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| *Vultures Knob>>>Dirt Bike |
Why do 2-stroke dirt bikes FOUL PLUGS? |
I understand it happens when you are 'putting' around and the oil and gas mixture are not moving fast enough. DOES THIS NOT HAPPEN ON A FOUR-STROKE DiRT BIKE? I am looking for a trail bike (as a rookie rider) and would like a bike that is better on trails and easier to maintain. I am deciding between a yz250F and a YZ250. *IF* your starting off with a new, or fairly new engine (or rebuild) so that worn rings, seals, ect can be removed from the equasion, the only reason that a plug will foul is because the air/fuel ratio is incorrect. The majority of two stroke engines that foul plugs do so simply because the jetting is incorrect. If the jetting is correct you can run a plug indefinately. I've gone as long as a year with the same plug in a 300 EXC with no issues what so ever. Changing your premix ratio is only a band aid and can be dangerous if you go to lean. It's much better in the long run to decide what type of oil (petroleum, semi-synthetic, pure synthetic) you want to use, use a ratio suited for that type of oil and STICK TO IT for the sake of consistancy. Then adjust your jetting around that. You'll get far better results over the long haul. I've been using a pure, ester based synthetic oil in 93 octane gas mixed at 50:1 for years. Once the jetting for the particular bike is sorted out I can usually go a year between engine rebuilds and not have to worry about any plug fouling issues. As for the maintaince issues between the bikes you have listed, the 250 2 stroke will be easier and cheaper to maintain. The new generation of RFS (racing four stokes) engines are high reving, high maintiance machines. Constant attention needs to be paid to valve and cam chain adjustment. Piston and ring wear occure at virtually the same rate as a two stroke and are *usually* more expensive to buy. There are issues floating around with the titainium valves as well. In your situation I'd suggest looking more towards a TTR or other air cooled four stroke play bike until you build some riding and mechanical skills. your gas an oil mixture may be wrong or the gas your using migh be to much octane or its not getting enough air or the starting system may be to strong for the plug or the timing may be off i would take it to a small engine repair shop look in your yellow pages under small engine repair 20 years fixing cars Doesn't happen as much on 4-strokes because you don't need to premix. Your plugs will four sooner if your mix has too much oil in it. Also, if you're running rich, the plugs will foul even faster. Lean out your carb and dilute the oil more. Hey ya i have the same thing with my 1978 Suzuki TF-100 it fouls them like im a matter of two mintes what it is to my knowlege is its oil getting into the crank case so me and my father pulled the whole motor apart to put new crank shaft seals in and replaced the bearings and put it back together and what do ya know it still doesnt run but ya its oil getting into the crank case. Too much oil in with the gas. Try less premix Your mixture between oil and gas it too heavy in oil. try another proportion of oil (a little less) this will improove. But, in a 2 stroke engine you will always suffer of this! I have had 2 stokes and 4 stokes motorcycles maybe a dozen.. or more... been in races and crossed country all weekends. If you like 2 stoke engines.. and go fast.. plugs will suffer! |
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