ESE's works engine tuner

[TZ350]

Thanks F5 for the confirmation, intuitively I thought the combustion chamber was the greatest source of heat. As there is a lot of surface area in the exhaust port to soak up heat. I didn't want to just assume. I have been tripped up before, by things that turn out to be counter intuitive.

Thomas has got hold of some really large heat sinks. Had they been just a bit thicker we could have machined a combustion chamber directly into them.

Thinking about it, there is not enough depth for a combustion chamber and sparkplug but we could machine a combustion chamber into the heat sink and bolt another piece on top with a sealing ring for the sparkplug.

This way we could use 3/4 inch reach plugs (better selection than 1/2 inch) and the piece the plug screws into could be extended out to help shift the heat from the combustion chamber to the outer ends of the heat sink.

If the spark plug bit could be made in copper it would really help in cooling the combustion chamber area.
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[speedpro]

range of plugs??

An "8" or maybe a "9" is all I've ever used from Shirriffs Road thru to Puke full circuit, on any motor. Outside of that I think you are trying to fix a problem by changing spark plugs. Just a theory.

[TZ350]

range of plugs??

An "8" or maybe a "9" is all I've ever used from Shirriffs Road thru to Puke full circuit, on any motor. Outside of that I think you are trying to fix a problem by changing spark plugs. Just a theory.

I have been buying surplus plugs in bulk from Ebay, 8's and 9's.

I would like to be able to get the plugs with the thin center electrode, gold palladium etc.

Thinking about it some more.

Have you ever noticed how the combustion chamber darkens around the plug area first. I assume this means it gets hottest here. Having a thick copper heat sink for this part of the combustion chamber might be a real benefit.

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[speedpro]

I used to use precious metal centre electrode plugs and found them to be of no benefit. They gave no more power, they didn't last any longer in the motor that went through plugs, and in the motor that used to melt pistons now and again it melted them irrespective of what plug was in it.

Do not use "-EGV" plugs. Only the last little bit of the centre electrode is all that precious and evidently it sometimes parts company. It never happened to me but I've heard of it happening.

HOWEVER, in the mighty 1800 Legnum the platinum plugs are definitely an improvement

[gav]

Have you researched if you'd be better with a 100cc water cooled head and barrell and running a bigger carb? Would this setup make more power than your air cooled 125cc 24mm carbed engine?

[F5 Dave]

Yeah anything with a barrier layer is off to a bad start with heat conduction so while you can add area it would be better if the main head is one piece. This is why the japs cast the barrels around the sleeves and why inserted sleeves aren’t as good as std & in turn why straight cast ally plated was better still, not that there are many bucket motors like this.

Sorichio Honda liked to think of himself as a pure engineer. He was determined to keep the old race engines aircooled as the air was what was doing the cooling of water; so why have the water & all the complication?

. . . He was wrong about 4 strokes too.

If you make any head the common mistake is not to use enough material near the sealing surface. It needs to be substantial to cope with temp variations without warping.

With plugs, don’t expect them to shed any real heat.
As far as type go I agree with Mike to an extent, but disagree in other points. I think the plug needs to suit the combustion condition it is in, a bit like fuel really. No point having high octane in a low compression engine.

In my H100 it was air-cooled & comparatively low revving. So I didn’t push the com up too high but high enough. On the std ignition it burned through plugs, a CR ign stopped that. Then I experimented with different plugs on the dyno. No extra power at all. The system was good enough as was for the situation.

However on my MB50 with same ignition a smaller chamber, more revs & higher com it picked up over ½ hp with a fine wire plug. I’ve seen another bike pick up ½ (or was it a whole) hp with a fancy shmancy $80 racing plug.

But despite being the same type of engine with same ignition, revs, fuel etc, the same plug (I borrowed in the same session) made no difference in mine. There were reasons for that, but the point is experiment.

Also the EGVs are fine, been using them for years in the 50 & various other bikes of all capacities. I think it is the EVs that are for tuning or some-such. Dropping ends do occur with normal plugs in some bikes like RM250s etc from vibration & they need special plugs.

[TZ350]

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A picture of my combustion chamber after Taupo. The wash from the transfer streams can be clearly see. If anyone can tell me anything about their shape, I would be interested to know if they look right or otherwise.

You can see how the heat builds near the plug, whys this?

I used a flat piston with a small dish in it. On the head you can see the squish area which is very clean, a darker area where the sleeve touches the head, then the ring where the "O" ring seals on the head and the black area is where the head and cylinder make metal to metal contact.

Thomas found a couple of these heat sinks and now we are looking at how we could use them.

As it turns out, they are thick enough so we could cut a combustion chamber in them or we could cut a chamber in a block of alloy and sandwich 3 or 4 sheets of 1.2mm copper between it and the heat sink.

With twice the heat transfer the copper would act like a copper bottom saucepan, spreading the heat from the center around the combustion chamber to the extremes of the heat sink.

