anthony96rm250
Member
- Aug 25, 2008
- 64
- 0
bwood said:The lower the number on NGK plugs the hotter. The factory plug for the 96-00 RM250 (according to NGK) is a R6918B-7 and they are expensive $25+. If you have been using BR8ES, the BR8EG will work also. The ES is a standard plug and the EG is a racing plug with a "Fine Wire Nickel Alloy Center Electrode".
But, it really sounds like a mechanical issue weather it be jetting, a leaking right side crank seal, bad reeds or a worn top end. I checked FMF's jetting center and they show similar jetting. Do you have to top your trans oil off often? THis could be a sign you are burning trans oil due to a leaking crank seal, simulating a lean condition.
Also remember that your oil mix and your jetting are two different things. Your oil mix refers to the amount of 2stroke oil in you fuel and the lubricating properties of the mix. 32:1 (16oz of oil to 4gal fuel) is 32 parts fuel to 1 part oil and 40:1 (16oz of oil to 5gal of fuel) is 40 parts fuel to 1 part oil. The more oil you run in the fuel, the better the bottom end and rings will love you.
Your jetting refers to how the carb mixes the fuel/oil mix and air that feed you cylinder. A rich mixture is a fuel to air mix with excess fuel. This will put more fuel/oil mix in the cylinder than it can burn at a certian rpm. Running rich generally will not hurt an engine, nut it can have plug issues and excess exhaust spooge. Running an engine lean means the fuel to air mix has excess air and is using less fuel for combustion, but remember less fuel in the cylinder means less lubrication. Running an engine lean will cause premature failure of the bottom end, piston/rings and possibly powervalve components. Also it can cause overheating and inconsistant performance (mainly due to overheating).
My 99 CR250 was a little lean on the bottom end to allow low speed woods riding w/o loading up and blubbering when it was time to open it up. Then was more rich on the top. I always used the BR8EG, it was also the stock plug.
I would start with failed parts first (ie crank seal or reeds), then doulble check the reeds. I believe there are some jetting links somewhere in the "sticky posts". Search them and see what you find. I would also recommend a service manual of some sort if you don't already have one. A Clymer manual will run you $32.95 at Tucker Rocky dealer (most bike dealer a TR reps).
bwood said:Just looking at it from the exhaust/intake port doesn't mean everythingis ok. I just means nothing is tearing up the piston and cylinder yet. The way to be sure would be to remove the cylinder head an check ring gaps and clearances.
How long have you owned the bike?
How often do you ride?
What have you done to it since you bought it?
These are some things to think about when guessing/estimating the wear on engine components with out tearing it down for inspection. When I rebuilt my 99CR, I torn the top end down about once every two months just to see how it was all wearing. I rode a couple times a week and raced some cross country about once a month or so, sometimes more. I found that about the 5-6 month mark things were wore enough to replace. I made this the standard for my bike and style of riding. If you are spending time in dusty sandy conditions like desert riding wear my be increased.
bwood said:Ok clean you air filter. Its easy, you should do it every time you ride in any kind of dusty conditions, the oil will begin to breakdown over time which can cause the filter to do the same and it is you first defence in protecting the engine. Has it been fouling plugs since you got it?
bwood said:If you are positive its not the crank seal or reeds, definitely look at jetting. I would check the jetting sticky link http://www.dirtrider.net/forums3/showthread.php?t=42618 and go from there. Jetting definitely changes with altitude. An owners manual will usually show necessary changes in a jetting chart.
_JOE_ said:What fuel are you running?
bwood said:If you are positive its not the crank seal or reeds, definitely look at jetting. I would check the jetting sticky link http://www.dirtrider.net/forums3/showthread.php?t=42618 and go from there. Jetting definitely changes with altitude. An owners manual will usually show necessary changes in a jetting chart.
yeah dont have money for it and it runs great anyways maybe later ,,_JOE_ said:I think so too. I would replace them just due to the age and price. I would suggest a leak down test and new top end as well.
bwood said:One more thing, I would recommend always using the highest octane gas you can get from the pump (here is Texas is 93). Most MX bikes are designed for 91-92 octane minimum.
anthony96rm250 said:i cleaned the air filter ,, what will cuase a leaner running getting more air into the carb,? or other way ?
i put the airfilter back on and ran it with used br8es br8eg br10eg plugs "i cleaned them " they all ran for a while bogged down and it shut off , maybe the air filter is causing richer mixture
dirt bike dave said:A dirty filter or an over oiled filter will make the bike run rich.
BTW, cleaning an old plug does not always make a bad plug work again.
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