Athena BB Kit Longevity?

I recently bought an Athena 478cc bigbore for my 03 yz450f and after reading through the instructions to it, they recommend a new piston after 15 hours! I usually tend to believe the manufacturer on their own specs, but is this realistic? I was hoping for maybe more like 50-60hrs, is this because it is a 2 ring piston setup? maybe fixed by a 3 ring piston?

also they specify 96 octane.. what are your thoughts on this?:thumbsup:

Man my questions must suck.. two threads and no replys to either:ride:

Any help/insight? Im starting to think maybe I should have just gone with a Hi-comp piston and stage 2 cams. but idk

I don't know whose piston Athena is using, but there are two main factors in piston longevity, other than the obvious stuff like getting enough oil, keeping temps under control, etc.:

  • The fit to the bore should be as tight as is practical. This keeps the piston running straighter, reduces wear, and improves heat transfer.
  • The design and construction of the piston itself. Pistons with single compression rings can wear faster than those with more conventional ring set ups, but they don't necessarily have to. A lot goes into piston design, and some people don't get it right. A three ring piston can be made poorly enough to last half as long as a good two ring, so it just depends.

It sounds like they might be trying to cover their butt here, or perhaps just going with a worst case scenario, like having Bubba race it for 15 hours, but 15 sounds pretty short to me. Might wait to see if anyone who has used the Athena kit has anything to say about it.

As far as octane goes, it sounds as if the piston is a 13.5:1. I spent a little time trying to find out if Athena is a US based company, or Euro/Asian, but I couldn't find it right away. That might bear on the stated octane requirement. Most countries outside the US use Research Octane Number, which is somewhat higher than the US Anti-Knock Index. The Yamaha manual calls for 95 RON Octane, but 91 octane from a US gas pump is more than adequate. In most cases, pump premium works in high compression YZ450's, too. If you ride in cool temps at sea level a lot, you could have some trouble with that, but most people don't.

I have the same kit in a 06 yz450f. I have 37 hours on it with no problems. I know Im a vet rider but I run it hard. MX. Change oil and filter every 3 hours. Hourmeter on bike. And I use ONLY YAMALUBE oil in it. Very happy with this kit.

I don't know whose piston Athena is using, but there are two main factors in piston longevity, other than the obvious stuff like getting enough oil, keeping temps under control, etc.:

  • The fit to the bore should be as tight as is practical. This keeps the piston running straighter, reduces wear, and improves heat transfer.
  • The design and construction of the piston itself. Pistons with single compression rings can wear faster than those with more conventional ring set ups, but they don't necessarily have to. A lot goes into piston design, and some people don't get it right. A three ring piston can be made poorly enough to last half as long as a good two ring, so it just depends.

It sounds like they might be trying to cover their butt here, or perhaps just going with a worst case scenario, like having Bubba race it for 15 hours, but 15 sounds pretty short to me. Might wait to see if anyone who has used the Athena kit has anything to say about it.

As far as octane goes, it sounds as if the piston is a 13.5:1. I spent a little time trying to find out if Athena is a US based company, or Euro/Asian, but I couldn't find it right away. That might bear on the stated octane requirement. Most countries outside the US use Research Octane Number, which is somewhat higher than the US Anti-Knock Index. The Yamaha manual calls for 95 RON Octane, but 91 octane from a US gas pump is more than adequate. In most cases, pump premium works in high compression YZ450's, too. If you ride in cool temps at sea level a lot, you could have some trouble with that, but most people don't.

When I got the piston/cylinder I measured the piston to cylinder gap and it was right in the middle of the factory specs..

I also checked in the the compression ratio and I think its 12.4:1 which might be a little better with the 92 octane we have here in Iowa..

I have the same kit in a 06 yz450f. I have 37 hours on it with no problems. I know Im a vet rider but I run it hard. MX. Change oil and filter every 3 hours. Hourmeter on bike. And I use ONLY YAMALUBE oil in it. Very happy with this kit.

Thanks for the input! it helps alot:thumbsup:

12.4:1 is in the same range as stock compression. If you had no problems with the stock piston, you should have none with this one with regards to fuel.

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