ESE's works engine tuner [Archive] - Page 113

Frits Overmars

16th December 2017, 00:06

Frits,Help a slow learner like me understand why you would prefer the longer rod with the pin higher in the piston. Is this just for the reduction in angle...longer/ less dwell at TDC / BDC...more leverage?Leverage is not my main concern and neither is dwell time at TDC/BDC; the variation would be minuscule.
Reduction in con rod angle and a corresponding reduction in friction is one good reason. Crankcase volume is another one. But my main reason is piston mass.
The bulk of a piston's mass is concentrated between its crown and the gudgeon pin holes. Raise the pin and you'll lighten the piston, simple as that.
This does not even depend on con rod length. It's true that I prefer a long con rod, but I would prefer a high piston pin in combination with any rod length.
And don't worry about the piston tipping over. Just look below at the piston hight, or rather lack of it, that four-strokes get away with. And two-stroke piston skirts are invariably longer than their four-stroke counterparts because when in TDC, they must keep the exhaust port closed.
333883 333884 333885

lohring

16th December 2017, 03:55

So no one has tried e85 then

We tested a lot of different fuels on an industrial style 26 cc racing engine. Because we could only change the mixture and ran the same pipe for all tests, there was very little power difference. The mixture needs to be richened for alcohol containing fuel. Below is the report.

Lohring Miller

333886

nitro2tfx

16th December 2017, 12:53

We tested a lot of different fuels on an industrial style 26 cc racing engine. Because we could only change the mixture and ran the same pipe for all tests, there was very little power difference. The mixture needs to be richened for alcohol containing fuel. Below is the report.

Lohring Miller

333886

15% nitro with no power increase and in fact arguably a power loss, is an interesting result, yet not quite as interesting as the time we put 40% nitro into a fuel concoction and had no power change and jetting/timing wouldn't fix it lol. Nitro is an anomaly in many, many ways. Under the right conditions it is amazing and under the wrong conditions it is neutered.

Haufen

16th December 2017, 13:33

Leverage is not my main concern and neither is dwell time at TDC/BDC; the variation would be minuscule.
Reduction in con rod angle and a corresponding reduction in friction is one good reason. Crankcase volume is another one. But my main reason is piston mass.
The bulk of a piston's mass is concentrated between its crown and the gudgeon pin holes. Raise the pin and you'll lighten the piston, simple as that.
This does not even depend on con rod length. It's true that I prefer a long con rod, but I would prefer a high piston pin in combination with any rod length.
And don't worry about the piston tipping over. Just look below at the piston hight, or rather lack of it, that four-strokes get away with. And two-stroke piston skirts are invariably longer than their four-stroke counterparts because when in TDC, they must keep the exhaust port closed.

I agree with you, and I would like to add one thing: moving the pin up increases the temperature the pin is subject to. After moving the pin up, I was able to repeatedly convert once silver colored piston pins to a nice blueish tan instead. So if anyone thinks about this modification, check your pin first. If it is alread showing signs of heat impact, then maybe there is not that much to gain.

From gut feeling I'd say everything at and above a compression height of 25mm is going to be fine.

F5 Dave

16th December 2017, 18:46

I've always thought moving that amount of mixture under the piston is unproductive. Shorter crown to pin heights have proven beneficial every time so far.

adegnes

16th December 2017, 19:34

Adegnes has:

https://m.youtube.com/user/TheAdegnes

https://m.youtube.com/results?q=2%20stroke%20stuffing&sm=1

https://m.youtube.com/watch?v=MbfQpjWMQN0

Well, I have before but jumped straight to nitromethanol in my videos...

I experimented with e85 in an earlier version of the Spx. Slight powergain(might be placebo, no dyno back then), definitely cooler exhaust, shifted the powerband about 1500rpm down if I remember correctly.
Was a pain to get consistent results, as Fletner has pointed out fuel demand changes with heat.

I've had good results with methanol/nitromethane so far, 2hp increase over gasoline without touching anything but carburetion.

The bike will soon be up and running again, now with less conservative port timing.

TZ350

16th December 2017, 20:33

... moving the pin up increases the temperature the pin is subject to. After moving the pin up, I was able to repeatedly convert once silver colored piston pins to a nice blueish tan instead.

Before EFI and the piston slot I used to get blue piston pins, but not now.

333900

I've always thought moving that amount of mixture under the piston is unproductive. Shorter crown to pin heights have proven beneficial every time so far.

A couple of advantages of the piston slot is expelling mixture from under the piston crown directly into the boost transfer with the added benefit of improved under piston cooling and pin lubrication.

333899 333901

philou

16th December 2017, 20:47

I have just seen that. produced by Di Carmine Technologies for vortex kart engine

https://img15.hostingpics.net/pics/1175152036883613097902891340344127837118710038235o .jpg

https://img15.hostingpics.net/pics/9920042127271713432552691208697682662350912263264o .jpg

https://img15.hostingpics.net/pics/2194102507519014351968165933804032269298896065545o .jpg

https://img15.hostingpics.net/pics/7697362531120614358774665253155341455679939433459o .jpg

Neal

17th December 2017, 01:18

I've had a look but yet to find a graph or spec sheet that shows what compression ratios unleaded pump fuels can handle , for example I understand avgas can handle 16:1 ,
What can 98 octane pump fuel handle ? Where can I read this info ?

Thanks , neal

Frits Overmars

17th December 2017, 05:27

I've had a look but yet to find a graph or spec sheet that shows what compression ratios unleaded pump fuels can handle , for example I understand avgas can handle 16:1 , What can 98 octane pump fuel handle ? Where can I read this info ? That is an unanswerable question Neal. Any engine can handle 16:1 and a lot more, even on 95 octane pump fuel, when it's idling.
When it's starting to make power, things become more complicated. Has it got modest porting that will limit the attainable power anyway or is it state of the art?
Has the combustion chamber an effective squish band and a compact shape for fast burning or is the mixture playing hide and seek in nooks and crannies, inviting detonation?
Is the engine watercooled with a nikasil bore coating, or aircooled with a shrunk-in iron sleeve, hampering heat transfer so much that the piston is almost melting?
Is the carburation spot-on or so rich that the engine is practically fuel-cooled from the inside? Is the ignition timing safe or a tad too early?

Where can you read this info? I'd say: here. But you'll have a lot of reading ahead of you, enough to get you through the holidays.

Which brings me to my final point: best season's wishes for all.
333902

wobbly

17th December 2017, 09:45

What you are up against is the definition of the engines two differing "compression's ".
The static com is easily measured and is simply the trapped volume at TDC.
But the big variable is the dynamic compression and this is tied directly to the bmep.
BMEP is tied to the Delivery Ratio, the Trapping Efficiency and the Scavenging Efficiency.
Thus the higher the above elements have been "tuned " by the builder, then the higher the effective volume ( and its composition ) is at TDC.
Put simply, the better the design,the static compression must be reduced to prevent detonation of the end gasses in the squish.
In a well designed race engine a very general, rule as you have read on here several times ,is that AvGas will handle 16:1 but a small bore will go well above that
and a bigger bore will not.
An example of 95/98 capability would be a KZ2 engine.
This has 11cc trapped,so 12.3 effective full stroke com.
But this engine has an extremely high bmep plus a debilitating straight line ignition, so is up against deto constantly - thus cannot handle high MSV at all.
If it had a proper retarding ignition curve, then my guess would be 14.5:1 would be fine on the 98 octane as used by the CIK in Europe,with a "real " squish .
But a full noise bigger bore engine on 95 pump gas would be lucky to survive that in a road race setup, maybe just ok in a sprint kart engine.
Very much swings and roundabouts - impossible to define as Frits said.

Neal

17th December 2017, 11:49

Thank you for the replies , I realise now my question had too little info really :corn:
I'll have another read through the various pages because it's highlighted how much I still don't understand .

Merry Christmas

Greg85

17th December 2017, 12:03

What you are up against is the definition of the engines two differing "compression's ".
The static com is easily measured and is simply the trapped volume at TDC.
But the big variable is the dynamic compression and this is tied directly to the bmep.
BMEP is tied to the Delivery Ratio, the Trapping Efficiency and the Scavenging Efficiency.
Thus the higher the above elements have been "tuned " by the builder, then the higher the effective volume ( and its composition ) is at TDC.
Put simply, the better the design,the static compression must be reduced to prevent detonation of the end gasses in the squish.
In a well designed race engine a very general, rule as you have read on here several times ,is that AvGas will handle 16:1 but a small bore will go well above that
and a bigger bore will not.
An example of 95/98 capability would be a KZ2 engine.
This has 11cc trapped,so 12.3 effective full stroke com.
But this engine has an extremely high bmep plus a debilitating straight line ignition, so is up against deto constantly - thus cannot handle high MSV at all.
If it had a proper retarding ignition curve, then my guess would be 14.5:1 would be fine on the 98 octane as used by the CIK in Europe,with a "real " squish .
But a full noise bigger bore engine on 95 pump gas would be lucky to survive that in a road race setup, maybe just ok in a sprint kart engine.
Very much swings and roundabouts - impossible to define as Frits said.

hello wobbly you talk about kz2 engine compression so more engine has trapping efficiency (better cylinder) need to decrease static compression for more power? I did a test recently on a kz2 engine outgoing a good power but I had 12.70cc of volume chambers, when I put the right volume so 13cc I had lost 1.4hp .. so in theory I ' have reduced my static compression by putting more volume chambers, does this mean that my cylinder has more enough trapping effiency to get to the power I had before putting the volume right? is it my relationship between up and down which is better or just the cylinder that needs to be improved?

Thanks

TZ350

17th December 2017, 20:04

333929 ... 333930

Kicked the beast into life tonight.

333927 ... 333928

And was able to see an ignition trigger pulse (the spiky trace) and the (fatter) pressure sensor trace. The pressure sensor is a 16 bar unit, 4-20mA output dropped across a 450 Ohm resistor so the Voltage is reading about twice as high as it should, I needed to do that to get some resolution.

So the concept works, definitely can see if the engine fired or not. Now to refine the idea and get it to do something useful.

peewee

18th December 2017, 05:36

Has the combustion chamber an effective squish band and a compact shape for fast burning or is the mixture playing hide and seek in nooks and crannies, inviting detonation?

hi frits can you tell me about the nook and cranies your talking about ? ive welded and machined a new head for my nitromethanol engine in order to lower the comp ratio way down. at the inner edge of the band it goes pretty much straight in to the bowl and then makes a radius toward the spark plug if that makes sense. ive made a arrow to show the straight in angle im talking about. the band width is 52% bore area so I could recut it to 50% which would decrease band width by about 1mm (green line) and make that angle into the bowl less straight in but im not sure if it would make a world of difference. do you think I should just try the head as is and recut it later if I gives any problem or just cut the 1mm now ? unless this straight in angle isn't a nook crannie that your talking about ?

Frits Overmars

18th December 2017, 06:40

hi frits can you tell me about the nook and cranies your talking about ? ive welded and machined a new head for my nitromethanol engine in order to lower the comp ratio way down. at the inner edge of the band it goes pretty much straight in to the bowl and then makes a radius toward the spark plug if that makes sense. ive made a arrow to show the straight in angle im talking about. the band width is 52% bore area so I could recut it to 50% which would decrease band width by about 1mm (green line) and make that angle into the bowl less straight in but im not sure if it would make a world of difference. do you think I should just try the head as is and recut it later if I gives any problem or just cut the 1mm now ? unless this straight in angle isn't a nook crannie that your talking about ?Straight in is OK Peewee. But don't continue the straight; use the biggest radius that you can fit in. You might take a look at the Aprilia head below to see what I mean.
If you have a head that will fit, try it before modifying it, or you'd be throwing away a chance to learn something.
The nooks and crannies I was talking about are too much squish clearance, a squish gap that does not follow the contour of the piston but radially opens to the outside of the bore, head gaskets with a bigger bore than the cylinder, a piston top land with too much radial clearance, etc.
333945

Bert

18th December 2017, 08:36

333929 ... 333930

Kicked the beast into life tonight.

333927 ... 333928

And was able to see an ignition trigger pulse (the spiky trace) and the (fatter) pressure sensor trace. The pressure sensor is a 16 bar unit, 4-20mA output dropped across a 450 Ohm resistor so the Voltage is reading about twice as high as it should, I needed to do that to get some resolution.

So the concept works, definitely can see if the engine fired or not. Now to refine the idea and get it to do something useful.

It would be interesting to see how much the pressure increases with the failed ignition- could be useful to enable a slightly advanced spark to ensure a complete combustion process over the next few cycles.
This method could also be interesting if you have one mounted in the crankcase.

wobbly

18th December 2017, 09:35

The KZ engine running ( illegal ) 12.7cc would have no overev power past 14,000, end of story.
The peak power generated would be used for such a short period as to be of little advantage during a lap.
Franco's factory engines all run 13.6cc to enable plenty of overev and much leaner jetting.
Running 12.7 I guarantee you would deto badly on track, and would need very rich jetting.
Using fuel to cool the squishband and not make power, is always doomed to failure.
Modifying the reeds, the exhaust manifold, the stinger , the porting and the head shape are easily capable of getting back the lost power from lowering the com.

