carbon buildup

[Voodoo]

is there any product u can put in your fuel or something to clean the carbon buildup in your engine, i seem to foul up plugs quite often and was reading that carbon buildup can happen in these two strokes (90 yz125)

[dhunt]

is there any product u can put in your fuel or something to clean the carbon buildup in your engine, i seem to foul up plugs quite often and was reading that carbon buildup can happen in these two strokes (90 yz125)

Do you give it a good thrashing? That normally helps lots.

[Voodoo]

yeah well i try, lol when i got the bike it seemed to have abit, it has a very small hole in exhaust where it leaks out, i was just wondering if the was some sort of engine clean like u can get in vehicles

my manual says they need to be pulled apart every now and then to clean the carbon out, just thought there maybe a quick fix, or just as u said, give it a good thrashing

[Oscar]

is there any product u can put in your fuel or something to clean the carbon buildup in your engine, i seem to foul up plugs quite often and was reading that carbon buildup can happen in these two strokes (90 yz125)

What oil do you use and what ratio do you mix it at?

[Cary]

What oil do you use and what ratio do you mix it at?

Good question.

May need to be leaned out.

I had a KX250 that used to foul plugs on certain brands of oil, changed brands, no more fouling.

Also, if you baby 2 strokes it will happen, if your not already try a 33:1 mix.

[Voodoo]

running it at 30.1 at mo
as for oil, carnt remember off my head what i used last, the last changed was done by the bike shop as it was getting a leak fixed

so if the right oil is used, maybe the mix leaned abit, and make sure its getting a good thrashing, then will that clear the engine/exhaust of any carbon buildup?

[Cary]

so if the right oil is used, maybe the mix leaned abit, and make sure its getting a good thrashing, then will that clear the engine/exhaust of any carbon buildup?

Be careful with air/oil/fuel mix as get it too lean and may seize.

No, carbon is there to stay unless you remove it. Used to dip mine in the acid bath at work but not sure what is normally done, if anything.

Have you repacked your muffler?

Maybe it's a little blocked? Easy to do and if it hasn't been done in a while will make a diff to power delivery and may help with fouling prob.

Is the sparkpulg in the bike the correct one? Other things to check is jetting and air screw setting, would help to find out and put them back to standard as a starting point.

[F5 Dave]

You have a competition model bike. The way they get awesome power from a small engine is to compromise a few things. No prob if you keep to some sort of rebuild schedule.
The fact that it is 15yrs old doesn’t change this.

Best you become acquainted with its inner workings. The carbon can stick the powervalve & damage it. The rings & possibly the piston likely need replacement. Crank life, well, you might as well keep running it & see how you go.

Don't dispair it is all quitre easy & parts are very reasonable as they are meant to be changed.

When people talk of being too rich or lean they (should) mean the petrol to air mix, not oil.

It IS too rich so the petrol/oil mix that doesn’t burn exits the cylinder. In that mixture the petrol disappears leaving burnt coloured oil reside. If the combustion was complete it would burn most of the oil no matter what ratio you run. You will always get a little.

Oil ratio is not your problem & anyone who says so needs a slap in the face with a wet kipper.

Your task is to find out where it is rich, pilot, main or all of the above. Guess one is pilot.

Read a jetting article & fiddle some brass.



Note; if it is too rich using less oil will make it richer & confound fouling problems. Just trust us on this one. Remember it is possible to be too rich on some jets & too lean on others.

Do the simple stuff first. Sparkplug, Sparkplug cap, clean or replace airfilter (replace by now) Check that the coil is grounded properly. (clean plug contacts, check with meter etc).

Clean carb out properly esp pilot jet (never poke with wire though).

Then start reaching for the jets.

New bikes are usually set up too rich as it is the safe option. If you are using a decent oil at the ratio recommended on the bottle then it will not be the problem, ever.

Once a plug fouls it may not recover properly. Out in the open it may spark well but in a combustion chamber may just foul up again. I really would look at the HT lead & cap as well as they might have been the initial reason for the plug fouling. Use the recommended heat range.

Start playing around with the jetting particularly at low throttle positions (Pilot etc).

Further your coil or stator coil may be weak & once heated up is a bit pathetic so fouls a plug.

[Voodoo]

cheers for that, ive just stuck in a competition sparkplug, well its states that, and it did cost alot more than standard ones, and noticed that the bike feels alot better, smoother, powerband kicks in sooner , acaully caught me out abit, and had a good off on it , haha,

but yeah, prob due for a few things like airfilter, etc