Athena Big Bore Kit or Local Rebore + Larger Piston

So last year I blew up my stock piston after only 20,000km of riding. Fine I ride pretty hard, but I honestly expected to get way more life out of the stock piston. So now I am thinking of going bigger instead of just re-boring it back to stock. My problem is that I live in Canada, and with the dollar so weak right now. Local shops are quoting me $1,600 for the Athena 290cc Kit. This is absurd, even if I order it from the states, after shipping and the exchange rate I am looking at around $1,000 at the absolute best.

So my question is, could I just order the Athena 290cc oversized piston kit, and then get a local shop to rebore my head to match? The piston kit online is only about $200 shipped to my door. So even after paying $100-$200 for a rebore at a local shop I will still be saving hundreds of dollars if I can go this route.

Is there anything provided with the full Athena Kit that I would be missing out on if I just got the Piston kit and re-bored myself? I already have full fmf exhaust, fmf programmer, and the airbox mod done.

The athena cylinder has bigger holes for the water, that will take a lot of machining and money for 1 guy to manually do it.

Do you know a company you trust to do the plating, ueh, and remember gaskets....

You cant bore the stock cylinder out to a 290 and replate it, the alum isn't thick enough, thats why Athena makes a new cylinder.

Check out thumper racings 280 kit, its cheaper than the Athena cylinder by quite a bit, the piston is as light as stock so theres no extra vibs and it has 3 rings like stock, some guys claim its a better big bore kit.
Buy it and have a local machine shop bore the cylinder and press in the new iron sleave.

Thanks for the info! I'm going to check out the thumper racing kit

FWIW I wanted a big bore kit on my WR so I set up a price drop alert on the item on Amazon if it ever hit $600 for the Athena kit alert me. It did in mid November so I bought it. Just put it together myself and if this snow would stop falling I would be able to tell you how it is. There are cheaper ways to do it. I already had the PC5 installed so I didn't mess with the included FI add on.

The 280 kit from Thumper Racing runs $555 plus freight. so figure about $570. You get a base gasket, head gasket and chain tensioner gasket, a newly plated cylinder, and a CP piston with 3 rings, pin and clips. $300 core charge until your cylinder is returned. They already credited me back, so it's pretty quick from when you ship it to them. Just did this Christmas day. REALLY want to get out and ride. Might rain this next weekend, so I might be able to see the ground again. Thinking about tires with ice spikes next winter...

Traveller wrote:

The 280 kit from Thumper Racing runs $555 plus freight. so figure about $570.   You get a base gasket, head gasket and chain tensioner gasket, a newly plated cylinder, and a CP piston with 3 rings, pin and clips.  $300 core charge until your cylinder is returned.   They already credited me back, so it's pretty quick from when you ship it to them.  Just did this Christmas day.   REALLY want to get out and ride.   Might rain this next weekend, so I might be able to see the ground again.  Thinking about tires with ice spikes next winter...

That sounds like a good deal. The Athena kit included all of the gaskets as well. I liked the idea of having everything I needed all together at once before I started and the ability to go back to stock if I wanted to. Not saying the 280 kit is not as good, there are pros and cons to each but you can save yourself a lot of money by doing it yourself.

The Athena kit looks like it comes with the exhaust gasket and the copper washers that go under the screws on the tensioner.   That isn't included in the Thumper Racing kit.  Also, no fuel controller comes with the Thumper Racing kit, but by all accounts the Athena is a fairly dumb controller.   In my opinion, the Athena kit is a little more complete as far as gaskets, but those are cheap gaskets to add, and might not be needed on a low mileage bike.  The piston is heavier, so there will be more vibration, but a lot of people don't think it's a deal killer and there doesn't seem to be a big longevity problem even running the 2 ring piston instead of 3.  It's usually quite a bit more expensive.

I'll see what I think of the 280 kit in mine once the snow goes away.   I'm hoping for similar vibration levels compared to stock, and more power.   Going by the dyno sheets online, it looks like they're pretty close between the Athena and Thumper kits with the Thumper kit making a bit more peak, and the Athena making a tiny bit more down low.  Both make about 5HP more at 5000 RPM, which is huge and usable.   I have high hopes.

I just installed the athena kit and the gaskets are oem designed
. 3 layer steel head and Teflon coated base plus exhaust, cam tensioner and o rings.

The athena kit look like well designed kit. I only put 75mi on hard single track so far. I does vibrate a tad more
But if you didnt think about it you wouldn't notice it. To cold for street riding but on trail the added torque is great make the bike feel lighter more nimble and it even handle better

One thing about the athena kit you can sell the oem cylinder. piston. athen controller and Recoup some money