Re the KTM 250 kart engine - this is still sitting on the workshop floor unfinished due to lack of payment.
Im happy to give you the EngMod file for it.

Michael Moore

18th December 2017, 13:02

wobbly, would you mind sending that EngMod file to Jeff Henise? I've got a 2015 250SX engine that Jeff will be helping me with.

thanks,
Michael

jfn2

18th December 2017, 14:41

wobbly;
I also would like to see the EngMod file for that KTM 250. I am also working on a similar motor. Thank you.
Jeff Neilan
jneilan46@gmail.com

wax

18th December 2017, 20:39

We tested a lot of different fuels on an industrial style 26 cc racing engine. Because we could only change the mixture and ran the same pipe for all tests, there was very little power difference. The mixture needs to be richened for alcohol containing fuel. Below is the report.

Lohring Miller

333886

Thank you, interesting reading

Muhr

19th December 2017, 03:21

Hello guys this I my first post!

I've followed this thread for a while and you guys seem to keep up with a lot of fun stuff.
I'm doing a small hobby project that is a bit out of my comfort zone (a rotary valve 100cc V-twin 90 °).
I was wondering if there is someone who has some heads up regarding twin rotary valve assembly?

best regards Johan

Part by part, had an ambition to start it in 2018 but feels far away.:confused:

Frits Overmars

19th December 2017, 04:23

Part by part, had an ambition to start it in 2018 but feels far away.:confused:Looking good, Muhr.
But I would leave the red plastic parts out if I were you. You do not need the crankcase volume reduction, and what's worse, they are shrouding the big end bearings that need all the lubrication and cooling they can get. I would also remove the cover over the crankshafts: better for lube and cooling, and better for the flow of the mixture between the crank webs.

You are right about 2018 being far, far away. First we will have to eat ourselves through a shipload (I spelled that deliberately correct) of turkey and accompanying carbohydrates. But don't worry: it doesn't matter how much you eat between Christmas and New year, as long as you are careful between New year and Christmas.

Muhr

19th December 2017, 05:37

Looking good, Muhr.
But I would leave the red plastic parts out if I were you. You do not need the crankcase volume reduction, and what's worse, they are shrouding the big end bearings that need all the lubrication and cooling they can get. I would also remove the cover over the crankshafts: better for lube and cooling, and better for the flow of the mixture between the crank webs.

You are right about 2018 being far, far away. First we will have to eat ourselves through a shipload (I spelled that deliberately correct) of turkey and accompanying carbohydrates. But don't worry: it doesn't matter how much you eat between Christmas and New year, as long as you are careful between New year and Christmas.

You're probably right, the plastic is 10.8cc a piece. I'm at about 263cc now TDC managed to get them very even with the offset disc.

I want some material on thecover left to make adjustments afterwards

Me and food have always been best friends:sweatdrop

jbiplane

19th December 2017, 12:24

Part by part, had an ambition to start it in 2018 but feels far away.:confused:

Where you going to place the rotary valwe? At both case sides? Or modify crank disk in the middle...

Jannem

19th December 2017, 18:10

Perhaps this is one of those out there, but anyone tried spraying metered amount of mixture to the ex port to extend pipe range?

Grumph

19th December 2017, 18:30

Perhaps this is one of those out there, but anyone tried spraying metered amount of mixture to the ex port to extend pipe range?

Does the engine then become a generator for a pulse jet ?

Jannem

19th December 2017, 18:33

Does the engine then become a generator for a pulse jet ?

:) Was thinking more like simply adding heat for something like high compression ratio engine.

Muhr

19th December 2017, 20:15

Where you going to place the rotary valwe? At both case sides? Or modify crank disk in the middle...

Like this.

philou

19th December 2017, 20:20

I present you the work of a French tuner on exhaust pipe.

I translated the text as best as I could :sweatdrop

The following graph shows the parent dimensions of the expansion pipe of several modern and efficient engines
the engines are very different:
- since a KX 500 1989, which must be rather progressive and having a modest relative power (for the cubic capacity)
- up to a Honda 125 RSR 1997 racing bike who makes 40 hp and who favors above all the maximum power

http://img97.xooimage.com/files/4/f/d/01-3e7705f.jpg

The shape of the pots is nevertheless very similar: the proportion of diameter (difference in diameter / deviation maximum diameter) as a function of the proportion of length (length / length "reference") follows almost always the same law:

- the position of the midpoint of the divergent is constant (68% of the reference length)
- the position of the midpoint of the convergent is constant (124% of the reference length)
- the length of the second half of the divergent is constant (25% of the length of the reference)
- the length of the first half of the divergent is at least (25% of the reference length)
- The length of the convergent is also constant (34% of the reference length)
- length of the right part (14% of the reference length)

The proportions in parentheses are an average of 35 engines, of which 10 are represented on the graph. This average is the red "reference" curve. These proportions are used to determine the dimensions of the pots afterwards.

It remains more to determine the length

I have complete information on 7 engines: all the dimensions, the curves of torque and power, the pressure readings in the exhaust:

On average, the peak of the pressure wave is formed at 1/10 of the exhaust time (thus 18 ° crankshaft after the opening of the exhaust (OE) for an exhaust of an opening time of 180 ° ).

After several tests of recipe, the "benchmark" constant of all these engines to wedge the motif of the pattern of pressures and depressions with that of the openings and closures of the port is the following: the cross between the depression and the pressure, which correspond at the rate of 10% before the closing of the transfers (FT) (10%: 10% of the transfer opening period). I give you a grace of physical interpretation. For those interested in it can talk about it more.

That is why I took as reference length, the length between the exhaust port and the center of the right portion (since the piston therefore, including the duct in the cylinder, the flange of the cylinder, the tube or elbow , the divergent and half of the right portion).

We know when the pressure wave is emitted (10% after OE), we know when it must return from the middle of the right portion (10% before FT). The formula for calculating the reference length, very simple from the desired speed and the speed of the wave, is written on the following page.

All of these values are set at the maximum speed power peak, because it is more available information and easier to use than another system. So the regime to take into account is the one wanted for the maximum power regime. If we want the maximum torque regime, it will be necessary to change the 10% (calculation to be done).

Full version => http://as3-rdx-club.clicforum.fr/t900-CALCUL-POT-DE-DETENTE.htm

jbiplane

19th December 2017, 20:41

Like this.

Thanks Muhr. Me thinking about placing cylindrical rotary valve at medium of cranckshaft to both functions:
separate volumes
regulate intakes.

BTW I made Excel spreadsheet to calculate balance of 2-cylinder engines. At my case V2 90 generates 4 time less shaking force than just one half of V2.
I have rather short connecting rods L=73 for 40mm stroke.

Muhr

19th December 2017, 23:06

Looking good, Muhr.
But I would leave the red plastic parts out if I were you. You do not need the crankcase volume reduction, and what's worse, they are shrouding the big end bearings that need all the lubrication and cooling they can get. I would also remove the cover over the crankshafts: better for lube and cooling, and better for the flow of the mixture between the crank webs.

You are right about 2018 being far, far away. First we will have to eat ourselves through a shipload (I spelled that deliberately correct) of turkey and accompanying carbohydrates. But don't worry: it doesn't matter how much you eat between Christmas and New year, as long as you are careful between New year and Christmas.

Do you know what crankcase volume the old gp 50 bike had like the Kreidler gp 50?

Thank Frits

Frits Overmars

20th December 2017, 00:17

I present you the work of a French tuner on exhaust pipe... Full version => http://as3-rdx-club.clicforum.fr/t900-CALCUL-POT-DE-DETENTE.htmI rather enjoyed that lecture, and it'll do your French some good as well. But we must remain critical, for example:
The following graph shows the parent dimensions of the expansion pipe of several modern and efficient engines
- since a KX 500 1989...- up to a Honda 125 RSR 1997 racing bike who makes 40 hpSo the most 'modern' engine in that lecture was a 20 year-old Honda that was 14 hp down on state-of-the-art power.

The proportions in parentheses are an average of 35 enginesThe outcome of any averaging will always be worse than the data of the best engine in the bunch. Sometimes averaging is sensible; sometimes it isn't .

Do you know what crankcase volume the old gp 50 bike had like the Kreidler gp 50?Are we talking about the twelve-speed works Kreidler of 1960 or the Van Veen Kreidler of 1983, or somewhere in-between? Never mind, I have not memorized those values for the good reason that they all were too small.
The Aprilia-values that I know off the top of my head, may be more useful to you. The RSW125 had a volume of 650 cc at BDC, including transfer duct volumes, and the RSA had 675 cc. For a 50 cc that would work out as 270 cc. But if you are going to try that, you will also need porting and pipe efficiency as high as the RSA's....

philou

20th December 2017, 00:33

The article I present and translate is not mine.

I think interressant to share it here

Muhr

20th December 2017, 04:15

Are we talking about the twelve-speed works Kreidler of 1960 or the Van Veen Kreidler of 1983, or somewhere in-between? Never mind, I have not memorized those values for the good reason that they all were too small.
The Aprilia-values that I know off the top of my head, may be more useful to you. The RSW125 had a volume of 650 cc at BDC, including transfer duct volumes, and the RSA had 675 cc. For a 50 cc that would work out as 270 cc. But if you are going to try that, you will also need porting and pipe efficiency as high as the RSA's....

Really good information, I'm going to start a little shy, then go bananas! Getting up to the RSA level is probobly many peoples goal(dream). It's just that it's damn far away!!!:scratch:
I was thinking of the Van Veen

Greg85

20th December 2017, 10:22

The KZ engine running ( illegal ) 12.7cc would have no overev power past 14,000, end of story.
The peak power generated would be used for such a short period as to be of little advantage during a lap.
Franco's factory engines all run 13.6cc to enable plenty of overev and much leaner jetting.
Running 12.7 I guarantee you would deto badly on track, and would need very rich jetting.
Using fuel to cool the squishband and not make power, is always doomed to failure.
Modifying the reeds, the exhaust manifold, the stinger , the porting and the head shape are easily capable of getting back the lost power from lowering the com.

Re the KTM 250 kart engine - this is still sitting on the workshop floor unfinished due to lack of payment.
Im happy to give you the EngMod file for it.

Thanks Wobbly for this information RE:you received my message inbox?

peewee

20th December 2017, 12:07

Straight in is OK Peewee. But don't continue the straight; use the biggest radius that you can fit in. You might take a look at the Aprilia head below to see what I mean.
If you have a head that will fit, try it before modifying it, or you'd be throwing away a chance to learn something.
The nooks and crannies I was talking about are too much squish clearance, a squish gap that does not follow the contour of the piston but radially opens to the outside of the bore, head gaskets with a bigger bore than the cylinder, a piston top land with too much radial clearance, etc.
333945

well mine surely goes in straight more than just a little bit so im going to change that as i dont have a good feeling how it is now.

can you remind me again about your piston to head clearance thoughts ? seems like it was 1% of stroke i think. in the past ive done fine with 1mm on big singles but i missed the mark alittle on this latest head. from outer bore edge toward center i ended up with .93-.83-.99 (domed piston and straight squish band). .82mm would be 1% stroke. piston doesnt seem excessively heavy and rpm under load is only about 8k so i dont think theres a ton of rod stretch. and all bearings only have couple hours runtime so i consider them still in great shape

DoldGuy

20th December 2017, 14:51

Indeed, there are a lot of Mean Squish Velocity calculators available on the internet, but I haven't yet seen a single one that takes the dynamic stretch of a high-revving engine into account, and it makes a lot of difference whether your squish clareance is 0,6 mm or 0,06 mm. As a rule of thumb that stretch will be about 0,1% of the stroke, assuming that your crankshaft is sound. I agree with Wobbly: reduce the squish clearance until you are going to suspect that the piston may be kissing the head. Then there will be zero clearance and zero mixture in the squish band. And you won't get detonation if there is nothing there to detonate :rolleyes:.[/QUOTE]

Found this by using TZ’s search recommendation....

Thanks TZ!:yes:

Muhr

20th December 2017, 20:20

Really good information, I'm going to start a little shy, then go bananas! Getting up to the RSA level is probobly many peoples goal(dream). It's just that it's damn far away!!!:scratch:
I was thinking of the Van Veen

If I go whit the left web it will give 23cc more and same weight/balance factor

Frits Overmars

20th December 2017, 22:05

Indeed, there are a lot of Mean Squish Velocity calculators available on the internet, but I haven't yet seen a single one that takes the dynamic stretch of a high-revving engine into account, and it makes a lot of difference whether your squish clareance is 0,6 mm or 0,06 mm. As a rule of thumb that stretch will be about 0,1% of the stroke, assuming that your crankshaft is sound. I agree with Wobbly: reduce the squish clearance until you are going to suspect that the piston may be kissing the head. Then there will be zero clearance and zero mixture in the squish band. And you won't get detonation if there is nothing there to detonate :rolleyes:.