The edges of the copper sheets would be bent out in a radial fashion so they form fins too.

I have wanted to try indexing the plug and even have indexing washers to do the job. Does any one have an idea about whether its better to have the plug gap facing the incoming transfer stream or should the gap face away or to the side even?

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[Fooman]

Check the alloy of the heat sink before you do anything - it is likely to be a conductor grade material (e.g. 1100 - 99% pure Al) so it won't be too strong, and quite soft, whereas the original head will be a cast alloy with a fair bit of silicon (for wear) e.g. a 356 alloy or similar.

Cheers,
FM

[F5 Dave]

Good point, heat treating it afterwards 'may' help.

Squish should be clean if it is working. Heat tends toward the exh port side. In a large chamber I doubt which way the plug faces will matter. However in my earlier example of the 50 with the racing plug it had a very short chamber, thus it was shrouding & a racing plug helped (strap from side of plugface rather than a overhead hook). Don't believe dished pistons are used in modern engines, flat or just off has been normal practice, elliptical chamber theory or not.

[TZ350]

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Fooman makes a good point about the alloy.

Dished pistons, I use them because I had a box of them, you know how bucketeers are.

Because of the dished (3.5cc) piston my combustion chamber is pretty small 5.5cc, deck height accounts for 1cc.

The diameter of the chamber is 42mm.

Not quite as small as the 50 but pretty small for a 14mm plug. I have been using B9HSC plugs, they have a tapered entry into the insulate area opening it up quite a bit compared to the ordinary B9HS.

B9HSC is on the left.

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[F5 Dave]

Yeah I used to use those in my H100. . . because someone gave me a box of them

Yeah that is a small chamber, expect a high MSV, but your squish probably isn't parallel reducing that. I'd consider reducing the squish area, but would need to recut squish to shorten chamber height.

[edit] Actually looking at the pic again that doesn't look that small & if 42mm on a 54mm bore (or were GPs a bit more oversq?) that only gives a 6mm squish, looks more like 8. ~ 70% chamber area would be good target, less if perhaps wanting Kart track explosive acceleration.

A decent squish area does help cooling piston so maybe don't go too small.

[TZ350]

I will measure the squish & head up with more care tommorow.

[TZ350]

range of plugs??

An "8" or maybe a "9" is all I've ever used from Shirriffs Road thru to Puke full circuit, on any motor. Outside of that I think you are trying to fix a problem by changing spark plugs. Just a theory.

Initially I dismissed the "Just a theory." idea, but thought about it some more. I was not looking for more power through a super spark plug, as I know a plug can't give more power on it's own, although it can unlock potential that is all ready there but if its wrong, fouled or just does not light the fire very well it can reduce power output.

Statistically the fire does not get lit every time. In the B9HSC's with their more open firing end and thinking about the way to orientate them I was looking for a plug end that is less masking and an orientation that was best for flame propagation.

I understand powers strictly a function of BMEP (how the engine breaths) and rev's but there is power to lose if you don't get the fire lighting right.

I remember TZ's would often go faster on exotic plugs but they were compensating for the TZ's notoriously poor ignition and oil fouling from Castrol R being run at 16-20 to 1.

I might be just looking for exotic plugs out of habit. If the bike runs better on these plugs, could the ignition be a little week?

Something for me to think about.

[speedpro]

The only time I've seen power increase from fitting a different type of plug was on a XS1100. It was all dyno tuned to hell and I fitted "J" gap plugs. Immediate 2hp increase.

If a plug helps then you have some other issue. Typically that other issue on a bucket is a weak ignition. JC fitted a FZR250 ignition to Olly's old CB125T on back to back dyno runs and got something like 3-4hp increase with no other mods. I've always run 80cc motocross ignitions as in the early days when I was starting to tune and test there was noticeable improvement in all-round engine behaviour with the better ignitions, easier to start, better throttle response, and a cleaner topend. Drawback was that they will fire "any" mixture including one that is a bit lean.

They run MONSTER ignitions on the blown methanol and fuel cars and the bigger the ignition the more power they make. My mates magneto has supposedly a 44A secondary. Whatever it is you will only hook yourself across it once, the spark is astounding even at one click of turn by hand.

[TZ350]

Why not try riding really fast and using the air flow to do all that?

I have looked into this some more and wouldn't you know it, good old nature challenges us again.

It turns out that cooling from the wind chill effect does not increase linearly with speed. Twice as fast is not twice the cooling.

The graph of the wind chill effect is steepest in the 0 to 30kma range and flattens out the faster you go.

In a generalized sort of way.

You only get 50% more cooling by doubling your speed from 30kmh to 60kmh.

To get 75% more cooling you need to have gone from 30kmh to 120kmh.

To get 100% increase in cooling means going faster than my bike can manage.

Doubling the fin area does not double the cooling effect either because the thermal path will have increased.

Because you get the most cooling for your blow at lower speeds it makes it worth looking at the larger fan cooled CPU heat sinks again.

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