Author Topic: Burnt valve - how bad?  (Read 6548 times)

Offline motogman

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Burnt valve - how bad?
« on: November 29, 2015, 06:51:51 PM »
In one of the heads on my 750 motor, the exhaust valve has seen better days.  I haven't pulled the valve yet to see what condition the seat is in but I thought I would see what the more experienced member here think I am looking at. 

I have picked up a new valve a while back but am now getting back to the project.  From experience - what do you think -  will I be able to lap a new valve in or will this need a new valve seat?  What else should I be looking at in doing these heads for a rebuild?  How about guides - are they problematic on these motors?




Offline Chuck in Indiana

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Re: Burnt valve - how bad?
« Reply #1 on: November 29, 2015, 06:54:10 PM »
It's only a guess without being able to see the seat..
Chuck in (Elwood) Indiana/sometimes SoCal
 
87 AeroLario
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Offline acogoff

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Re: Burnt valve - how bad?
« Reply #2 on: November 29, 2015, 07:04:21 PM »
     Looks like you had a feather edge with a glowing valve and detonation. Even looks like you may have a crack in the head between the sparkplug hole and the valve. Seen that before, but not on a Guzzi. Just take it apart and clean it up a bit and use a magnifying glass- Hopefully I am wrong.
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Vasco DG

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Re: Burnt valve - how bad?
« Reply #3 on: November 29, 2015, 07:07:23 PM »
No way will a new valve lap in. Just do the right thing and get the heads serviced. New valves, K-lines and a proper three angle cut on a SERDI bench and you'll be right for another thirty years.

Pete

Wildguzzi.com

Re: Burnt valve - how bad?
« Reply #3 on: November 29, 2015, 07:07:23 PM »

Offline motogman

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Re: Burnt valve - how bad?
« Reply #4 on: November 29, 2015, 07:57:26 PM »
I suspected that might be where I was headed. 

I just tried to remove the valve but my compressor is not up to this task - it is a cheap pos.

What are K-lines?  And a SERDI?

Is a three angle cut typical?  Will a typical machine shop know what this is?  And how to do a guzzi head?  Is there anything in particular to ask for?

Is there someone on this forum to recommend sending them to?

What is a good spring compressor for doing these?

Vasco DG

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Re: Burnt valve - how bad?
« Reply #5 on: November 29, 2015, 08:15:14 PM »
K-lines are an interrupted scroll liner or the valve guides. As long as the guides are still firm in the head they are actually superior than the parent material as they absorb oil better and last longer. They also keep the valve concentric with the seat so that you need to remove less seat material.

SERDI is just a manufacturer and the name has become sort of generic. It's a head servicing bench that takes the hard work out of cutting seats accurately.

Most valves use the same three angles to get the seats cut correctly, any head shop will know what to do unless the are Cro-magnons in which case they won't be around very long......... :grin:

Pete

Offline flapjack

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Re: Burnt valve - how bad?
« Reply #6 on: November 30, 2015, 06:15:13 AM »
Pete has it pretty much spot on.  As far as the possible crack from the plug hole to the seat, have the seat cut out, v out and weld crack,have new seat installed and recut.  We do this all the time and it is a simple operation on a Serdi>

Jack
1975 BMW R90S, 1976 R90S, 1978 R100RS,1978 Buell S1,750 Triumph short rod flatracker,750 Triumph long rod flatracker,1976 T3 cafe

Offline motogman

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Re: Burnt valve - how bad?
« Reply #7 on: November 30, 2015, 07:58:00 PM »
I checked with a couple of buddies today and the only shop they knew that did K-Lines has apparently gone out of business.  I will be checking around as it sounds like a good approach.

Anybody here know of a good shop in SE Michigan (suburban Detroit area toward the west side - i.e. Livonia, Plymouth, Ann Arbor, Ypsilanti, Belleville etc.) that does bike heads and has experience with doing K-Line guide inserts?

Offcamber1

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Re: Burnt valve - how bad?
« Reply #8 on: November 30, 2015, 08:50:24 PM »
heads are light and shipping is cheap.  Why not wrap them in bubble wrap and ship them to one of the vendors that advertises here on this forum?  (no suggestions as I would not want to insult any of the good vendors by accidentally omitting them.)

