serdi job w/stock valves...

[JimmyHoffa]

Does this work? I'm a ghetto old school steel valve guy, but I'll be building up a 450r super soon, and I was going to go the serdi route. I suppose, deep down, I just want to know how to get the most life out of the stock Ti valves.

[Elduner]

I run stock valves on my 04... Work was done by Dasa.

the stock valves where cut and then I had a 5 angle valve job done to my head... All this done with precision on the the Serdi by Dan.

And all I can say is that my bike moves!!!!!!!

[JimmyHoffa]

I'm lost now. How do you cut stock valves without destroying them? I was under the impression that the titanium has some kind of oxidized surface that can't be taken off. I was thinking about the type of valve job shown in the link below.
(probably by someone reputable.)

http://cgi.ebay.com/ebaymotors/HONDA-TRX450R-SERDI-VALVE-JOB-TRX-450R-TRX-450-CRF450_W0QQcmdZViewItemQQcategoryZ43977QQihZ011QQi temZ320113546844QQrdZ1QQsspagenameZWD1V

[JimmyHoffa]

Darn. Well. the link is broken. Donno why. Go to ebay and type in "450 serdi" and you'll see what I was thinking about.

[GPracer2500]

Pretty sure the 04 had stainless steel valves.

[Scro]

Originally posted by GPracer2500
Pretty sure the 04 had stainless steel valves.

This is correct.

[JimmyHoffa]

Holy hot sweetness. Do both '04 and '05 have SS valves? I apologize for not doing my homework. However, since these are the only years I can actually afford, this would be good... if the '04's go longer than the years with Ti valves without needing valve jobs. Is this the case?

With this info in mind, would Serdi be the way to go as far as longevity? Possibly I don't really know what a true Serdi valve job is. I thought the valve seats were round, not multiple-angled when a Serdi machine was used. I looked up lots of diagrams, and saw my friend's head, and I was pretty sure I wasn't insane... I didn't see multiple distinct angles...

[GPracer2500]

Originally posted by JimmyHoffa
Holy hot sweetness. Do both '04 and '05 have SS valves? I apologize for not doing my homework. However, since these are the only years I can actually afford, this would be good... if the '04's go longer than the years with Ti valves without needing valve jobs. Is this the case?

With this info in mind, would Serdi be the way to go as far as longevity? Possibly I don't really know what a true Serdi valve job is. I thought the valve seats were round, not multiple-angled when a Serdi machine was used. I looked up lots of diagrams, and saw my friend's head, and I was pretty sure I wasn't insane... I didn't see multiple distinct angles...

04's and 05's use the same valves.

On a Serdi machine, the exact cut depends on cutter bit that's used. It could be anything from a "standard" three angle cut to a fully radiused cut to anything in between. Serdi probably makes many hundreds of different cutters depending on what you're after.

As I understand it, Serdi machines are well known as one of the leading tools for valve seat cutting because they were the first to cut all angles at the same time. The alternative, traditional way, is to cut each angle with a separate cutter, one angle at a time. A Serdi can do that to though--they have staight angle cutters as well. But the advantage of having all the angles cut at the same time is 1) the added precision of each angles' width and 2) having each valve seat being cut exactly the same.

Some examples...

Straight angle 45* cutter:
http://www.serdi.com/files/ftp/tooling/503.jpg

3 angle, 75* 45* 30* cutter:
http://www.serdi.com/files/ftp/tooling/031.jpg

5 angle:
http://www.serdi.com/files/ftp/tooling/605.jpg

Radius with 45* sealing seat:
http://www.serdi.com/files/ftp/tooling/603.jpg

As you may notice, 5 angles over such a short distance is practically one smooth radius.



AFAIK (and I could be mistaken), there needs to be at least one flat surface. This is the surface the valve actually contacts. 45* would be a typical angle for this surface. 45* is the sealing surface angle for the stock 3 angle valve job.

As fas as durability, you'll need to talk to a professional to see what's what. The sealing surface can be wide, narrow, high up, or pushed down on the seat. There's a give and take in these areas regarding performance vs. durability. I'd guess only the highest end machine shops off a whole lotta choice in these areas for any given application. I'd bet most of the time you either get their high dollar performance cut or their standard 3 angle. If they use a Serdi (or similar), even if it's just a 3 angle cut it's still "good" because they're likely cutting all three angles at the same time with a single cutter head. And that's better then cutting each angle separately.

[GPracer2500]

I was thinking and I suppose you could have a 100% fully radiused cut and no flat angle anywhere on the seat. But I think you'd then need the sealing surface on the valve itself to have a concaved radius that matches the seat. Maybe this can be done but I've never specifically heard of it. And if it can be done, a concaved radius on the valve doesn't sound too good for flow past the valve [shrug]. The alternative would to keep a flat sealing surface on the valve. But I would expect those valves to burn up fast and not seal well.

The idea here is that you need some valve to seat surface area contact. Having the valve and seat touch each other at only a very thin line is no good. Some surface area is tremendously important not just for sealing, but for cooling. The whole time the valve is touching the seat the head is sucking heat out of the valve. The more contact between the valve and seat the cooler the valves will stay.

[JimmyHoffa]

Ok. My understanding of everything I need to know has been deepened significantly.