I have a 1984 200M that goes through spark plugs faster that fuel quite litterally.
I should begin by saying that the bike typically gets used on very short trips of less than 5 minutes.
Since restoring the bike I have gone through 2 tanks of fuel and at least 20 plugs!
The few times that I used the bike on long trips it ran beautifully and a check of the plug at the end of the ride showed that it was running well as the colour was brown.
I have been concentrating my carb fine tuning on the low speed screw as opposed to the main jet because the plugs only foul after opperating at slow speed for a while.
Could the ignition timing possibly cause or contribute this problem?
Is this a common problem that I will have to live with?
Any help would be appreciated.

 

Hey how long have u owned that 200m? I sold one like 2 summers ago at our garage sale...i miss that thing like crazy..that thing ran STRONG..in the winter it'd sit in the garage..which isn't heated and a month later i'd go out minus like 25 and pop the choke not even full..hit that electric start and it'd fire right up...went thru the snow like mad too! near the end i noticed it was goin thru plugs alot...and stalling out on me...but then left it for a few days and it ran perfect again

 

I bought mine off of my neighbour about 3 years ago and it was in rough shape, he had just finished puting in a new piston and rings but didnt put the cam chain on properly and it wouldnt run.
Long story short, he got fed up with it and told me I could have it if for free, but because I felt bad for him I gave him a hundred bucks.
Then the restoration began... new rear axle bearings and seals, drive chain, brake drum, brake cables and handle, fixed rotted out gas tank, new tires, put on a rear rack etc. etc. I even picked up 2 parts bikes along the way.
The bike is in great shape now and I would really like to figure out the spark plug problem.
Im going to set the ignition timing up on the weekend since I know that the previous owner was adjusting it trying to get the motor running after puting the chain on wrong.
Nice to hear from a fellow Ontarian.
By the way, do you regret selling yours?

 

cookster, the only time I had problems with fouling spark plugs on a 4 stroke was when the main jet in my xr75 had been drilled out. It was a basket case and I didnt realize the jet had been modified until I had fouling problems.

 

Thanks for the response, I have taken the carb apart before and the main jet and needle look good, I dont have a problem with plugs fouling if I am riding at higher speeds and for longer runs, only if I putt around in first or second gear. I read somthing in my manual about the approximate throttle positions where the main fuel supply transition from the low speed to the main jet occures, and I figured that the low speed setting was too rich.
I have adjusted it in to the point where I can hardly get the bike to start (which is too far) but the plugs still fouled.
If the timing adjustment doesnt fix it, Im going to try swapping the carb off of my parts bike.
If and when I get this problem resolved I will post with an update.

 

Oh ya i really regret selling it...i'm lookin for another one...maybe a 70 or 110 or 185 or a 200....just something to work on tweak it and bomb around on...

 

Try putting the needle down a setting or 2 (you will have to move the clip up on the needle to do so) that will lean it out....I've had many old honda atc's with the same problem and thats been the fix...Then you can adjust air fuel mix screw...Should be 1 and a half to 2 turns out...hope this works for ya...

 

Just wanted to give an update on the topic... I finally got around to checking the ignition timing and sure enough it was off. (too far advanced) Im hoping that this was the cause of the fouling spark plugs, my theory is that if the ignition occures too early there may be an incomplete fuel burn??
Thanks to all who offered assistance and I will post again with an update.

 

hallo am going true similar problem on 200 big red...my carb is stock no modification ,it sound like it gas mixture ,my plug are little dark but not to bad,so the needle and seat is the first thing a carb job , I was thinking to buy all new electronic should I do that can a bad cdi or coil kill plug. verymuch

 

Cookster, where in Ontario are you, I am in hamilton. I have 2 Big Red 200's, and 82 and an 83, both are in great shape, I keep working to keep them up, need some front fork parts now, but they are lots of fun.

hope the timing fixes up your plug issue. Do you have the maintenance manual for your bike?