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2004 RM250


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Hey everyone, just got myself a 2004 RM250 a few weeks ago and been having a blast riding it!!!

 

I've been running the oil at 30:1 with Maxima Castor 927 and its very smokey.. the previous owner was running it at 40:1 because he said it fouled plugs running more oil..  I thought I would do what the manual says. Today I fouled a plug within 2 minutes of riding after filling up the tank (30:1) and replaced the plug and it ran fine for the rest of the day (probably only like 30 minutes more of total riding lol). I was wondering if you guys think I fouled the plug because I am running to rich an oil content?

 

On another note, ( how it runs). I've noticed the bike has a powerful midrange hit but the power goes away very quickly if I turn the throttle any more. It seems I need to short shift quite quickly and I run through the gears rather quick. This is my first 2 stroke bike so I am new to how they act but I've always had this stereotype in my mind I guess that they rev to the moon and most of the power is in the very high rpm ranges. My bike does have the stock pipes on it and I've done some reading and I think this is the reason why I am having to shift so soon because the power is low and has a short midrange powerband. Dont get me wrong, the bike is plenty fast but I just kind of wish I could stay in each gear longer. I do not race but I do ride some preety open trails that I can go fast on. I think I might need a new pipe...but I've read this calls for rejetting and I have left the carb alone so far. My mechanical knowledge is preety basic but I want to learn and have a passion for this new hobby!

 

So far what I've done to the bike

 

Changed the gear oil with Honda Pro 80w85w, drained and changed the coolant with PEAK 50/50 diluted from Ace, need to bleed brakes and change brake fluid with DOT 4..

 

put on a new Twin Air filter with PC Racing gasket, Devol skid plate, and I'm about to replace the entire drive train with 13t and 50t JT Steel sprockets and a DID 520 VX2 X-ring chain

 

I've also shaved off the old layer of plastic with a razor blade and sanded it to make it smooth (almost looks like new plastics!) 🙂

 

If you guys could give me some feed back on what I could do to the bike to make it better and on how its running I'd greatly appreciate it.

 

I will try to post pictures soon!!!

 

 

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The coolant needs to be formulated for the aluminum radiators, the Peak you put in is Dex cool compatible meaning it is going to eat up all the seals/gel up. It is not designed for motorcycles, buy Honda coolant, Yamaha or some with the formula for aluminum radiators that can be a costly mistake. That coolant has silicates and will eat the seals, plus mixing the residue from the 'non-silicate' is another disaster.

 

The coolant from Honda/Yamaha or some other vendor is not very much compared to the damage auto coolant is going to do.

Edited by ar2stroke
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Most likely you fouled a plug because the jetting is off (assuming the engine is in good mechanical condition). Now would be a good time as ever to learn jetting...

Or drop 2 sizes in the main and pilot and raise the needle as a starting point...

 

Every Suzuki I've owned seems to like those similar kinds of jetting changes.

 

On my 03 RM250 I have gone to the next leanest pilot and needle, set needle to 3rd clip position, bought a #7 slide, 2 sizes leaner on the main, air screw 1.5 turns out, run premium gas with klotz octane booster to about 100 octane, and run oil at a 33:1 ratio. I also run the stock plug with the gap in spec, I've had a couple bikes that benefited from going to a hotter plug but my 250 doesn't seem to need it, and that is one of the last things to resort to changing if you ask me. As the temperatures increase I will be going leaner on a couple of those jets as well.

 

I've found a number of octane boosters that all seem to perform similarly, but I have always had good experiences and a better running engine once I have started using them. I wouldn't say you have to use high octane gas, but at least use the best premium pump gas you can.

 

Best way to learn jetting your self in my opinion is to pick up an owners manual if you don't already have one, learn it well, and start tuning from the low speed jets and up like the manual suggests. Make small changes one at a time. If you are truly worried about running too lean and seizing your engine up always err on the side of slightly rich. Better to spew a little smoke and foul plugs than to burn up your engine right?

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I agree with Monk on the jetting. Before you get carried away, you need to get as much information as possible on jetting techniques, or pay a professional to assist the 1st. time. Jetting can be a very expensive learning curve.

Thanks for the info, the problem is The shop downtown does not work on Suzukis anymore I think because they stopped selling them.. I really want to learn how to do it myself but yea ..I am on a very tight budget Edited by bigislandboi
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The coolant needs to be formulated for the aluminum radiators, the Peak you put in is Dex cool compatible meaning it is going to eat up all the seals/gel up. It is not designed for motorcycles, buy Honda coolant, Yamaha or some with the formula for aluminum radiators that can be a costly mistake. That coolant has silicates and will eat the seals, plus mixing the residue from the 'non-silicate' is another disaster.

