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Author Topic: INDIAN 741 Supercharged...See you in 2011  (Read 447964 times)
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ironwigwam
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« Reply #510 on: September 28, 2010, 04:08:23 AM »

Lars,
    Great to see/ hear you again.
    On the indian cams, the overlap can be seen/felt while the cam moves thru BDC, there will be an overlap where the exhaust is still open while the intake begins to open. This is why I have go to 4 lobes so I can make corrections? or shoot myself in foot on a tune up.
   By the way, look for me in 2011, I'll be the fellow with the red streamliner with an Indian on the side
   Rocky
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thefrenchowl
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« Reply #511 on: September 28, 2010, 07:35:53 AM »

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Ironwigwam: the overlap can be seen/felt while the cam moves thru BDC

grin I think you mean TDC... grin

Patrick

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Flat Head Forever

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« Reply #512 on: September 28, 2010, 11:25:31 AM »

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« Last Edit: October 03, 2010, 09:04:12 AM by panic » Logged
octane
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« Reply #513 on: September 28, 2010, 02:36:46 PM »

.





My head is spinning !




.
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"A designer knows he has achieved perfection
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« Reply #514 on: September 28, 2010, 04:50:09 PM »

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« Last Edit: October 03, 2010, 09:04:31 AM by panic » Logged
wobblywalrus
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« Reply #515 on: September 29, 2010, 01:19:40 AM »

Lars, the dynamic compression ratio stuff might be too confusing.  The coverage we just had of Cook's shootout showed the blown out plenum chamber on the Speed Demon.  It is the aluminum sheet metal box that is all bent up.  A fellow in the forum said that chamber was a pressure release valve.  It was not designed to be one, it just acted as one.

On the salt I watched the little Scout.  It was really moving along.  As I remember, it averaged just under 90 mph through the mile with a blown head gasket slowing it down near the exit.  This is much, much faster than a standard Scout would go at that altitude and on that surface.  Most of the bike's build is fairly conventional and it is running on gasoline.  Lots of boost must be giving the bike the speed.

The Speed Demon problem got me to thinking about the Scout.  Could the head gaskets be acting like pressure relief valves?  Would fixing the gasket problem keep excessive combustion pressures in the engine and cause more expensive damage?  The failures I see on the close up views of the gaskets make me very concerned about excessive combustion chamber pressures.  These are not old gaskets that have been eroding after long use and many heat cycles, and they finally let go.  They are new gaskets with very few miles on them.  No heat erosion or fatigue issues here.  Pressure may be the culprit. 

It is getting late.  Somewhere in this mess of an office I have some dynamic compression ratio data from the old days.  I will dig it up.

       
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ironwigwam
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« Reply #516 on: September 29, 2010, 03:52:40 AM »

All I know is what I touched with my hands when doing this yesterday,
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thefrenchowl
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« Reply #517 on: September 29, 2010, 07:48:53 AM »

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wobblywalrus: Could the head gaskets be acting like pressure relief valves?

These fiber ones did... I think copper gasket would have more inherant strenght in them.

What I've noticed over the years of abuse I gave to my 900 H-D side valve KHK is that, no matter how well you mate the heads to the cyls by lapping (no head gasket on these), there's always traces of combustion leaks between the chamber and some of the head bolts.

I'm thinking of actually remachining part of my cyls and heads to press in some sort of individual "fire rings" around each of the head bolts... These would sit half way in the heads, half way in the cyls and make a better "labyrinthe" type of seal to avoid leaks.

More head bolts would help as well!!!

Patrick
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« Reply #518 on: September 29, 2010, 02:53:21 PM »

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« Last Edit: October 03, 2010, 09:04:56 AM by panic » Logged
octane
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« Reply #519 on: October 01, 2010, 03:20:25 AM »

Lars, the dynamic compression ratio stuff might be too confusing.

Oh yes, but I do believe I understand ( more or less....er....less ) what it's all about.
This one explains it quite well:
Dynamic compression ratio

BTW: that site has a link to this:
Cam Timing vs. Compression Analysis
written by none other than  'panic' / Jeff

Quote
On the salt I watched the little Scout.  It was really moving along.  As I remember, it averaged just under 90 mph through the mile with a blown head gasket slowing it down near the exit.  This is much, much faster than a standard Scout would go at that altitude and on that surface.  Most of the bike's build is fairly conventional and it is running on gasoline.  Lots of boost must be giving the bike the speed.
Yep...and maybe too much. I do think I am on the limit as to how much power I can squeeze out of the poor thing
without doing some serious damage to it.
Remember this used to be a little 500cc thingy that went maybe 45-50mph and now it goes
close to 90 mph ( with two farting head gaskets at a density altitude of 6290 feet ).

