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detonation! #708310
09/13/17 10:34 pm
09/13/17 10:34 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
i took my hot-shot 650 triumph to loring in july, and ran the [censored] out of it trying to get close to tony. i never did, but i did manage to get 128 mph out of it, which would have been a record not so long ago. so i'm happy with it for the moment. anyway, i'm taking it apart right now to see whether there are any rod bearings left, and discovered that i'd been detonating, at least on the last several runs or so.

left combustion chamber:

[Linked Image]

right combustion chamber:

[Linked Image]

on the left chamber, the pecking at the carbon is where i would expect it to be, opposite the plug. but on the right side, the pecked-at carbon is right there near the plug. pre-ignition? dunno.

looking at the piston crowns, what i took for fuel deposits at first look more like little bits of aluminum under magnification:

[Linked Image] [Linked Image] [Linked Image]

this bike has 11.75 or so compression (JE pistons worked over by ed vallicutt), a megacycle 510-x2 cam, 35mm FCR carbs running 130 or 135 main jets, and a fixed advance ARD that was set at 38 BTDC, fuel was 110 octane VP C12.

i'd had a clutch pushrod failure on the dyno when i went to find optimum tuning settings, so i ran with 38 BTDC and mains that seemed to color the plugs correctly. i'm thinking that 38 BTDC was too advanced for this motor, and so if i were to do nothing else, i'd be trying more retarded settings on the dyno when it goes back on and stay with the richer main jets. but in the meantime, i'm sending the head back to rob hall to have it drilled for dual plugs. i've run those very successfully on my street bike for years, and had intended to do it to this one originally.

that will require some changes on the ignition, which is currently running a harley-style dual-fire coil. i'll have to switch to single fire, and then run splitter diodes on the plug wires to fire two plugs from a single-tower coil. dunno how well that will work, but the parts are available.



live every day.
die once.
Re: detonation! [Re: kevin roberts] #708317
09/13/17 11:17 pm
09/13/17 11:17 pm
Joined: Oct 2012
Posts: 3,347
Running from demons in WNY
Hillbilly bike Online content
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Running from demons in WNY
Big domes, slow burn, more time for detonation to occur...That's why I gave up some compression to use the faster burn of flat top dome 10.5 pistons..You may just need a different type of racing fuel....Look at this list of John Healys' and read Kevin Cameron's article on fuel volatility.....Then go to the VP racing fuel fuel website and check out the 90c volatility and select one with a lower temp than C-12, there are quite a few...
Octane is not all there is


Kevin, great signature, I could hear it in my mind but had to Google the words to find out why I heard it many times in the past..



650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: detonation! [Re: kevin roberts] #708344
09/14/17 2:20 am
09/14/17 2:20 am
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
that's what i'm doing on my street bike, nick.

[Linked Image]

although this awful cobbled-up mount was intended only to be temporary. it works great on a stock morgo.

on the high-compression machine, i'm running an ARD magneto in order to dispense with the electrical system:

[Linked Image]

i can use one of two coils-- either the dual fire double-ended coil that i have now:

[Linked Image]

or a single-fire one-lead coil that uses a rotor and a distributor cap:

[Linked Image]

either one works fine, but to use the ARD with dual plugs means another component in the system to split the plug wires.


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708357
09/14/17 7:39 am
09/14/17 7:39 am
Joined: Apr 2006
Posts: 1,397
New Zealand
J
johnm Offline
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New Zealand
Without wishing to be cruel about Triumphs but looking at the dome on those pistons to get 11.75 CR - I'm sorry but it really does demonstrate why a Norton engine - specifically the post 63 SS head style - is a fundamentally better place to start for racing.

Will I get banned after this post ;-) ?

Re: detonation! [Re: johnm] #708362
09/14/17 10:15 am
09/14/17 10:15 am
Joined: Oct 2012
Posts: 3,347
Running from demons in WNY
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Running from demons in WNY
Originally Posted by johnm
Without wishing to be cruel about Triumphs but looking at the dome on those pistons to get 11.75 CR - I'm sorry but it really does demonstrate why a Norton engine - specifically the post 63 SS head style - is a fundamentally better place to start for racing.

Will I get banned after this post ;-) ?