Found this by using TZ’s search recommendation....Thanks TZ!:yes:The 0,1% in the above text was a typo; not TZ's fault but mine. It should read 1 %. I can't edit that post anymore because it's too old, so please take care yourself: https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131059758#post1131059758

If I go whit the left web it will give 23cc more and same weight/balance factorWith those flat inside web faces, that crank of yours is starting to look more and more familiar Muhr :D
334052 334051

TZ350

21st December 2017, 08:15

334063

My totally un-shrouded crankshaft big end pin. An idea picked up from Frits's Aprilia crank and comments on crankcase volume.

Good cooling and lubrication with the added benefits of reduced wind-age as the con-rod passes between the wheels and extra crankcase volume.

The stroke is 48mm and the rod is 115mm C/C from a Yamaha RD400.

334062

Other random engine bits from the Suzuki GP100, now 110cc with a dry sump gearbox, water cooling and a large RV cover from a Kawasaki KE175.

Muhr

21st December 2017, 10:44

With those flat inside web faces, that crank of yours is starting to look more and more familiar Muhr :D
334052 334051

I don’t know what you men! :2thumbsup There is a crazy amount of weights on those cranks

Went through all the parts and realise I needed to make it a bitt heavier

334063

My totally un-shrouded crankshaft big end pin. An idea picked up from Frits's Aprilia crank and comments on crankcase volume.

Good cooling and lubrication with the added benefits of reduced wind-age as the con-rod passes between the wheels and extra crankcase volume.

The stroke is 48mm and the rod is 115mm C/C from a Yamaha RD400.

334062

Other random engine bits from the Suzuki GP100, now 110cc with a dry sump gearbox, water cooling and a large RV cover from a Kawasaki KE175.

Nice work! Allays great to get some inspiration and ideas

F5 Dave

21st December 2017, 14:39

To the Brains trust Inc.

I’m trying to avoid this, but I’ve been pulled into fitting an Ignitech to a TV200 roadbike. Based on the RG125/150 bottom end.

Last test is swapping out the alternator, but if not I have to dive in & cope with unknown Ignition & PV curves for an orphan machine, but you just can’t seem to get an RG/TV200 CDI.

RG150 CDI doesn’t run right it seems.
The bike has a 4 stroke stator setup with stator coils bolted to the side-cover & inverted flywheel on the crank all in gearbox oil.
My question is this:
How do you set up the static timing? Can’t think of anything that hangs out that spins at 1:1 with the crank. Take the cover off & the pulser coil goes with it.
This side of carving a hole in the sidecover & making marks on the flywheel how would you do it?
Anyone running an RG150 bottom end?
Nigel made a whole new CNC sidecover & would have undoubtedly put on a smaller flywheel arrangement so I haven’t bothered calling him.

Yow Ling

21st December 2017, 16:25

To the Brains trust Inc.

I’m trying to avoid this, but I’ve been pulled into fitting an Ignitech to a TV200 roadbike. Based on the RG125/150 bottom end.

Last test is swapping out the alternator, but if not I have to dive in & cope with unknown Ignition & PV curves for an orphan machine, but you just can’t seem to get an RG/TV200 CDI.

RG150 CDI doesn’t run right it seems.
The bike has a 4 stroke stator setup with stator coils bolted to the side-cover & inverted flywheel on the crank all in gearbox oil.
My question is this:
How do you set up the static timing? Can’t think of anything that hangs out that spins at 1:1 with the crank. Take the cover off & the pulser coil goes with it.
This side of carving a hole in the sidecover & making marks on the flywheel how would you do it?
Anyone running an RG150 bottom end?
Nigel made a whole new CNC sidecover & would have undoubtedly put on a smaller flywheel arrangement so I haven’t bothered calling him.

Isnt the clue in the word "static"

F5 Dave

21st December 2017, 18:16

Well I can dial gauge the piston but its relationship to the pulser coil is fairly parsimonious.

Yow Ling

21st December 2017, 19:54

Well I can dial gauge the piston but its relationship to the pulser coil is fairly parsimonious.
If you put a scope on the pulser coil you may get an indication when the pickup drops the trailing edge of the trigger bump as the flux collapses. if you print out a 360 degree strip and put it on the outside of the rotor you can read the numbers when you take the sidecover off without disturbing anything

F5 Dave

21st December 2017, 19:59

So like when a coil passes through a magnetic field. The passes bit is difficult. it would have to be done at least at some speed. If you could generate electricity Just by placing a coil in a field you'd solve the worlds energy problems.
I'd have to stop it at exactly the right place instantaneously and know that I had.

speedpro

21st December 2017, 21:15

Or have something like the FZR250 which is a threaded hole in the alternator cover. Inside the hole is an indicator pointer which lines up with marks on the rotor as it rotates. I'd have to have another look to be sure but IIRC there are 3 marks - TDC, full retard, and full advance.

varthrix

21st December 2017, 23:31

Hello everybody, I was going to refrain from posting until I had read the whole thread, but I'm only about 700 pages in and I have a question. Tee Zee, I saw the post about moving the ring positioning peg and that it went wrong, if you were going to do it again what approach would you pick to do it? I'm fiddling with an old Simson cylinder and to get more blowdown I need to move the ring positioning peg. I made a new cast iron liner with a bridged exhaust and currently that's what's stopping me from widening the exhaust for more blowdown.
Also I'd like to thank all the contributors, especially TeeZee, Wobbly, FritsOvermars, Speedpro and all the others for the great information on the thread.
Sorry for the stupid question but I couldn’t find anything with the search function, but it's probably my fault.
Greetings from Bulgaria.

Frits Overmars

22nd December 2017, 00:31

I saw the post about moving the ring positioning peg and that it went wrong, if you were going to do it again what approach would you pick to do it?... Sorry for the stupid question...Welcome Varthrix. Asking about someone's experience is not stupid; it is one of the smartest things you can do :msn-wink:.

TZ350

22nd December 2017, 03:17

Hello everybody, I was going to refrain from posting until I had read the whole thread, but I'm only about 700 pages in and I have a question. Tee Zee, I saw the post about moving the ring positioning peg and that it went wrong, if you were going to do it again what approach would you pick to do it?

This thread is best read backwards, that way you get to the good stuff first. Page's 500, 1000 and 1500 are worth a visit.

And there are thousands of pictures you can look through if you use the thread tools.

What went wrong, poor workmanship and the retaining tip of stainless wire I used fractured from vibration.

If I was to try again I would use the Yamaha racing TZ approach of drilling down from the top and piano wire with the tip bent over in the hole. Piano wire wont fracture like the SS did.

334094

I couldn’t find anything with the search function, but it's probably my fault. Greetings from Bulgaria.

Emess posted a very helpful tip for searching this or any other thread.

Rather than use the site search which usually fails, use Google so to search this site use an ordinary search phrase and after it add

site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz/)

Frits pisa site:www.kiwibiker.co.nz (http://www.kiwibiker.co.nz/)

the same will work for other sites with the appropriate site address

wobbly

22nd December 2017, 07:11

I had the same problem with setting up the Ignitech static timing on an old Ducati.
What you need to do is using a straight edge,line up the center of the timing cover and the middle of the trigger pole, and make a mark on the
cover gasket face.
Then fit the cover, and transfer that mark onto the engine gasket face.
Again, using the straight edge, line up the rotor center and the new mark on the engine, this gives you the trigger position in relation to
the trailing edge of the lobe on the rotor ( with the piston at TDC ).
Measure the base timing angle using a protractor ,or trig, or using piston position height with the center line and lobe edge lined up.

ief

22nd December 2017, 11:27

Hi all,

engmod question time again...

Turbulent mode, I still don't get it.

I start with a 'simple' cbd file, run it in engmod, get result (purple line) Put it in turbulent mode, run engmod and get a result, (black line) looks good, fine.

Write the new combustion file, load it in dat2t, set it on prescribed burn rate and... I get this result (green line)

And I can't figure out what is happening or why cause I a. don't understand what engmods magic is doing and b. what the chicken or the egg is in the differences I see (tubmax, delivery ratio etc.)

What am I missing?

F5 Dave

22nd December 2017, 12:02

Thanks Wob, that makes good sense. With an asymmetric cover I'll lengthen the crank somehow to provide a tit I can engineers blue a centre point to mark on the inner cover.

Which means draining the oil again, oh well. A path ahead. Cheers.

jfn2

22nd December 2017, 16:43

wobbly:
Thank you very much for the KTM 250 RR engmod file. But when I try to unpack it I'm getting a message that the engine file is incomplete and I get a bunch of error messages. I tried to unpack it again but no go. Could you resend it when you have the time? Thanks Jeff

Vannik

22nd December 2017, 16:53

Jeff,
You need the latest version, I sent out update notification yesterday. If you did not get it let me know. The notification is via bulk email with links which gets blocked by some firewalls.
Vannik

jbiplane

22nd December 2017, 21:51

If I go whit the left web it will give 23cc more and same weight/balance factor

BTW what is the best possible, but still easy to get material for disk valve? Me experienced in reeds, but 0 in disks.

Frits Overmars

22nd December 2017, 22:40

Hi all, engmod question time again... Turbulent mode, I still don't get it. I start with a 'simple' cbd file, run it in engmod, get result (purple line) Put it in turbulent mode....Hi Ief, those Engmod pics look rather familiar. You don't happen to be working on a Dutch 50cc twin, are you? :msn-wink:

what is the best possible, but still easy to get material for disk valve? Me experienced in reeds, but 0 in disks.Carbon. It used to be hard to get, but nowadays you can simply order it: http://www.emot.nl/.

dutchpower

22nd December 2017, 22:49

Yes Frits looks familiar

Change AV gas to regular

Muhr

23rd December 2017, 00:02

BTW what is the best possible, but still easy to get material for disk valve? Me experienced in reeds, but 0 in disks.

https://www.rockwestcomposites.com/plates-panels-angles/carbon-fiber-plate/carbon-fiber-fabric-plate/401-410-group

https://www.carbontech.com/

ief

23rd December 2017, 02:15

Hmm, what gave it away? ;)

Saw Dutch posted some numbers so figured I'd give it a go.

Regular, ok. Not related to what I experience I presume.

jfn2

23rd December 2017, 03:12

Hello Neels:
No I did not get your update notification. I also tried to contact you using your form on your website but it doesn't seem to work. I am using Windows 10 if that helps you. Thank you very much.
e-mail is jneilan46@gmail.com

dutchpower

23rd December 2017, 03:25

Hmm, what gave it away? ;)

Saw Dutch posted some numbers so figured I'd give it a go.

Regular, ok. Not related to what I experience I presume.

Looks very simulair Ief :laugh:

ief

23rd December 2017, 04:19

Oh, I see I've got some work to do, is that with a realistic model you'd say?

Having detonation issues as is :)

Changing to regular lowered my dip with 1000 rpm, otherwise no change.

On we go :)

dutchpower

23rd December 2017, 04:38

Then go to Premium

After installing the update from Neels lots of deto

Muhr

23rd December 2017, 05:15

Looks very simulair Ief :laugh:

Thats insane:ride:

Is it a 31-32 stroke?

dutchpower

23rd December 2017, 05:42

Thats insane:ride:

Is it a 31-32 stroke?

Here some data Muhr

ief

23rd December 2017, 07:05

Then go to Premium

After installing the update from Neels lots of deto

Ah, it WAS related I understand, that hardly seems a viable way to get to a proper model. Mix some nitrous in while we're at it haha ;)

To be sure, your pic shows the outcome of only one barrel right, that seems insane but what do I know (?)

I made some changes to your stated numbers here and there in an effort to get tubmax down and I didn't understand, 1:16 CR and a head volume of 2.4cc so changed that as well.

Anyway, I'll keep on playing with this some more.

dutchpower

23rd December 2017, 07:29

Yep one barrel Ief

9.1 trapped

Pic. are from my friend Nico ( tomorrow big test )

ief

23rd December 2017, 07:43

Cool. Did you try to round the sleeve where the transfers are?

My CR is way lower... Guess I have something not right, haha.

I'm just trying to get a model which seems to correlate reality and without deto.

But you know reality :D

Frits Overmars

23rd December 2017, 07:56

Thats insane:ride: Is it a 31-32 stroke?Yep. Some more pictures of Nico's 50cc twin:
334120 334121 334122

dutchpower

23rd December 2017, 07:58

Mine are different
Nico is difficult to persuade

Hopefully tomorrow :lol:

ief

23rd December 2017, 08:09

Could you show your temp file dutch?

dutchpower

23rd December 2017, 08:27

Wobbly RSW temp is a good start

TZ350

23rd December 2017, 08:42

But you know reality :D

Do we at Team ESE know Reality???? .... No, we try not to go there, when dreams are free .... :laugh:

But Nico's 50cc twin is a seriously cool looking engine, we are very impressed.

ief

23rd December 2017, 08:45

Still think there should be a dedicated forum for engmod....

No magic in the temp file, that's for sure.

Well, we'll just see what tomorrow brings then dutch... eagerly :)

(lol, TZ, just make more then 30 hp for once will ya ;) )

dutchpower

23rd December 2017, 08:59

Good idea

2 hour engmod

2 years in the workshop

Dreaming is wast of time :laugh::laugh::laugh:

TZ350

23rd December 2017, 09:15

.

While I wait for some pressure sensors to arrive for my EFI project I thought I would get on with developing the switch that determines if the engine has fired or not.