You are doing both heads, right?

oldbike54

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Re: Burnt valve - how bad?
« Reply #9 on: November 30, 2015, 08:56:49 PM »
heads are light and shipping is cheap.  Why not wrap them in bubble wrap and ship them to one of the vendors that advertises here on this forum?  (no suggestions as I would not want to insult any of the good vendors by accidentally omitting them.)

You are doing both heads, right?

 Maybe Flapjack can help .

  Dusty

Offline motogman

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Re: Burnt valve - how bad?
« Reply #10 on: December 22, 2015, 08:13:58 PM »
Picked up my heads, motor and other bits from Flap Jack at Automotive Machine in Franklin Mi today.  Thanks for the introduction Dusty.  Jack and his son did nice work on my Guzzi parts and I enjoyed seeing some of the bikes he has around his shop.  Here are some of the results...

 :evil: :evil: :evil:

My computer is hosed up...  I will try to post some pics tomorrow.

oldbike54

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Re: Burnt valve - how bad?
« Reply #11 on: December 22, 2015, 08:19:38 PM »
Picked up my heads, motor and other bits from Flap Jack at Automotive Machine in Franklin Mi today.  Thanks for the introduction Dusty.  Jack and his son did nice work on my Guzzi parts and I enjoyed seeing some of the bikes he has around his shop.  Here are some of the results...

 :evil: :evil: :evil:

My computer is hosed up...  I will try to post some pics tomorrow.

 Wasn't me , is there another Dusty ? Glad it worked out though  :thumb:

  Dusty

Offline Chuck in Indiana

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Re: Burnt valve - how bad?
« Reply #12 on: December 22, 2015, 08:59:35 PM »
Maybe Flapjack can help .

  Dusty

Yer losing it, Dusty.. :cool: :boozing:
Chuck in (Elwood) Indiana/sometimes SoCal
 
87 AeroLario
95 Skorpion tour
22 Royal Enfield Classic 3 fiddy
 "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
Albert Einstein

oldbike54

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Re: Burnt valve - how bad?
« Reply #13 on: December 22, 2015, 09:03:30 PM »
Yer losing it, Dusty.. :cool: :boozing:

 Well damn , anyway , no credit due , just glad it worked out .

  Dusty

Offline motogman

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Re: Burnt valve - how bad?
« Reply #14 on: December 22, 2015, 09:03:44 PM »
Who is that masked moderator guy?  Only the shadow knows....

oldbike54

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Re: Burnt valve - how bad?
« Reply #15 on: December 22, 2015, 09:10:06 PM »
Who is that masked moderator guy?  Only the shadow knows....


 Now I'm tickled .

  Dusty

 

Offline NCAmother

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Re: Burnt valve - how bad?
« Reply #16 on: December 22, 2015, 09:20:38 PM »
glad it worked out.  Did they magna flux both heads?  (Easy way to show cracks)

Offline Chuck in Indiana

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Re: Burnt valve - how bad?
« Reply #17 on: December 22, 2015, 09:50:37 PM »
glad it worked out.  Did they magna flux both heads?  (Easy way to show cracks)

Magna = magnetic I think..  :smiley: Dye penetrant for aluminum.
Chuck in (Elwood) Indiana/sometimes SoCal
 
87 AeroLario
95 Skorpion tour
22 Royal Enfield Classic 3 fiddy
 "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
Albert Einstein

Offline Antietam Classic Cycle

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Re: Burnt valve - how bad?
« Reply #18 on: December 22, 2015, 10:46:58 PM »
Magna = magnetic I think..  :smiley: Dye penetrant for aluminum.

Lots of folks use "magnaflux" interchangeable with "Zyglo testing". Since Zyglo® is a Magnaflux product, it makes sense.
Charlie

Offline LaGrasta

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Re: Burnt valve - how bad?
« Reply #19 on: December 23, 2015, 12:45:59 PM »
what year/model, how many miles?
You can buy style, but you have to build character.