Talk is cheap..I challenge you to best the speed of the 650 Triumph I built for LSR... wink


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: detonation! [Re: Hillbilly bike] #708364
09/14/17 10:32 am
09/14/17 10:32 am
Joined: Apr 2006
Posts: 1,397
New Zealand
J
johnm Offline
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Joined: Apr 2006
Posts: 1,397
New Zealand
beerchug

Yes it may be a bit difficult. Not exactly the same type of racing - and I've been out of it for 7 years now.

This is the last time my bike ran back in 2010.

Norton 500 built to NZ pre 1963 Clubmans rules. No 500 ridden by Tony McQueen. The white bike - 212 a mates Velo - is ridden by Chris Swallow who I mentioned in another post today. Two weeks ago he made the first BSA Goldstar 100 mph race average at the Manx Classic Senior race finishing 7 th overall. But Tony got him in this race :-)

https://www.youtube.com/watch?v=TyekqMox4tw

Last edited by johnm; 09/14/17 10:36 am.
Re: detonation! [Re: NickL] #708403
09/14/17 3:01 pm
09/14/17 3:01 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
Originally Posted by NickL
Ahhhh, with a mag you will have to use 2 HT diodes on each leg, that will reduce the actual spark power on each plug by 50%.

I think there are a couple of firms that sell them but you can just get some HT diodes and make up modules in series/parallel
to get the volts/amps you need. (to be safe 25kv 1a would do the trick)

Check out microwave oven types, they are cheap enough.



you're right about halving the spark energy. but that's what i did already when i switched the mag coil from single to dual fire, and i seem to have gotten away with the half-output. with a dual plug setup i'd switch back to the distributor cap and single fire coil. i'd give up simplicity but the spark energy would be the same as what i have now.

i'd have no idea how to construct a set of diodes from scratch, but i'm interested. the wires from joe hunt magneto are US $135, and i'd need two of them.



live every day.
die once.
Re: detonation! [Re: johnm] #708408
09/14/17 3:33 pm
09/14/17 3:33 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
Originally Posted by johnm
Without wishing to be cruel about Triumphs but looking at the dome on those pistons to get 11.75 CR - I'm sorry but it really does demonstrate why a Norton engine - specifically the post 63 SS head style - is a fundamentally better place to start for racing.

Will I get banned after this post ;-) ?



lol

you won't catch me trying to defend a hemi head against flat tops, or better, a pentroof.

but its what there is . . .


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708410
09/14/17 3:53 pm
09/14/17 3:53 pm
Joined: Aug 2001
Posts: 383
Iowa
konon Online content

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konon  Online Content

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Posts: 383
Iowa
Think you'll have to stay with dual fire coil. When hooking up wires , one wire goes left cylinder other to right cylinder. You now have a firing order.


1968 BSA Firebird
1200 HD
XS 1100
1972 Rickman 125
Re: detonation! [Re: konon] #708418
09/14/17 5:09 pm
09/14/17 5:09 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
Originally Posted by konon
Think you'll have to stay with dual fire coil. When hooking up wires , one wire goes left cylinder other to right cylinder. You now have a firing order.


yes. if i stayed with the harley configuration, the coil would have to spark four plugs at once, each time the pistons approached TDC. with the original ARD distributor cap, the ignition only has to do two plugs at a time (. . . which is no worse than the harley).

these are the commercially available wires:

[Linked Image]

don't you have these on your BSA?


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708434
09/14/17 7:12 pm
09/14/17 7:12 pm
Joined: Aug 2001
Posts: 383
Iowa
konon Online content

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Iowa
Yes I have them on the BSA . As you know you have to buy 2 units, each unit has a marked wire that have to go on opposite cylinders. That's why the dual fire. Your still only firing 2 plugs on one cylinder, and you will have a firing order.


1968 BSA Firebird
1200 HD
XS 1100
1972 Rickman 125
Re: detonation! [Re: NickL] #708472
09/14/17 10:48 pm
09/14/17 10:48 pm
Joined: Aug 2014
Posts: 1,389
OZ
Triless Online content
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Triless  Online Content
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OZ
Now, this is seriously clever stuff and great lateral thinking. This is what makes the forum so interesting. Yeah, so much for you telling me not to believe what you write, Nick !

