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High consumption - RM250 '98

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Hi,

my RM250 1998 has a really high consumption, I would like to know if this is normal or what can I do about it.

 

During a 2 hours ride it used 1.8 gallons when at the same time my friend's CRF 450 used 0.6 gallons.

 

Any ideas?

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That is a lot of fuel. I usually can ride my 98 for 2 hours and barely notice a difference in fuel level. How does it run?

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I think this all depends on what sort of riding you are doing- in my experience an RM will always use more than a CRF, at least double (more if it's one of the latest generation CRFs), while 1.8 gallons in 2 hours is pretty low to me- I did a 2 hour race today and used somewhere around 12-15 litres, in the worst case (fast events on sand) I expect 8 litres per hour. For more range there are big tanks available, it might be worth considering them.

 

One further thing, is there much ethanol in the fuel in Brazil? Some european fuel is 10% ethanol now & it seemed to affect my road bike's mpg quite badly. 

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Actually the fuel consumption for the RM250 seems reasonable.  I know that I can drain a stock RM250 (2.1 gallon) tank in 2 hours, so it's entirely possible that you are too.  At the same time, if the CRF450 rider is riding a gear higher, using the low end power of a 450, then it's also possible that he only used .6 gallons ~ not likely, but "possible".  So again, if the RM250 rider is screaming it and the CRF450 rider short shifting then that's the difference.

 

If the RM250 needs to go farther on one tank then learn how to ride a gear higher (like ... use 3rd more than 2nd) or buy a larger gas tank.  IMS makes a nice 3.0 gallon tank for this bike, if you need more range "buy it", you'll hardly notice the extra size ~ except when you fill it or notice how much farther you've ridden on one tank.

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That is a lot of fuel. I usually can ride my 98 for 2 hours and barely notice a difference in fuel level. How does it run?
It runs really good but sometimes loses power at a certain high rpm with 100% throttle. I believe the reason is because it is running rich.What size main jet do you have?
I think this all depends on what sort of riding you are doing- in my experience an RM will always use more than a CRF, at least double (more if it's one of the latest generation CRFs), while 1.8 gallons in 2 hours is pretty low to me- I did a 2 hour race today and used somewhere around 12-15 litres, in the worst case (fast events on sand) I expect 8 litres per hour. For more range there are big tanks available, it might be worth considering them.One further thing, is there much ethanol in the fuel in Brazil? Some european fuel is 10% ethanol now & it seemed to affect my road bike's mpg quite badly.
Yes, I would expect a higher consumption than the CRFs, but I was surprised on how fast that tank gets empty.Fuel in Brazil has 22% ethanol.
If the RM250 needs to go farther on one tank then learn how to ride a gear higher (like ... use 3rd more than 2nd) or buy a larger gas tank. IMS makes a nice 3.0 gallon tank for this bike, if you need more range "buy it", you'll hardly notice the extra size ~ except when you fill it or notice how much farther you've ridden on one tank.
I'm considering an oversized tank as a B plan. First I would like to adjust the jetting so that the bike has the right consumption, because I think it might be running too rich. How does the jetting affects consumption? If I use a smaller Main Jet (current is #170), should I expect a difference in consumption and fix that power 'hole' I have with full gas high rev? Edited by David_Luz

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If you are using a fuel with 22% ethanol then there's no way you can go smaller on your jets, ethanol enriched fuels do not as much energy as pure gas fuels so you need more of it to be equal.  See if you can find a "pure gas" fuel.  Otherwise your going to have to live with crappy fuel mileage, that's what ethanol fuel does.

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22% ethanol... I thought I'd heard that about Brazil before which is why I mentioned it. I've never encountered fuel like that - a quick Google found me http://www.raceone85.com/ which refers to 15% ethanol fuel and advises 

"No matter what type of fuel system you are running you must increase flow (volume) by roughly 30% over a (gas) setup. This is more than just increasing the main jets (in a carburetor) by 30%. Flow must be increased throughout the whole system and fuel curve."   

 

Hoepfully you can get some 0% ethanol fuel, or find someone local who has experience of setting up a race engine to run on the current stuff. 

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If I was you I would use Avgas.

I would imagine it would be easy to get in Brazil.

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I agree that gas mixed with ethanol requires more flow and that means a higher consumption. Here in Brazil we have the gasoline with 22% ethanol (E22) and just ethanol 100% (E100). Most cars have what we call 'flex fuel' engines, which are made to work with E22, E100 or any blend in between that in the tank. Normally a car using E100 will use 30% more fuel than the same car using E22.

If the engine was running clean I would think the consumption is normal and wouldn't be complaining. But it has these 'power gaps' with 100% throttle and rpm from mid to high.

Question... What are the symptoms of running rich or lean?

Can these power gaps be caused by too rich mixture?

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Anyone who is running 22% ethanol through their two stroke motor, is an idiot. That amount of moonshine in ill damage your crank bearings. I run fuel with no moonshine, I race XC with my RM, and it uses 6 litres per hour. At the pure sand course we run, it's close to 8 litres per hour, which is almost a full tank.

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Then I might be an idiot. And will continue to be. Like I have an option since it is the fuel available all over the country.

If you have the correct amount of 2 stroke oil in the fuel it won't harm anything more than with pure gas. Makes no sense.

By the way, I'm not the only rider. There are many many riders in the country, using the fuel available at the gas stations... 22% ethanol. Thanks for the advice.

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Then I might be an idiot. And will continue to be. Like I have an option since it is the fuel available all over the country.

If you have the correct amount of 2 stroke oil in the fuel it won't harm anything more than with pure gas. Makes no sense.

By the way, I'm not the only rider. There are many many riders in the country, using the fuel available at the gas stations... 22% ethanol. Thanks for the advice.

