ESE's works engine tuner

[husaberg]

Hello,
funny to find his sofa at the other end of the earth : ailes
Francis.

Hello Francis, A pleasure to have you here. Now I guess I are now going to have to stop referring to you as Mr Paykart.
I have posted many many picures of you work here.
They might be considered the breadcrumbs that lead you to here behind the sofa.........

For the few people here that might be unfamiliar with Mr Payarts work
http://www.pit-lane.biz/t875-techniq...ight=superkart




Anyway this was the other find for the evening for the Bucket racer set.
Bloody shame about the 20mm diameter small end but guess it would suit the YZ100 piston for the 100cc
Note the length..........117mm


MODEL K-125 W/W
OEM No. -08003
CODE No. BS0290B
B.E.BEARING DIA (mm)：Ａ 26.0
S.E.BEARING DIA (mm)：Ｂ 20.0
B.E.& S.E. PITCH (mm)：Ｃ 117.0
B.E.THICKNESS (mm)：Ｄ 17.0
S.E.THICKNESS （mm)：Ｅ 18.0
CRANK PIN DIA (mm)：Ｆ 20.0
CRANK PIN LENGTH (mm)：Ｇ 49.0
http://www.tkrj.co.jp/goods/m-BS0290B--08003.php

[F5 Dave]

Ahh slinging together parts from obscure 30 year old bikes to race with. This mx85 thing is more appealing by the day. But let's not digress into that debate. Or I'll turn this into an oil thread. I'll do it.

[husaberg]

Ahh slinging together parts from obscure 30 year old bikes to race with. This mx85 thing is more appealing by the day. But let's not digress into that debate. Or I'll turn this into an oil thread. I'll do it.

The Suzuki the rod is designed for is 41 years old, so its actually much younger than you.......
The rod conversely is brand new made the other day using the most modern Wok making materials and metallurgy.
So the answer to the oil debate is therefor sunflower.

Hello,
Funny to find his sofa at the other end of the earth
Francis.

I wonder if Francis could tell what the diameter of the crankshafts in his Superkart engines.
I note there seems to be a couple of different styles.
From a triangular early Rotax type to a asymmetrical chamfer an the intake side. and I think one for the 125 single

[wobbly]

The high inertia full circle Aprilia style cranks I have designed for PVP - DEA etc are all 94 OD

[fpayart]

Hi,
The outside diameter is 93.5 mm

"I note there seems to be a couple of different styles.
From a triangular early Rotax type to a asymmetrical chamfer an the intake side. and I think one for the 125 single"

Correct, the three left pictures are the last generation and the right one is the first generation, same as the ROTAX one.

The damaged engine is the perfect illustration of the major disadvantage of this type of engine.
The incident occurred at the Sachsenring in the downhill with a beginner driver. A simple seizure can turn into disaster.
The piston has seized heavily in the rear cylinder, the engine continued to run because the other cylinder still working and due to the inertia of the kart launched at very high speed.
The rod ultimately snatch the lower part of the piston, the shaft still attached to the rod strolled into the cylinder, eventually entering in a lateral port and so on ...
The driver finally stopped when the rod penetrated the front case.

[F5 Dave]

Glen what I meant is when you need to do a quick rebuild you won't find one of those in the country. Or ebay. Or on anything other than 4 month special backorder. As opposed to if you were rebuilding a yz. Or even a TS.

[husaberg]

The high inertia full circle Aprilia style cranks I have designed for PVP - DEA etc are all 94 OD

Hi,
The outside diameter is 93.5 mm

"I note there seems to be a couple of different styles.
From a triangular early Rotax type to a asymmetrical chamfer an the intake side. and I think one for the 125 single"

Correct, the three left pictures are the last generation and the right one is the first generation, same as the ROTAX one.

