Fouling plug?

[Fraser]

Hi all, I'm wondering my my spree keeps fouling out the plug lately....
I'm pretty sure it's being fouled by gas, not oil- and compression seems decent. (haven't tested w/a guage yet.) Is it just a matter of mixture or something? I live at 5300 ft by the way.

Thanks for any advice! The spree runs pretty good for a while until it fouls the plug.

[Jerry]

A lot could have to do with the TYPE of riding you're doing. Extended high speed and idling around or riding at part throttle calls for different numbered plugs. Try changing to a hotter plug for a while and see if it improves. Make sure the exhaust is not restricted either. Both of these items could cause your symptoms.

[noiseguy]

Jerry,

At 5300 ft, shouldn't he be playing with his mix off stock levels?

What do your plugs look like, light brown, dark brown, or white?

[Jerry]

All plugs run with a light tan color. Never black, that's too much gas. Too low of a heat range for the type of driving you do will cause blackness. I'm thinking my altitude is around 3500 and I've never seen any that had to be compensated for altitude even in Colorado.
Make sure the air cleaner is not restricted in any way. I still tend toward the hotter plug taking care of your bike.

[noiseguy]

I would tend to agree with trying the plug first. What plug are you running currently?

[Shane4188]

I had been having problems with the NGK spark plugs holding up well. I had tried the NGK BPR4HS, BPR6HS, BPR6HSA, and BPR8HS. None of these worked for very long, only about 20 miles before it was becoming hard to start. I went down to the auto parts store and they gave me an Autolite 275. Ever since I put that plug in my 1986 Honda Spree NQ50, which has about 400 miles on the plug it has been great. Starts perfectly anytime. I would suggest this plug, it is only like $1.50 so it is definately worth a try. I also suggest that Lucas 2 stroke semi-synthetic motor oil. It burns very cleanly, and smells much better. They call it "smokeless." It should prevent a lot of buildup on the exhaust outlet and exhaust pipe. Good luck.

[Fraser]

At the moment I am using the BPR6HSA plug- the scooter hasn't had this problem until the last week or so, regardless of what plug I'm running.

I can throw a *brand new* plug in there and it will run a few blocks until it chokes a bit, dies, and won't start. The plug then looks blackened and charred, with a bit of brown around the real cooked parts. Too much gas?

The carb has been recently cleaned, and the air filter is clean and in good condition.

Is it possible that the muffler has become significantly clogged recently, causing it to run rich?
Thanks for any help you guys can offer! I'm quite handy at fixing old BMW's and import cars, but I'm really out of my element with 2-stroke stuff.

Fraser

[Jerry]

The words 'black and charred' are scaring me a bit here. If it's 'charred' then you are running WAY TOO HOT. That's a sign of LEAN mix. A clogged muffler should make it run RICH as the flow is being interrupted and it's unable to pass the unburned fuel/oil mix out the exhaust and therefore it will accumulate carbon very fast in the cylinder. Carbon buildup on the piston usually results in misfires and stumbling as the carbon is holding heat and igniting the fuel mix irregardless of the plug's spark.
I think I would pull the head and check for carbon buildup first. Then recheck the adjustments on the carb for a lean mix (float level and cable adjustment). Note the size on the main jet and make sure it's clean. Even if the carb was just cleaned, it can have a small chunk of goop on it and restrict the fuel flow. Check the compression and see if it's running high. That indicates carbon buildup also.
Keep us informed.