334127

Handy little kit-set signal generator I found on Trademe. Real easy to put together and works great too.

334125

The signal is about 7 crank shaft degrees wide at 12,000 rpm.

The trick is to see if we can use an Arduino Nano to identify the peaks between the leading edges of the square wave.

And use the Arduino Nano and Relay module to switch the relay when there is none, ie the motor has not fired.

334126

It is truly amazing what you can learn of the internet using Google, programming the Arduino does not look that hard. Who said old dogs can't learn new tricks.

I will be using the classic If/Then/Else routine in an endless loop.

If its fired Then do nothing Else activate the relay.

The first step is to be able to identify and refresh the signals then develop the application to discriminate between firing or not and activating the relay.

And at a total processing cycle speed of 200 hz all this should be possible.

varthrix

23rd December 2017, 09:24

[QUOTE=TZ350;1131077307]This thread is best read backwards, that way you get to the good stuff first. Page's 500, 1000 and 1500 are worth a visit.

And there are thousands of pictures you can look through if you use the thread tools.

What went wrong, poor workmanship and the retaining tip of stainless wire I used fractured from vibration.

If I was to try again I would use the Yamaha racing TZ approach of drilling down from the top and piano wire with the tip bent over in the hole. Piano wire wont fracture like the SS did.
Thanks for the searching tips TeeZee, they helped out a lot. Also Frits, I usually try to learn from other people's mistakes, but sometimes I actually repeat them a time or two just to be sure.
By using the search method TeeZee suggested, I managed to find only one post talking about reed area vs carburetor bore area and it was from Husaberg. It mentioned a rule of thumb 0.8 reed area vs carb area, but noone confirmed it, so is there actually a different formula for determining reed petal area?
Also sorry if my wording is bad, English isn't my native language.

Frits Overmars

23rd December 2017, 10:07

It is truly amazing what you can learn of the internet using Google, programming the Arduino does not look that hard. I will be using the classic If/Then/Else routine in an endless loop.
If its fired Then do nothing Else activate the relay.Programming hmm? You'd better prepare for a life of misunderstanding and ignorance...
334128

ief

23rd December 2017, 10:13

lol........

Muhr

23rd December 2017, 11:45

Here some data Muhr

Thanks looks great!

I'm trying to get together a 100cc v twin.

Yep one barrel Ief

9.1 trapped

Like a 1,3-4 head? :)

Yep. Some more pictures of Nico's 50cc twin:
334120 334121 334122

Is a amazing peace of mean machine :wings:

TZ350

23rd December 2017, 11:45

Programming hmm?

334128

........ :laugh:

Askor

23rd December 2017, 16:21

.

I will be using the classic If/Then/Else routine in an endless loop.

If its fired Then do nothing Else activate the relay.

The first step is to be able to identify and refresh the signals then develop the application to discriminate between firing or not and activating the relay.

And at a total processing cycle speed of 200 hz all this should be possible.

Lookup a comparison of "interrupts" vs "polling". You're going to use polling to determine when there's a signal, using interrupts could/should be more reliable.

jbiplane

23rd December 2017, 16:48

Hi Ief, those Engmod pics look rather familiar. You don't happen to be working on a Dutch 50cc twin, are you? :msn-wink:

Carbon. It used to be hard to get, but nowadays you can simply order it: http://www.emot.nl/.

Thanks Frits. I have an experience to make reed petals of carbon. Will try to make disks of carbons and coated TiN steel and compare.

Other question. Can I use common tuning pipe? For inline this work fine, but for V... May be use headers of different length?
Could any software like Engmod correctly simulate exhaust behavior for 2 headers and common tuning pipe for different 2-cylinder configurations
(opposite, inline, V)?

Vannik

23rd December 2017, 19:32

Still think there should be a dedicated forum for engmod....

https://www.kiwibiker.co.nz/forums/showthread.php/143620-EngMod2T-Q-amp-A

Frits Overmars

24th December 2017, 04:31

Can I use common tuning pipe? For inline this work fine, but for V... May be use headers of different length?You can use a common pipe on a 180°-firing twin, on a 120°-firing triple, etc, but not on a 90°/270°-firing twin; not if you want any pipe efficiency.

jbiplane

24th December 2017, 17:22

You can use a common pipe on a 180°-firing twin, on a 120°-firing triple, etc, but not on a 90°/270°-firing twin; not if you want any pipe efficiency.

So on 2-stroke with common crankpin impossible make good (not excelent) muffler?

Vannik

24th December 2017, 20:07

So on 2-stroke with common crankpin impossible make good (not excellent) muffler?

If you are talking about a non-tuned pipe it is possible to make a good common exhaust, also if you have just two quarter wave straight pipes terminating in a common box will work. But this will be for a specific speed and for an UAV type engine where mass and space is a big issue. The UAV engines I worked on (Zanzottera and Limbach) had either a stub exhaust which was very noisy or two quarter wave pipes with absorption silencer included which was less noisy. You have to decide what is best for your application.

jbiplane

24th December 2017, 22:19

If you are talking about a non-tuned pipe it is possible to make a good common exhaust, also if you have just two quarter wave straight pipes terminating in a common box will work.

Yes, Vannik. "two quarter wave straight pipes terminating in a common box will work" completelly suit me. I want to get just one vital point - 20hp at 7200 rpm using Stihl 090 cylinders.
One 137cc cylinder stihl 090 with simplest muffler connected directly to cylinder without any header (piston driven intake) produce 8.5hp.

Niels Abildgaard

24th December 2017, 23:29

Yes, Vannik. "two quarter wave straight pipes terminating in a common box will work" completelly suit me. I want to get just one vital point - 20hp at 7200 rpm using Stihl 090 cylinders.
One 137cc cylinder stihl 090 with simplest muffler connected directly to cylinder without any header (piston driven intake) produce 8.5hp.

Bore 66mm stroke 40mm ca and 120 rps means a mean effective pressure of 5 bar to make 20 horsepower and a piston speed of ca 10 meter per second.
My MZ301 ran around 800 hours at PME 6bar and 11 meter per second and plug was changed once.Very long and happy life.

Niels Abildgaard

24th December 2017, 23:46

If you are talking about a non-tuned pipe it is possible to make a good common exhaust, also if you have just two quarter wave straight pipes terminating in a common box will work. But this will be for a specific speed and for an UAV type engine where mass and space is a big issue. The UAV engines I worked on (Zanzottera and Limbach) had either a stub exhaust which was very noisy or two quarter wave pipes with absorption silencer included which was less noisy. You have to decide what is best for your application.

Can we see a picture of a quarter wave pipe with silencer?
Please?

jbiplane

25th December 2017, 00:45

Bore 60mm stroke 40mm ca and 120 rps means a mean effective pressure of 5 bar to make 20 horsepower and a piston speed of ca 10 meter per second.

2 cylinders 66bore 40 stroke and common volume 274cc, but very short 73mm conrod. We made some opposites for paramotor use and 274cc heavy to start with pull starter on someone the back. And 7kg opposite have terrible torque vibrations on idle. We sucseed to get only 16,8hp...

So I want make V90 with common crankpin which will much more easy to start and still want to use OEM cylinders. I will make new crankshafts, disk valve intake, exhaust system, but complete engine should weight below 8kg.

I planing to simulate it in Engmod2t and Ricardo Vawe 2017 before production.

Haufen

25th December 2017, 00:48

When preparing a freshly cast cylinder for the first plating, is it advisable to put a bevel or radius at the end of the bore at tdc? What is this good for? From a combustion chamber point of view I don't like this idea at all.

But as the combustion chamber is going reach into the bore by 1mm anyway, this should not do too much harm. Would you have the same radius at the chamber to minimize trapped volume? I would like to do so, but suspect that the shape of the radius will have changed once plated.

Niels Abildgaard

25th December 2017, 01:08

2 cylinders 66bore 40 stroke and common volume 274cc, but very short 73mm conrod. We made some opposites for paramotor use and 274cc heavy to start with pull starter on someone the back. And 7kg opposite have terrible torque vibrations on idle. We sucseed to get only 16,8hp...

So I want make V90 with common crankpin which will much more easy to start and still want to use OEM cylinders. I will make new crankshafts, disk valve intake, exhaust system, but complete engine should weight below 8kg.

I planing to simulate it in Engmod2t and Ricardo Vawe 2017 before production.

Is it direct drive or belt-reduction between crank and airscrew?

jbiplane

25th December 2017, 01:54

Is it direct drive or belt-reduction between crank and airscrew?

Hi Niels. We produce 90, 120, 183, 236, 294 and 350cc opposites, as direct drive as belt-reduction. We made one engine with planetary gearbox.

Now we want add to product line 141cc inline, V90 141cc and V90 274cc. Some engines would be tailored for paramotoring. We want make much less vibrating then novadays one cylinder stuff.

One question to comunity. We sucseed to plate cylinders by our nikasil like coating. It have + and -. We got very high 17% fraction of ceramic, much more than in third party engines we analysed. It very hard, but piston rings survive only 70 hours. What is better - try to source better rings or decrease ceramic content in the coating?

Frits Overmars

25th December 2017, 02:20

We sucseed to plate cylinders by our nikasil like coating. It have + and -. We got very high 17% fraction of ceramic, much more than in third party engines we analysed. It very hard, but piston rings survive only 70 hours. What is better - try to source better rings or decrease ceramic content in the coating?My experience with average nikasil is that the first piston ring wears away very quick; the second ring lasts a bit longer, and then the sharp nikasil peaks are polished away and the third ring lasts forever. So maybe you should concentrate on honing.

lohring

25th December 2017, 02:36

You can use a common pipe on a 180°-firing twin, on a 120°-firing triple, etc, but not on a 90°/270°-firing twin; not if you want any pipe efficiency.

A flat twin with a common crankpin will be 180 degree alternate firing. It will need a 1:1 balance shaft for good balance.

Lohring Miller

varthrix

25th December 2017, 10:05

A question to Frits or Wobbly, what method should one use to find needed reed petal area for a certain carburetor size? I read about a rule of thumb reed area = 0.8 carburetor area. Is that an okay way to calculate things?
I wish everybody a Merry Christmas!

TZ350

25th December 2017, 10:11

.

The perfect Xmas Day. all the family stuff done and dusted Xmas Eve and today can be spent thinking about the reason for the season and enjoying a quiet day playing with the Aduino Nano.

334180 334181

Lookup a comparison of "interrupts" vs "polling", using interrupts could/should be more reliable.

Following up on Askors suggestion of using Interupts I was able to write a short bit of code that counts 3000 pulses and then turns on the relay for half a second.

Now that I know the Nano can see the simulated 12,000rpm pulses quickly and reliably enough, in fact it can do this at several times the speed required. I can now try my hand at writing some code to discriminate between Ignition and Cylinder pressure pulses and identify when there is combustion or not.

chrisc

25th December 2017, 10:20

Sounds like a winner of a day Rob. Merry Christmas everyone. I'm rebuilding my NX4 RS125 engine and my Christmas presents are all HRC parts. Stoked.

lodgernz

25th December 2017, 15:00

Christmas Day and I'm working on my bucket 50 engine. I guess my life is in the bucket.

Anyway, I have a question for Wobbly, Frits or anyone else who feels like contributing:

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area.
We now know that I need to reduce the CSA steadily from the (single) port to achieve a flange area of 90% of the port area.
If I open this bottleneck up to say 95% of the port area in keeping with that philosophy, I will be increasing the volume of the duct.
Some of this extra volume will be reduced by the insert I will add to the outer part of the duct, but the overall volume will still be larger.
We know increased duct volume is not good, so I'd appreciate any comments or advice on what would be a good course of action.
Perhaps a bottleneck like this is not an issue. Does anyone have experience of this?

Niels Abildgaard

25th December 2017, 17:58

Hi Niels.
Now we want add to product line 141cc inline, V90 141cc and V90 274cc.

What OEM cylinders and pistons are You planning for the 141 engine?

Hope Your X-Mas morning is as nice as mine.

Niels

Frits Overmars

25th December 2017, 23:11

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area. We now know that I need to reduce the CSA steadily from the (single) port to achieve a flange area of 90% of the port area. If I open this bottleneck up to say 95% of the port area in keeping with that philosophy, I will be increasing the volume of the duct.
Some of this extra volume will be reduced by the insert I will add to the outer part of the duct, but the overall volume will still be larger.
We know increased duct volume is not good, so I'd appreciate any comments or advice on what would be a good course of action.
Perhaps a bottleneck like this is not an issue. Does anyone have experience of this?That bottleneck CSA is probably bigger than the blowdown CSA, and in that case it need not hurt blowdown, provided there are no abrupt CSA changes in the duct.

Wobbly's rule of thumb is based on the total exhaust port area and I can very well understand his approach because it is more practical than my blowdown area-based method: you can establish the total port area fairly easily whereas the blowdown area is something you cannot measure at all because there is no measurable way of knowing at what crank angle the blowdown phase is completed. You'll need something like EngMod for that.

