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Author Topic: INDIAN 741 Supercharged...See you in 2011  (Read 447737 times)
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Unkl Ian
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« Reply #615 on: March 09, 2011, 10:32:16 PM »

Do the head gaskets always leak in the same place ?

Cometic will make custom head gaskets in Copper etc.
http://cometic.com/custom.aspx

IIRC, the rules don't require you to run stock cylinder heads.
Only the case and barrels need to start out stock.

So you might be able to make your own heads, to help improve sealing.
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I guess the answer is "a Secret" .
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« Reply #616 on: June 03, 2011, 09:19:51 AM »

Lars, you are a very busy guy. So I will patiently wait for a PM. You have a mighty full plate, good luck!
I'm terribly sorry Bob!
A lot of...erh...stuff got in the way, so it slipped my mind.
I'll get back to you

Land Speed Larry, The term "brothers" refers to lapping the front head to the front cylinder using small 13mm circles using coarse, then fine and now to extra extra fine lapping compond. Now they are perfectly flat to each other  , no need for head gasket , no worries about leakage
Thanks Rocky...I get it now.
My worry ( which might be unfounded ) would be if the head(s) , due to the heat
somehow would warp/twist ever-so-slightly, and there would be nothing to take up that.
Must say : for now it will be copper gaskets.


Hi Lars,
When I was racing a turbo nitrous funny bike, we used to use a burst plate on the plenum chamber.

It consisted of 2 round rings with approx a 2" bore. The first ring was welded to the plenum, and drilled and tapped with 6 M4 screws threads
The second ring had clearance for the M4 screws.
The actual burst panel material started off as a coke can, but we found that the panting of the engine induced stress failures of the ally disc. We then changed over to plastic milk carton which never failed mechanically, but would burst at around 40 PSI.
If you would like, I could possibly dig out an old photo if this would help

Neil
Hi Neil.

Now the problem is that I'm running at about 5-6 psi and I would have a hard time
'calibrating' a burst-panel to burst at , let's say, 9psi.
On the other hand, with a set-up similar to mine its a question of picking
the right coil-spring and adjusting the nut-tension on the spring



I do however see the advantage of having a big-area panel to burst open in an instant.
Mmmmmm: I'll give it some thought.

Thanks !


Do the head gaskets always leak in the same place ?
No.

Quote
Cometic will make custom head gaskets in Copper etc.
http://cometic.com/custom.aspx

IIRC, the rules don't require you to run stock cylinder heads.
Only the case and barrels need to start out stock.

So you might be able to make your own heads, to help improve sealing.
Thanks for the info !
...but I'm afraid that making my own heads are way outside of my
capabilities and AMA ( BUB ) rules says that running "Vintage" class
I must
"..retain the O.E.M heads..."

Strangely that doesn't appear to be the case for the S.C.T.A ( Speedweek ) rules.
« Last Edit: June 03, 2011, 09:26:56 AM by octane » Logged

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« Reply #617 on: June 03, 2011, 09:48:15 AM »

Well: long time, no see
so time for an update:

Finally got around to disassemble the engine





Basically it was all good news.
Nothing broken, no twisted con-rods, no scratches inside the cylinders etc.

Except for one thing:
ever since I ran it at Bonneville I've been completely mystified by something
strange going on:
When I twisted the throttle ----> the blower-drive-pulley ( and therefore the whole crank assembly)
moved to the left
When letting go of the throttle---> it moved to the right

One thing was certain ; the crank end-flow had risen from when we put the engine together
where it was shim'ed to the factory spec: 0.015" / 0.4mm.
When I measured it having the bike back in the work-shop it was a whooping 0.040" / 1.0mm

so obviously some strange 'sideways' force, that I couldn't phantom, was at play here.
No one I talked to could explain it.


