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Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #578696 12/30/14 10:49 am
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After looking at those video's I wonder what gearing are you using?

The only time I can select out pinging from general engine noise is when the engine is struggling.

Morgo always set-up those cylinders pretty loose. Is the engine noise worse when its cold or warming up?


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Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #578702 12/30/14 11:35 am
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I use one 21 teeth what implies 4100 rpm in the 4th speed and 120 Km/h on the highway
I agree which it would be preferable a front sprocket smaller than 21 teeth for hill climb sand or abestos as at the time of the 2nd video one
But that returns expensive and tiring to ride on the highway or forest road to 4100 rpm for only 90 Km/h by using one 16 teeth
There are no gasoline station between Parent and LaTuque in Quebec for a distance of 200 kilometers and my tank of gasoline has only 12 liters
Then I do not have the choice to optimize the petrol consumption of the bike not to undergo a gasoline breakdown in middle of the night when full with wild beasts as the black bears grind in trimmings

The noise is really with timing
I am a mechanic of motorcycle Japanese and English for 40 years, then I have known and I must make the difference of the noises of engine to earn my living wink

I readjusted my last pistons Morgo .020" oversize with .008" because the engine had partially seizes when I had put it at .006"

The knocking arrives especially the summer when the weather is hot and that the engine functions since a certain time

The only time that I knew pinging is while returning from Parent at north of Quebec of the video last
The engine was seriously carbonized what had increased the ratio compression and had created hot spot to cause the pinging
Before 2012 I was accustomed to adding a little oil 2-cycle in the gasoline while thinking better of lubricating the combustion chamber
I ceased this useless practice after having dismounted the cylinder head and having decarbonized the pistons and the combustion chamber

This day there, I knew all the mechanical forms of musics. The pinging and the knocking


Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #578720 12/30/14 2:37 pm
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Kevin,

What I was meaning to say about octane is that in the crudest way, more octane is a bad thing because the higher the octane, the slower the burn. Of course, there is a situation where slowing down the burn rate is beneficial. This is when you increase the compression, which is the easiest way to get more power. The trick is matching the two.

So, I don't pick the octane as a tuning method, but I pick the fuel I will use for the season and tune for the octane rating of that fuel. If I choose 100 octane and all that is available at the track is 110 octane, the engine will most likely be down on power. Thus, it is as much a choice about availability as it is about performance.

If, for example, your pump gas is 93 octane, you could probably run a 12.5:1 CR piston without detonation. This assumes that your DCR (dynamic compression ratio) would be about 8:1 with lots of other considerations like sea level, humidity and temperature.

In general, the target DCR for pump gas is 8:1 plus a little, maybe plus .25, but if you use DCR it will be true for all the engines using DCR, single cylinder or v-8. You can't do this with the static CR figure that we are all familiar with because it is a purely theoretical number that will always be higher than the DCR by an unknown amount.

If I were running 110 octane I would think that I would be at 14:1 advertised CR with no detonation. So, I am curious about the mismatch.

I think your goal with the bike is laudable. It is a great challenge to get as much out of your engine as possible. When you begin to ask the questions that you are asking you realize that there is power in the engine for the taking if you can only find the right balance. The basis of all engine power begins with measurement, something I did not do enough of with my own endeavors.

Here are some DCR data that may be interesting:

http://purplesagetradingpost.com/sumner/techinfo/tech--dcr%20comb-sm-1.html

David

Re: where do the coil wires go on dual plug heads? [Re: David Dunfey] #578724 12/30/14 3:00 pm
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David, higher octane does not mean a slower burn..Octane effect on detonation is quite complex...I use racing fuel in my LSR Triumph and have spent time looking into what goes on...I'm not a fuel chemist so I have to believe what they say...
Here's some basics from Sunoco ...

High Octane

This is what I think a good explanation of detonation and preignition. And why the hole in your piston may not be from detonation. This may have been posted before and there are other opinions on this matter.

Ping ping


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: where do the coil wires go on dual plug heads? [Re: Hillbilly bike] #578738 12/30/14 4:21 pm
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Originally Posted by Hillbilly bike
David, higher octane does not mean a slower burn..


High octane fuels which I have used do burn slower than low octane fuels which I have used.

But you're right to say that the meaning of "high octane" is not "slow burning."


Amateur Loctite enthusiast.
Re: where do the coil wires go on dual plug heads? [Re: triton thrasher] #578747 12/30/14 5:29 pm
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Thank you both. I will defend myself by saying I did use the word "crudest", but I always appreciate learning more. I particularly liked the section on detonation caused pre-ignition!