Having said that, in your case it may be possible to raise the exhaust floor so that your bottleneck is no longer the tightest point. It might promote flow and reduce the duct volume at the same time.

jbiplane

26th December 2017, 02:24

What OEM cylinders and pistons are You planning for the 141 engine?
Niels

Hi Niels. We mill most of our cylinder in 5-axis from alu alloys. The reason is weight. Says 70cc cylinder with integrated head weight just 380 gramms. But as a common our rule 141cc compatible with OEM Husqvarna 372, other engines with Stihl 090, 660...

Related cylinder coating. Does it have any reason to try use Nitrid Boron aditions together or instead of Silicon carbide? Does anyone know any supplier for Kawasaki Electrofusion? My objective is 750+ hours rings and cylinder life on medium loads.

Merry Christmass all forum folks :)

TZ350

26th December 2017, 09:22

334208

Got my Arduino Nano project working Ok on the test bench. Next step is to try it on the bike when my new pressure sensors arrive.

Full code can be found in the link below.

// Arduino Nano map switch routine.
// Routine for Switching between Alpha-N maps on a 2T engine.
// By determining from residual cylinder pressure if the EFI 2T engine has fired or not.
// Switches to an alternative map if the engine did not fire on the last cycle.

Computer programming, who said an old dog can't learn new tricks ...... Woof.

lodgernz

26th December 2017, 10:31

That bottleneck CSA is probably bigger than the blowdown CSA, and in that case it need not hurt blowdown, provided there are no abrupt CSA changes in the duct.

Wobbly's rule of thumb is based on the total exhaust port area and I can very well understand his approach because it is more practical than my blowdown area-based method: you can establish the total port area fairly easily whereas the blowdown area is something you cannot measure at all because there is not measurable way of knowing at what crank angle the blowdown phase is completed. You'll need something like EngMod for that.

Having said that, in your case it may be possible to raise the exhaust floor so that your bottleneck is no longer the tightest point. It might promote flow and reduce the duct volume at the same time.

Thank you Frits. I imagine Wobbly's philosophy might also consider that, at maximum over-rev RPM, when exhaust gas is heading down the transfers because blowdown is incomplete, then the exhaust port area IS the blowdown area.

My cylinder has been decked and raised, so the bottom of the exhaust port is already 2mm above BDC, but of course this has not reduced the duct volume. In fact, by the time I widen the top of the port, the volume will be even larger.
I hesitate to try and raise this floor further by other means, as I know of no published experimental data on the effects of the floor being higher than about that amount. I believe Jan tried 2mm on the RSA125 with some improvement but did not go any further than that.

In case you're wondering about the consequently raised transfers, I have lowered them to an appropriate point by grinding the lower edge, using Devcon to fill the top edge, and hoping the latter can stand transfer temperatures and ring battering. I'll let you know...:(

peewee

26th December 2017, 18:39

Christmas Day and I'm working on my bucket 50 engine. I guess my life is in the bucket.

Anyway, I have a question for Wobbly, Frits or anyone else who feels like contributing:

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area.
We now know that I need to reduce the CSA steadily from the (single) port to achieve a flange area of 90% of the port area.
If I open this bottleneck up to say 95% of the port area in keeping with that philosophy, I will be increasing the volume of the duct.
Some of this extra volume will be reduced by the insert I will add to the outer part of the duct, but the overall volume will still be larger.
We know increased duct volume is not good, so I'd appreciate any comments or advice on what would be a good course of action.
Perhaps a bottleneck like this is not an issue. Does anyone have experience of this?

currently your flange face is 66% of port area at the bore and theres a bottle neck midway in the passage ? if i understand you correct it sounds like you need to grind out the midway pinched section and open the passage to get your 90%

ive never seen any one ask this but what if the passage is far shorter in length than ideal. should the flange face still be 90% (single port) and 75% (triple port) or should it be more like 95 or 85 etc ? my big ktm has only a 50mm long passage. far to short i rekon but packaging limitations wont allow more or the front tire smashes the pipe. still i made the flange face 75% but i question if it was the best decision since the passage length is very short for such a large capacity engine

devcon putty is pretty good stuff. ive filled my transfer ports with it and used atleast 10gal methanol and about 1gal nitromethane and the devcon seems to be doing fine but i do flush the engine with petrol. recently i picked up a jar of devcon titanium putty as ive read it may be even better than the type F alumi.

you should be fine if you grinded the putty down a hair shallower than the bore wall so the rings dont snag it

lodgernz

26th December 2017, 20:02

currently your flange face is 66% of port area at the bore and theres a bottle neck midway in the passage ? if i understand you correct it sounds like you need to grind out the midway pinched section and open the passage to get your 90%
ive never seen any one ask this but what if the passage is far shorter in length than ideal. should the flange face still be 90% (single port) and 75% (triple port) or should it be more like 95 or 85 etc ? my big ktm has only a 50mm long passage. far to short i rekon but packaging limitations wont allow more or the front tire smashes the pipe. still i made the flange face 75% but i question if it was the best decision since the passage length is very short for such a large capacity engine
devcon putty is pretty good stuff. ive filled my transfer ports with it and used atleast 10gal methanol and about 1gal nitromethane and the devcon seems to be doing fine but i do flush the engine with petrol. recently i picked up a jar of devcon titanium putty as ive read it may be even better than the type F alumi.
you should be fine if you grinded the putty down a hair shallower than the bore wall so the rings dont snag it

Thanks for the info on Devcon peewee.
No, the flange face of my exhaust port is about 110% of the port cylinder window area, which is why I will add an insert there. It's the bottleneck about halfway that is 66%.
The distance from piston to flange face is 39mm on average, the same as the bore, so about right, but your question about that dimension is interesting. I hope someone can answer it.

Frits Overmars

26th December 2017, 22:56

Thank you Frits. I imagine Wobbly's philosophy might also consider that, at maximum over-rev RPM, when exhaust gas is heading down the transfers because blowdown is incomplete, then the exhaust port area IS the blowdown area.
That would imply that the blowdown period lasts all the way from exhaust opening to where the piston reaches the exhaust floor. Then at the end of blowdown,
the transfer ducts will be completely filled with exhaust gases, and it will take a similar amount of time and crankshaft degrees, i.e. from BDC to transfer closure,
to expell those exhaust gases again. In other words: the 'scavenging' will be performed with exhaust gas only. I can guarantee that no engine will run like that.

My cylinder has been decked and raised, so the bottom of the exhaust port is already 2mm above BDC... I hesitate to try and raise this floor further by other means, as I know of no published experimental data on the effects of the floor being higher than about that amount. I believe Jan tried 2mm on the RSA125 with some improvement but did not go any further than that.That is more or less correct, but it needs some explaining. Jan had cylinders cast with the exhaust floors much higher-up than that, but he realized that at age 67
he would be retired by the time those cylinders would perform their tricks on the dyno (a lot of time used to pass between casting and running).
Knowing the mentality of some who would grab any opportunity to boast that they had improved on Jan's work, Jan decided to grind those experimental exhaust floors down to their conventional position before leaving.

The distance from piston to flange face is 39mm on average, the same as the bore, so about right...Assuming (and hoping) that your exhaust duct diameter is smaller than the bore, then the duct volume will be a lot smaller than the cylinder volume. And this would imply that part of the washed-through charge makes it into the hot exhaust header before being shoved back by the pipe effects. Not quite what you want.

lodgernz

27th December 2017, 07:22

That would imply that the blowdown period lasts all the way from exhaust opening to where the piston reaches the exhaust floor. Then at the end of blowdown,
the transfer ducts will be completely filled with exhaust gases, and it will take a similar amount of time and crankshaft degrees, i.e. from BDC to transfer closure,
to expell those exhaust gases again. In other words: the 'scavenging' will be performed with exhaust gas only. I can guarantee that no engine will run like that.

Of course you're right.
Could we postulate that, at peak power RPM, blowdown is complete by first transfer opening? Wouldn't that be the ideal situation for best power?

Assuming (and hoping) that your exhaust duct diameter is smaller than the bore, then the duct volume will be a lot smaller than the cylinder volume. And this would imply that part of the washed-through charge makes it into the hot exhaust header before being shoved back by the pipe effects. Not quite what you want.

Yes, I was mistaken in thinking that Wobbly had said that duct length is usually about 1 x bore. He actually said 2 x bore. In which case my duct is very short, and as you said, must negatively affect washed-through charge.

Should the volume of the duct be related in some way to the capacity of the cylinder? Would the efficacy of the pipe effects also be a factor, since this must affect the volume of washed-through charge?

If I find a way to extend the duct on my (water-cooled) engine, can I assume I must also find a way to cool it?

Thank you for your advice.

_____

27th December 2017, 08:42

The exhaust duct of this engine has a bit of a bottleneck about halfway down, whose CSA is about 66% of the port window area.

If you got an exhaust port that is too small for sufficient blowdown (undersquare engines with single exhaust f.e.) reducing the cross sectional area behind it will make things worse. I have seen engines benefiting over the whole power band from grinding the flange diameter bigger as 90%.
So the percentual approach needs a sidekick: a rule of thumb how big your exhaust area must be according to your cubic capacity.

This rule of thumb might be found using Time Area or Wobblys approach to get the area of carb, transfers and exhaust in the same ballpark. But this ballpark gets wide whilst comparing a bunch of high bmep engines...

A friend told me that in an old version of Mota, there was a good working formula for the needed exhaust window size and exhaust flange diameter. Anyone here that knows the maths behind it?

Happy Holidays
Chris

Muhr

27th December 2017, 09:48

Hey all
I'm doing some work with the exhaust systems, I am thinking of doing a few different for testing.
The first system I have thought of is with a shorter register to cylinder B, don’t not know if it's stupid but felt like it might be good,
but what do I know about 2-cylinder applications or V twin for that matter.:confused:
Thankful for thoughts and ideas!

It will be a variator engine with peak at 15800 rpm (2x50cc 41 stroke)

Muhr

katinas

27th December 2017, 10:42

My cylinder has been decked and raised, so the bottom of the exhaust port is already 2mm above BDC, but of course this has not reduced the duct volume. In fact, by the time I widen the top of the port, the volume will be even larger.
I hesitate to try and raise this floor further by other means, as I know of no published experimental data on the effects of the floor being higher than about that amount. I believe Jan tried 2mm on the RSA125 with some improvement but did not go any further than that.

...:(

Rotax Max kart ( engine without gearbox ) original cylinder - 2.2mm barrier.

And two other pic: pressure at partly open EX port and reed petal shape at different rpm. From old book, but interesting theory and experimentation.

SwePatrick

27th December 2017, 11:17

Someone help me! ;)

I´m redesigning my crankcase as i had a HUGE volume due to ~20mm spaced upwards cylinder.
I´m reading '1.3' here in the thread.

Is that cylindervolume x 1.3 ?

In my case 211x1.3=274,3cc

Or have i misunderstood the way to calculate it?

Rgds
Patrick

Muhr

27th December 2017, 11:35

Someone help me! ;)

I´m redesigning my crankcase as i had a HUGE volume due to ~20mm spaced upwards cylinder.
I´m reading '1.3' here in the thread.

Is that cylindervolume x 1.3 ?

In my case 211x1.3=274,3cc

Or have i misunderstood the way to calculate it?

Rgds
Patrick

(slagvolym + vevhusvolym "bdc)/ vevhusvolym "bdc= comp

in your case (211cc) 703,3cc BDC = 1,30001422

FastFred

27th December 2017, 13:43

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Got my Arduino Nano project working Ok on the test bench.

Computer programming, who said an old dog can't learn new tricks ...... Woof.

Always impressed by what you do TZ, good doggy, very clever. :niceone:

mr bucketracer

27th December 2017, 16:11

Always impressed by what you do TZ, good doggy, very clever. :niceone:he told me he would get more done if his tired sons helped him out(-;

teriks

27th December 2017, 21:29

Hey all
I'm doing some work with the exhaust systems, I am thinking of doing a few different for testing.
The first system I have thought of is with a shorter register to cylinder B, don’t not know if it's stupid but felt like it might be good,
but what do I know about 2-cylinder applications or V twin for that matter.:confused:
Thankful for thoughts and ideas!

It will be a variator engine with peak at 15800 rpm (2x50cc 41 stroke)

Muhr
I recon that your setup would be used for "moped" drag racing?
Anyway, it looks to me that such a wheel would have a rather high moment of inertia. Perhaps you could improve your results using a different wheel setup?

SwePatrick

27th December 2017, 22:21

(slagvolym + vevhusvolym "bdc)/ vevhusvolym "bdc= comp

in your case (211cc) 703,3cc BDC = 1,30001422

Thanks!

I had it all confused there for a while :)

Frits Overmars

27th December 2017, 22:50

If you got an exhaust port that is too small for sufficient blowdown (undersquare engines with single exhaust f.e.) reducing the cross sectional area behind it will make things worse. I have seen engines benefiting over the whole power band from grinding the flange diameter bigger as 90%. So the percentual approach needs a sidekick: a rule of thumb how big your exhaust area must be according to your cubic capacity. This rule of thumb might be found using Time Area...Chris, from your text I gather that in your 'undersquare' engine the bore is bigger than the stroke, but that is usually called oversquare.
There has been confusion over this before but if we stick to long-stroke and short-stroke instead of undersquare and oversquare, we can avoid this ambiguity risk.

