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95” Piston selection question???

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  #21  
Old 02-28-2012, 03:26 PM
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Originally Posted by V-RoyD
1931, I put the frt. cyl. together & torqued head to Cometic specs, 42 fp. Then when I took the rear off, I saw the o-ring on the case dowel which I didn't know was there on the front. (It stuck to the bottom of the frt. cyl and I didn't see it). Dumb A$$ mistake but glad I saw it before getting it all back together. So I will not be able to re-use the MLS gasket? Crap, that's another $30 & 1 week wasted since I gotta order that. Looks like I'll at least have 1 spare gasket since they come in pairs.
You can resuse the MLS gasket if all you have done is torque it down; they don't compress. I have torqued heads to check squish and reused them in the final assembly several times, no issues.

The OEM .045" gasket compresses, down to .040"-.042" so your calcs could be a bit off if you use the OEM gasket but not enough to make any difference.
 
  #22  
Old 02-29-2012, 10:04 AM
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I should have no issues with valve to piston clearance. The valves are 1.94/1.61, heads are not milled, SE-203 .510 lift cam, KB pistons only have 6.7cc dome & valve reliefs are 2" diam. Do I have to check it?
 
  #23  
Old 02-29-2012, 10:25 PM
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Default Valve to piston clearance

How much Valve to piston clearance should this engine have? I got a piece of .100 solder down the spark plug hole since the head was already torqued. Installed rockers & adjusting pushrods to chek clearance. djl recommended .065 solder but I only had .100, stopped till I get an answer.
Thanks,
Roy
 
  #24  
Old 02-29-2012, 10:34 PM
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I use modeling clay but play-doh will work. Never tried solder but Im sure it will work also. Big Boyz website shows pictures and an article on how its done.. Good on ya for taking the time to do things right.
 
  #25  
Old 03-01-2012, 09:28 AM
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Originally Posted by V-RoyD
How much Valve to piston clearance should this engine have? I got a piece of .100 solder down the spark plug hole since the head was already torqued. Installed rockers & adjusting pushrods to chek clearance. djl recommended .065 solder but I only had .100, stopped till I get an answer.Thanks,
Roy
.060" is the general rule for the minimum piston to valve clearance but I am running a 95" right now with .040" on the exhaust. Not by design, it just worked out that way and I wouldn't recommend it.

I use .060" solder because that is the minimum and, in most cases, you have that clearance so the solder never gets compressed. I would be concerned about using the .100" solder fearing that for some reason, the solder would be compressed and possibley break off a piece and the head would have to come off. But that's just my **** retentive nature; might not be an issue.

I can't believe you can't find .060" solder; it's such a common size. Radio Shak and Home Depot both carry it.

You probably don't have an issue but better safe than sorry and I would check even if I had to pull a head but that's your call.
 
  #26  
Old 03-02-2012, 12:43 PM
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Originally Posted by djl
If the bike were EFI and could be "fine tuned" I would be less concerned about being able to adjust timing to address detonation without degrading performance but can't be done with a carbed bike.
Just curious, are there no aftermarket ignition modules for a carbed TC that let you tweak the timing curve?
 
  #27  
Old 03-02-2012, 01:02 PM
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  #28  
Old 03-02-2012, 01:29 PM
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Daytona Twin Tec and Crane both make a programmable ignition for carbed Twin Cams. I am guessing based general knowledged but would guess the DTT is the more commonly used hardware. While these units are programmable, there are pre-programmed ignition curves and, usually, one of those will work just fine. But, if you have the cables and hardware (separate purchase) you can tweak.

http://www.daytona-twintec.com/products_carb.html
 
  #29  
Old 03-06-2012, 09:14 AM
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All cleances checked good & A few questions as I wrap this thing up. I Just need to get the exhaust, carb & fuel tank back on & ready to fire it up. It was jetted very good before. With the same cams but now big bore, higher comp. & prted heads what can I expect? I wonder how much the jetting will change? Also what's the recommended breakin? Just a couple of heat cycles?
 
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