The damaged engine is the perfect illustration of the major disadvantage of this type of engine.
The incident occurred at the Sachsenring in the downhill with a beginner driver. A simple seizure can turn into disaster.
The piston has seized heavily in the rear cylinder, the engine continued to run because the other cylinder still working and due to the inertia of the kart launched at very high speed.
The rod ultimately snatch the lower part of the piston, the shaft still attached to the rod strolled into the cylinder, eventually entering in a lateral port and so on ...
The driver finally stopped when the rod penetrated the front case.

Thanks for both your answers.
Francis you have built a Single also is that correct?
If so are the cranks the same od?
I hope my silly questions are not taking up too much of your time.

Glen what I meant is when you need to do a quick rebuild you won't find one of those in the country. Or ebay. Or on anything other than 4 month special backorder. As opposed to if you were rebuilding a yz. Or even a TS.

By now everyone should know that speed of doing anything is not my forte.
I know what you are saying though Dave because I am looking for a ke125 or similar crank at the moment. I can get them on Ebay but the freight is a killer.

The reason I have become obsessed with using one is not just the small diameter full wheels and correct stroke and pin.

I had actually missed something Frits had posted about the advantage smooth inner wheels until the other day which is something most later cranks lack.
It was from a conversation you and frits were having that I missed.

Good point, Dave; in fact several good points.
Most of the volume is concentrated in the transfer ducts. Then there is the volume inside the piston of course, and the 1 mm shear-avoiding clearance at all surfaces of the crank.
But that is not nearly enough volume. If you take another look at the Aprilia crank below left, you will notice that the space between the crank webs is the same as the space needed for the big end bearing. In other words: the crank webs have flat insides, good for another 60 cc or so, if I remember correctly.Additional benefits: the con rod has an easier time pushing the mixture aside as it moves between the webs, and the big end bearing gets a lot more cooling and lubrication because it is not shrouded in any way.
Because there are no overhung bobweights, the crank webs are stuffed with tungsten to get the balance factor right.In the RSA125, the con rod was lengthened from the RSW's 115 mm to 120 mm to create even more crankcase volume.

The paddling is a mixed blessing; it creates aerodynamical drag but it also greatly improves the homogenity of the mixture.
Smooth, full-circle crank webs have the advantage that there is little mixture hiding in nooks and crannies. An example of it's importance: in a certain engine there were 20 mm spaces between the crankshaft bearings and the seals. these ill-accessible volumes acted as pneumatic dampers on the crankcase pressure fluctuation. Filling those volumes with plastic bushes gave a measurable improvement.
Summary: you need a large crankcase volume. Ideally all of this volume should be situated in the transfer ducts. In real life you will also need to lodge part of this volume between crankshaft and piston, i.e: use a long con rod. Avoid nooks and crannies. Crankshafts should be small and smooth. Big end bearings must never be shrouded by recesses in the crank webs or by stuffers.
.....

Thus my intention if I was to use something like this.

As opposed to say the MB100 (below) With its generic pork chop inner weights.

but alas the recess for the rod is I guess still a shroud I think the GP125 Suzuki is exactly as frits described but some folks have no doubt tucked all spare ones of those away already.
Maybe I are too obsessed with trying to get the inlet straight with a large disk 118mm and small crank 85mm as the Aprilia and other superkarts are it seems a much larger than I thought.
For some reason I thought the RSW crank (with its 20mm pin) od was around 88mm. based on 46mm radius plus 1mm clearance.
In this drawing which was propertied to be a drawing from a RSV250
http://www.kiwibiker.co.nz/forums/at...6&d=1413591175
Which I reasoned, as it was contrary to normal crank design *that Frits had previously posted as having the equivalent half the crankpins diameter as material outside the pin.)

On a more serious note: I just took a look at the crank web + pin you showed above. As a rule-of-thumb the web material around the crank pin hole should have a thickness of at least 50% of the pin diameter. I'm afraid yours hasn't. And I am not even regarding the large bevel....

Let me start by complimenting you on a very clear description plus illustration of the balancing act. But you should not have drilled those holes where you did. As a rule of thumb, a good press fit requires that a big end pin hole should be surrounded by at least half its diameter in material. So for a 20 mm pin there should be at least 10 mm of crank web material everywhere around the hole. As you can see, the large original balancing holes already intrude into this zone, and with the small holes you added there will be little stiffness left.