« Last Edit: June 03, 2011, 10:42:55 AM by octane » Logged

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« Reply #618 on: June 03, 2011, 10:41:50 AM »

To make a long story short(er):
fortunately I have friends in the USA who are waaaaaay smarter than I am.
David in Santa Fe dug into the problem and came up with , what I believe is,
the perfect explanation. There's even a term for it:

"Corkscrewing"

The easiest way to explain it is quote from the link to KIWI Indians
that David provided:

"...Cork screwing is when the flywheels are fitted between
the case halves and are rotated, they pull to 1 side or the other
..
..."
[ which mine does]
"... During service cork screwing causes side
loading (thrusting) which will cause damage to our lower end which is usually
evidenced by grooved or blued thrustwashers.
.."
...in other words; 'grinding' the thrush-washers/shims and the result
will be a larger end-play...as I have now
"...Possible causes are flywheel
misalignment
, pinion and drive housings out of alignment (possibly caused by
improper installation), mismatched case halves or case halves have damaged
mating surfaces (causing cocking)
..."

What I DO know is that my cases were 'matched' and line-honed,
so I took out the manual and went through the flywheel checking procedures:

First a visual check, for what the manual calls
"truing the flywheels"



..by holding a scale to the face of both wheels
to check wheel-alignment

Whooha, mine didn't quite pass the test.
One side was like this ( note the distance between scale and 'lower' flywheel ):



....and the opposite side ( 180 degrees around ) had just a tiny bit of distance
but the other way around ( at the 'upper' flywheel )

Then the manual calls for a way to "true up the rotation of the wheels"
by testing them in contraption like this



and measure the "high spots" ( out of true ) on each wheel.
The height of these spots should be no bigger than 0.002" / 0.05mm

Borrowed this nifty thingy from a friend



and measured both sides



The high spots were  0.004" / 0.10 mm and 0.006" / 0.14 mm,
so that's twice and three times what it should be,
so obviously the two flywheels are out of true, in relation to each other,
making the assembly turn in a sort of 'tilted' whooply manner , causing the corkscrewing.
The KIWI link explains how to check for corkscrewing:

"...To check for cork screwing, rotate flywheel
assembly in 1 direction and see if it winds towards one side of the case. Now
rotate flywheel assembly in the opposite direction and see if it cork screws
towards the opposite side. Repeat this procedure several times ensuring that
"you" do not cause the side thrusting
..."

....and YEP that's exactly what happened.
I rechecked ( to make sure it wasn't the contraption on which I rotated it, that
somehow made it move sideways )
by turning the crank assembly so left side rested on the right side of the contraption
and yep, the result was the same but of cause it moved sideways in the opposite direction


Bad news that it's out of whack, but then again: it's in fact GOOD news,
as the source of the problem is now found and it's relatively easy to correct

According to the manual, one simply take a big lead-hammer and whack them good
till they are true .
Seriously (!!!). That's what the book says.
I don't have the nerve for that, and anyway I'll take it to the machinist to
examine the rod bearings ( though I can't find any undue play ) and put
the thing together in a correct way.

What I did find ( very much in accordance whit what KIWI describes )
is some discoloration and marks on the shim on the left side
from the 'grinding' caused by the corkscrewing



One other thing I checked was the flywheel balance.
This is a new one to me, but the book calls for:

..assemble one piston with all the rings and attach it to the 'male'
connecting rod.
..place them on two parallel bars or 'knife edges'



Now , the piston and rod assembly should stay in any
position if perfectly balanced........should be capable of of balancing in
any rotated position
.

I didn't have such a set of parallel bars, but put it back on the thingy
where the shafts rest on both sides on a pair of roller bearings.
I take it the result is the same.
First I removed the piston from the 'female' rod.



...and NOPE.
It was not in perfect balance. One thing is that the result probably isn't
quite accurate due to the out-of-whack flywheels.
I'll do the test again when that thing is corrected.
If it's still out of balance the book says to drill 5/16" holes
through both flywheels on the 'heavy' side.

Never a boring moment...erh ?



