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In your February Service column (‘‘Smoky and the Bandit”) about defective pistons in Suzuki 1200 Bandits, you only mention the 2001 models, but a dealer told me that Suzuki continued putting these same pistons into bikes until early in 2002. The faulty pistons have 2.4mm drain back holes at the back of the oil-ring groove, whereas the pistons used before and after have 1.7mm holes. The ring land itself is only 2mm wide, so machining the larger holes required removal of some material from the land. When doing this (it’s an old hot-rod trick), material should be removed only from the bottom of the land, not the top. The top of the oil ring has to seal against the top of the land on the piston’s downstroke; otherwise, oil will escape past the ring, onto the cylinder wall, past the compression rings and into the combustion chamber. But Suzuki drilled the drainback holes so that material was removed from both the top and bottom ring lands, giving oil exit paths over the top of the oil ring. Suzuki has reverted back to pistons with 1.7mm holes, which do not require the removal of any material from the ring land.

Interestingly, I visited the Richard Childress museum in Welcome, NC, last October, and they had a box of old pistons from Winston Cup cars for sale as souvenirs. I looked them over, and some had oil drainback holes that were larger in diameter than the oilring grooves themselves. Every one had been drilled so the material was removed from the bottom land, leaving the top land undisturbed. That’s the way to do it if you don’t want an oil-burning engine. Brian Furman

Posted on www.cycleworld.com

Fabulous input, Brian. It helps clear up what has been a very murky affair. Thank you very much. Maybe Suzuki should start sending engineers to Winston Cup races?