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-   -   Mayot running problems with Brazilian fuel (30% alcohol) - HELP (http://www.horizonsunlimited.com/hubb/yamaha-tech/mayot-running-problems-brazilian-fuel-34401)

*Touring Ted* 8 Apr 2008 21:33

Mayot running problems with Brazilian fuel (30% alcohol) - HELP
 
Does anyone have experience of running brazilian or alchol rich fuel ?????

Im currently in Brazil and having major running problems with my XT600E

It was running fine until I got here and started using the fuel (which is 30% alcohol)

The bike keeps cutting out and feels like its being starved of fuel. It will cut out when I open the throttle to accelerate or overtake trucks.. Sometimes it will just cut out in town and I have to wait a few minutes before it will start again.

Im travelling with 3 other bikes who although they are feeling the effects with poor starting and less power, they are not having problems like me.

I have just stripped the carb in my hotel room and all the jets, pipes clear and diaphrams in great shape (the bike only have 12000 miles). I have also changed the plug and the filter before hand which made no difference.

I am also getting 30% better fuel economy so my guess is that the alcohol is making the bike run very lean.

Im going to change the clip pĆ³sition on the jets and try and richen her up top see if it makes a difference.

Im all ears to suggestions.

bacardi23 8 Apr 2008 22:36

I've heard of people putting more octanes in their fuel...duno if it is a good ideia or not...

How was Buenos Aires?
:funmeteryes:

bruken 9 Apr 2008 10:04

I have no experience of Brazilian feuls.

I have some experience of Zimbabwe alcohol rich feuls. But there if you could just get fuel you were made; so...

Firstly you dont want to add octane boosters. Alcohol / Ethanol tolerates much higher compression levels than fossil fuel.

Ethanol burns much hotter. (Timing may be of issue) For once praise to fuel injection over Carbs :-(

Ethanol will probably eat your rubber components. Ethanol is highly corrosive that way. Tolerance of rubber to EU or common standards is only 10% mix.

Brazil runs "Flexifuel" vehicles. Your bike is probably not.


The calorific value of Ethanol is 55% lower than fossil fuel. Running a "richer mix" is probbly your best answer alongside a hotter spark plug. Watch your engine temp.

bruken 9 Apr 2008 11:37

some more info.

Quoted from Alcohol for Motor Fuels

Blending Alcohol and Gasoline
Mixing alcohol with gasoline produces gasohol. Advantages of fuel blends are that alcohol tends to increase the octane rating, which is particularly important in unleaded fuel, and reduce carbon monoxide (CO) emissions from the engine.

The primary disadvantage of mixing methyl and ethyl alcohol with gasoline is that under certain conditions these alcohols may separate from the gasoline. An engine adjusted to burn gasoline efficiently will produce less power from alcohol should it separate from the gasoline. Separation is caused by the polar nature of the alcohol molecules and their tendency to absorb water, also a polar substance. Methyl alcohol is the most likely to separate, butyl alcohol the least likely. The tendency for separation increases as the temperature decreases, the quantity of water absorbed increases, and the quality of the gasoline decreases.


Figure 2: Gasoline engine full throttle exhaust emissions using ethanol fuel blends.

The effect of using a blend of alcohol and gasoline in an engine adjusted for gasoline is to "lean out" the fuel mixture. This is illustrated in Figure 1 for an engine burning blends of ethanol and gasoline. A mixture of 10 percent ethanol in gasoline produced more power when the carburetor was adjusted for gasoline. Increasing the ethanol content to 25 percent reduced the power output. The test results in Figure 1 were obtained at an elevation of 5,000 feet where an engine adjusted to operate on gasoline is expected to run rich. The 10 percent blend produced a leaner and better air-fuel ratio; the 25 percent blend was too lean.

Because of its higher stoichiometric air-fuel ratio, butyl alcohol can be mixed with gasoline in higher concentrations without affecting performance. Similarly, because of its low stoichiometric air-fuel ratio, only a small quantity of methyl alcohol can be mixed with gasoline without affecting performance. In other words, a fuel blend containing 20 percent methyl alcohol requires modification of the carburetor fuel jets to optimize power output, whereas a 20 percent blend of butyl alcohol does not.

The effect on exhaust emissions of increasing the ethanol concentration in the fuel is shown in Figure 2. The primary effect of ethanol is to reduce the CO emissions. It should be noted that the same effect was obtained using straight gasoline and carefully leaning the air-fuel ratio.

bruken 9 Apr 2008 11:38

Further reading

Adapting your engine for ethanol

*Touring Ted* 9 Apr 2008 11:39

Thanks for the info....

The bike actually runs much worse in the wet too here.

So, iv richened up the secondary carb and ill post back my results...

Working on carbs in a hotel room in tropical heat with a limited tool kit is surprisingly difficult and frustrating :innocent:

*Touring Ted* 9 Apr 2008 11:43

Thanks Bruken, loads of useful infor there to help me sort this !!