BIG BIG thanks and kudos to David for solving the mystery
and to George of "Tri-Mac Speedsters" for patiently explaining the 'dynamics' involved.
« Last Edit: June 03, 2011, 02:20:38 PM by octane » Logged

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« Reply #619 on: June 03, 2011, 02:45:24 PM »

Land Speed Larry,
  The flywheels are never in true balance to each other. Usually around 62-68% of total mass.
   I can send a balancing manual courtesy of ironwigwam.com if you PM me your address.
  Rocky
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octane
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« Reply #620 on: June 03, 2011, 03:00:37 PM »

  ...The flywheels are never in true balance to each other. Usually around 62-68% of total mass...
Sorry Rocky, I just don't know what that means
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« Reply #621 on: June 03, 2011, 11:15:53 PM »

Lars, do not worry about the big lead hammer.  It is standard operating procedure for a lot of us to use one to do the final truing, if needed.  Always use a lead hammer.  Nothing harder.
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« Reply #622 on: June 04, 2011, 03:41:17 AM »

Hi Octane,

Balancing and trueing!!! real challange...

I do my own trueing... If you can manage to align the flywheels with a straight edge all round the periphery, you'll usually be within 2 to 4 thou from perfect, then careful use of the lead hammer to bring it dead true.

I also don't think balancing with one piston fitted as you show in that picture will be anywhere near since the rod without piston also comes in the picture. The balancing factor (I use 50% like most "old" H-D racers) applies to whole pistons, rings, wrist pins and upper part of the rods, all the bits that are concidered to be alternating weight, while the lower part of the rods, the crank pin and nuts, are concidered as a purely rotating weight. Balancing factor only applies to the reciprocating weight.

I usually calculate my balancing weight, but leave it to an expert to do the drilling/balancing for me from my calcs, they are a few shops that do it, day in day out, here in GB, costs about 50.00 or so if you only send them the flywheels. A lot more required if you send the complete crank since it will also include dismantling and reassembling/trueing...

Patrick
« Last Edit: June 04, 2011, 03:56:40 AM by thefrenchowl » Logged

Flat Head Forever

...What exactly are we trying to do here?...
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« Reply #623 on: June 04, 2011, 04:03:43 AM »

Larry,
   PM sent
   Rocky
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octane
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« Reply #624 on: June 04, 2011, 06:33:10 AM »

  ...The flywheels are never in true balance to each other. Usually around 62-68% of total mass...
Sorry Rocky, I just don't know what that means
Ahhh. Get it.
I think you inadvertently mixed apples and oranges...the "to each other" part, that is.
That threw me off.

We're talking two different things here:

1...truing the flywheels ( the two in relation to each other )

2...balancing the ( complete assembly ) flywheels.
THAT's where the percentage of total mass comes in.

I only have rudimetarily knowledge on that subject.
I do remenber from back when I shared workshop with a guy who set
up his bike with new Wiseco pistons and Carillo rods , how they sat night after
night with digital scales and pocket calculators and large pieces of
paper with large numbers of ...er....numbers, trying to figure out
the closest to perfect balance for the flywheel.
I do understand ...somewhat...the dynamics of how the weight
( and therefore the 'balance' ) on the flywheels
shifts as the position of the weight of rods and pistons move about relative to the center
and how one can never get a 'perfect' balance

This link provided by David explains it rather well in laymans terms:
RB Racing on V-Twin Balance

Lars, do not worry about the big lead hammer.  It is standard operating procedure for a lot of us to use one to do the final truing, if needed.  Always use a lead hammer.  Nothing harder.
OK , but frankly I just can't bring myself to do it.
I'll leave it to a local machinist who do just about nothing than rebuilding
HD flat head / knocklehead / panhead and Brit bike engines.
He's been doing it from the beginning of the world....well, almost

Hi Octane,

Balancing and trueing!!! real challange...

I do my own trueing... If you can manage to align the flywheels with a straight edge all round the periphery, you'll usually be within 2 to 4 thou from perfect, then careful use of the lead hammer to bring it dead true.

I also don't think balancing with one piston fitted as you show in that picture will be anywhere near since the rod without piston also comes in the picture.
Yep, I'm sure the Indian guys knew that,
BUT I think what the Indian manual it trying to say is
that with the method they propose ( only one piston ) you will get something
which in the end will get you to the same ( or nearly the same ) result as long complicated calculations etc.
In fact they , by using only one piston and the flywheel in perfect 360 degrees balance,
they 'build-in' the prefered "un-balance"...be it 62% or whatever.