David

Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #578785 12/30/14 10:28 pm
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well, i've followed these links on CR, and burning, and octane, and detonation. I've skimmed the links they link to, and looked at some of the links the links link to. and now i understand a great deal less than i thought i did when i started.

it seems as if DCR is a useful way to incorporate cam timing into compression ratio, generating a number that can be used with more predictive value than just static CR alone. but now i've got a lot more to think about.

my head hurts.

HB, this id from your link and seems similar to what david was suggesting earlier:

Quote
Production engines are optimized for the type or grade of fuel that the marketplace desires or offers. Engine designers use the term called MBT ( Minimum spark for Best Torque) for efficiency and maximum power; it is desirable to operate at MBT at all times. For example, let's pick a specific engine operating point, 4000 RPM, WOT, 98 kPa MAP. At that operating point with the engine on the dynamometer and using non-knocking fuel, we adjust the spark advance. There is going to be a point where the power is the greatest. Less spark than that, the power falls off, more spark advance than that, you don't get any additional power.

Now our engine was initially designed for premium fuel and was calibrated for 20 degrees of spark advance. Suppose we put regular fuel in the engine and it spark knocks at 20 degrees? We back off the timing down to 10 degrees to get the detonation to stop. It doesn't detonate any more, but with 10 degrees of spark retard, the engine is not optimized anymore. The engine now suffers about a 5-6 percent loss in torque output. That's an unacceptable situation To optimize for regular fuel engine designers will lower the compression ratio to allow an increase in the spark advance to MBT. The result, typically, is only a 1-2 percent torque loss by lowering the compression. This is a better trade-off. Engine test data determines how much compression an engine can have and run at the optimum spark advance.

For emphasis, the design compression ratio is adjusted to maximize efficiency/power on the available fuel. Many times in the aftermarket the opposite occurs. A compression ratio is "picked" and the end user tries to find good enough fuel and/or retards the spark to live with the situation...or suffers engine damage due to detonation.


point being, these folks are saying that once you have determined what spark advance is optimum for a given engine configuration/operating condition/benchmark, that any fuel change that results in detonation is better compensated for by reducing compression ratio than by retarding the spark.

but i's still lots easier to change timing than to change compression ratio, except by deciding in advance at the beginning of the season, as david suggests.

my head still hurts

Last edited by kevin; 12/31/14 11:41 am.

every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #578803 12/31/14 1:12 am
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After a score of 20 years to be ride with a cylinder head twin-plug by cylinder; I can say to you that that made pretty but not really necessary wink

Re: where do the coil wires go on dual plug heads? [Re: triton thrasher] #579359 01/04/15 8:50 am
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On the higher octane burning slower it seems there is no simple answer and it's a yes and no....
This is an explanation from a racer/ fuel chemist...A bit complex for my simple mind..


" You can have a higher octane fuel with any number of boiling points and igntion points. They have nothing to do with burning faster.

Fuel octane values (either RON or MON) have NOTHING to do with combustion flame speed. They are completely unrelated.

If we run an engine on the dyno using straight “isooctane” (224TriMethylPentane) it would have RON and MON values of 100. Interestingly, there are actually 18 different isomers for isooctane with different octane values.
We could then add measured amounts of Tetra Methyl Lead(TML) to increase the octane values in steps. We would find:

TML
g/gal ........ MON .......... RON
0 ........ 100 .......... 100
2 ........ 108.6 ........ 108.6
4 ........ 118.0 ........ 118.0
6 ........ 120.3 ........ 120.3

While the fuel octane values are increasing, there would be absolutely no change in engine performance or in ignition temperature, flame temperature, laminar flame speed, peak combustion pressure angle and total burn angle.

Fuel octane alone does not change these combustion values. But a change in blend composition is another matter. It is possible to have two fuel blends with the same octane numbers, but they will behave quite differently in the combustion chamber. This is due to the fuel blend components and not to their octane values.

Different fuel blend components do have a substantial effect on combustion properties.

..................................... nHeptane .... Methanol .... Toluene .... Isooctane

Laminar flame speed ................. 42.4 ....... 52.3 .......... 38.6 .........37.7
(cm/s)

A/F ratio for max FS .................. 122 ........ 101 ........... 105 ......... 106
(% of stoich)

Ignition temp ........................... 476 ........ 878 .......... 1052 ......... 874
(F)

Flame temp ............................ 3525 ........ 5050 ........ 3759 ........ 4193
(F)

Laminar flame speed is not affected by octane value but is a function of fuel blend components. Laminar flame speed is much too slow to burn properly in modern engines; chamber turbulence is necessary. When chamber turbulence (primarily squish velocity) is added to laminar flame speed, turbulent flame speed is the result. That is what will determine combustion burn angle, peak combustion pressure location, flame temperature and engine performance.