Re: detonation! [Re: konon] #708492
09/15/17 1:32 am
09/15/17 1:32 am
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
Originally Posted by konon
Yes I have them on the BSA . As you know you have to buy 2 units, each unit has a marked wire that have to go on opposite cylinders. That's why the dual fire. Your still only firing 2 plugs on one cylinder, and you will have a firing order.


okay, i'm missing something here. ARD terminology calls the unit with the rotor "single fire." this one, which takes a single-tower coil, rotor, and no waste spark:

[Linked Image]

this one they call dual fire, and it takes a dual-tower coil, no rotor, and a waste spark every 360 degrees:

[Linked Image]

i'm thinking if i put in a diode system like nick has outlined, that i'll need to use the upper setup, and run both wires from the same magneto cap socket to the same cylinder.

is this correct?


live every day.
die once.
Re: detonation! [Re: NickL] #708493
09/15/17 1:34 am
09/15/17 1:34 am
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
Originally Posted by NickL
These will do for the diodes, build up in rows of 3 in series, then parallel 3 rows of 3 for each leg/plug. (allowing for chinese specs this will be adequate)
Make them up in small potting boxes and fill with epoxy once you've soldered the ht lead on.
On each coil or distributor output 1 plug will be cathode to plug, 1 plug will be anode to plug.

http://www.ebay.com.au/itm/50Pcs-CL04-12-Microwave-Oven-High-Voltage-Diode-Rectifier-Electronic-Parts-gib-/192300043887?hash=item2cc5f9ce6f:g:xIUAAOSwS9pZclmE

.

i just saw those diodes were for sale in packs of 50.

that might be a solution.


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708503
09/15/17 3:33 am
09/15/17 3:33 am
Joined: Mar 2014
Posts: 567
Denver CO
J
Jerry Roy Online content
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Jerry Roy  Online Content
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Posts: 567
Denver CO
Just a caution. Don't use JB Weld epoxy as a potting medium.

JR

Re: detonation! [Re: kevin roberts] #708567
09/15/17 6:47 pm
09/15/17 6:47 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
lol

there's my weekend project, nick. i'll post how it goes.


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708579
09/15/17 9:05 pm
09/15/17 9:05 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
okay i bought 50 of these:

[Linked Image]

[Linked Image]

when they show up i'll see how big they are so i'll know what to come up with for a potting box


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708582
09/15/17 9:13 pm
09/15/17 9:13 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
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Posts: 3,648
ohio, usa

what about this:

Originally Posted by NickL
. . . then pot them in silicon rubber, with no acetic acid cure.


acetic acid seems to be universal with RTV. is there a silicone rubber that doesn't use it? i'll have to go smell all the tubes in my chemicals box now.


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die once.
Re: detonation! [Re: Jerry Roy] #708639
09/16/17 11:50 am
09/16/17 11:50 am
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
Originally Posted by Jerry Roy
Just a caution. Don't use JB Weld epoxy as a potting medium.

JR


whats the issue with JB weld? is there metal in it?


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708659
09/16/17 3:13 pm
09/16/17 3:13 pm
Joined: Jan 2004
Posts: 3,597
ca, us
D
DMadigan Online content
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DMadigan  Online Content
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ca, us
JBweld says on the tube "kwik set epoxy steel".
What is so special about Hunt wires, the ends? You can buy solid wire or spiral wrap plug wire kits for V8s for much less and custom make what you need.
I think you would be better off with pyramid top pistons. It appears you do not have a squish band and high crown pistons forms a dividing wall between the two sides of the chamber and cuts off the plug from the two. A pyramid top with the peak on the far side from the plug makes a squish area that forces the charge over to the plug.
Putting the diodes in RTV or chalking will heat insulate them possibly causing a problem there. Maybe putting them between two aluminum plates with thermal paste then heat shrink the leads and epoxy fill the ends and wires would be better.

Re: detonation! [Re: DMadigan] #708666
09/16/17 4:03 pm
09/16/17 4:03 pm
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
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Posts: 3,648
ohio, usa
Originally Posted by DMadigan

What is so special about Hunt wires, the ends? You can buy solid wire or spiral wrap plug wire kits for V8s for much less and custom make what you need.


i think it's just the diode kit, like nick says, they're the only ones who sell anything like this for a magneto. they have an existing market with harley people who dual-plug their heads. i already buy all my plug wires at farm supply stores, because they sell solid-core wires for old machinery.