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Offline motogman

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Re: Burnt valve - how bad?
« Reply #20 on: December 23, 2015, 05:51:04 PM »
Some before and after pics...  nothing like 'new' clean parts...

Once again - good work by Flap Jack and his guys at Automotive Machine.

I ended up having the engine bead blasted.  Question to the group - is any treatment of the aluminum warranted or just let it age in the natural state?

Before:

After:


More after:





The mains were not bad but on the low end of spec so decided to clean it up and get new bearing throughout...

Before:


After:
An after a fine grind...


oldbike54

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Re: Burnt valve - how bad?
« Reply #21 on: December 23, 2015, 05:54:10 PM »
 Looking good gman  :bow:

  Dusty

Offline lucian

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Re: Burnt valve - how bad?
« Reply #22 on: December 23, 2015, 06:02:33 PM »
Nice work Gman. Just curious as to how you plan to preserve that shiny clean alum.

Offline Rich A

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Re: Burnt valve - how bad?
« Reply #23 on: December 23, 2015, 07:38:01 PM »
I use some stuff called Alumaguard to protect aluminum. Some guys who fabricated leaning posts and tuna towers for boats recommended it, and I've found it to be quite good.

Rich A

Offline motogman

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Re: Burnt valve - how bad?
« Reply #24 on: December 23, 2015, 07:42:39 PM »
Nice work Gman. Just curious as to how you plan to preserve that shiny clean alum.

That is what I  am looking for help with.  It looks great now and it would seem some sort of treatment is in order but I am looking for recommendations.


I use some stuff called Alumaguard to protect aluminum. Some guys who fabricated leaning posts and tuna towers for boats recommended it, and I've found it to be quite good.

Rich A

I am going to check this out.  What do others recommend.


Offline Antietam Classic Cycle

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Re: Burnt valve - how bad?
« Reply #25 on: December 23, 2015, 08:38:47 PM »
That is what I  am looking for help with.  It looks great now and it would seem some sort of treatment is in order but I am looking for recommendations.


I am going to check this out.  What do others recommend.

All I do is clean with S100. Seems to do the trick.
Charlie

Offline Chuck in Indiana

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Re: Burnt valve - how bad?
« Reply #26 on: December 23, 2015, 08:42:28 PM »
All I do is clean with S100. Seems to do the trick.
Me, too.. seems to do the trick. Make *absolutely sure* you rinse it all off. It's corrosive, and will do what corrosive stuff does if left on. Don't ask me how I know.
Chuck in (Elwood) Indiana/sometimes SoCal
 
87 AeroLario
95 Skorpion tour
22 Royal Enfield Classic 3 fiddy
 "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
Albert Einstein

father guzzi obrian

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Re: Burnt valve - how bad?
« Reply #27 on: December 23, 2015, 09:21:23 PM »
Magna = magnetic I think..  :smiley: Dye penetrant for aluminum.

Fluorescent penetrant is so much more effective than the old dye pen, but if its all you got.... And the Flour pen kits are cheap

Offline motogman

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Re: Burnt valve - how bad?
« Reply #28 on: January 01, 2016, 06:50:26 PM »
I use some stuff called Alumaguard to protect aluminum. Some guys who fabricated leaning posts and tuna towers for boats recommended it, and I've found it to be quite good.

Rich A

Has anybody else tried this Aluma Guard on shot cleaned aluminum cases, wheels etc?   What kind of experience with this or other aluminum protection?


canuck750

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Re: Burnt valve - how bad?
« Reply #29 on: January 01, 2016, 07:32:12 PM »
Your engine looks great :1:

I use ACF50 on bare aluminum, it is very popular in the UK, been tested and reviewed in lots of bike magazines over the years. I found it here in Canada at an aircraft maintenance supply store. Spray or brush it on and it will resist corrosion in a salt atmosphere for a year. Here in the dry west the stuff has kept the engine and wheels of my bikes looking as good as they day I cleaned them.

http://www.ebay.com/itm/ACF-50-ANTI-CORROSION-MOTORCYCLE-SPRAY-PROTECTION-ACF50-/301814998278?hash=item4645936506:g:6~MAAOSw4SlV71bz

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