The coolant from Honda/Yamaha or some other vendor is not very much compared to the damage auto coolant is going to do.

thanks for telling me this man!!! I will dump the coolant I am using and replace it with something from a dealership that sells dirt bikes downtown ASAP! I'll make sure it's compatible with aluminum radiators
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Every Suzuki I've owned seems to like those similar kinds of jetting changes.

On my 03 RM250 I have gone to the next leanest pilot and needle, set needle to 3rd clip position, bought a #7 slide, 2 sizes leaner on the main, air screw 1.5 turns out, run premium gas with klotz octane booster to about 100 octane, and run oil at a 33:1 ratio. I also run the stock plug with the gap in spec, I've had a couple bikes that benefited from going to a hotter plug but my 250 doesn't seem to need it, and that is one of the last things to resort to changing if you ask me. As the temperatures increase I will be going leaner on a couple of those jets as well.

I've found a number of octane boosters that all seem to perform similarly, but I have always had good experiences and a better running engine once I have started using them. I wouldn't say you have to use high octane gas, but at least use the best premium pump gas you can.

Best way to learn jetting your self in my opinion is to pick up an owners manual if you don't already have one, learn it well, and start tuning from the low speed jets and up like the manual suggests. Make small changes one at a time. If you are truly worried about running too lean and seizing your engine up always err on the side of slightly rich. Better to spew a little smoke and foul plugs than to burn up your engine right?

thanks for the reply man! Yes I do have an owners manual for my model. But yeah I am worried about making it too lean like you say but at the same time I would really like to dial it in to the point where the smoke is not so excessive and it doesn't foul plugs. U think i should be okay and not make any big mistake if I just make small adjustments? Edited by bigislandboi
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Most likely you fouled a plug because the jetting is off (assuming the engine is in good mechanical condition). Now would be a good time as ever to learn jetting...

Or drop 2 sizes in the main and pilot and raise the needle as a starting point...

Cool man thanks, yea I agree with you.. Now would be a good time to learn . I probably need to clean the carb anyway ..
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thanks for telling me this man!!! I will dump the coolant I am using and replace it with something from a dealership that sells dirt bikes downtown ASAP! I'll make sure it's compatible with aluminum radiators

 

Anytime :ride:

 

They got like Yamacool and others, it is premixed so you don't even have to worry about mixing it.

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thanks for the reply man! Yes I do have an owners manual for my model. But yeah I am worried about making it too lean like you say but at the same time I would really like to dial it in to the point where the smoke is not so excessive and it doesn't foul plugs. U think i should be okay and not make any big mistake if I just make small adjustments?

If you just make small changes and pay attention to how the bike is running, things like throttle response, engine sound (dull or crisp), exhaust smokiness you should be able to tell the effects of what you adjusted. You'll only be able to tell the true changes once the engine is warmed up completely and being ridden. When you're done running the bike after you change jets check the plug color. As long as it doesn't appear to be baked white you are still in the clear. The plug should look slightly oil stained. I'm sure there are pictures out there that show what a good running 2 stroke spark plug should look like color wise. Enjoy the Suzuki.

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Since the very late 80's tried out VP race fuel, it was a lot less back then than today. But on that note, it does burn cooler and it is consistent without any of that garbage ethanol or other oxygenated additives. The top end/bottom end lasts longer as well, it is more money but long term I am sold on leaded fuel (what they were designed for to begin with). Also, always ran Maxima Castor 927, sold on this combo depends where someone lives and one can get a good discount on leaded fuel.

 

Living down south it is more humid, with the leaded fuel keeps the engine from detonation from hot humid weather. 

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If you just make small changes and pay attention to how the bike is running, things like throttle response, engine sound (dull or crisp), exhaust smokiness you should be able to tell the effects of what you adjusted. You'll only be able to tell the true changes once the engine is warmed up completely and being ridden. When you're done running the bike after you change jets check the plug color. As long as it doesn't appear to be baked white you are still in the clear. The plug should look slightly oil stained. I'm sure there are pictures out there that show what a good running 2 stroke spark plug should look like color wise. Enjoy the Suzuki.

Cool man I got an experienced motorcycle friend helping me, I think we're gona figure it out!

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Since the very late 80's tried out VP race fuel, it was a lot less back then than today. But on that note, it does burn cooler and it is consistent without any of that garbage ethanol or other oxygenated additives. The top end/bottom end lasts longer as well, it is more money but long term I am sold on leaded fuel (what they were designed for to begin with). Also, always ran Maxima Castor 927, sold on this combo depends where someone lives and one can get a good discount on leaded fuel.

Living down south it is more humid, with the leaded fuel keeps the engine from detonation from hot humid weather.

I'm not sure if I can get race fuEl anywhere near me lol. I try to run the highest octane non ethanol gas I get at the marina

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