Regarding your suggestion to base exhaust duct cross flow areas on blowdown time.area, that is what I keep preaching. But as I wrote on the previous page, Wobbly's approach has its reasons too.

PS: good that you signed your post with your first name; I would not have paid attention to scribblings from an anonymous contributor :msn-wink:.

And two other pic: pressure at partly open EX port and reed petal shape at different rpm. From old book, but interesting theory and experimentation.Благодарю вас Katinas :msn-wink:

Frits Overmars

28th December 2017, 03:49

Of course you're right.
Could we postulate that, at peak power RPM, blowdown is complete by first transfer opening? Wouldn't that be the ideal situation for best power?In disregard of Ryger phenomena with a single exhaust port and huge rpm, I'd say yes it would.

Should the volume of the duct be related in some way to the capacity of the cylinder? Would the efficacy of the pipe effects also be a factor, since this must affect the volume of washed-through charge?Yes, and yes again.

If I find a way to extend the duct on my (water-cooled) engine, can I assume I must also find a way to cool it?That would be good.

Muhr

28th December 2017, 04:14

I recon that your setup would be used for "moped" drag racing?
Anyway, it looks to me that such a wheel would have a rather high moment of inertia. Perhaps you could improve your results using a different wheel setup?

It may look like they are heavier then a standard wheel but the are actually significantly lighter, and friction is relatively low.
Having said that, I do not know if it's something I'm going to use. However, I wanted to make sure it was possible if you wanted to.
I do not know what to do with the engine the trip is the goal.

Maybe it will be something to go to the store with.:clap:

varthrix

29th December 2017, 10:37

Frits, I have a question about your FOS pipe, before I knew about this thread someone sent me a link to http://www.underdogsracing.com/fospipe/ I used it to calculate a pipe, but used the 5 stage experimental calculator thinking it would be better. The pipe was almost complete, but got stolen from my place along with a lot of other things. My question was should I make the same pipe again, or should I use the original FOS formula? With the 5 stage calc I came up with this.
The hp figure is a bit generous I think, it's a Simson S51 motor, with a different sleeve to accomodate a 44.98 mm piston, which is due for rebore now, 6 transfers with okay scavenging now, it was really bad before but I need to work on it a bit more and fix the transfer timing to 130°, either using jbweld or by machining 1 mm from the cylinder base (it's 134° now), running a 28 mm pwk carburetor and a reed valve from minarelli horizontal which I think has insufficient area for the given carburetor, but I'm not really sure how to calculate needed reed petal area. Husaberg had posted it should be 0.8 reed petal area per 1 carburetor area.
Kind regards from Bulgaria, Jordan.

Greg85

29th December 2017, 13:19

https://www.kiwibiker.co.nz/forums/showthread.php/143620-EngMod2T-Q-amp-A
hello mr vannik is engmod2t compatible with any windows?Thanks

peewee

29th December 2017, 18:18

i use it with windows7 and it seems to do fine

Vannik

29th December 2017, 18:38

hello mr vannik is engmod2t compatible with any windows?Thanks

Win XP and newer. I cannot test on older so do not know. 32bit and 64bit.

Greg85

29th December 2017, 23:48

thanks peewee, vannik for the information

ranasada

30th December 2017, 01:17

Question to Wobbly & Frits working on a TM KZ10B:
using this link (http://www.underdogsracing.com/fospipe/) just posted i tried to find setting for having right parameters (similar: only lengths are not correct but total and central lengths are right) with the fixed pipe in homologated fiche. But setting are a lot of distance for the reality about "target HP" (72 :eek5:) and "Lcyl" (the real is 60.25).
334312
So, why this pipe have these measures? What TM want to get in this way?

Frits Overmars

30th December 2017, 03:13

Frits, I have a question about your FOS pipe, before I knew about this thread someone sent me a link to http://www.underdogsracing.com/fospipe/ I used it to calculate a pipe, but used the 5 stage experimental calculator thinking it would be better.... My question was should I make the same pipe again, or should I use the original FOS formula? Jordan.Jordan, all these programs claiming to calculate a FOS-pipe were created without my involvement.
Moreover, several of those programs are based on obsolete data, so I won't comment on any of them. Here is my recent version.
334313

Question to Wobbly & Frits working on a TM KZ10B: using this link (http://www.underdogsracing.com/fospipe/) just posted i tried to find setting for having right parameters (similar: only lengths are not correct but total and central lengths are right) with the fixed pipe in homologated fiche. But setting are a lot of distance for the reality about "target HP" (72 :eek5:) and "Lcyl" (the real is 60.25).Ranasada, see my above answer to Varthrix.

varthrix

30th December 2017, 03:37

Thank you for the quick answer Frits, I will do some calculations later when I have the time. What would you say about the reed valve area I asked about? I'm thinking of ditching the reed valve altogether, seeing people from Germany making 20 hp from 85 cc Simson engine with piston port, I should be able to get at least 10-12 hp from my 70 cc engine.
Also I hope it's not a problem that I'm calling you by your first name, read a couple hundred pages ago that you like to be referenced by your first name.
Sorry for all the questions, kind regards Jordan.

Frits Overmars

30th December 2017, 09:16

What would you say about the reed valve area I asked about? I'm thinking of ditching the reed valve altogether, seeing people from Germany making 20 hp from 85 cc Simson engine with piston port, I should be able to get at least 10-12 hp from my 70 cc engine.
Also I hope it's not a problem that I'm calling you by your first name, read a couple hundred pages ago that you like to be referenced by your first name. Piston port induction will be fine for getting 10 to 12 hp from a 70 cc engine. If you're not careful, you will get more power than that.
I haven't got the faintest idea about the dimensions of a 'Minarelli horizontal' so I cannot comment on your reed valve question. Maybe Wobbly can help you there.
And I still prefer to be called by my first name :niceone:.

wobbly

30th December 2017, 09:17

The TM-B pipe you have shown is not close at all.The stinger of a stock engine is 24mm for example.
And a stock B will make around 44HP @13200 at the sprocket thus the crank power will be only +5% on this.
The big issue with the engine is the straight line ignition and this dictates the pipe is VERY short for peak power at 13200.
I cannot give you any more info at this point as my very expensive video card has let out the smoke - due to constant use on EngMod
to design the D model pipe for TM.
Hopefully I will have a new 5MHz overclocked rocket computer running in the New Year.

varthrix

30th December 2017, 12:13

Frits, sorry about missing out on information. I just measured up and came up with this.
Reed petal area - 243.09 mm2
Total reed petal area - 972.36 mm2
Area of reed cage entry from carburetor flange side - 930 mm2
Reed lift 5 mm
Reed cage angle 60°
Reed stopper angle 16° ( Relative to the reed itself - assuming it's flat (0°))
Carburetor area (28 mm bore) 615 mm2
Inlet port area 619 mm2
So pretty much I have no idea if the reeds are suitable, got them for about $3, everything I did on the engine was in the spirit of buckets - low or no cost and diy. Most expensive part I bought was the carburetor - 50$. Even the cylinder liner was free, found an old wheelcart bushing and machined it on the lathe. I hope I can squeeze out some power out of it, there is a word that there will be a Simson cross race this year and if all is well I hope that I can participate.
334314
Attached a drawing of the measurements, excuse my poor drawing and writing skills.
Also thanks for the time spent helping me out.
Kind regards
Jordan

Twopints

30th December 2017, 13:44

Hi All I hope this is a good spot to put this , I am trying to find some information about the Yamaha RD48 and RD56 engine A 250cc Disk valve twin, 1961 to 1964

The crank diameter and length

Disk valve diameter

conrod length

piston compression height

would any one know if any of these motorcycles sold to customers or purely works bikes

F5 Dave

30th December 2017, 19:28

Presumably you've read this

https://www.amazon.com/Yamaha-Racing-Motorcycles-Road-Racing-Two-Strokes/dp/1852239204

Can't imagine any escaped the clutches of the factory.

Frits Overmars

30th December 2017, 19:42

Hi All I hope this is a good spot to put this , I am trying to find some information about the Yamaha RD48 and RD56 engine A 250cc Disk valve twin, 1961 to 1964
The crank diameter and length
Disk valve diameter
conrod length
piston compression height
would any one know if any of these motorcycles sold to customers or purely works bikesTo the best of my knowledge neither the RD48 nor the RD56 were ever sold; they were pure works bikes and it won't be easy to find any information about them after more than 50 years. The best I can do is a couple of lists and drawings from the RD56 and the 125cc RA41 which had the same relevant dimensions as the 250cc RD48. Working from the known bore dimension you may be able to extract approximates of the other dimensions you were asking about.
334333 334334 334335 334336

You made me curious: what are you planning to do with those dimensions? Build replicas maybe? And while you're at it, you might tell us a bit about yourself as well.

husaberg

30th December 2017, 19:44

Hi All I hope this is a good spot to put this , I am trying to find some information about the Yamaha RD48 and RD56 engine A 250cc Disk valve twin, 1961 to 1964

The crank diameter and length

Disk valve diameter

conrod length

piston compression height

would any one know if any of these motorcycles sold to customers or purely works bikes
Pretty sure the "Dutch Yamaha Fairy" has built a replica
https://www.pressreader.com/australia/old-bike-australasia/20170201/283102773739289
http://www.classicyams.com/early-factory-racers/early-factory-racers/yamaha-rd56-250-cc.html
http://blog-883r.jp/archives/52479023.html
334337

ranasada

30th December 2017, 20:42

Jordan, all these programs claiming to calculate a FOS-pipe were created without my involvement.
Moreover, many of those programs are based on obsolete data, so I won't comment on any of them. Here is my recent version.
334313
Ranasada, see my above answer to Varthrix.

The TM-B pipe you have shown is not close at all.The stinger of a stock engine is 24mm for example.
And a stock B will make around 44HP @13200 at the sprocket thus the crank power will be only +5% on this.
The big issue with the engine is the straight line ignition and this dictates the pipe is VERY short for peak power at 13200.
I cannot give you any more info at this point as my very expensive video card has let out the smoke - due to constant use on EngMod
to design the D model pipe for TM.
Hopefully I will have a new 5MHz overclocked rocket computer running in the New Year.

thank you Frits and Wobbly for your answer.
i take misures from homologation form for finding setting in inversal way having fixed pipe, so i find that the big problem is on D5 (from Frits attachement) that is 26 and it is for more than 70hp. Why so bigger?
334338

Frits Overmars

30th December 2017, 20:54

i take misures from homologation form for finding setting in inversal way having fixed pipe, so i find that the big problem is on D5 (from Frits attachement) that is 26 and it is for more than 70hp. Why so bigger? I suppose the diameters on that sheet are external. Internal diameters on a homologation sheet wouldn't make sense; nobody would be able to check those without cutting the pipe up.

Frits Overmars

30th December 2017, 21:12

Pretty sure the "Dutch Yamaha Fairy" has built a replica.I haven't seen my mate Ferry Brouwer being called a fairy before :D. I'll give him your love, Husa. But Ferry did not build a replica of the Yamaha RD65; he amused himself with the four-cylinder 125cc RA31 (the first bike he worked on as a Yamaha works mechanic) and the 250cc RD05A (and a lot of other Yamaha-related stuff).
334340 334339 334341

ranasada

30th December 2017, 21:19

I suppose the diameters on that sheet are external. Internal diameters on a homologation sheet wouldn't make sense; nobody would be able to check those without cutting the pipe up.

:facepalm:

thanks a lot

husaberg

30th December 2017, 21:54

I haven't seen my mate Ferry Brouwer being called a fairy before :D. I'll give him your love, Husa. But Ferry did not build a replica of the Yamaha RD65; he amused himself with the four-cylinder 125cc RA31 (the first bike he worked on as a Yamaha works mechanic) and the 250cc RD05A (and a lot of other Yamaha-related stuff).

Pretty sure he did do a OW15 as well "works TA125"
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i googled but i couldn't find a RD56 but i bet he has a file of info tucked away.

Frits Overmars

30th December 2017, 22:59

Pretty sure he did do a OW15 as well "works TA125". i googled but i couldn't find a RD56 but i bet he has a file of info tucked away.I was reacting to Twopints question about the 1960's works bikes, but as I wrote, Ferry did 'a lot of other Yamaha-related stuff' as well, from 50 to 500 cc.
That RD56 info may be scarse though. Ferry knows that the RD56 is my all-time favorite Yamaha and I'm sure he would have shown any paperwork he would have.

Twopints

30th December 2017, 23:09

To the best of my knowledge neither the RD48 nor the RD56 were ever sold; they were pure works bikes and it won't be easy to find any information about them after more than 50 years. The best I can do is a couple of lists and drawings from the RD56 and the 125cc RA41 which had the same relevant dimensions as the 250cc RD48. Working from the known bore dimension you may be able to extract approximates of the other dimensions you were asking about.
334333 334334 334335 334336

You made me curious: what are you planning to do with those dimensions? Build replicas maybe? And while you're at it, you might tell us a bit about yourself as well.

