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Author Topic: 90mm bore?  (Read 103 times)


  • Neophyte
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90mm bore?
« on: February 12, 2015, 05:53:07 PM »
Is it possible for the "ordinary Bullet owner" to get a 90mm bore? This would give a "square" engine with 90mm stroke. Or is 87mm (535cc) the max possible with standard barrel and crankcase. And, of course, a piston would be required, but maybe from another bike?
Just a thought as I consider 535cc with my alloy barrel


  • Grand Gearhead
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Re: 90mm bore?
« Reply #1 on: February 12, 2015, 06:11:47 PM »
Not feasible with the currently made barrels, because it would leave the liner too thin for good rigidity. For all reasonable intents, 87mm bore is it. For very ambitious builders, barrels could be sleeved oversize, or custom made with larger liners. However it would also require enlarging the engine case mouth to fit the larger liner, etc.
So, not impossible, but generally not considered worth the effort unless there is a very specific need for it
Also, piston mass starts to become even more of an issue, so a de-stroke to reduce piston speeds would probably be helpful to offset the paint-shaker effects.