How many hours before a top end rebuild?

[Morgan_Pew]

I have an 09 450x that runs great and is very easy to start. I have heard anywhere from 100 hours to 160 hours a new top end is going to have to be done. just curious about how many hours some of your bikes have without having a top end done.

Thanks,

[skylerj]

I have an 09 450x that runs great and is very easy to start. I have heard anywhere from 100 hours to 160 hours a new top end is going to have to be done. just curious about how many hours some of your bikes have without having a top end done.
Thanks,

I have a 2015 x with 95 hours on the original piston. I am wondering the same thing myself.

[kgish475]

Can’t tell you how many hours my 09 had on it when I got it 3 years ago but it finally seized (bad crank) on me in October. If I had to guess I put 200 hours on it myself with no knowledge of how much the first 2 owners had ridden it. I think the owners manual will say every 100(?) hours on the top end.

[BMRFlagstaff]

After the first shimming over 100+ hrs start to plan for it, the shimming will last less and less then you are bummed.  Most likely depends on how hard you ride, I got my head done at 180 and now 400 on the rebuilt.  I did SS TRX valves from AS Racing, same on the wife's 450x at 175 hrs, highly recommended, I did a piston and 02 r cam and new chain also.  Have heard to go with the TRX 3 ring piston but I don't burn much oil at all so just went OEM.  

 

 

[trollope]

my 08 had 160 hours before the factory piston came out, a new oem Honda standard unit went back in. The only reson for the change was the rings smoking, the bike still performed as it did at 120 hours when I bought it. Just today, only 15 minutes ago and at 207 hours I have pulled the head off due to popping / farting and hard starting, and one inlet has been on it's final shim for about 2 hours riding only... so it's time for some Kibblewhite inlets... 

[Morgan_Pew]

Can i do valves and a piston without doing a complete top end of the head is still true?

[mlatour]

If you replace the valves, the seats must be re-cut.
At that point you might as well replace their guides and seals as well.

This far into the engine, 'might as well / just to be safe' preventative maintenance also means a piston and rings, cam chain and tensioner.

 

Perhaps not so much on a moderately trail ridden 450 but certainly on a 250F,

this is where being 'frugal' doing a 4-stroke top end always end up costing a LOT more later on.

Edited February 26, 2018 by mlatour

[Nayther]

So 332 hours is a bit much?

CRF Doc was amazed when I showed him the hour meter, guess it was done right the last time. These hours are on TRX valves, not the OEM Titaniums; Don't know when we did it but it was a LONG time ago. Finally being hard to start, thought it was weak battery, replaced it and same problem. Then noticed it was a bit harder to kick indicating decompressor too tight.

[CRF DOC]

5 minutes ago, Nayther said:

So 332 hours is a bit much?

CRF Doc was amazed when I showed him the hour meter, guess it was done right the last time. These hours are on TRX valves, not the OEM Titaniums; Don't know when we did it but it was a LONG time ago. Finally being hard to start, thought it was weak battery, replaced it and same problem. Then noticed it was a bit harder to kick indicating decompressor too tight.

Your head was redone by me on 6/19/2009...hard to make a living off customers like you who take care of their stuff...

[Nayther]

Just now, CRF DOC said:

Your head was redone by me on 6/19/2009...hard to make a living off customers like you who take care of their stuff...?

you found the records? I was trying to remember when it was.

Yes, I'm not good for your business since I ride so slow and do frequent PM.

Will get it torn down this weekend and we'll talk.

[CRF DOC]

Just now, Nayther said:

you found the records? I was trying to remember when it was.

Yes, I'm not good for your business since I ride so slow and do frequent PM.

Will get it torn down this weekend and we'll talk.

Absolutely! I even have the pictures from the job...

[Todd Nelson]

On 2/24/2018 at 6:58 AM, Morgan_Pew said:

I have an 09 450x that runs great and is very easy to start. I have heard anywhere from 100 hours to 160 hours a new top end is going to have to be done. just curious about how many hours some of your bikes have without having a top end done.

Thanks,

With the TRX piston I’m 317 hours since my last complete rebuild. 

Edited February 16, 2021 by Todd Nelson