I think if you use ebay.com as opposed to the local variant, then you can see everything.

For a while you couldn't see DEET's stuff on ebay.uk, although you can now.

Thanks for that info above.
Here's a Wossner YZ400 87mm which could just be the answer, but ignore me i'm just googling & doodling. Might even go faster with the inlet cutaway. I run, or have run an "82mm YZ400 piston kit in my 80mm RT2 360 with no problems. Yamaha ran an 82mm bore for one year only in 1979 in the YZ400's as opposed to 85mm 400 before "79, long story & not relevant to this case which is 87mm required so here's the link to one before i forget.

Thanks for that, I hadn't heard of LA Sleeves. I'll get ion touch.

Thanks, I've seen that one and one other. Both pricey. I think that one is available in the states for around £70 but postage is another £80:(

That's interesting! If I could be 100% sure it would work, I'd buy that. I would need to be sure though.....$250 to get it to the uk

Afternoon Nick.

A slightly left field alternative is to buy a complete engine, take off what you need and flog the rest on.

Link attached to one in the UK (Fakenham) below that comes with other bits and bobs. Clearly you'll want to find a way of making sure that you don't end up buying another jiggered engine!

Out of interest, how many miles was your bike showing? By and large, the US bikes don't rack up a lot of miles and so I must admit that I was surprised yours had maxed out on the oversizes.

Alan

Cheers Alan, I'll try that.

Yes, I have considered that Alan. I looked at that advert a while back but the barrel looks different. Not so many fins.
My bike shows 11k. I thought, like you did, that the cylinder would have some meat left on it.

So it has - well spotted that man!

.

RT325 had mentioned checking into the Yamaha 490 piston as a possible donor ... back in post # 5.
He's correct, and it is doable with a little machining work.

1. The 490 piston has the same 18mm pin size and deck height, but is 10mm taller . . . So the piston skirt will need to be shortened by that amount to match the 400's height.

2. The next problem, and a bit more of a challenge to over come, is relocating the ring end locating pins, so that the ring gaps match that of the 400 piston. The 400 pins are 32mm apart, while the 490 is 42mm apart.

This must be done correctly by someone that has the equipment and experience to do it properly.
Which means, heating the piston up and then jig drilling the new pin holes (not free hand) . . . then, while still hot, pressing the new pins in with a slight interference fit.
Naturally, the new pins must be the same exact size to fit the rings, and the old pins must be either removed and their holes plugged, or "carefully" ground down to match the depth of the ring lands without damaging the ring grooves in the process.
If not done correctly, you risk the pins coming out and doing damage when the motor heats up and the piston expands.

If you can lick those two problems, then a 1st oversize (87.25) Yamaha 490 piston will work.

If you lived here is the states, then picking up a used cylinder would probably be the way to go, but availability and shipping expenses may not make sense in other parts of the world.

.