Valve Opinion

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Valve Opinion

Postby britbikemike » Wed Aug 31, 2011 6:23 am

Do these valves look burned or bad to you guys? I only ask because I am not sure what used ones look like, and I could use the opinions.[img][img]http://i1130.photobucket.com/albums/m530/britbikemike/atlas6.jpg[/img][/img]
Traction is kind of like bowel control. Once you think you are going to lose it, it's probably too late!
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Re: Valve Opinion

Postby britbikemike » Wed Aug 31, 2011 6:27 am

Image
Traction is kind of like bowel control. Once you think you are going to lose it, it's probably too late!
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Re: Valve Opinion

Postby britbikemike » Wed Aug 31, 2011 6:27 am

Image
Traction is kind of like bowel control. Once you think you are going to lose it, it's probably too late!
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Re: Valve Opinion

Postby grandpaul » Wed Aug 31, 2011 6:45 am

The valve seats aren't sunken, that's a good thing.

You'll need to pop the springs off and have a look at the valve and seat mating faces, plus see if you can grab each valve by the head and wiggle it from side-to-side in the guide; anything more than a barely perceptible wiggle needs to be measured against spec. You can look at the stems and see if they are excessively worn and scratched.
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Re: Valve Opinion

Postby beng » Wed Aug 31, 2011 8:07 am

No way to tell from photos. You have to take the valves out of the head and measure the stems for wear. If the stems are in spec, then you chuck them up in a valve grinder and then you can tell if they are bent by whether or not they grind concentrically..... If that all goes well then you heat the head up and knock in new guides, ream them to suit your stems and kiss the seats with some stones to suit how you are going to use the bike.....
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Re: Valve Opinion

Postby Matt Spencer » Wed Aug 31, 2011 6:32 pm

NO , they look ' piled ' ! :shock:

Ancient valves will errode and get all thin, primarilly from the chamber face.
3 or 4 Valve face ' recuts ' will have the edge ( circumferance ) Knife Edge .

Which is a bit thin .Cowboys might reface seats ( ON Valves ) excessively .
Correct is to do worst and match other tio identivcal, so youve got two cylinders,
not Two Singles. :P

Valves out look for pitting n the seats ( valves & seats )

You need a wire wheel ( & goggles ) to clean all grotty olde motorcycle parts. and hand cleaner.And lots of old newspapers or suchlike
to scew up when covered in muck , put in plastic bags , and trash .

IF the valves arnt all scraped and scoured on the stems , they look good. To Me . :mrgreen:

Nasty Grotty ones wouldve sunk 5 foot back into the head .
BURNING is usually blistering & errodeing in the chamber
.
seen a car on gas recently , semi melted craters like the moon , almost. getthepicture.
OTHERWISE its some pillock has had clearances tight or rockers gunged beyond etc
holding valve unseated , where the aforesaid nasty gas quickly erodes a path through the edge of the valve, and if youre particularly slack , the seat also .
in which case buy a honda. your mecanical aptitude is unsatisfactory . :P
The one rule to the exception , is theres the exeption to each rule .
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Re: Valve Opinion

Postby Rohan » Fri Sep 02, 2011 1:24 am

That engine looks like its been a real oil burner.
That heavy carbon buildup is usually burned oil.

You'd want to check if it was rings, or worn valve guides....
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Re: Valve Opinion

Postby Matt Spencer » Sat Sep 03, 2011 4:31 am

or cheap oil . :? probly doesnt realise you need the throttle on the stop for 10 miles for a good ' plug chop ' . :P
The one rule to the exception , is theres the exeption to each rule .
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Re: Valve Opinion

Postby Bernhard » Wed Sep 14, 2011 8:24 am

Matt Spencer wrote:or cheap oil . :? probly doesnt realise you need the throttle on the stop for 10 miles for a good ' plug chop ' . :P


A tad bit excessive –a good half mile flat out, pulling up a slight incline should be sufficient.
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Re: Valve Opinion

Postby britbikemike » Wed Sep 14, 2011 8:59 am

I sold the AJS today, so it is getting a complete head job anyway. lol I figure I want to make sure it is right, and not"good enough".
Traction is kind of like bowel control. Once you think you are going to lose it, it's probably too late!
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