Removing material in the blue circles would have been a safer approach, although it might not haved raised the balance factor sufficiently.
The best way would be to remove material from the inside faces of the crank webs, around the big end recesses. That would have two additional benefits: it would improve lubrication and cooling of the big end bearing and it would enlarge the crankcase volume.
Now that I am grumbling anyway: big end pins should be massive. The large void in the pictured pin is not exactly promoting a good press fit.

So I reasoned it must have been done on the aprilia's as a compromise in order to achieve more hp.

[Dutch Fisher]

The outside diameter is 93.5 mm

Is that with a 22 or 24mm pin?

[TZ350]

Thus my intention if I was to use something like this.

The KE has lead counter balance weights which will work loose in no time at all at high rpm. Need to replace them with Tungsten (Malory Metal).

[husaberg]

The high inertia full circle Aprilia style cranks I have designed for PVP - DEA etc are all 94 OD

The KE has lead counter balance weights which will work loose in no time at all at high rpm. Need to replace them with Tungsten (Malory Metal).

I was on to that one and tracked down a source of depleted uranium (joke for Jon Key and the GCSB)

Lozza (2Tinstitute) posted a source for not quite Mallory the other day.

http://www.ebay.com.au/itm/Woodland-...item4190b30113

Here are some screw in tungstens 14g/ half oz each net add should be 11g

http://www.ebay.com.au/itm/Pinecar-T...item5b0c86b902
http://www.maximum-velocity.com/tungstencylinders.htm
http://www.abs-products.com/heavy-me...in-chart.shtml
http://www.abs-products.com/heavy-me...ce-sheet.shtml

[wobbly]

If you really want to do it properly make your own.
Ive done a heap of them as home jobs with a local CNC shop, and as long as you have the rod and piston you will be
using, dong the balance is easy.
The KE crank is holes in it - these will need to be filled with alloy, so the balance will need to be redone with Mallory anyway.

[husaberg]

If you really want to do it properly make your own.
Ive done a heap of them as home jobs with a local CNC shop, and as long as you have the rod and piston you will be
using, dong the balance is easy.
The KE crank is holes in it - these will need to be filled with alloy, so the balance will need to be redone with Mallory anyway.

I know what you are saying Wob and I was expecting the same from Neil, but the cost is likely more than a complete FXR150.
A custom made case and a cylinder is enough. plus it looks highly likely I will have to do a custom (cha-ching) primary gear now too.
Cause I still want to fit in that water cooled case.

Simply put by compromising on the crank it allows for less compromises to be made elsewhere....

[RomeuPT]

There is No heat going into the piston from advanced ignition as there is no darkness underneath.
RS125 ignitions retard shitloads after peak torque to get heat into the pipe and make it rev.
Thus I suspect a combination of not enough static advance to go with the head cc, and running too lean.
All give the end result of alot of heat in the header - too much in this case.
What fuel, what cc, what static advance?
The other possibility is that the later RS125 has the ability to change the powerjet switch rpm, maybe its too low.
But another suspect is maybe the powerjet is too big, and too much fuel is being turned off by the solenoid when in the overev area past 12500.

The piston and cylinder are from Honda RS, but they are running in my NSR 125 engine with ignitech

Last change was lowering the cylinder and also squish clearance from 1mm to around 0.7mm. Didn't seem to run lean, but iridium plugs fool me :/.
Before this change runned alot at high rpm with no problem. So I guess either the compression is on the limit for fuel and I was running a little lean.

[F5 Dave]

Yes reducing the pork chop on the MB is a written down evolution (thanks to that very post from about a year or more back).

Incidentally thinking about the volume in the transfers, I dropped the vinamold of my modified MB into some water (all 5) and got an increase of less than 80cc. I wonder how much is in a proper performance engine.

[wobbly]

Be carefull about what you measure when considering transfer ducts.
In Engmod the duct is defined as follows - not what many would think.