Laminar flame speeds are on the order of about 40cm/s (.4m/s). Squish velocity is on the order of 40m/s or about 100 times that of laminar flame speed. Combined turbulent flame speed would be 40.4m/s; the laminar flame speed having contributed very little to burn time or burn angle.

The ignition temperature of the fuel will determine the ignition delay period. The flame temperature of the fuel will affect the flame speed and combustion pressure.

It is most unfortunate that when race fuels are mentioned, even by fuel company marketing reps, octane seems to be the only fuel property that is mentioned. We very often find fuel company marketing reps to be very underinformed regarding their fuels. While every true race fuel refinery has fuel blenders and fuel chemists on staff, they are mostly kept out of sight and contact with race fuel customers. And the promotional literature is commonly written by some ad agency copy gal who knows only the buzz words and little else.

Fuel companies could provide real data regarding their products to help racers make the right decisions. But then, who would listen? frown "


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: where do the coil wires go on dual plug heads? [Re: Hillbilly bike] #579365 01/04/15 9:28 am
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Originally Posted by Hillbilly bike
Fuel companies could provide real data regarding their products to help racers make the right decisions. But then, who would listen? frown "

Yep wink

Re: where do the coil wires go on dual plug heads? [Re: Hillbilly bike] #579568 01/05/15 4:10 pm
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well, this is interesting, tony

Originally Posted by Hillbilly bike
. . .
While the fuel octane values are increasing, there would be absolutely no change in engine performance or in ignition temperature, flame temperature, laminar flame speed, peak combustion pressure angle and total burn angle.


what exactly is it in tetraethyl lead that retards knock? how does it work, if octane value and flame speed aren't necessarily related? is it all about suppressing pressure-ignition?

Quote
Fuel octane alone does not change these combustion values. But a change in blend composition is another matter. It is possible to have two fuel blends with the same octane numbers, but they will behave quite differently in the combustion chamber. This is due to the fuel blend components and not to their octane values.


^^^this is not encouraging.


every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579612 01/05/15 10:27 pm
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Kevin,

I don't want to attempt to explain the chemical properties of lead, but it did replace MBTE, which was carcinogenic, and MBTE was replaced by ethanol, another octane booster, so to speak. You say correctly that the increase in octane effectively increases the pressure under which the intake charge will ignite. Thus, with low octane fuel, the intake charge will self ignite under high compression. So, the major cure is to increase the octane or lower the compression. Once your are close to the correct compression/octane combination you can fine tune by adjusting the timing.

Higher octane fuels can burn both faster or slower and this usually depends upon the blend as well as the architecture of the molecules. But, this should not matter to you, yet, and in general the flame propagation is usually quite similar at different octanes.

As HB points out, the "slower burning" characterization probably says to much even though it is true in certain instances. I think this has also become a popular characterization because high octane fuels can be "slower" to ignite under the same pressure as low octane fuels even if the flame propagation is equal.

If you think about the ethanol as increasing octane, you may also realize that ethanol has less energy than an equal amount of gasoline without ethanol. This can be a problem with running higher octane fuels. It does not automatically translate into higher energy that is available to push your piston down harder.

So, if you want more performance from your engine the object should be to match your compression ratio to the best fuel at the closest gas station. You don't even have to do the engineering. Just use the DCR that every motorcycle manufacturer uses: about 8.2:1. Then go to the dyno and set your timing. You should then have the best power that you can expect from your motor with the accepted inputs.

The process will be more involved for a race engine, but measuring and matching components and inputs should be the foundation for the work.

David

Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579645 01/06/15 7:34 am
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Originally Posted by Kevin
. . .

what exactly is it in tetraethyl lead that retards knock? how does it work, if octane value and flame speed aren't necessarily related? is it all about suppressing pressure-ignition?

Here's what I read....
Quote
The anti-knocking agents reduce the activity of free radicals in the burning mixture, either by eliminating them, or by converting them to radicals that are relatively stable (and thus unreactive).

Burning proceeds as a chain reaction mediated by free radicals. If the radicals are unstable, the reaction is fast, and less heat is needed to initiate it. Branched alkanes (isooctane) and aromatic compounds produce relatively stable radicals which allow the chain reaction to die down. Tetraethyl lead eliminates free radicals by allowing them to combine with its ethyl groups.



