ESE's works engine tuner

[TZ350]

GPR, poster boys of Auckland buckets hahaha Check out the back drop of the bucket section of the AMCC website... two Welly region riders front and center. Probably saw those leathers and thought "shit that's definitely a bucket rider". http://amcc.org.nz/buckets/#bucket-news

Welly riders, they come and take our trophy's, steel our women and get pictured pride of place on our club website .......

[TZ350]

Page 1480 .......

Seems like "cht", "egt", or any other three letter word is not a valid search term on this forum, I get zero results. 4 is the magic number, "idle" works fine. Dumb

I use google custom search engine for looking up older items (items just posted don't show up directly)
https://cse.google.com/cse/publicurl...90:5pd9xdluxce

As these are still running the standard ignition, ie no retard at max RPM, (I think) could it be that this is causing the overheating issue when used as a race bike and max RPM most of the time?

Many if not most bikes run out of blowdown time.area before they run out of revs. Then exhaust gases enter the transfer ducts, rapidly heating the cylinder.
Maybe you can insert some distance pieces between the cylinders and the exhaust headers, or advance the ignition a bit in order to prevent the rider from revving too high all the time.

There is no such thing as "good" Avgas at any place but an airport tank.
In those tanks it has to be checked constantly for volatility and water content.
At Ruapuna - Philip Island is even worse, the tanked fuel is absolute rubbish as it sits forever,flashing off all the good front ends in no time at all.
A small aircraft crashing due to fuel related engine failure simply isnt allowed,full stop.

I thought the avgas at Ruapuna was decent? I'm assuming you'll tell me it's just old stuff from the airport?

Yes, 909 will settle out in AvGas after only a few minutes of mixing it up - did exactly that to me on the dyno.
We tested for probably 20mins,stopped for a cup of tea,and it would not restart,I could see straight oil in the bowls of the Lectrons.
But add a cup of acetone in 5L and no issues after that.
Motul Kart GP does not do this in Avgas, I have had some mixed , sitting in the kart dyno plastic tank for weeks to test this.

Modern forged pistons made by Wossner run the same sort of initial clearances as cast ones.
In my TZ400 the 66mm Wossners run at 0.06mm,they get 2 - 5min heat cycles then thrashed.
After 1 race meeting they had shrunk by 0.02, and at 580Km I replaced them as they were now with 0.04 extra ie they were at 0.1mm in the bore.
This is with a 58 stroke spinning to 11200 in every gear, and topping out at 11800 in 6th.
They looked like brand new on the skirts, but I thought why take a chance.
As it stands I wouldnt use a Wiseco if they gave them away.

Re cooling the spigot in KZ2 engines - yes, this idea if done by milling slots thru the flange face on the cylinder allows water
to cool right around the duct to the face, then also the steel spigot face is cooler as well if you cut the slots thru the gasket material.
I can touch the tapered spigot on the engine after a hard dyno pull without being burnt.
As you say this keeps the trapped mixture in the cylinder duct much cooler,and the egt further out in the header dropped as well.
I can run at least 2 jets leaner to get the egt back , without getting into deto using that system.
The pic is an early testing one, now the slots go right thru to water,top and bottom.

The 100cc engines really wide power band is down to the pipe design, with its series of bleed holes in the rear cone.
This pulls down the peak power and adds plenty at the bottom, and in the overev area.
Take that pipe and remove the rear cone holes,and it becomes all but impossible to tune the pumper carb properly,and the power band is basically 1/2 as wide.
OK for a slipper clutch setup on direct drive, no good at all without the clutch set to peak torque rpm.
The 3 port system has plenty of STA for the power produced, and the scavenging regime has been slowly developed over time to enhance the band width as well.

It looks like burnt oil residue on top of more burnt oil residue.
My guess, you have had oil separation at some stage, and a period where the thing has been burning a mixture of mostly oil, with little fuel.
Many oils will separate under certain conditions - many semi synthetics do it all the time in AvGas without something like acetone in the mix.

It looks like a lot of bad oil in the mixture and a piston that didn't get hot enough to keep its nose clean. Maybe the engine has been slurping gearbox oil through a faulty oil seal.