 

David, you are most definitely NOT an idiot, 717 MOTORSPORTS is the small minded idiot here.  Clearly he doesn't understand that different countries have different fuel laws, and in your case Brazil has a mandatory E22 requirement that you have to deal with. 

 

There was one suggestion (if possible) for you to try to use some small airplane fuel (AVGAS), smaller piston engine planes run a pure gas 100 octane fuel (or about that octane), so is it possible for you to buy and run that?  Other wise I'm sort of out of suggestions as you are being forced to use a fuel that just about all of us have zero experience running.  I have heard that because ethanol is a higher octane fuel, so it can handle more compression which in turn will give you the ability to squeeze more power out of your engine... but your mileage will go down even more.  Does your dealership have any suggestions?

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David, you are most definitely NOT an idiot, 717 MOTORSPORTS is the small minded idiot here.  Clearly he doesn't understand that different countries have different fuel laws, and in your case Brazil has a mandatory E22 requirement that you have to deal with. 

 

There was one suggestion (if possible) for you to try to use some small airplane fuel (AVGAS), smaller piston engine planes run a pure gas 100 octane fuel (or about that octane), so is it possible for you to buy and run that?  Other wise I'm sort of out of suggestions as you are being forced to use a fuel that just about all of us have zero experience running.  I have heard that because ethanol is a higher octane fuel, so it can handle more compression which in turn will give you the ability to squeeze more power out of your engine... but your mileage will go down even more.  Does your dealership have any suggestions?

Obviously Im not the idiot, if you're agreeing with me, and telling him to use av gas you hypocritical goof!  22% ethanol is not safe to use in a 2 stroke...period!!! Do your research on ethanol. Im quite sure you'll find quite quickly that fuel containing any alcohol over the amount of 10% is not recommended in a two stroke engine, as it will wash the oil off of all metal, including the bottom end. If that is the only fuel you can run, I guess that is what you have to deal with.There is now, I hear an oil which does mix with ethanol fuel.... Ethanol when mixed with gas will produce a higher octane, BUT!!! it produces up to 30% less energy, so no power is gained...

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Obviously Im not the idiot, if you're agreeing with me, and telling him to use av gas you hypocritical goof!  22% ethanol is not safe to use in a 2 stroke...period!!! Do your research on ethanol. Im quite sure you'll find quite quickly that fuel containing any alcohol over the amount of 10% is not recommended in a two stroke engine, as it will wash the oil off of all metal, including the bottom end. If that is the only fuel you can run, I guess that is what you have to deal with.There is now, I hear an oil which does mix with ethanol fuel.... Ethanol when mixed with gas will produce a higher octane, BUT!!! it produces up to 30% less energy, so no power is gained...

 

 

We've had this argument before but I know you're a slow learner. 2 strokes can run on straight ethanol, and make more power, with big jets and poor fuel economy. There are plenty of high performance karts that do it

But, it is a pita and not worth the hassle in my eyes. But for you to say a 2 stroke can't be run on 22% ethanol is ludicrous. Optimum no, but definitely possible..

 

OP like I said, get some avgas from your local small airport.100ll, the blue stuff. You and your bike will be much happier for it.

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Obviously Im not the idiot, if you're agreeing with me, and telling him to use av gas you hypocritical goof!  22% ethanol is not safe to use in a 2 stroke...period!!! Do your research on ethanol. Im quite sure you'll find quite quickly that fuel containing any alcohol over the amount of 10% is not recommended in a two stroke engine, as it will wash the oil off of all metal, including the bottom end. If that is the only fuel you can run, I guess that is what you have to deal with.There is now, I hear an oil which does mix with ethanol fuel.... Ethanol when mixed with gas will produce a higher octane, BUT!!! it produces up to 30% less energy, so no power is gained...

 

You just don't get it.  The OP lives in Brazil ... ! ... get it??  He doesn't have access to a fuel that's below 22% ... get it??

 

This is why tribalbc rightly suggested AVGAS (not sure if he can get that), but it is a valid suggestion that I hope the OP can check into.  If it's hard to get, but still possible ~ he could consider mixing it 50/50 which would bring it down to a more reasonable (but still high) 11%.  The only other thing that I can think of is to talk with his local dealership.

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Do either of you two hypocrytes happen to read what the fug you type, before posting?? You go, and make out I don't know what the hell Im talking about concerning ethanol, and two strokes, which I do, and obviously more than either of you. THEN!!! You turn the fq around, and in the same post tell the guy to find av gas. LOFL!!!!

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tribalbc and zig06, thanks for the advices. I'm sure avgas is easily available here, might be worth a try. It all depends on the cost, if it is TOO expensive I might have to sacrifice some mileage and keep running with E22 fuel, which I know will do no harm to the engine. That's what EVERYONE runs here in dirt bikes and I've never heard of any issues.

I was just surprised about the consumption at first, but if this is normal as a few people said then fine, I'll live with that.

 

For the other guy, I'll ignore. Nothing useful coming from him, just talking shit.

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tribalbc and zig06, thanks for the advices. I'm sure avgas is easily available here, might be worth a try. It all depends on the cost, if it is TOO expensive I might have to sacrifice some mileage and keep running with E22 fuel, which I know will do no harm to the engine. That's what EVERYONE runs here in dirt bikes and I've never heard of any issues.

I was just surprised about the consumption at first, but if this is normal as a few people said then fine, I'll live with that.

 

For the other guy, I'll ignore. Nothing useful coming from him, just talking shit.

go ahead, and ignore me..., but keep running that 22% shiit, and have a good time rebuilding bottom ends

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go ahead, and ignore me..., but keep running that 22% shiit, and have a good time rebuilding bottom ends

Yep. Thanks. I love rebuilding engines.

Go find another post to comment.

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