Defouling spark plugs.

[AlpinePossum]

So my son has a 2 stroke... which does the 2 stroke thing of fouling it's spark plug and not starting.

Any recommendations on how to clean them?

[nadroj]

If it's not being ridden hard then use a hotter plug. A hotter plug will break down if worked too hard but a cold plug will foul when not worked hard enough.

Clean with wire brush, tooth brush or sharp tip to scrape off baked on deposits then rinse with petrol & blow dry.

Pro's use a sand blaster.

[paturoa]

I use vinegar. I get an old plastic or glass jam jar of suitable diameter so the plug can lie down. It needs to be able to lie down so that bubbles dont stop the acid doing its thing.

Pour an inch or so of vinegar in the bottom. Leave the plug in there for 24 hours and all done for you.

I just use compressed air to clean the plug from there. The porcelain bit will discolour as the glaze is eaten away, but who cares about that.

[The Lone Rider]

I've always used fine grit sandpaper.

[pete376403]

Is the fuel/oil ratio correct ? Correct heat range plug?

I had a problem with an IT400 fouling the plug, turned out a crankshaft seal was failing and it was getting extra oil from the gearbox. Didn't help that the ignition coil was marginal.

[Latte]

Yep fine sandpaper works well, make sure you you try and clean the insulator as well (as much as you can).

Also the bikes that used to foul for me had known issues (crank seals etc) so might be worth looking for the cause, rather than the fix.

[pete376403]

One disadvantage of abrasive cleaning (sand blasting, wire brushing, etc) is that the smooth surface of the porcelain insulator gets rough, making it easier for crap to adhere. A cleaned plug is never as good as a new one (but it is a lot cheaper)

It is worth finding out why the plug is fouling, rather than just putting up with it and cleaning the plug .

[F5 Dave]

Pete is entirely correct, though after the bike is rebuilt (from your other post).

Jetting will be wrong, that's why they foul. First though give it a good check & replace the knackered clogged foam filter. Plug cap etc. Clean out the carb, record the jet sizes. Check float valve isn't leaking, that would flood the bike & could be the main issue.

250s vibrate like a bitch so the carbs can wear the emulsion tube where the needle rests near idle. Check for wear on the needle & then with a torch, a real bright one check for ovality. A little will be enough to screw the pitch. Sadly it will be a PWK & they aren't replaceable. Though a clever engineer could fit a new sleeve. The slide will be worn too & they are ~ $190.

A grade hotter plug for trail riding is usual safe, but look up std - not what came out.

Once a plug is fouled sometimes they don't recover.

Then one might decide how the bike is carburetting off closed throttle. If it is burbley when blipped (from closed throttle only we are talking about) then wind the idle mixture screw out a little but don't go much more than 2 turn out. If it is still not right try a size smaller pilot jet (the small one to the side of the main) & readjust the mixture screw in.