Quote

I think you would be better off with pyramid top pistons. It appears you do not have a squish band and high crown pistons forms a dividing wall between the two sides of the chamber and cuts off the plug from the two. A pyramid top with the peak on the far side from the plug makes a squish area that forces the charge over to the plug..


the combustion chamber shape (including piston crown) on these things has always been a real problem. no squish band, nothing really to force any turbulence at all. tony has already shown that he can go faster than anybody else with lower compression. i don't want to start experimenting with piston crown shape until i exhaust the possibilities changing stuff i know a little more about. my hope is to keep the compression but compensate with extra spark plugs. this is my old street bike, with inner 12mm plugs drilled in many years ago by Big D:

[Linked Image]

^^^this machine is fastest with the timing retarded 8 degrees from the stock 38 BTDC, so it seems clear that the combustion has been speeded up. it had stock 9 to 1 morgo pistons and a little head work by MAP, from back when they did that sort of thing. they were also experimenting with dual-plugging heads using ordinary 14mm plugs, but i went Big D because they had more experience at it.

Originally Posted by DMadigan

Putting the diodes in RTV or chalking will heat insulate them possibly causing a problem there. Maybe putting them between two aluminum plates with thermal paste then heat shrink the leads and epoxy fill the ends and wires would be better


i dunno. how hot do they get? is commercial potting medium a heat conductor? i'm way out of depth with even basic electronics, but learning about things i don't know anything about is really why i'm here in the first place.


live every day.
die once.
Re: detonation! [Re: DMadigan] #708676
09/16/17 4:26 pm
09/16/17 4:26 pm
Joined: Oct 2012
Posts: 3,347
Running from demons in WNY
Hillbilly bike Online content
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Hillbilly bike  Online Content
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Running from demons in WNY
Originally Posted by DMadigan

I think you would be better off with pyramid top pistons. It appears you do not have a squish band and high crown pistons forms a dividing wall between the two sides of the chamber and cuts off the plug from the two. A pyramid top with the peak on the far side from the plug makes a squish area that forces the charge over to the plug.
.


Hmm, my 650 Triumph holds the current modified production 650 pushrod LSR class record has these 10.5 flat top MAP forged pistons...I was measuring the quench (squish) here and it's .032........The engine uses single sparkplug, smaller carbs, less compression and less cam lift and duration but goes faster than the others...So either I know something or the other guys know less... grin And again, the volatility of the fuel plays a role in power and detonation control....

[Linked Image]


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: detonation! [Re: kevin roberts] #708701
09/16/17 9:24 pm
09/16/17 9:24 pm
Joined: Jan 2004
Posts: 3,597
ca, us
D
DMadigan Online content
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Joined: Jan 2004
Posts: 3,597
ca, us
HB - yes, yours has a squish band but it appears Kevin's does not. You pistons allow more of a connected volume between the two sides of the combustion chamber. Very high domes tend to divide the chamber making the burn harder to control and spread evenly. Cartridge fire chambers have a small volume around the plug and the piston almost fills the main chamber but very hard to do on a hemi-head. You would need a bathtub chamber.
The triple race bikes did not start making power until they added a squish band around the face of the piston where it meets the head deck. And, as you say, having that turbulence makes the other factors less critical.
Before they controlled the fuels in F1, the team with the latest fuel formula from the manufacturer usually had the advantage.

Re: detonation! [Re: kevin roberts] #708733
09/17/17 3:41 am
09/17/17 3:41 am
Joined: Dec 2013
Posts: 3,648
ohio, usa
kevin roberts Online content OP

fefsa
kevin roberts  Online Content OP

fefsa
Joined: Dec 2013
Posts: 3,648
ohio, usa
no squish on my stuff

[Linked Image][Linked Image]


live every day.
die once.
Re: detonation! [Re: kevin roberts] #708755
09/17/17 12:02 pm
09/17/17 12:02 pm
Joined: Oct 2012
Posts: 3,347
Running from demons in WNY
Hillbilly bike Online content
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Running from demons in WNY
[quote=kevin roberts]no squish on my stuff

No quench is the root of all evil.... grin....


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
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