ESE's works engine tuner

[Grumph]

I remember Barry Lynch repairing KT100 cranks that had pitted on the surfaces rollers run on. He blamed the use of R for the pitting
R is hygroscopic - attracts and absorbs water.
He may well have been right too, I've seen similar pitting on things like Manx Norton cams - and a lot of those are still run on R.

Barry had quite a production line going at one time. Hard chroming and finish grinding KT100 cranks.

[katinas]

Re head

I still haven't tried a similar design, only instead of holes, the black head cover has a deflector that directs the flow down closer to squish band and then up towards the exit near the spark plug.

[karter444]

TIG welding the Mallory to the wheel is easy , even Flet could do it without a microscope.

Re questions - the 100cc engines when you really lean ( yea jetting too ) on them always had issues locking up pistons.
But not bearings flying apart due to 20,000 rpm. Thus as long as you dont lean it down and are looking to extend life I would use a full synthetic like 800 simply due to the film strength.
Using Maxima 927 or Elf 909 which is what they would normally use ( R is bloody old hat now ) is only needed if it gets real hot.
In the Timken/Falex oil test machine a castor has bugger all film strength but has a lovely smooth wear pattern , a synthetic has well over 10 times the load capability , but the instant it is abused it breaks down into non lubricating
components.
Castor base , even when smoking up on the machine still lubricates the wear surfaces - the synthetic causes metal to tear off due to micro welding.

Re the TM head insert - I dont think this is covered by an NDA so here you are.
This idea makes more power - simple. The reason is that a hot combustion chamber surface has less temp delta with the burning combustion gas , thus conducts less of the finite fuel energy
away into the water. The squish band is closer to water thus stays cooler to help retard deto.
The only down side is the plug threads are hot as well , but in this case due to the straight line ignition we are deto limited in the squish , not limited by overheating the plug body and thus punching holes
in pistons due to pre ignition.
If you really wanted to get trick , put a clear ceramic on the combustion chamber surface only - ceramic is illegal , but hey you cant tech what you cant see.
I have tested super trick chambers that cooled the squish , and the plug , no dramatic advantage sadly.

Hi Wob thanks for the reply .
re oil .Are you saying that under normal conditions a synthetic will have 10 x more load capabilities until it reaches a certain critical temp and then a castor based oil will out perform the synthetic .So if you stay away from that critical temp synthetic is the way to go .
cheers

[speedpro]

[QUOTE=Vannik;1131214764]A cautionary tale about crank balancing (I know it is 4T but still relevant):

That was one of the worst jobs I have ever seen, especially as SME is supposed to be a premium engine builder. The welding is crap, probably no weld prep, and I think I saw that it was only welded on one side.

[wobbly]

The fully synthetic oils became popular around the same time as the FIM mandated lead free race gas.
This fuel ( 100 octane ) made more power running slightly rich with more ignition and less com.
Thus the egt numbers were way below those when running 130 octane with 18:1.
This suited the synthetic stock perfectly , contrasted to most teams who earlier had various oil sponsors but all ran Castrol A 747 - a castor based product.
So yes , as long as the synthetic is not taken near its limit , it has far superior wear and lubricating properties.
The 10X film strength comment applied to using R30 - todays castor based oils are much , much better.

Edit - that SME video showing the idiot attempt at balancing the crank was doomed from the start. There is a rule of thumb we use in 2T that when fitting a bigger pin , or stroking you should
leave 1/2 the pin diameter of material in the wheel , above the hole. They didnt do that even close , and putting all the Mallory in one web , instead of splitting it across both for each cylinder pairs
was again plain dumb. SM I must say has manned up to fix it though , a very very expensive mistake.

[Frits Overmars]

That SME video showing the idiot attempt at balancing the crank was doomed from the start. There is a rule of thumb we use in 2T that when fitting a bigger pin , or stroking you should leave 1/2 the pin diameter of material in the wheel , above the hole. They didnt do that even close , and putting all the Mallory in one web , instead of splitting it across both for each cylinder pairs
was again plain dumb. SM I must say has manned up to fix it though , a very very expensive mistake.

For mallory plugs, that do not require as much press fit as a big end pin, 1/4 x the plug diameter of material around the hole may be enough.

[wobbly]

Oh dear Frits , the memory retention is slipping , my appreciation for you still being clever.

[pete376403]

The fully synthetic oils became popular around the same time as the FIM mandated lead free race gas.
This fuel ( 100 octane ) made more power running slightly rich with more ignition and less com.
Thus the egt numbers were way below those when running 130 octane with 18:1.
This suited the synthetic stock perfectly , contrasted to most teams who earlier had various oil sponsors but all ran Castrol A 747 - a castor based product.
So yes , as long as the synthetic is not taken near its limit , it has far superior wear and lubricating properties.
The 10X film strength comment applied to using R30 - todays castor based oils are much , much better..

But does the exhaust smell as good?

[TZ350]

2Stroke Stuffing.

[Gradella23]

hello guys,
since there is limited literature around the web, i'd like to ask wobbly and all of you what your findings are about surface discharge plugs on 2 strokes.
The only sure thing i read online is that they need a steady and strong spark, but is this reachable in fact? Are there any comparison or bench test?

[wobbly]

Originally surface discharge plugs were used commercially in outboards when first CDI became available.
They needed a high discharge voltage as the effective spark gap was large from the center electrode out to the body.
Plug technology has advanced hugely since then with rare earth center and ground fine wire electrodes , that require less voltage than "ordinary " plugs and now we have no issues with fouling.
I can see no logic in using these nowdays in any specific application where they might be an advantage.

[Grumph]

Surface gap plugs were of course OE on the Kawasaki Mach 3. Which had I think one of the first CDI systems. Word at the time was that the higher discharge voltage eroded conventional plugs and shortened their service life. Surface gap plugs don't change the gap with age and use.

As Wob says, no reason to use them now. Technology has moved on.

[husaberg]

Surface gap plugs were of course OE on the Kawasaki Mach 3. Which had I think one of the first CDI systems. Word at the time was that the higher discharge voltage eroded conventional plugs and shortened their service life. Surface gap plugs don't change the gap with age and use.

As Wob says, no reason to use them now. Technology has moved on.

Weren't they spec'ed for the Mazda rotaries.

[Flettner]

This one runs a surface fire plug, out of a Rotary, 10 heat range, E85 fuel.

[pete376403]

This one runs a surface fire plug, out of a Rotary, 10 heat range, E85 fuel.

Surface gap plug was standard on my '72 F9, supposedly not as suceptible to fouling as a regular plug. It still did though.