1999 SX700 fouls plugs a lot

bruham

bruham

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My son and are trying to figure out why or SX700 fouls plugs so much, we've cleaned the carbs adjusted everything fuel/air screw 1-3/4 turns
as they were, stock jetting still is in it. It seems like the mag and pto plugs fouls 5 min. after riding we've tried both NGK br9es/br8es with no luck. Compression is 130 pto,130 center and 120 Mag side...Last we put new Boyessen reeds in also but it's still fouls plugs...All the basic things have been looked over ....................HELP I'm out of things to check.
 
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Center being 27 lbs less than PTO and 17 lbs less than mag would concern me. 2 more things for you to check. Oil cable adjusted properly? (if yes has pump gone bad and is using oil at full bore all the time) and float level adjustment/needle and seat sealing versus leaking. If floats are set to high and aren't ever shutting off fuel its flooding/fouling. If needle and seat aren't sealing shutting off fuel has same result.
 
Thanks we'll check out them area's , I'm meant to say 130,130,120 on comp..not 103 on the center...
also one more thing ...when going to wide open throttle off the start is seems groggy on the top until you feather the throttle quick and then go wide open again then it's fine ....it could have something to do why it's fouling plugs..
 
I don't what plugs your are running. You can switch to BR9EYA or the Hotter BR8EYA plugs. If you are that rich its not going to overheat an burn the piston. In fact I am using the BR8EYA in my Venture all last winter and again now. Check them this month and barely dark brown tips. EYA's are the way to go as the resist fouling a lot. My son Doo has always fouled oem spec'd plugs unless you were riding fairly fast but stop and idle too long and it would start missing and took a while to clear again. I ran the BR9EYA for the previous years and never had plug problems.
 
I would replace the sparkplug caps with the newer yamy style it helped with my sleds and your secondary might need some work.
 
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I've used about every hot/cold NGK plug with not much diff. Could my air/fuel mixture screw be not set right right now it's at 1-3/4 turn...other then that it's all stock jetting, everything's been cleaned but I'm missing something if I'm fouling plugs after a few minutes of riding.
 
Plug caps? Stator my be breaking down when it warms up? I know you said you replaced reeds but the Yamaha reeds are better than boyson. Im assuming choke plunger caps are not cracked since you said you went through the carbs....they break easy then the plungers don't stay all the way off.

Tod
 
I've replaced all three lugs caps and so far so good...I never would of tried replacing these but thanks guys for the advise. Now it's going to get in the 40's go figure so riding might be limited to really see if this is long term fix..I can only hope.
 
That should do it my wifes 600 would foul a plug twice a day tried the ngk caps and was better for a while but started again so I went with the newer yamy style and haven't fouled another plug in the last 10 years.
 
bluewho said:
That should do it my wifes 600 would foul a plug twice a day tried the ngk caps and was better for a while but started again so I went with the newer yamy style and haven't fouled another plug in the last 10 years.
Click to expand...
I have been reading a lot of post on fouling this weekend. I read that ECS is now the recommended plug but if you're not running wide open on lakes you're probably fine. Also need to check a bunch in the carbs, and the oil pump cable. And last but not least, change the caps if the carbs check out. Now, that all seams good, but I've read to use the newer Yamaha caps not the NGK ones, but no one has shared the part number? Do you use just do to your year sled in Yamaha parts or go to a newer 700 triple? Say a 2004 and get those caps? They seam to be different part numbers? Or can someone post what part number they used?

Thanks,
Nator
 
I would definately go with the br9 eya's .. much better plug for the notorious plug fouling of the SX
 
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