Thanks Frits, i am reverse engineering but not the Yamaha, i have the remnants of the Clisby 24 cylinder motor, the cranks ,barrels and heads have been removed in the late 1960's and are not in my possession and not available to me

I have seen the above drawings before but these look sharper than previous ones , I will give it a go scaling from these

I have found out the Bore and stroke of the Clisby is 56 X 50

Kevin Drage who worked on the project has been kind enough to help me , he looked through his notes and found the original shopping list of parts that he picked up from Pitmans Yamaha here in Adelaide, Yamaha crank parts , conrod, pistons ,disk valve, studs , a cylinder ,etc, Kevins list has the prices of the parts but sadly not the parts numbers other than for the points and cam lobe for the ignition these are common Lucas parts

After a bit of googling i decided that the Yamaha YA 6 was the source of the parts as it was available in Australia at the time , had the 56 X 50 bore and stroke so it fit the bill, so i bought a NOS crank piston and disk valve , and a replacement liner , the crank won't fit in the crankcase as it is 110 mm in dia. ,the crank case is 94mm ID , the conrod is 120mm C to C and the Piston has 30mm from pin to top of the piston, the overall height is to tall,

I have no really good photos of the complete engine ( sharp focus and at 90 degrees) to scale from but i think the height of the cylinder would be closer to 95mm rather than the 120mm from the YA 6 cylinder

This all led me to looking further and it left the RD48 and RD56, i was apprehensive that Pitmans could have sourced such exotic parts, and sold to a member of the public
but i believe Pitmans were the local importers and did have access directly to the factory

At the end of the day i would like put the 24 cylinder together as a display motor and possibly get a single engine unit (125cc) running

i only need to make one pattern and core box for the cylinder and one pattern and core box for the head, and lots of repetitive machining, ( for the display motor) but i am not confident with my scaling to start with the pattern work

I have the port timing from Kevin but i don't know how to post photos here other than a general arrangement drawing of the complete 24 cyl i don't think any other drawings have survived but i do have the drawing index but no drawings to accompany the numbers

There are photos of the Clisby floating about the internet ,mine is the 2 Stroke not the 4 stroke V6 that Harold Did as well

http://collingrovehillclimb.com.au/site_files/52/Harold%20Clisby%20two%20stroke%20rotary%20valve%20 jpg.jpg

http://collingrovehillclimb.com.au/site_files/52/Harold%20ClisbyTwo%20Stroke%20overhead%20jpg.jpg

at the end of the day none of the Yamaha YA 6 parts that i have don't seem to match the proportions of the Clisby other than bore and stroke

the picture of the single cylinder engine has a splined output shaft , does this look like the shaft on an inner crank half ( the one the couples with the other cylinder ?) the YA 6 crank has a short spline on the disk valve side, the drive side is a taper

for any one that is interested a bit of a write up on Harold http://www.collingrovehillclimb.com.au/haroldclisby/

any help is appreciated

Your mates work on his replica bikes is epic

Cheers

Fred Radman

diesel pig

30th December 2017, 23:58

at the end of the day none of the Yamaha YA 6 parts that i have don't seem to match the proportions of the Clisby other than bore and stroke

Have you looked at Production Yamaha Road Racers model TD1 to TD2B which have the same bore and stroke?

These parts were able to be had from any Yamaha dealer in the 1960,s and would of been the highest performance

Yamaha pistons and con rods you could get at the time.

The TD,s are piston port not disc but after looking at your link for Harold Clisby I think a man who built hovercraft and steam engines

converting TD cranks to drive discs would not of been too hard for him.

Cheers

_____

31st December 2017, 06:51

Hi everyone!

Here is my recent version.
334313

I just clicked a bit of your pipe programm in an excel-sheet. Whilst increasing the exhaust opening duration, the exhaust diameter at the piston (respective X) is decreasing. When I look at this statement:

Regarding your suggestion to base exhaust duct cross flow areas on blowdown time.area, that is what I keep preaching.

This seems not to be right. Is this an error in the programm?

Regards,
Chris

Grumph

31st December 2017, 07:00

I'd endorse TD1 too. Pitmans were one of the few sources of parts for those in period. A crank from a twin makes more sense in terms of the OD as less flywheel is needed in that application. I believe - though can't be dead sure - that YDS2 street cranks have the same dimensions.

husaberg

31st December 2017, 08:36

Thanks Frits, i am reverse engineering but not the Yamaha, i have the remnants of the Clisby 24 cylinder motor, the cranks ,barrels and heads have been removed in the late 1960's and are not in my possession and not available to me

I have seen the above drawings before but these look sharper than previous ones , I will give it a go scaling from these

I have found out the Bore and stroke of the Clisby is 56 X 50

Kevin Drage who worked on the project has been kind enough to help me , he looked through his notes and found the original shopping list of parts that he picked up from Pitmans Yamaha here in Adelaide, Yamaha crank parts , conrod, pistons ,disk valve, studs , a cylinder ,etc, Kevins list has the prices of the parts but sadly not the parts numbers other than for the points and cam lobe for the ignition these are common Lucas parts

Have you looked at Production Yamaha Road Racers model TD1 to TD2B which have the same bore and stroke?

These parts were able to be had from any Yamaha dealer in the 1960,s and would of been the highest performance

Yamaha pistons and con rods you could get at the time.

The TD,s are piston port not disc but after looking at your link for Harold Clisby I think a man who built hovercraft and steam engines

converting TD cranks to drive discs would not of been too hard for him.

Cheers

I'd endorse TD1 too. Pitmans were one of the few sources of parts for those in period. A crank from a twin makes more sense in terms of the OD as less flywheel is needed in that application. I believe - though can't be dead sure - that YDS2 street cranks have the same dimensions.

They also have a high area above the pin
334355
i have measurements somewhere for them somewhere.

In regards to the disc they might be bridgestone or kawaaski.
although Yamaha did make a KT100 that was disc valve they did a reed valve one to as well as thw well known piston port KT100.
but i cant see it being large enough.
another option is the AT1for pistons.
334354
Yamahas up to about the TDB/yds2 had the clucth on the crankshaft.
https://www.tapatalk.com/groups/yamahatwostroketwins/td1b-crankshaft-upgrade-t99.html
Yamaha twins of that period had two dia big end pins.
334353
also tha 120mm c-c rod is very long for a piston port yam compared to others in the range
maybe its from the Longer stroke TR2 series or from an outboard do you have the numbers on the conrod
334352

Grumph

31st December 2017, 10:37

[QUOTE=husaberg;
also tha 120mm c-c rod is very long for a piston port yam compared to others in the range
maybe its from the Longer stroke TR2 series or from an outboard do you have the numbers on the conrod[/QUOTE]

No...he's saying the 120mm rod from the YA6 is too long to match the estimated dimensions.

I'd go back to YDS2. In period and going through Pitmans, it's what I'd have gone for first.
The bits were available, they probably had at least one crank on hand to show him - and they were relatively cheap.

Knowing how much restoration goes on around Adelaide, Fred, someone will have a DS2 apart....

husaberg

31st December 2017, 12:42

No...he's saying the 120mm rod from the YA6 is too long to match the estimated dimensions.

I'd go back to YDS2. In period and going through Pitmans, it's what I'd have gone for first.
The bits were available, they probably had at least one crank on hand to show him - and they were relatively cheap.

Knowing how much restoration goes on around Adelaide, Fred, someone will have a DS2 apart....
pretty sure there is some YDS3 crank bits apart and my fathers place

Twopints

31st December 2017, 13:25

thanks every on for the info so far

I scaled from Frits excellent drawing of the RD56 , allowing for errors and some rounding up of numbers on my part

Rod length 103mm c to c

Piston 56 mm overall and 29mm compression height ( this is from the centre of pin to top of piston edge not the "dome")

the crank is 92mm Dia and 56mm wide

giving me a crank centre line to top of cylinder deck 156mm

Scaling from a grainy Clisby photo a crank centre line to top of cylinder deck is 158mm

this is looking good so far

the RD56 disk valve is 128mm by 3mm thick ,scaled from the drawing

the YA6 disk valve i have is 117.3 by 4mm thick

the Clisby disk valve chamber is 95mm in Dia.

yes i did look at the TD type cranks ,from a Yamaha service news i found they are 93mm in Dia. and 50mm wide for 1 cylinder

From Kevins list the list price i have is $24.98 1966 or 1967 Australian dollars for each half , that sounds a lot to me , any thoughts ?

I am starting to think the disk valve may have been from some thing else ,it was $4.50 from Pitmans ,any thoughts on a 95mm disk valve from the period, but
as per the crank it may have been modified from the purchased part

I had made the assumption all the Yamaha parts were from one engine, but they may have been selected from parts books and what was on the shelf at Pitmans
would any one know if Pitmans were a Bridgestone or Kawasaki agent at the time ?

I am starting to jell at around a 103 to 105mm rod and a piston with a 30mm compression height , pointing to the TD1 ? do these numbers seem ok for a disk valve motor ? as you guys may have guessed i am not that familiar with 2 strokes

The Timing numbers i have are, reading around the chart

0 is at TDC

Inlet closes 60 Deg

Exhaust opens 92 Deg

Transfer opens 120 Deg

Inlet opens 230 Deg

Transfer closes 241 Deg

Exhaust closes 269 Deg

Inlet period 190 Deg

Exhaust period 177 Deg

Transfer period 121 Deg

were they barking up the right track for the time ?

Cheers

Fred

Grumph

31st December 2017, 13:53

Re the prices anyway - Pitmans could well have had a stock of used but good crankwebs on hand from warranty work....Would explain the lack of part nos.

$25 or so for a crank half does sound like secondhand to me....

husaberg

31st December 2017, 14:59

thanks every on for the info so far

I scaled from Frits excellent drawing of the RD56 , allowing for errors and some rounding up of numbers on my part

Rod length 103mm c to c

Piston 56 mm overall and 29mm compression height ( this is from the centre of pin to top of piston edge not the "dome")

the crank is 92mm Dia and 56mm wide

giving me a crank centre line to top of cylinder deck 156mm

Scaling from a grainy Clisby photo a crank centre line to top of cylinder deck is 158mm

this is looking good so far

the RD56 disk valve is 128mm by 3mm thick ,scaled from the drawing

the YA6 disk valve i have is 117.3 by 4mm thick

the Clisby disk valve chamber is 95mm in Dia.

yes i did look at the TD type cranks ,from a Yamaha service news i found they are 93mm in Dia. and 50mm wide for 1 cylinder

From Kevins list the list price i have is $24.98 1966 or 1967 Australian dollars for each half , that sounds a lot to me , any thoughts ?

I am starting to think the disk valve may have been from some thing else ,it was $4.50 from Pitmans ,any thoughts on a 95mm disk valve from the period, but
as per the crank it may have been modified from the purchased part

I had made the assumption all the Yamaha parts were from one engine, but they may have been selected from parts books and what was on the shelf at Pitmans
would any one know if Pitmans were a Bridgestone or Kawasaki agent at the time ?

I am starting to jell at around a 103 to 105mm rod and a piston with a 30mm compression height , pointing to the TD1 ? do these numbers seem ok for a disk valve motor ? as you guys may have guessed i am not that familiar with 2 strokes

The Timing numbers i have are, reading around the chart

0 is at TDC

Inlet closes 60 Deg

Exhaust opens 92 Deg

Transfer opens 120 Deg

Inlet opens 230 Deg

Transfer closes 241 Deg

Exhaust closes 269 Deg

Inlet period 190 Deg

Exhaust period 177 Deg

Transfer period 121 Deg

were they barking up the right track for the time ?

Cheers

Fred

Disc valve of the period yamaha YL2
https://www.cmsnl.com/yamaha-yl2-1967-1968-usa_model8308/partslist/A-04.html#results
334364
the oring is 102mm which puts it sub 100mm disc

Haufen

31st December 2017, 23:00

When preparing a freshly cast cylinder for the first plating, is it advisable to put a bevel or radius at the end of the bore at tdc? What is this good for? From a combustion chamber point of view I don't like this idea at all.

But as the combustion chamber is going reach into the bore by 1mm anyway, this should not do too much harm. Would you have the same radius at the chamber to minimize trapped volume? I would like to do so, but suspect that the shape of the radius will have changed once plated.

anyone?

will the bevel be filled with plating anyway, or am I going to trap dead volume?

emess

31st December 2017, 23:01

Hi everyone!

I just clicked a bit of your pipe programm in an excel-sheet. Whilst increasing the exhaust opening duration, the exhaust diameter at the piston (respective X) is decreasing. When I look at this statement:

This seems not to be right. Is this an error in the programm?

Regards,
Chris

Hi Chris
look at Frits' formula -
The diameters depend on X
X depends on 407 - Exhaust timing ..... etc
So as Exhaust timing increases, X decreases and hence so do the diameters.

so your spreadsheet is going the way Frits intended.

