- Jan 25, 2000
- 1,822
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I just received the latest issue of Dirt Bike, where they test the Thumper Racing YZ290F. The only modification they make to the engine is sleeve and bore it for an 80mm piston in place of the stock 77mm piston. Sorry, but this brings the displacement to 269.4 cc.
An 83mm piston would bring the displacement to almost exactly 290cc, but I doubt if they could get the piston weight within 3 grams of the stock piston weight (as stated in the article) with this large an overbore (if such a bore is even possible without interfering with the water jackets in the stock cylinder).To make matters worse, they call it the YZ300F on the cover, to further puff it up.
I've heard of fuzzy math, but this destroys Dirt Bikes credibility IMO.
I was about to venture into what they said about using Mobil 1 in four strokes, but thankfully, Mweissen has it covered in another thread in this forum.
Not that I believe in anything I read in a magazine........:confused:
An 83mm piston would bring the displacement to almost exactly 290cc, but I doubt if they could get the piston weight within 3 grams of the stock piston weight (as stated in the article) with this large an overbore (if such a bore is even possible without interfering with the water jackets in the stock cylinder).To make matters worse, they call it the YZ300F on the cover, to further puff it up.
I've heard of fuzzy math, but this destroys Dirt Bikes credibility IMO.
I was about to venture into what they said about using Mobil 1 in four strokes, but thankfully, Mweissen has it covered in another thread in this forum.
Not that I believe in anything I read in a magazine........:confused:
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