 80 kph+ rather than just droning along like in a four stroke.  And, for five or six thousand baht!

Anyway, why should I care about the environoment?  I'm old already.  

By the way the Tiara is running better with each passing day, seems pretty much back to normal.  Thank goodness - perhaps the old girl will be providing thrills and smuttying up the place for another half-a-decade.

Edited June 11, 2010 by ClareQuilty

[enginerevision]

It's just the burning oil that gives the 2 stroke smell. Anyhow for instance a 747-400 plane cruising at 576 mph (927 km/h), burns 12788 liters (3378 US gallons) of fuel per hour !! You know how many planes fly daily? Blaming the two strokes again?

@ TS: One time only doesn't matter much.

[jay1980]

I love the smell of a 2-stroke engine, reminds be of when I raced100cc karts. Hope there are always some about to remind me of this fun time.

[seedy]

The best way to ensure a clean-burning and long lasting two stroke is to be vigilant with the fuel/oil ratio and the fuel/air mixture. Do not add more oil that required - the belief of more two stroke oil equals more lubrication is a fallacy. It is OK to use a little bit less than called for. The reason - adding more oil equals less fuel. Less fuel means a leaner mixture. Leaner mixture means hotter combustion - which leads to overheating and seized pistons. Make sure that the intake tract has no leaks - too much air again/not enough fuel.

In my 3 cylinder Mach 4 we went up 3 to 4 jet sizes in the center cylinder to ensure that it did not seize.

[ClareQuilty]

The best way to ensure a clean-burning and long lasting two stroke is to be vigilant with the fuel/oil ratio and the fuel/air mixture. Do not add more oil that required - the belief of more two stroke oil equals more lubrication is a fallacy. It is OK to use a little bit less than called for. The reason - adding more oil equals less fuel. Less fuel means a leaner mixture. Leaner mixture means hotter combustion - which leads to overheating and seized pistons. Make sure that the intake tract has no leaks - too much air again/not enough fuel.

OK now this is a very interesting reply and I thank you for it. This old Tiara was running a bit so-so when I first bought it - kind of tended to die at low revs. I took it in for some unrelated work to an old man's shop, and I think the old guy sort of tuned it up or adjusted something, because when I got it back it ran totally differently. I had to keep the choke almost fully open the whole time to make it run, but it ran much better, without any tendency to die, and with a much lower idle speed. It seemed however like it might have a slight bit less high-end power.

I'm not sure what he did, but it always seems to me like the old duffers have the knack with these old bikes much more than the young guys.

[seedy]

By keeping it open, I take it you mean no choke i.e. normal running state. If you need to apply - or close - the choke to make your bike run better, this indicates that it is getting too much air - or not enough fuel. A lean mixture. Choke should only be needed for starting when cold, and in a tropical climate you should not need it on for long.

A good way - if a little messy - to check for intake leaks is to warm up bike fully, let idle, and spray WD40 or some such around the intake tract. Any air leaks will be temporarily sealed by the spray, and the idle will increase. This will pinpoint the leak.

By far the best way to tell if the mixture is correct is by spark plug insulator color. On 2 strokes I like a nice chocolate brown. This will carbon up the motor a little faster, but it pays off in long life by the cooler running engine.

[ClareQuilty]

By keeping it open, I take it you mean no choke i.e. normal running state. If you need to apply - or close - the choke to make your bike run better, this indicates that it is getting too much air - or not enough fuel. A lean mixture. Choke should only be needed for starting when cold, and in a tropical climate you should not need it on for long.

No I meant that I have to have the choke lever pulled all the way out - as in it is fully 'choked' in order to run. Sadly I do not know where is the 'intake tract' - I'm ignorant of the parts and their location. But will it harm the bike to be running it the way I am?

[seedy]

If you must have the choke 'on' to make the bike run, you are either not getting enough fuel, or getting too much air. Applying the choke stops air entering the carb, so the mixture is more rich to aid starting. The intake tract is the air filter, manifold, and the spacer between the carb and the cylinder head. It is possible that the carb just needs to be adjusted - there should be a slow speed mixture screw, and possibly a needle which you can adjust up or down for 1/4 - 3/4 throttle. But if you have to have the choke on for full throttle riding, it could be either an air leak into the intake or lack of fuel. It needs to be fixed, as running it lean will melt a hole in the piston crown if allowed to continue.

[VocalNeal]

I hate two strokes, filthy machines that poison everyone around them...the sooner they are all off the road the better.

Besides you should be riding something cleaner and modern. Thought the Government is trying to phase out 2 strokes. Since they are dirty, noisy, messy and downright polluting the very environment we all live in.

I humbly suggest that the two green meanies above should consider kitting themselves a pair of sandals. Or at least answer the OP.

THE SURGEON GENERAL SAYS IT IS OK TO SMOKE THE OPPOSITION WITH TWO-STROKE POWER.

I love the smell of a 2-stroke engine, reminds be of when I raced100cc karts. Hope there are always some about to remind me of this fun time.

Jay if you are in BKK and need a beer.

Ex. #70 100 Intl.

[jay1980]

Hi Neal, I only did club racing in the 100 TKM class, mostly at Buckmore park, sometimes Rye house and Tilbury. Not in Thailand right now but will be for a few months later in the year, catch up then. Cheers

[VocalNeal]

Hi Neal, I only did club racing in the 100 TKM class, mostly at Buckmore park, sometimes Rye house and Tilbury. Not in Thailand right now but will be for a few months later in the year, catch up then. Cheers

Sounds like I'm a bit older.

Lane Kart, K88 with K77 barrel tuned by Brian Steeds. Rye house once or twice but mostly, Rissington, Shennington.Brownhills?, Clay Pigeon once, Fulbeck a couple of times. Oh and Morecambe once.

Then in NA Stock Lite, Yamaha KT100 (obviously)

I go to Pattaya Kart Speedway very infrequently just to see if I have at least some of it left.

[MaiChai]

Most of the soot in Bangkok comes from buses and trucks, plus some from petrol/gas cars and tyre wear. The 2stroke bikes are far and few between now, to be honest. There is actually a revival for the 2strokers and loads of parts available. I have three 2stroke bikes; can't see any point of going for a 4stroke bike unless you go for a big bike or want an auto. Just my 2 cents worth!