Quote
The failures I see on the close up views of the gaskets make me very concerned about excessive combustion chamber pressures.  These are not old gaskets that have been eroding after long use and many heat cycles, and they finally let go.  They are new gaskets with very few miles on them.  No heat erosion or fatigue issues here.  Pressure may be the culprit.
Yep; these are new gaskets and yesterday I finally had the time to take off the front cylinder-head to check
the gasket. That one had VERY few miles on it as it was installed prior to the last run I made.



....but even so, it was slightly leaking as seen here
( so I was in fact running two leaking gaskets on the timed run )



Yes pressure is the problem ....BUT I'm tempted to disagree with you on the "heat-erosion" issue.
Again one can see how the edge of the gasket has melted
so I do believe there's a "heat-erosion" problem that makes the gaskets unable to cope with the pressure

As you know one want to avoid any sharp edges in the combustion chamber
(and I did go through a lot of work on the head to polish them to erase all sharp edges)
as these will act as 'hot-spots' where pre-ignition can take place
My theory is that that's exactly what the edges of the gaskets are doing
....heating up the edges, and eventually melt them.
It's a LOT 'easier' to suffer pre-ignition on a supercharged engine than on a N/A.

BTW: I took a look at the spark plug, and to me it looks good.
I did read somewhere in the forum how you can't 'read' the plugs in the usual way
when running on racing-gas ( I was running the 108 octane racing gas )
as it will never give the blown(ish) color we're usually looking for.
This one should give an good indication as I 'killed'  the engine right after leaving the timed mile




If you have the room above the engine, a single piece of heavy steel plate above all bolts can be jacked into place by levering against a frame tube.
...mmmmm: that may be an idea.
We'll see after I tested how things go with the copper gaskets

I agree that based on the video the power is there, so the cams can't be too bad. Unless you have some alternate parts that can be simply swapped in (cams, rockers) I'd leave that stuff alone to avoid introducing a variable.
I will.
As I said ; I do believe too that the power is there and
the exact amount of valve overlap isn't that interesting to me.
All I know is that it's VERY small and everything I've read on supercharging tell
that small overlap is a good thing in a supercharged engine...which is quite logical come to think of it

Quote
How much spring are you running?


I take it you mean valve-spring pressure ?!

 200 psi ( valves fully opened )  / 110 psi ( valves closed )
as 'simulated' here in this set up I did





BTW ; I realized I had a couple of small video-files that Tom took out there
and I put them together to make a little video.
Now I wished I had more, as this will be a great souvenir for when I get
old and fart'y, and sit there and dwell on memories
.-)

Click image



OK. so I cheated on the narrative, as the last shot is from the first ( un-timed ) run
but heeey; that's called 'artistic freedom' ...ha ha.
« Last Edit: October 01, 2010, 04:24:10 AM by octane » Logged

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« Reply #520 on: October 01, 2010, 06:53:30 AM »

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ol38y
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« Reply #521 on: October 01, 2010, 09:38:21 AM »

Lars,
  Here's a little read about plug reading. Everyones opinion will be different but it gives some good basics. There is also another one but I can't find it right now. When I do I'll attach it...

http://xlforum.net/vbportal/forums/showthread.php?t=920271

Larry
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Larry Cason
Bakersfield,CA    It's a dry heat!

2010 BUB 1350 M-PG record
2012 Speedweek  1350 A-PG record 169.975
2014 El Mirage Dry Lake  1350 A-PG  172.651
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« Reply #522 on: October 01, 2010, 11:05:30 AM »

  Hi Lars,  Did you check your valve springs for coil bind?Huh?  When you read your plugs, you should look all the way down looking at the porcelin and plug body, Do you have a plug reading light?    Mike R.
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« Reply #523 on: October 01, 2010, 05:40:45 PM »

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« Last Edit: October 03, 2010, 09:05:38 AM by panic » Logged
ironwigwam
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« Reply #524 on: October 03, 2010, 08:59:56 AM »

Isn't it about time to delete your earlier posts?
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