Just stripped my Macio after a day's of testing and I have this strange carbon build up on the piston. It has had around 30 min running time.

It looks like the frying pan after cooking honey bacon. (Now I feel hungry)

It has these miniature hills and valleys. Any suggestions ?

Thanks Wallace.

I would like to believe that moving the rear Aprlia studs and then pulling back the rear wall would have a positive effect if that
operation reduced the backward lean of the B duct ie getting rid of the two dimensional bending of the flow around the corner into the port..
But as you say Frits this would upset the scavenging pattern by increasing the B port flow regime, but if the extra space gained was used then to increase the A port
flow area, this may then restore the balance - and gain an overall increase in transfer Cd.
That would then maybe allow slightly lower timings, to increase the all important ( and ultimately power limiting ) blowdown STA.
We started this discussion when it was suggested we look at ways of "improving " what Jan had achieved, but unless the same effort was put into restoring the leaning tower
geometry, then failure would be more than likely.
As we know well, several geniuses in R&D had a go at improving what Jan had done,as of course its obvious the crank needed cheek plates to reduce the case volume - only
to find the bikes thus delivered to the teams were somehow slower.
As it stands the only really optimistic direction of improvement would be to try my Ex duct length/area recommendations that work so well in the sim, and
maybe to improve the Ex duct cooling by having water all the way up to,and around the back of the spigot that I know works well in KZ2 engines.

Thanks!
Shure! I've posted some info here in this thread, just search for posts by me containing "spx"

I've also documented it pretty well on mopedarmy.com
Here's the thread where it all started:

http://www.mopedarmy.com/forums/read.php?7,3494948

This is the continuation and where I went custom cases and rotary valve:

http://www.mopedarmy.com/forums/read.php?7,3747121

These threads are basically documentation of my journey through the two stroke world. Lots of stupid ideas and failures, but I've kept at it, and still do!

Yes, Jans modification of the B-ducts front wall caused a reduction of the duct entrance area. But when I said that this area, and the duct volume, could easily be enlarged, I was not thinking of undoing this modification, but of removing material in the direction of the cylinder stud holes.

That seems like a logical thing to do if you look at the backward-leaning B-duct rear wall as it rises from the crankcase to the port, and if you notice the available amount of material between the duct entrances and the studs, both in the crankcase and the cylinder. It would certainly improve the inflow into the duct and enhance the kinetic energy of the flow exiting from the B-window. But that would be too much of a good thing. The B-windows are already higher and wider than the A-windows; increasing their flow even more would push the central scavenging column over to the exhaust side, causing scavenging deterioration and short-circuiting.
This peculiar set of circumstances came into being because Jan was obliged to develop new cylinders that should also do well on older engines.

Below you see an RSA cylinder with its small B-duct entry area and the extra area that seems so inviting to be added, but that would do the scavenging no good.

Attachment 319932

Thanks Wob. I wasn't actually talking about duct entry, but volume. Older ports are of course less curved but also often skinnier. There must be an ideal volume to draw from and especially if you create a bigger engine which in effect Sketchy is doing stroking the already over bored 125 barrels the original design came from, say optimistically to 160cc

Just a couple of points about transfer duct geometry.
The main thing many dont " get " is that virtually all the bulk flow in a race engine occurs around BDC when the pipe
effects are at a maximum when the biggest depression is seen at the Ex port face.
When the transfers open there is more blowdown pressure above the dropping piston, than there is case pressure, thus for the port that
opens first there will always be backflow.
This is how stagger works, retarding the initial outflow from one particular pair of ports, and favouring the flow from the lower set (s).

Secondly is that All of the mixture that enters the cylinder, is stored in the duct volume - there is NO flow from the case,thru the duct and on out thru the ports.
Remember as I have shown before there is NO flow thru the reeds until the transfers are almost closed by the rising piston, and this flow is created " again " by
the depression in the case,caused earlier by the pipe ( and helped by intake tuning length if done right ) - Not a reduced pressure ratio due to the piston rising.

And as far as the measured dynamics as seen by EngMod, that is the wave action within the duct, moving from one end to the other,there is no difference
in power when going from a duct entry/exit ratio of 1:1 up to 1.4:1.
I tested this keeping the case volume the same in both cases.
But a change in case volume from 1.36 down to 1.32 had a huge effect.

