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#708310 - 09/13/17 10:34 pm detonation!  
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kevin roberts Online content
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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.



Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708317 - 09/13/17 11:17 pm Re: detonation! [Re: kevin roberts]  
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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...
#708318 - 09/13/17 11:28 pm Re: detonation! [Re: kevin roberts]  
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NickL Online content
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Aus
Just use 2 x 6v double ended coils in series if you are going to dual plugs.
1 lead off each coil to each cylinder.



#708344 - 09/14/17 2:20 am Re: detonation! [Re: kevin roberts]  
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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.


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708352 - 09/14/17 3:41 am Re: detonation! [Re: kevin roberts]  
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NickL Online content
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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.


Last edited by NickL; 09/14/17 3:56 am.


#708357 - 09/14/17 7:39 am Re: detonation! [Re: kevin roberts]  
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johnm Offline
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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 ;-) ?

#708362 - 09/14/17 10:15 am Re: detonation! [Re: johnm]  
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Hillbilly bike Online content
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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...
#708364 - 09/14/17 10:32 am Re: detonation! [Re: Hillbilly bike]  
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johnm Offline
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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.
#708403 - 09/14/17 3:01 pm Re: detonation! [Re: NickL]  
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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.



Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708408 - 09/14/17 3:33 pm Re: detonation! [Re: johnm]  
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kevin roberts Online content
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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 . . .


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708410 - 09/14/17 3:53 pm Re: detonation! [Re: kevin roberts]  
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Posts: 360
konon Online content
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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
1971 Rickman 125
#708418 - 09/14/17 5:09 pm Re: detonation! [Re: konon]  
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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?


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708434 - 09/14/17 7:12 pm Re: detonation! [Re: kevin roberts]  
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Posts: 360
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
1971 Rickman 125
#708467 - 09/14/17 10:28 pm Re: detonation! [Re: kevin roberts]  
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NickL Online content
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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



#708472 - 09/14/17 10:48 pm Re: detonation! [Re: NickL]  
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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 !

#708482 - 09/14/17 11:55 pm Re: detonation! [Re: kevin roberts]  
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Stephen, there is nothing clever about this, it's only what the commercial unit is.
If i was clever, i would be the bloke asking $150.00 each for them.
If i doubled my IQ i'd still be a half-wit. smirk



#708492 - 09/15/17 1:32 am Re: detonation! [Re: konon]  
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kevin roberts Online content
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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?


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708493 - 09/15/17 1:34 am Re: detonation! [Re: NickL]  
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kevin roberts Online content
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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.


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708503 - 09/15/17 3:33 am Re: detonation! [Re: kevin roberts]  
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Jerry Roy Online content
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Just a caution. Don't use JB Weld epoxy as a potting medium.

JR

#708516 - 09/15/17 6:47 am Re: detonation! [Re: kevin roberts]  
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NickL Online content
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Aus
Use the top one. Best to sleeve the diodes in some heat shrink in their rows, then link the rows then pot them in silicon rubber, with no acetic acid cure.
Sorry about the sketch............


cyl 1 centre plug----------------------------->]-->]-->]-----------------------------------------HT1
cyl 1 side plug-----------------------------[<--[<--[<-----------------------------------------HT1


cyl 2 centre plug----------------------------->]-->]-->]-----------------------------------------HT2
cyl 2 side plug-----------------------------[<--[<--[<-----------------------------------------HT2


Have fun.
Nick



#708567 - 09/15/17 6:47 pm Re: detonation! [Re: kevin roberts]  
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kevin roberts Online content
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lol

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


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708579 - 09/15/17 9:05 pm Re: detonation! [Re: kevin roberts]  
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kevin roberts Online content
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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


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708582 - 09/15/17 9:13 pm Re: detonation! [Re: kevin roberts]  
Joined: Dec 2013
Posts: 3,097
kevin roberts Online content
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kevin roberts  Online Content

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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.


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
#708597 - 09/15/17 10:17 pm Re: detonation! [Re: kevin roberts]  
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NickL Online content
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Aus
You can get it at a builders store. They use it quite a lot now as people don't like the small of the acetic cure gear.
Dow Corning have made it for years.

If not use a general purpose 2 part non metal loaded epoxy. Araldite etc.

A length of plastic tube is all you need for a potting box the diodes will only be 1/4 diameter by an inch long or so.
Plastic electrical conduit will be ideal.

Last edited by NickL; 09/15/17 10:23 pm.


#708639 - 09/16/17 11:50 am Re: detonation! [Re: Jerry Roy]  
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kevin roberts Online content
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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?


Into the distance a ribbon of black
Stretched to the point of no turning back
A flight of fancy on a windswept field
Standing alone my senses reeled
A fatal attraction is holding me fast how
How can I escape this irresistible grasp?
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