Quote
The balancing factor (I use 50% like most "old" H-D racers) applies to whole pistons, rings, wrist pins and upper part of the rods, all the bits that are concidered to be alternating weight, while the lower part of the rods, the crank pin and nuts, are concidered as a purely rotating weight. Balancing factor only applies to the reciprocating weight.

I usually calculate my balancing weight, but leave it to an expert to do the drilling/balancing for me from my calcs, they are a few shops that do it, day in day out, here in GB, costs about 50.00 or so if you only send them the flywheels. A lot more required if you send the complete crank since it will also include dismantling and reassembling/trueing...

Thanks Patrick
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« Reply #625 on: June 18, 2011, 08:42:26 AM »

Busybusybusy in the workshop.....timeisrunningfasttimeisrunningfasttimeisrunningoutshortly


Tested ( the un-harmed ) cylinder-head for flatness,
using the scribble-with-a-marker / run-it-over-a-flat-surface-with-abrasive-paper-glued-to-it method;



Ooops: it was flat when I put it on the bike...well, not anymore.
Something tells me it is warping , more or less, along this line
which is obviously not 'supported' 'horizontally' as there are no
cooling-fins 'supporting' it in that direction



..shown from a different angle here



...and one of those 'low' spots is actually where the gasket failed




...and then it gets worse:
tested the cylinders for flatness





...same thing, but the 'other' way, which of cause just makes things worse,
but could explain the failed gaskets.......no ?

It was flat for sure when I put it on. The machinist had seen to that
when it was bored etc.
At first I thought "WTF", a cylinder can't do that !!!..forgetting that
this a flat-head , which ( still to me ) looks a bit weird
see from the side :



I could be wrong, but with that shape it could very well do just that
ever so slightly.....no ?


I guess the heat has a lot to do with this.
Hopefully running alcohol this year, will somewhat help the situation.
I've bought an extra carb that I will set up for alcohol
and keep the old one jetted for gas.

What to do ?
Dunno what to do about the cylinder, but a few ideas for the heads
has been floating around the workshop with help from the local
motorcycle-intelligentsia.

One idea would be to strength the heads by grinding of
the 'outer' part of the cooling-fins ( around 1/4" ) and then
weld on ( to the 'base' of the head ) an 'upright' piece of aluminum
( 1/4" by maybe 1" ) like this



...maybe just in the 'direction' shown on the picture,
maybe on the entire circumference.
« Last Edit: June 18, 2011, 09:07:48 AM by octane » Logged

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« Reply #626 on: June 18, 2011, 06:52:04 PM »

Some things you might consider:

Stronger, smaller diameter, (and longer?) head bolts (which would be stretchier) at higher torque (preload).  To increase initial preload and then minimize its loss due to various (thermal?) distortions.

Re-torque after heat cycles.

Trim away the outside of the head gasket so that the gasket unit contact stress is higher and located more on the interior contour instead of spread across the relatively broad gasket land.

O-ring it.
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« Reply #627 on: June 18, 2011, 08:14:04 PM »

Larry,
  As you may not know, I have worked on the cylinder pressure sealing area as well.
1. Machined heads and cylinders flat on mill first,

2. Added dowels so heads repeat their position on valves and also to slow head growth from heat.


3. Flat within .002, not good enough as I am not using head gaskets to increase compression


4. Now it is time to use lapping compond and a vibratory power unit to let eacjh surface ;ap it self to the other to be a perfect match.



5. Now its closer than ever before.




Not to hijack this thread but only to explain my misguided effort.
« Last Edit: June 18, 2011, 08:19:16 PM by ironwigwam » Logged
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« Reply #628 on: June 20, 2011, 12:29:01 AM »

Is it possible to weld a knob onto the head. mill it flat, drill a hole in it?  Then drill and tap a hole in the same location on the cyl, and add a stud?
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« Reply #629 on: June 20, 2011, 03:40:47 AM »

I should have mentioneed before that I am converting to studs on this go-around rather than the stock fine thread bolts
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