And as always Frits hits the nail on the head,in that although the Aprilia has a very small B port entry area, most of the reduction came from Jan filling in the B duct front wall.
By making it perpendicular to the bore,the effect of this along with the large ( wide and high ) port area had a much more beneficial effect on scavenging ( thus power ) than any perceived ( real or not )
issue with duct volume or flow " ability ".

So with a bigger capacity presumably the transfer duct area should be larger to feed the cylinder if the mixture is firstly drawn from that general area.

On my MB I glued inserts to shape the flatish inner walls but I believe my mistake was removing area and not replacing it by removing from the outer wall.

Cutting away the duct outer entry will have more effect on the case compression ratio ( may not be what is needed ) than it will
affect the flow " ability " of the duct.
Adding a BIG radius to the inner entrance is far more a guarantee of a power increase, and I have sort of sketched what Frits was alluding to, change the radius such
that the duct CSA is constantly reducing, with a bigger radius that starts and finishes earlier and later.

Sure, removing that area will increase the volume. But it will considerably decrease the gasket area. And you really need that area. The cylinder is moving about on the cases more than you would believe.
A second consideration: Enlarging the entrance to the transfer ports is usually a good thing, but not always. In an Aprilia RSA cylinder you can easily improve the inflow from the crankcase into the B-ports. There's one snag: it will cost power; it will upset the scavenging balance that Jan Thiel established after years of testing.

By today's standards: yes. Initially there is a big radius that tightens up as the duct gets narrower. In theory it should be the other way around: as the duct narrows, the flow velocity increases and so will the tendency of the flow to detach from the inner curvature. Ideally the radius should increase as the duct narrows, but that would lead to very wide cylinders, so we content ourselves with constant-radius inner duct walls.

So i'm officially a addict with my computer desk looking more like the workbench!

A little question for the gods of two strokes (aka all of you lot

In the photo that I have marked, is it beneficial to remove this area to increase the volume at the entrance to the transfer ports? Also to be the curvature of the inside wall looks wrong?

[seymour14]

Welly riders, they come and take our trophy's, steel our women and get pictured pride of place on our club website .......

Flamin hillbillies...

[Bert]

Welly riders, they come and take our trophy's, steel our women and get pictured pride of place on our club website .......

Yea, not a great look. But thanks AMCC for recognising the out of towners that added such joy to your racing.

[ken seeber]

Only a few weeks and everything will be explained, so be patient for a little while.

OK Luc, two weeks have nearly passed, so time's up tomorrow We've been sitting on the edge of our seats, twiddling our thumbs, waiting for the big moment. Is it only 30 hp? Does it break? Was it just a plan to sell VM engines? How does it really work?

You seem to be pretty close to the action. The whole of the southern hemisphere is waiting on you. Put us out of our misery. We're all looking forward to it.

Thanks

[Sketchy_Racer]

So i'm officially a addict with my computer desk looking more like the workbench!

A little question for the gods of two strokes (aka all of you lot

In the photo that I have marked, is it beneficial to remove this area to increase the volume at the entrance to the transfer ports? Also to be the curvature of the inside wall looks wrong?

[Frits Overmars]

In the photo that I have marked, is it beneficial to remove this area to increase the volume at the entrance to the transfer ports?

Sure, removing that area will increase the volume. But it will considerably decrease the gasket area. And you really need that area. The cylinder is moving about on the cases more than you would believe.
A second consideration: Enlarging the entrance to the transfer ports is usually a good thing, but not always. In an Aprilia RSA cylinder you can easily improve the inflow from the crankcase into the B-ports. There's one snag: it will cost power; it will upset the scavenging balance that Jan Thiel established after years of testing.

the curvature of the inside wall looks wrong?

By today's standards: yes. Initially there is a big radius that tightens up as the duct gets narrower. In theory it should be the other way around: as the duct narrows, the flow velocity increases and so will the tendency of the flow to detach from the inner curvature. Ideally the radius should increase as the duct narrows, but that would lead to very wide cylinders, so we content ourselves with constant-radius inner duct walls.

