2A2/2L0 Pistons

Hi all,

My lovely XS400 has barely seen the road, only going a few miles to get to the local garage to have a minor issue with running rough resolved. Many months later and I'm in need of a new piston, so wanted to get some advice first.

The garage tell me that only 1 piston needs to be replaced. I've seen that the 2A2 piston was superceded by the 2L0, but are they identical? I don't know which one is in the bike at the moment, but I'm wary of having mixed pistons, in case there's a slight weight difference that'll throw off the balance.

It looks like the rings are 2A2, regardless of which pistons are used, is that right?

Are the 2A2 or 2L0 numbers stamped on the pistons anywhere?

Pistons are standard size and the bores are fine. We've got a long-standing Yamaha dealer locally, Granby Motors, who have a pair at a decent price. Really bad news for Yamaha owners generally, they went bust over Christmas. I'm now scrabbling around, trying to find a piston at a reasonable price.

The part may have the same numbers just different model numbers, just check if everything else is the same as I've found a 04 yzfr1 has the same conrods bearing but the retainer notch is in a different posistion. Best bet is take your old one and compare it side by side

I might've confused things by mentioning the local shop. They've gone bust, so I can't get the pistons that they have. That leaves me searching online where they could be anywhere in the world, no chance of a comparison with what I've got.

Even if I could, they're should look the same as the 2L0 supercedes the 2A2, so should be a direct replacement, but a slight weight difference would unbalance the crank causing problems.

I think I'll err on the side of caution and get a pair of pistons. More costly, but that way they should match and not cause more problems.

No matter what pistons you get they'll never way the same as eachother. Could be 0.5 of a gram could be more. If your replacing them yourself try balancing yourself too all youll need is some sand paper, a drill and suitable bits, scales that can measure to 0.1 of a gram and some small weights to counter balance the crank tangible from 1g to 10g. Plenty of videos online on how to balance crank shafts very few on balancing pistons and it'll help you further along to learn your mAchine Ms save money too