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Hi Jon

Hope you can help with a small query I've just purchased a 1999 TXT 270 after a break in riding of 20 years. I am being given varying information on what fuel and mixture to use. Should I use unleaded fuel, super unleaded or lead replacement? What oil should I mix, natural, part synthetic or fully synthetic? Finally what mixture 50:1, 60:1 or 80:1

Thank you for your help

Ian (UK)


Gas-Gas reccommends fuel of at least 95 octane, which would call for a mixture of preminum pump fuel (93 octane where I live) and about a 20 or 30 per cent addition of high octane unleaded race fuel (around 104 to 110 in most cases). The octane rating in the U.S. is an average of "Motor" and "Research" numbers. These rating numbers are similar but the "Motor" rating is done under more severe conditions and is more like the conditions that a competition engine would see. As a consequence, all pump fuels, inspite of their same octane ratings, are not the same. Try different ones to see what your bike runs best on. Use only unleaded pump and race gas. A two-stroke (and all the newer four-strokes) engine does not need Lead additives and it will actually be detremential and it can lead to sparkplug lead fouling.

As for premix oils, a full synthetic is probably the best (speaking as a competition engine builder) and most all of the major brands are good. Gas-Gas says a premix ratio between 70 and 100 to one is good. I run my 96' 370 on 80 to one and that works very well. Trials engines are somewhat understressed so the same mixture as a Motocross bike will actually not work as well as it will lead to oil deposits in the exhaust system.

Hope this helps.


Professional tuner and 'Trials Competition' writer Jon Stoodley has very kindly stepped up to the plate to answer your questions. If you're having problems, or need some advice just send an email to Jon. If it's something that could be useful to others, we'll post it on the site.
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