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iestrada

XR650-valve grind

11 posts in this topic

A friend of mine make his 650 big bore, on the bill there was a charge for "3 valve grind 4 valve" Any one knows what it is that job :cry: ?

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just a guess.

he needed three valves ground. the fourth didnt need anything?

is there good riding in Moldova?

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It's probably supposed to be a 3 angle valve grind on all four valve seats. Now days, it's more common for higher end shops to use a Serdi multi-angle machine or something similar to accurately cut the seats with carbide tooling instead of grinding them, but grnding still works well when done properly.

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A friend of mine make his 650 big bore, on the bill there was a charge for "3 valve grind 4 valve" Any one knows what it is that job :cry: ?

Maybe a 3 ANGLE grind job on the 4 valveseats :cry:

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I've been doing mach. work over 25 years, IMO you are not doing a valve job,seat grind,whatever ya wanta call it,unless there is 3 or more angles on the seat.... :cry:

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Sorry I'm a newbe to valve work, but what are the angles in the seat? It seems like it would just be one slanted angle to match the face of the valve.

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The angles are important for good seating, but mostly important for air flow (improved efficiency, especially during low and medium valve lift). Even the stem size of the valve is vital in regards to air flow.

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Here's an interesting link I've kept the link to which shows a picture of a Serdi machine and talks a bit about valve grinding & cutting.

http://www.d.umn.edu/~dmorriso/sciencewriting/webcontest/webcontest/student%20samples%20of%20term%20project/Mark%20Smith%20final%20paper/SerdiReport.PDF

Here's another interesting article that talks about the importance of multi-angles.

http://www.chevyhiperformance.com/techarticles/89678/

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ya gotta wonder just how often most guys have their grinders re-calibrated to 30/45/60 degrees?

with all these new 4 smokes coming out...theres going to me a lot more interest in the subject...

thanks for the articles. great reading.

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i run a automotive machine shop and do the valve jobs for most every repair shop in town you can do a valve job or valve grind with just about any angle you want but you must go by what the valve face has it is most of the time a 45 and that will be your seal surface the 30 and the 60 are used for how wide you want that sealing surface 2mm,3mm,1mm what ever your application the intake side is usualy set narrow like 1mm the exhaust needs to be a little wide because it has to get rid of the heat the 30 and the 60 are also used to move the sealing surface up and down the valve face like closer to the outside edge of the valve face which is good on the intake side the exhaust needs to be closer to the middle because of the heat transfer you could even have 5 angles if felt it needed it i dont realy see any gains from it though

hope this wasnt more than you wanted to know

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