2005 RXP Valve Job needed

[bigburd]

Hi Guys,

I have a 2008 RXP which i discovered has a 2005 motor and and I just checked the exhaust valve stems and they save 72xxxxxx. Motor hasn't blown up and i have 135 hours, i guess im on borrowed time. As i understand the 72xxx are the bad ones...

My question is what is a good OEM replacement that is cheap, there are tons on ebay. I dont plan on boosting more than the OEM 215 supercharger etc. Is there any reason to get a different size etc? I plan on having as machine shop do the work.

I also have a 2010 RXTX that has a leaky exhaust valve and i need to replace/re-hone the head on that one as well. Should i use the same valves?


I'm in Boston

Sorry if this is a redundant post.

Thanks!

[Drewski1126]

Did my 05 rep with the super tech valves and springs. I think they are cheaper then oem also. Had 138hr on it when I did them and haven't had any issues.

[bigburd]

Did you need to machine the head as well or just swap em out?
Do you think replacing the springs is necessary or just reuse em?

Was looking at this: https://www.ebay.com/itm/Supertech-V...EAAOSwvGVa1L9B

[Drewski1126]

On my ski there was no damage to the head to warrent machining. I just used lapping compound to seat the valves.
I used the stock springs. But mine doesn't have any major mods to it. I'm sure someone will chime in on the springs if they are needed. I think I remember hearing if you go with an aftermarket SC (Et127) wheel then valve springs are a necessity.

[r1goombah]

Eastside Powersports is pretty mush the goto spot on the east coast for head work or engine work as for your springs, if your in there might as well change them, if you ever deside to add mods or just a higher reving tune, your mind is clear that they are done,

[dcuhpw]

I used super tech valves on mine. I think Jerry has them for like $350ish for the set. Lapping compound is all I used as well. I would recommend doing the valve seals at the same time. FYI mine had 182Hrs on it and I've read of many with well over 200 on this forum. The. Again others seem to go much sooner. Seems to depend on maintenance and environment.

[bigburd]

any particular lapping compound, i know they have different grits.

[Sea Dood]

Just lapping valves is a very bad idea. There is a spec on the width of the valve seats, most used heads exceed this value. There is a tradeoff on seat width, you want them just wide enough to draw heat from the valve head, but if they are too wide, then carbon builds up on the face and you lose a good seal. You need to measure the width of the seat, if anywhere near the max value, it is time for a valve job.

Excessive seat width is corrected with a three angle valve job.

[dcuhpw]

Lapping the valves has worked just fine for a great many of us. Not saying a valve job isn’t better. If time permits and you have a good machine shop then have them do it if you like. They should still lap the valves in though even after the angle cuts. And if seat width spec is so crucial then make sure to give that spec to the machine shop. New valve guides might as well be installed at the same time. If we are talking about perfect specs needed for a high performance setup than make sure everything is within spec. While your at it, flow match the ports, and machine all the combustion chambers to be identical. As I’m sure you are aware, one can go to painstaking lengths to get things “perfect” but you probably won’t gain much of anything on a stock setup in terms of reliability or power. Or you could keep it simple and just lap them in correctly...

[Sea Dood]

Lapping the valves has worked just fine for a great many of us. Not saying a valve job isn’t better. If time permits and you have a good machine shop then have them do it if you like. They should still lap the valves in though even after the angle cuts. And if seat width spec is so crucial then make sure to give that spec to the machine shop. New valve guides might as well be installed at the same time. If we are talking about perfect specs needed for a high performance setup than make sure everything is within spec. While your at it, flow match the ports, and machine all the combustion chambers to be identical. As I’m sure you are aware, one can go to painstaking lengths to get things “perfect” but you probably won’t gain much of anything on a stock setup in terms of reliability or power. Or you could keep it simple and just lap them in correctly...

Don't think you quite understand. Lapping is a backyard yokel way of doing things, and just because you got it to work doesn't mean it's right. Many of the engines I have worked on have had excessive carbon on the seats because they are too wide. Carbon on the seats means leaking exhaust.

It is about doing things right, not doing things half-assed.

[dcuhpw]

Don't think you quite understand. Lapping is a backyard yokel way of doing things, and just because you got it to work doesn't mean it's right. Many of the engines I have worked on have had excessive carbon on the seats because they are too wide. Carbon on the seats means leaking exhaust.

It is about doing things right, not doing things half-assed.

Ok, first off, I am not the only one who has lapped in valves and it worked successfully in fact most every valve job posted on this forum recommends lapping. I agree that a that a good valve job is a great idea but if you are going to do that you should do your guides as well since a good valve job would be quickly ruined by a bad guide. While your machining the head why not cc the chambers and work flow match the ports?

[dcuhpw]

Really though, I’m not arguing with you so please don’t take offense.