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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc. |
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#1
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i keep fouling spark plugs???
2 weeks ago i bought a 250 supermotard sm 2002 and ever since i got it home it has been fouling spark plugs.
i got it from a friend who has said he never had a problem with it but i have only been able to get a few miles out of it before it fouls the plug. i have had a look through some other threads but still would like any advice that people can give me. so far i have gone through a few different plugs but the same thing happens every time. plugs tried - BR8EG, BR8EVX, BR9IEX, BR8ES AND B8EG tonight i have taken the carb off to check the jets and have a 185 and 40 in there with a #7 slide, the needle was on the 3rd position out of 5. i have read that it should be on the 2nd but dont know if that means from the top or bottom out of the 5 that are on it. i also read that a ltr jet kit would help or it could even be the cdi unit but dont know where to start so all in all im a bit stump and any suggestions would be great |
#2
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Quote:
I run my 300 on 180 main, 42 pilot. Main in middle clip. Motul 800 at 45-50:1. Powercore2 muffler. All cool. Mark |
#3
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I,d say look at crank seal on gearbox side maybe sucking oil in has this bike been stored before you got it doe's it smoke a lot????
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#4
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it wasn't stored but only used as a bit of fun at weekends, only smokes a bit till warmed up then looks fine. If the seal has gone how would the plug look because it doesnt seem to be oiled up at all
Last edited by tom-s; 08-24-2009 at 01:30 PM. |
#5
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I would think for an SM you need slightly different jetting to dirt. Very likely slightly larger main but the rest could be a tad leaner with a larger main. I don't know that for a fact though. Just thinking you'll be spending more time on the main than dirt bikes and you don't want to run too lean / hot.
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#6
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I think the OP said he was running a 185 main. That is pretty large.
I have a 1998 EC250SM conversion. I am running the LTR supplied needle in the third clip down from the top. With a 178 main and a 45 pilot. Using a #7 slide. I have VERY little spooge out the pipe and I have never fouled a plug. It idles smooth and seems to me. To pull well in a linear drive. The only time it sees any real throttle is on acceleration from a stop light or up a hill. I use mine as a street putting fun machine. In a steady 50mph cruise. I'd guess the throttle is not open more that 1/8-1/4 of the way. I think my gearing is a 14/47. I do re-pack the silencer fairly often though. Maybe every 300-400 miles, or less. BTW, I am @ sea level most of the time. With canyon rides up to 3,500-4,000ft. YMMV, Jeff, So. Cal. USA |
#7
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My '00 XC250 would foul the plug almost every time I rode slow like a long downhill or following my son (when he was young!) or maybe like riding in traffic? (plus excessive spooge) The LTR kit needle change made a huge difference but the weird part was the idle jet went from a 42 to a 48 (??) Don't ask why but with the needle it works real well. He had supplied a 175 main jet but the original 185 worked best for me. I know that is against what most folks here run but I wonder if the earlier "XC" bikes had some type differant ignition curve?
I get almost no "spooge" when I ride it like it is intended to be rode. I also use the B8EG (?) non-resistor plug and have never fouled a plug since and that has been about 7yrs. And I used to use 2 or 3 per day. ($$!) edit.. I do have a #7 slide too.
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jeff '00 XC250 (mine) LTS front and rear suspension, power valve cover, carb jet kit and rear chain glide, RB Designs head mod, BRP tall triple clamp, backyard foot-peg lowering conversion. '04 EC250 (the kids) (he can do his own mods haha!) |
#8
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What do the fouled plugs look like? I would be tempted to move the needle clip position one higher (drops the needle more, is leaner at 1/4-3/4 throttle position) to see if that improves things.
What's the mileage on the bike - it could well be the emulsion tube in the carb is worn (wears from the needle rubbing on it) which would make it run rich I guess a 2002 SM may of had a lot of use. I don't think it's possible to replace the emulsion tube however it woudl be possible to re-jet around it. Also what needle have you got - remove it completely the numbers on the side and check for any signs of wear scuffing scratches etc. Incidentally iriduim plugs have the best resistance to fouling though cost a bit more but it sounds more like you ned to sort out whatever is causing the problem in the first place...
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'05 Gas Gas 300 '97 Aprilia Pegaso 650 '99 KTM 200 '95 ish XR630 (died many times in Oz) |
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