Here's the thread I started on Speedtalk, a site populated by professional racers and engine builders,fuel chemists and so on...There's some good info and of course some pure opinion...
Octane


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: where do the coil wires go on dual plug heads? [Re: David Dunfey] #579742 01/06/15 10:40 pm
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Originally Posted by David Dunfey

So, if you want more performance from your engine the object should be to match your compression ratio to the best fuel at the closest gas station. You don't even have to do the engineering. Just use the DCR that every motorcycle manufacturer uses: about 8.2:1. Then go to the dyno and set your timing. You should then have the best power that you can expect from your motor with the accepted inputs.


well, i've gone through the DCR calculator from your link (lots of other information in there as well), and it appears that there are some physical measurements i need to do on that head first. luckily, it's apart at the moment, so i'll see what i can do. regarding fuel, i've got access to that 110 leaded premium, and also to ordinary 93 unleaded. when the snow melts i'll try out both of them and see what timing works best. i'm very curious about the results of switching the inner coil leads, because that would seem to make the biggest difference, from what i've read here.


every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579754 01/07/15 12:27 am
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damn, i hate losing stuff i typed. short version:

HB, have you encountered situations in tuning where the spark timing could be advanced until horsepower began to fall, without going into detonation first? any engine.


every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579766 01/07/15 8:00 am
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Yes,my 650 race Triumph. 10.5 compression using 107 octane leaded race fuel. And many years ago with "muscle cars" using 260 Sunoco pump gas.
Disclaimer, short periods of full throttle high rpm detonation can go unnoticed in more robust engine designs.Detonation in V-8 powered circle track race cars causes excessive bearing wear or even cracked cylinder walls and a lesser experienced racer might just think the engine block is defective.


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: where do the coil wires go on dual plug heads? [Re: Hillbilly bike] #579849 01/07/15 11:00 pm
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that's been my impression from what people say, in that detonation-limited engines seem to be more gasoline-quality-limited engines. holding the gas quality constant, reducing compression ratio but holding the advance seems to keep the most horsepower. (this is theoretical. i haven't done it).

not being able to hear detonation is a problem with loud pipes. i've been trying to learn about exhaust gas temperature, and it seems that it can reflect detonation that you might not be able to hear by showing a sudden decrease in temperature, as that extra heat goes into the piston and head, rather than the exhaust.

innovate sells one that can be linked to a data logger:

[Linked Image]


every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: NickL] #579878 01/08/15 8:55 am
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Nick,the operator of the dyno shop I use for the race bike has a very simply mechanical device to detect detonation. A short length of a small diameter copper tubing is mechanically fastened to the engine head. it's connected with rubber tubing to a set of "headphones" just like a doctor's stethoscope.The sound of detonation can be heard clearly over the normal engine clatter.


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579890 01/08/15 11:34 am
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that's a really useful suggestion.

kevin cameron once wrote that detonation sounded like smacking rocks together underwater, hard. i've heard that in my motor before using poor quality gasoline in an emergency, but the continuous knock that you can't hear because of pipes and concentration would be extremely useful to detect.

there's too many variables to keep track of it all if you're running a motor at the edge, especially fuel blending.



every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579904 01/08/15 12:48 pm
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And piezoresistive chips are used to plot cylinder pressure under varying loads. But all of this is theory and the problems I see day-in-day and day-out are more of a practical nature. As Kevin Cameron is fond of saying, you must toughen you engine to prevent detonation and pre-ignition long before your offer fuel to the engine. The first thoughts about detonation should be in the workshop, not the gas station or the dyno room. It is way to late to make any meaningful changes.

Unlike BSA and Norton, who have by some measure almost modern combustion chambers, Triumph's hemi combustion chamber design was abandoned by engine designers years ago. It is a relic from the distant past. The design is further inhibited being air cooled, very minimal in mass and with no where adequate fining for what some people expect from the engine.

While static compression and intake cam closing are a starting point they are just that.
Just as important are:
• Valve margin thickness, margin shape and seat widths.
• Removing all sharp edges from the piston, spark plug hole, and blending valve pockets.
• Selection of the proper grade of spark plug.
• Selecting cams, and timing those cams, with the intended use in mind.
• Of course timing and fuel mixture.
• Matching individual gear ratios and overall gear ratios for the engines power band and intended use. There is a reason Triumph provided wide ratio transmissions on their dual-purpose models.
• Selecting piston ring thickness that matches the engine design. Thin rinshould not be ones first choice for street engines using pump gasoline.
• Making sure rings seat during initial start-up as 75%, or more of the heat in the piston is removed through the rings. Those low tension thin rings have there place, but it is not always in one of these motors.
• The over all gear ratios are matched to the intended use and riders ability. There is a reason Triumph provided wide ratio transmissions on their dual-purpose models.
• And while those early light flywheels worked well for the likes of Eddie Mulder on the soft sand, they provided more opportunity for combustion mischief with the novice rider. At low rpm they lack the kinetic energy