[RGVforme]

So i'm officially a addict with my computer desk looking more like the workbench!

A little question for the gods of two strokes (aka all of you lot

In the photo that I have marked, is it beneficial to remove this area to increase the volume at the entrance to the transfer ports? Also to be the curvature of the inside wall looks wrong?

Sure but remember that any increase in volume in the entrance must be matched to the flow restrictions coming out or a mod like this a waste of time esp if you upset the back pressure too much.

[TZ350]

But thanks AMCC for recognising the out of towners that added such joy to your racing.

It was a great day, really enjoyed it and catching up with the PN and Welly crew. ....

[wobbly]

Cutting away the duct outer entry will have more effect on the case compression ratio ( may not be what is needed ) than it will
affect the flow " ability " of the duct.
Adding a BIG radius to the inner entrance is far more a guarantee of a power increase, and I have sort of sketched what Frits was alluding to, change the radius such
that the duct CSA is constantly reducing, with a bigger radius that starts and finishes earlier and later.

[F5 Dave]

So with a bigger capacity presumably the transfer duct area should be larger to feed the cylinder if the mixture is firstly drawn from that general area.

On my MB I glued inserts to shape the flatish inner walls but I believe my mistake was removing area and not replacing it by removing from the outer wall.

[wobbly]

Just a couple of points about transfer duct geometry.
The main thing many dont " get " is that virtually all the bulk flow in a race engine occurs around BDC when the pipe
effects are at a maximum when the biggest depression is seen at the Ex port face.
When the transfers open there is more blowdown pressure above the dropping piston, than there is case pressure, thus for the port that
opens first there will always be backflow.
This is how stagger works, retarding the initial outflow from one particular pair of ports, and favouring the flow from the lower set (s).

Secondly is that All of the mixture that enters the cylinder, is stored in the duct volume - there is NO flow from the case,thru the duct and on out thru the ports.
Remember as I have shown before there is NO flow thru the reeds until the transfers are almost closed by the rising piston, and this flow is created " again " by
the depression in the case,caused earlier by the pipe ( and helped by intake tuning length if done right ) - Not a reduced pressure ratio due to the piston rising.

And as far as the measured dynamics as seen by EngMod, that is the wave action within the duct, moving from one end to the other,there is no difference
in power when going from a duct entry/exit ratio of 1:1 up to 1.4:1.
I tested this keeping the case volume the same in both cases.
But a change in case volume from 1.36 down to 1.32 had a huge effect.

And as always Frits hits the nail on the head,in that although the Aprilia has a very small B port entry area, most of the reduction came from Jan filling in the B duct front wall.
By making it perpendicular to the bore,the effect of this along with the large ( wide and high ) port area had a much more beneficial effect on scavenging ( thus power ) than any perceived ( real or not )
issue with duct volume or flow " ability ".

[husaberg]

From Brian Dmarge
Air cooled tech ignore the extra valves and oiling.
url]https://www.dropbox.com/s/g83k5qveoa533v8/_cylinder%20review%20.pdf?dl=0[/url]
https://www.dropbox.com/s/qumzhe8k27..._fins.pdf?dl=0

[F5 Dave]

Thanks Wob. I wasn't actually talking about duct entry, but volume. Older ports are of course less curved but also often skinnier. There must be an ideal volume to draw from and especially if you create a bigger engine which in effect Sketchy is doing stroking the already over bored 125 barrels the original design came from, say optimistically to 160cc

[husaberg]

Thanks Wob. I wasn't actually talking about duct entry, but volume. Older ports are of course less curved but also often skinnier. There must be an ideal volume to draw from and especially if you create a bigger engine which in effect Sketchy is doing stroking the already over bored 125 barrels the original design came from, say optimistically to 160cc

From memory the NSR150 rods are about 6mm longer than the NSR125, which means they are likely about 6mm longer than the NSR250's
I have the measurements somewhere
NSR150 110mm
NSR125 104mm
NSR250 104mm

Pretty sure most of the NSR300 conversions involve making the NSR150 cylinders shorter. But Food for thought.
I am not sure how the piston deck heights work re the 150 and the 125/250
(it looks like 32mm vs 30mm)