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Discussion Starter #1
I was recently discussing my progress with a fellow from work and he suggested a few things in an effort to produce more power.

Can anyone enlighten me with regards to a couple of his suggestions...
1. Port match and polish. Cut ports to an exact match of the intake gasket/manifold and polish flow path.
2. Multiple angle valve job. 45 degree seats and then 30 and 60 degree cuts to improve flow.

Any ideas, hints or wisdom???
He has offered help and is a very experienced engine builder but not bikes...4x4's and muscle cars!
 

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Sensei
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"Porting and polishing" and "flowing" are best left to those Experts familiar with this specific engine....While the principle is the same, there are "Quirks" that each engine design displays that must be taken into account.......Team Hanson would be one choice for this....
 

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GBones said:
I was recently discussing my progress with a fellow from work and he suggested a few things in an effort to produce more power.

Can anyone enlighten me with regards to a couple of his suggestions...
1. Port match and polish. Cut ports to an exact match of the intake gasket/manifold and polish flow path.
2. Multiple angle valve job. 45 degree seats and then 30 and 60 degree cuts to improve flow.

Any ideas, hints or wisdom???
He has offered help and is a very experienced engine builder but not bikes...4x4's and muscle cars!
Before I read the end of your message I was thinking to myself, "he must be talking with a car guy". :)

Porting/Polishing and multi-angled valve job are worth maybe 3 or 5 percent on a good day. That would be one or two HP on a 450 with nothing else.

Do you plan on racing the bike?
 

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No I won't be racing it...and I had been thinking to myself while discussing peformance improvements... "It's a good thing I have a couple spare heads laying about in the event that something goes wrong..."

Thanks for the input guys...I will have a reputable guy here in town do my cylinder bore, I'll do a standard valve job, and leave it at that.
 

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GBones said:
No I won't be racing it...and I had been thinking to myself while discussing peformance improvements... "It's a good thing I have a couple spare heads laying about in the event that something goes wrong..."

Thanks for the input guys...I will have a reputable guy here in town do my cylinder bore, I'll do a standard valve job, and leave it at that.

That's a prudent decision - stock 450 valves can be problematic when deviating from stock specs, and the seats especially.
 

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I am replacing one of my valves that I managed to bend while working on the engine. First question, does the seat need to be recut for the new valve, or will lapping suffice? Second, when I took the head apart, I noticed some of the valve seats were pretty grimey. I'm guessing they weren't seating properly so they were getting some buildup. Do I need to get these recut, or will lapping suffice. I talked to my local vintage bike mechanic and he said he cuts 3 angle valve seats. I didn't ask him if he could cut a single angle. Should I ask him if he can do the standard cut? This is my first time inside an engine so I'm not sure what is typically done on a valve job.

Mike
 

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Flugtechnik said:
I am replacing one of my valves that I managed to bend while working on the engine. First question, does the seat need to be recut for the new valve, or will lapping suffice? Second, when I took the head apart, I noticed some of the valve seats were pretty grimey. I'm guessing they weren't seating properly so they were getting some buildup. Do I need to get these recut, or will lapping suffice. I talked to my local vintage bike mechanic and he said he cuts 3 angle valve seats. I didn't ask him if he could cut a single angle. Should I ask him if he can do the standard cut? This is my first time inside an engine so I'm not sure what is typically done on a valve job.

Mike
Your mechanic/machinist has it right - download this file, print it and give it to the machinist, it gives all the specs for valve faces - http://home.comcast.net/~tbpmusic6/valvecut.pdf

If the valve did not leak before you bent it, a brand new valve has a good chance of not leaking either, but it's not a given.....

Check to see if any of them leak - stand the head on its "side" and pour acetone into the intake/exhaust ports.
Watch carefully to see of there is any leakage/seepage around the valve faces, in the combustion "dome" - give it 10 minutes or so. NO leakage at all is allowable, I mean NONE.

In all cases, allow your machinist to make the call as to whether cutting new faces is required or if lapping will do the job......
 

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Thanks Bill, you are invaluable as always. I'll let the mechanic tell me what it needs. I can't run the leak test because the head is already fully disassembled. As I said the seats were grimy and certainly would have failed the test without at least cleaning them.
 

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Thanks for the heads up Rod. I was wondering about that. I couldn't figure out how much deeper they would have to cut into the head to do a three angle grind. My seats actually look OK, just dirty. Hopefully just lapping them will get them back to good. Save me some $ too. I am pretty confident in the mechanic I'm using. He works almost exclusively on vintage bikes and has been around as long as they have. I didn't have the parts with me when I was talking to him.

BTW, thanks for the valve guide. Since you didn't give me your paypal address, you have a present on the way.

Mike
 

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otr002 said:
WARNING WARNING :shock: Do not do any work on the valves until you talk to an mechanic/engine builder that has rebuilt/modified these engines :shock: They have some hidden pitfalls that can render them useless, the next head i'll be doing is being sent to Terry Hanson, as i have learnt the hard way with one head near on useless and another just saved.

The big issue is that the valve to cam follower distance is crucial and unlike other heads that can take the valve sitting deeper in the head without much concern, these can't :cry: as you recess the valve the clearance for the follower is reduced quickly to a point that there will be no clearance. This does two things one it will unload the valve torsion bar and secondly require the valve tip to be ground to give you that clearance back. my advice is to contact Terry and listen to him exclusively. Do not let anyone not experienced with these heads to touch them otherwise the $$$$ will mount up.

500T heads are a little different and can be modified with $ and ease as they do not have the steel skull cap combustion chamber.

GOOD

BAD


Rod from OZ :cool:
good advice.....Terry did the work on my head and i have no complaints....he gave me alot of info about those heads....he really is a wealth of knowledge i mean hell he has been working on them and modifying them for years.
 

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Dropped my head of with the mechanic today. He actually brought up the problem with removing too much material when recutting the seats and mentioned the torsion bars. Gave me a warm fuzzy feeling. He is going to try and get everything cleaned up with a good lapping, but he said one of the seats looked pitted. We'll see.
 
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