There is a lot of talk about squish and "swirl" helping control detonation. You also hear talk about about squish this, and squish that about Triumph heads. While there might be flat areas near the edge of some Triumph pistons and heads are thought to be squish bands the only head that comes near having a true squish band is the early unit 500 twin. And although the physical parts are in place, the gap between the piston and head is such that it is a squish band in name only. It is too wide to be effective. If you are not measuring and setting the gap in the .035" range it is of no benefit in creating enough swirl to help control detonation.

In the end Triumph did two things that were an effort to help prevent detonation, but it was very late coming. The T140D head with the parallel ports and the constant velocity carburetor. The T140D port design dramatically increased swirl improving combustion and lowered combustion temperatures to a point where it required running spark plugs 2 ranges hotter to prevent fouling. The CV carburetors prevented high dynamic cylinder pressures caused by rapid opening of the carburetor while the engine is under even a light load (often referred to as lugging).

Before Triumph started to use the CV carb the rider had to remember to shift to a lower gear when he sensed that the bike did not respond with an increase in speed as the throttle was opened. While your car does this without you thinking about it, with your Triumph you have to remember to do this. And when you sort the motor a lot of the detonation, and even modern engines designed to use current fuels will detonate, can be managed with intelligent use of the throttle and the shift lever. Modern cars have a computer... your Triumph only has you.


Re: where do the coil wires go on dual plug heads? [Re: John Healy] #579916 01/08/15 1:42 pm
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Originally Posted by John Healy
And piezoresistive chips are used to plot cylinder pressure under varying loads. But all of this is theory and the problems I see day-in-day and day-out are more of a practical nature. As Kevin Cameron is fond of saying, you must toughen you engine to prevent detonation and pre-ignition long before your offer fuel to the engine. The first thoughts about detonation should be in the workshop, not the gas station or the dyno room. It is way to late to make any meaningful changes.


In my opinion you have to be on guard for detonation when testing on an engine on the track or in the dyno room.Especially hobbyist builders like me who don't have years of experience on a Triumph engine to know the limits.
All might be fine with the engine build but a bad or mislabeled fuel load could turn the pistons inside out....

Last edited by Hillbilly bike; 01/08/15 1:43 pm.

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Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579937 01/08/15 3:46 pm
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Quote
All might be fine with the engine build but a bad or mislabeled fuel load could turn the pistons inside out....


I am not totally unfamiliar with detonation! But over some 50 years of preparing Triumph engines for racing of all sorts, I have learned not to wait, but to anticipate these kinds of problems. Most of the failures I personally have experienced have been of my lack of understanding, not the fuel's.

And my post was not inspired by your previous post...

This is where I like to start:
[Linked Image]
These are the piston blanks we use when setting up an early 500 squish band head so it works.


Re: where do the coil wires go on dual plug heads? [Re: John Healy] #579939 01/08/15 3:51 pm
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kevin roberts Offline OP
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Originally Posted by John Healy

There is a lot of talk about squish and "swirl" helping control detonation. You also hear talk about about squish this, and squish that about Triumph heads. While there might be flat areas near the edge of some Triumph pistons and heads are thought to be squish bands the only head that comes near having a true squish band is the early unit 500 twin.


hi john

i'm used to seeing much better squish bands on old two-stroke cylinder heads than i've ever seen in a triumph. i didn't even recognize one being there the first time i looked.

are there modifications that one can do to a stock triumph T120 head that can significantly increase swirl? maybe my question includes increasing velocity in general, as it seems to me that one would help the other.


every day you do not take a chance is a day of your life that you will never get back.
Re: where do the coil wires go on dual plug heads? [Re: John Healy] #579942 01/08/15 4:17 pm
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JH,I saw that photo of yours recently and meant to ask...Why are the rings located so far below the piston crown ? It appears the they be moved up quite a bit before fouling the valve relief. All modern piston designs seems to have the ring package pushed up as high as possible to eliminate unburned gases remained in the 'dead space"

[Linked Image]


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: where do the coil wires go on dual plug heads? [Re: kevin roberts] #579946 01/08/15 4:50 pm
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triton thrasher Offline
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I don't think the rings can go much higher, when you look at the complicated shape of the crown.


Amateur Loctite enthusiast.
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