:thumbup1:

yhprum 9 Apr 2008 15:34

Did it run better with the choke on? That would enrichen the mixture, at least for troubleshooting.

mollydog 9 Apr 2008 18:21

Since this type of fuel tends to absorb water, is it possible you've simply got a "bad batch" of Ethanol with too much water in it? Maybe drain it and fill up at a different location/brand? When fuel storage tanks get low, the last 10% to 20% of capacity at the bottom tends to have a LOT of water and crud in it.

Maybe talk to locals to find out which brand of fuel seems to work best. As I recall, Brazil used to have regular petrol as well as Ethanol? No? I'm sure you would have found this by now. Or have they converted to 100% Ethanol everywhere?

Checking/adjusting Jetting and mixture:
Using the choke will richen mixture, hopefully enough to determine if that is the problem/solution.

To go the other way (lean) , open the air box cover/door, or pull the air screen out or air filter to add more air flow. (temporarily of course)
Any change? Better? Worse?

If water is in the fuel perhaps you can find products that absorb water from fuel that allows it to be burned and run through? I would think local products would be available since this seems to be a common issue there? Funnily enough, in the US, we use Isopropyl Alcolhol in fuel to remove water! :eek3:
So this gets a bit confusing! :confused1:

I would not change your main jet yet. Remember: it only comes into play at full throttle. I would start with the fuel/air screw first. Simple to get to and simple to change.(AKA fuel screw, air mixture screw, or whatever)
Most bikes have this screw plugged up so you may not have access to it.
But its easy to remove plug.

See if you can get a proper idle and better starting. OUT is richer, IN is leaner.

Warm up bike some.
Turn it OUT/Loosen to richen mixture. The fuel/air screw only affects idle and up to 1/8 throttle opening only. Go no more than two full turns out at most. Adjust for highest/smoothest idle.

Next, adjust needle jet clip position. The needle-jet has a clip with notches. Adjust in the rich direction a notch or two.
Test ride.

Next, try a LARGER pilot jet. (Larger number = Rich) Try one size larger to start.
Test Ride.

I'm sure you can solve this. Handle carb with care.

good luck!

Patrick:mchappy:

*Touring Ted* 11 Apr 2008 00:39

Problem sorted
 
Well, its sorted...

It wasnt the fuel after all.

I changed the needle and got about 50k out of town before the bike completely died...

FUUUUUUUUUUUUUCk !!! Thank god I was with other bikers.

We pushed it back to a gas station and tried to fix it. We couldnt find the problem. I even put it back to standard settings in a petrol station car park in tropical heat (not fun)..

After a couple of hours we decided to hobble back to town and find the local yamaha guru. I BRILLIANT mechanic in town knew the problem.

It wasnt te fuel after all. I have a micro filter in my carb which was blocked. Although I blew though it when i cleaned the cardb, i didnt have the tools available to dissasemble and check it properly. It was cleaned out and now the bike is running fine. Its still a little lean and running hot, but its running !!!

the gas here is shit but you can buy premium fuel at 2 USD a litre which runs good !! Thats what im doing !!

Thanks

*Touring Ted* 11 Apr 2008 00:40

Problem sorted
 
Well, its sorted...

It wasnt the fuel after all.

I changed the needle and got about 50k out of town before the bike completely died...

FUUUUUUUUUUUUUCk !!! Thank god I was with other bikers.

We pushed it back to a gas station and tried to fix it. We couldnt find the problem. I even put it back to standard settings in a petrol station car park in tropical heat (not fun)..

After a couple of hours we decided to hobble back to town and find the local yamaha guru. I BRILLIANT mechanic in town knew the problem.

It wasnt te fuel after all. I have a micro filter in my carb which was blocked. Although I blew though it when i cleaned the cardb, i didnt have the tools available to dissasemble and check it properly. It was cleaned out and now the bike is running fine. Its still a little lean and running hot, but its running !!!

the gas here is shit but you can buy premium fuel at 2 USD a litre which runs good !! Thats what im doing !!

Thanks for all the help.

Frank Warner 11 Apr 2008 00:43

Quote:

Originally Posted by tedmagnum (Post 184042)
I have a micro filter in my carb

DR650s have something similar on the carb inlet pipe... most people remove them and throw them away .. more trouble than they are worth..

aukeboss 11 Apr 2008 05:55

?
 
Dear Ted and XT travellers,

How many times do I have to repeat that this sh*tty little filter should be removed, shot and burned on a bonfire?
It is the XT's only real design flaw .... !

Good to hear your problem is solved!
Auke

Walkabout 11 Apr 2008 09:37

One day
 
Quote:

Originally Posted by aukeboss (Post 184063)
Dear Ted and XT travellers,

How many times do I have to repeat that this sh*tty little filter should be removed, shot and burned on a bonfire?
It is the XT's only real design flaw .... !

Good to hear your problem is solved!
Auke

One day in the future, someday, there will be a technical page over there on the left for bikes, even XTs, that will save you posting this advice every couple of months.
There is some there now, for the DR650 and Beemers.

bacardi23 11 Apr 2008 13:24

Hi.. I found this post here on the forum...

http://www.horizonsunlimited.com/hub...problems-11679

For the 22% ethanol brazilian fuel, the carb should be jetted 9-10% richer than with pure gas.... :cool4:

Vando


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