Author Topic: Decarbonization, piston upgrade, drill case for old style breather  (Read 11171 times)

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ERC

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When the piston is on the rod the side play is 1/8" on the standard rod and piston. There shouldn't be any up and down play. Also I would measure the thickness of the crankcase wall where you plan to put the breather in. On the 700cc twins the cut out for the breather is 1/4" where the cylinder slides in.   ERC
« Last Edit: July 28, 2013, 11:41:46 pm by ERC »
2-57 Apaches, 2-57 Trailblazers, 60 Chief, 65 Interceptor, 2004 Bullet, 612 Bullet chopped.


mattjohnson207

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Sent out cylinder for honing, can't see any wear on wrist pin, don't have any expertise in this area.  I would guess it would be prudent to re-ring...what would be the best rings to get?  Machinist says piston looks ok.
       The brass barb is almost 7mm
        I could not find any evidence  of the 3mm hole the IB bullets have drilled out to complete the breathing circuit.
         Therefore the breathing circuit must be incomplete in my uneducated opinion.
          Proposal:  why not drill a 3 mm hole next to the 7mm on the other side of the stud; and run a rubber breathing hose to the timing case nipple ( this is a 2009 AVL). , or as I've seen another Brit bike, to the valve cover... To complete the circuit.
           It would be ugly, but efficient,  but at a later date when I open the cases for a bottom end rebuild, it would be simple to drill a proper 3 mm hole in its proper place,  like the  iron barrels are, then just plug the ugly hole with a brass screw, grind off...leaving a beauty mole for the discerning critic.
     Matt
     No children were within earshot of the mechanic during this procedure


mattjohnson207

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A very sketchy  and risky operation.  Drill bound up and twisted on me twice,  though final pass was good.
     Tapping the threads went badly, finally used a 6 inch extension with ratchet , did it in one pass.
       Thickness of the case is about 1/4"
        Used paper towels lined with grease to keep grinding debris out of the engine
         Used a Mikita  grinder; disc about the size of the bore,there was some cosmetic damage to the bore which will be invisable, and of no consequence.
           I'm a pretty good carpenter and used to these tools, and still, disaster almost ensued.
            If anyone is tempted to try this mod, please, use a lot more preparation and planning  before drilling and tapping, and sealing off the innards of the engine then  I did.
           For example, perhaps a cardboard cut out to seal off the inside  bore of the engine, sealed  with  silicone, then you could just vacume the sand from the grinder.
           Fabricate a holding device for your drill.
           Better yet, wait 'til it's time for a bottom end rebuild and do it right.
           But I am so happy with the results... Can't wait to ride a cooler , smoother running AVL!
« Last Edit: August 17, 2013, 09:03:59 pm by mattjohnson207 »


ace.cafe

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It looks good.
I don't think that you would be able to see the 3mm hole in the wall between the crankcase and the oil tank. It's obscured by the flywheels. It should be there, but you just can't see it.
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D the D

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Very nice machining.  Congrats on doing it by hand.
'07 Iron Barrel Military (Deceased 14 September, 2013)
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Ice

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Beers to you for doing what till now has only been talked about.
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ERC

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Frankly I can't see how that will work with the cylinder in place the liner will block any cylinder pressure getting to the fitting you've put in there. I think you'll have to mill a passage to the crankcase area below to get it to work. Don't have a bullet apart to check this but all the twins I have are cut like what I described above. Maybe Ace can fill me in on this.   ERC
« Last Edit: August 18, 2013, 02:27:49 pm by ERC »
2-57 Apaches, 2-57 Trailblazers, 60 Chief, 65 Interceptor, 2004 Bullet, 612 Bullet chopped.


ace.cafe

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Frankly I can't see how that will work with the cylinder in place the liner will block any cylinder pressure getting to the fitting you've put in there. I think you'll have to mill a passage to the crankcase area below to get it to work. Don't have a bullet apart to check this but all the twins I have are cut like what I described above. Maybe Ace can fill me in on this.   ERC

In the Iron Barrel engine, there is a gap between the lower portion of the barrel liner that goes into the top of the crankcase, below the breather crescent location.  Maybe somewhere around 1/8" or something like that. This allows air to get out the breather, and uses the lower portion of the barrel liner as a baffle to prevent too much liquid oil from blowing out. I sort of expect that the AVL has a similar arrangement, since the crankcases are basically the same as the Iron Barrel.
« Last Edit: August 18, 2013, 04:21:58 pm by ace.cafe »
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ERC

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Thanks Ace, When I look at the pictures it looks like the case would be very close to the sides of the cylinder. Will be interesting to see how this turns out having never worked on an AVL.  ERC
2-57 Apaches, 2-57 Trailblazers, 60 Chief, 65 Interceptor, 2004 Bullet, 612 Bullet chopped.


mattjohnson207

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Thanks everybody for the encouragement.  I have an iron barrel short block I picked up on e-bay, probably just for the purposes of this discussion,  have to go to work, will look at it later.
       Matt


mattjohnson207

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Here's some pics of the iron barrel, if it helps.the depth is the same, 3  3/16 for both
       There is a 3  22/32"vs 3 21/32" for the opening diameter.. The iron barrel has a slightly wider opening,  looks to be 1/16.  Can't tell about the inside where  the air flow is for the breather,  have to get a set of  gauges... Sure they're probably identical, don't see any reason they would change it
     Matt
« Last Edit: August 18, 2013, 07:49:00 pm by mattjohnson207 »


DanB

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Reply #41 on: November 06, 2013, 03:07:48 am
I'm bumping this. Matt, how did this turn out?  You happy with the results?
Suppose I were an idiot, and suppose I were a member of Congress; but I repeat myself. ... Mark Twain
2006 AVL Electra


mattjohnson207

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Reply #42 on: November 07, 2013, 05:26:52 pm
Hi Dan, while I had the bike apart I had super finishers in Phoenix, Deer Valley, put in a decompression valve...did a nice job,will post a pic later. 
        Waiting on new rings, gaskets etc,  some stuff on back order, hopefully I'll know how it all works out in a couple of months...finances.
           I'm sure it will be fine
             Thanks for asking....Matt


DanB

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Reply #43 on: November 07, 2013, 07:04:24 pm
Cool!  Cant wait to see the pics.  Thanks Matt for updating.

Dan
Suppose I were an idiot, and suppose I were a member of Congress; but I repeat myself. ... Mark Twain
2006 AVL Electra


mattjohnson207

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Reply #44 on: November 07, 2013, 07:46:48 pm
Dan, if you try this breather mod, the aluminum case is very soft and the drill can easily get away from you
        Matt