Mick

TZ350

31st December 2017, 23:47

The Timing numbers i have are, reading around the chart
0 is at TDC, Inlet closes 60 Deg, Exhaust opens 92 Deg, Transfer opens 120 Deg, Inlet opens 230 Deg, Transfer closes 241 Deg, Exhaust closes 269 Deg, Inlet period 190 Deg, Exhaust period 177 Deg, Transfer period 121 Deg, Were they barking up the right track for the time ? Cheers Fred

Hi Fred, those look to be very pedestrian timings, for comparison, my 56mm bore 50mm stroke rotary valve 1978 air cooled modified Suzuki GP125 Bucket engine.
Exhaust 200 degrees duration opens 80 atdc closes 80 btdc
Inlet 220 degrees duration opens 140 btdc closes 80 atdc
Transfers 132 degrees duration open 114 atdc close 114 btdc

334370

Flat torque curve, repeatable runs.

varthrix

1st January 2018, 03:38

Happy New Year to TeeZee, Wobbly, Husa and all other kiwis. Frits, and all the other Europeans will have to wait for a couple more hours, but I wish you all Happy New Year in advance. Thanks to everyone who has contributed on this thread, I've learned a lot and have yet to learn even more.
Cheers everyone,
Kind Regards Jordan

adegnes

1st January 2018, 03:51

Happy New Year!

TZ350

1st January 2018, 21:01

334399

Hi Fred, I have not worked with a Yamaha RV engine but here are some more 1978 Suzuki GP125/100 parts for comparison, hopefully they are helpful.

50.5mm stroke (56mm bore for the 125, 50 for the 100)
Crank wheels 86mm diameter.
Big end pin 19mm diameter.
Crank width 50mm
Rotary valve diameter 116mm and 1mm thick.
Inlet tract 25mm (24mm carb) for the GP125. Smaller for the 100.

The 56 bore x 50 stroke Kawasaki KE125 has a notably smaller diameter RV than the Suzuki. I think the 1978 Suzuki GP125 commuter bike engine was modeled fairly closely on the Suzuki RV racers of the 60's. By the late 60's and early 70's Suzuki certainly had a lot of experience and accumulated knowledge on how to make fast RV engines.

334400

Rods, from left to right.

GP100/125 100mm C-C, 19mm bigend pin and 14mm little end pin.
RGV250 105mm C-C, 22mm bigend pin and 16mm little end pin.
Yamaha TZ/RD/RZ 110mm C-C, 22mm bigend pin and 16mm little end pin.
Yamaha RD400mm 115mm C-C, 22mm bigend pin and 16mm little end pin.

As the engine developed I have tried each rod. The RD400 rod is currently the rod of choice in my Suzuki GP engine and with the right L/E brg any of the longer rods can run a 15mm piston pin too.

The 50 and 56mm Suzuki GP piston had a 14mm pin but generally 56mm (and 54mm) pistons from the late 70's and 80's tend to have 16mm pins and later pistons from the 90's & 2000's tend to be 54mm and have 15mm pins.

The Timing numbers i have are, reading around the chart
0 is at TDC, Inlet closes 60 Deg, Exhaust opens 92 Deg, Transfer opens 120 Deg, Inlet opens 230 Deg, Transfer closes 241 Deg, Exhaust closes 269 Deg, Inlet period 190 Deg, Exhaust period 177 Deg, Transfer period 121 Deg, Were they barking up the right track for the time ? Cheers Fred

Hi Fred, those look to be very pedestrian timings, for comparison, my 56mm bore 50mm stroke rotary valve 1978 air cooled modified Suzuki GP125 Bucket engine.
Exhaust 200 degrees duration opens 80 atdc closes 80 btdc
Inlet 220 degrees duration opens 140 btdc closes 80 atdc
Transfers 132 degrees duration open 114 atdc close 114 btdc

334370

Flat torque curve, and repeatable runs from my tuned Suzuki GP125 commuter bike engine.

Standard 1978 Suzuki GP125 commuter bike specs.

For what its worth here are our measurements taken from a Standard Suzuki GP125.
Bore 56mm Stroke 50mm 15hp at 8500 Rpm Carb 24mm. MJ 90 to 97.5
Inlet opens 145 BTDC closes 55 ATDC.
Exhaust opens 91 degrees ATDC Duration 178 degrees.
Area of exhaust port is 85mm# and 64% of bore width.
Exhaust port diameter at the flange is 36mm.
Trans1 opens 120 degrees ATDC Duration 120 degrees.
Trans2 opens 120.5 degrees ATDC Duration 119 degrees.
Boost opens 122 degrees ATDC Duration 118 degrees.

Lots of details about developing my Suzuki Bucket engine here:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page270?p=1130055762#post1130055762

Frits Overmars

2nd January 2018, 00:26

I just clicked a bit of your pipe programm in an excel-sheet. Whilst increasing the exhaust opening duration, the exhaust diameter at the piston (respective X) is decreasing. When I look at this statement:
Regarding your suggestion to base exhaust duct cross flow areas on blowdown time.area, that is what I keep preaching.This seems not to be right. Is this an error in the programm?Why should it not be right Chris? No error in your program either. You don't even need any maths or physics knowledge to figure this out; a bit of logic will do.
Time.area is time * area.
Increasing the exhaust opening duration means more time available for blowdown, so you'll need less port area for the same amount of blowndown time.area.

EDIT: I see that Emess beat me to it. Thanks Mick :niceone:

Hi Chris, look at Frits' formula - The diameters depend on X X depends on 407 - Exhaust timing ..... etc
So as Exhaust timing increases, X decreases and hence so do the diameters. so your spreadsheet is going the way Frits intended.

Twopints

2nd January 2018, 19:40

Thanks hasaberg, Grumph and TZ350 , prior to getting in contact with Kevin Drage and found out the Yamaha i was looking at one of these Suzuki specification

I as i said i don't know much about 2 strokes but comparing photos on the web of other engines ,the porting in the mouth of the crankcase of the Clisby the porting is very small, the inlet port that the disk valve opens is 19mm by 19mm and square

Then general arrangement drawing of the 24cyl motor the exhausts are packed in tight ,no expansion chambers and a difficult installation in a car that ends up with 6 of the carbs pointing down and 24 sets of points to adjust and 24 cylinders to be timed

In 1967 when it first came out the Cosworth DFV made 400Hp at 9000 Rpm using the standard Suzuki power figures (15Hp) the Clisby would have been 360 Hp and if an big if ,it could have been developed to point of your racer power it would be 686 Hp discounting for other losses in the bevel drives etc

But i think they had a lot of development ahead of them from were they started

TZ350 i will look through your bucket build

Grumph

2nd January 2018, 19:53

Drivability would have been a big thing with the Clisby. Probably only a 4 speed box...So very conservative tuning to get it running.
Kevin Drage should be able to tell you how little the Repco made first up...But it was very drivable.

Muhr

3rd January 2018, 08:31

I am not sure that this is everything SS90 has been talking about but it is good information.

I had to draw pictures and high light stuff to get my head around this.

Pic 1. As more power is developed, a hole/dip (Point B) appears in the the power curve just before max output (Point A).

The drivability of the bike is affected by this dip just before max power.

There is a trade off between power and drivability. (as we all know)

The main things that make more power, are, and in order of priority (1) the primary transfer tangental angle, (2) the inner transfer port radius, (3) the main transfer port axial inclination, (4) and main transfer port open size and shape. All high lighted in pic 2.

Pic 3 data from tests that show the trade off between power and drivability for the different variables.

Pic 4 configuration of the better test cylinders.

Get a copy of the paper from here:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

.

I was fiddling around with port arrangements and came to think about the inner radius of the ports(Pink in picture below). Searched a little on this thread and of course this topic has been touched. Found YZ350 posts, but unfortunately the link did not work. Has anyone done any tests on the subject?
I have felt that cylinders have gone against a bigger bulge over the last 10 years without having put any major thought on it

Best Regards Muhr

SwePatrick

3rd January 2018, 09:15

Muhr, My experiance with porting both twostroke and foulstrokes is that one should beware of too tapered design in runners.
Flow might 'choke' and just halt the flow.

I would try to get more volume more upwards in the transferrunners.
And maybe a slight less big opening down to crankcase.
But still transferport as the smallest area to get airpseed to fill the cylinder properly.

Rgds.
Patrick

TZ350

3rd January 2018, 10:11

Pic 4 configuration of the better test cylinders.I was fiddling around with port arrangements and came to think about the inner radius of the ports. .... Has anyone done any tests on the subject?

The Yamaha paper in the post you quoted studied port arrangement extensively and their conclusion (picture 4) was that for a 125 an inner radius of 15mm and an outer of 55 gave the best transfer ratio on their test bench.

There will be pictures and drawings of the 50hp 125cc Aprilia race cylinder on here some place and you can bet those dimensions will have been the result of a great deal of experimental work.

There is a link on this page all about transfer port theory:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1000

Muhr

3rd January 2018, 10:17

The Yamaha paper in the post you quoted studied port arrangement extensively and their conclusion (picture 4) was that for a 125 an inner radius of 15mm and an outer of 55 gave the best transfer ratio on their test bench.

Thanks! =)

I will dive into the archive and se if I can find something.

TZ350

3rd January 2018, 10:22

Thanks! =)

Also there is a link on this page all about transfer port theory:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1000

Muhr

3rd January 2018, 11:02

Also there is a link on this page all about transfer port theory:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1000

Super:niceone:

philou

3rd January 2018, 22:09

New piston wiseco :scratch:

"the piston to self-adjust to the cylinder. The Racer Elite 2-Stroke Series pistons have enough clearance for the smallest cylinder, adequate clearance for the largest cylinder, and everything in between."

http://blog.wiseco.com/one-size-fits-all-wiseco-racer-elite-2-stroke-pistons

Frits Overmars

3rd January 2018, 23:11

I was fiddling around with port arrangements and came to think about the inner radius of the ports... Has anyone done any tests on the subject? I have felt that cylinders have gone against a bigger bulge over the last 10 years without having put any major thought on itLooking at your picture on the previous page I get the impression that the relation between the outer bulge and the inner radii of the ducts is way off, Muhr.
Someone has done some tests on the subject, a feller named Jan Thiel.
Below is the Aprilia RSA A-duct geometry, showing the inner and outer radii dimensions and the whereabouts of their centers.
334443

The Yamaha paper... studied port arrangement extensively and their conclusion was that for a 125 an inner radius of 15mm and an outer of 55 gave the best transfer ratio.The 32,44 mm outer radius of the Aprilia is noticeably smaller than the 55 mm Yamaha radius, confirming Swepatricks remark:
My experience with porting both twostroke and foulstrokes is that one should beware of too tapered design in runners.

The main difference between Aprilia and Yamaha (and Honda for that matter) is in the inner radius: the 22,6 mm RSA-radius is 50% bigger, which makes a huge difference in flow attachment, flow coefficient and flow direction stability.
There was some difference in horsepower as well...:p

Muhr

4th January 2018, 04:05

Looking at your picture on the previous page I get the impression that the relation between the outer bulge and the inner radii of the ducts is way off, Muhr.
Someone has done some tests on the subject, a feller named Jan Thiel.
Below is the Aprilia RSA A-duct geometry, showing the inner and outer radii dimensions and the whereabouts of their centers.
334443

The 32,44 mm outer radius of the Aprilia is noticeably smaller than the 55 mm Yamaha radius, confirming Swepatricks remark:

The main difference between Aprilia and Yamaha (and Honda for that matter) is in the inner radius: the 22,6 mm RSA-radius is 50% bigger, which makes a huge difference in flow attachment, flow coefficient and flow direction stability.
There was some difference in horsepower as well...:p

Thank you for all the answers

Yes, Frits is true, I have stretched the outer radius to be able to drive an other cylinder in the same crankcase for comparison. but that's obviously something I can give up.
I have also had to shorten them 4mm because of shorter conrod, piston height and probably crankcase deck height (in comparison).
To the left is so close to an RSA I can come.

Jannem

4th January 2018, 09:48

Thank you for all the answers

Yes, Frits is true, I have stretched the outer radius to be able to drive an other cylinder in the same crankcase for comparison. but that's obviously something I can give up.
I have also had to shorten them 4mm because of shorter conrod, piston height and probably crankcase deck height (in comparison).
To the left is so close to an RSA I can come.

Did you keep the inner radius the same?

Muhr

4th January 2018, 10:10

Did you keep the inner radius the same?

It's changed!:yes: The bulge is 0.7mm less so it's hard to see

Brett S

4th January 2018, 19:48

New piston wiseco :scratch:

"the piston to self-adjust to the cylinder. The Racer Elite 2-Stroke Series pistons have enough clearance for the smallest cylinder, adequate clearance for the largest cylinder, and everything in between."

http://blog.wiseco.com/one-size-fits-all-wiseco-racer-elite-2-stroke-pistons

I see their anti rotation pin for the piston ring has grooved the bottom of the ring land.

SwePatrick

5th January 2018, 01:10

Look inside the hole for the wristpin.
I wouldn´t be happy with that machining, rough cut has left almost none material left to set tolerance in with hone.

Muhr

5th January 2018, 02:42

Thank you for all the answers

Yes, Frits is true, I have stretched the outer radius to be able to drive an other cylinder in the same crankcase for comparison. but that's obviously something I can give up.
I have also had to shorten them 4mm because of shorter conrod, piston height and probably crankcase deck height (in comparison).
To the left is so close to an RSA I can come.

If anyone thinks it's interesting

Jannem

5th January 2018, 06:29

It's changed!:yes: The bulge is 0.7mm less so it's hard to see

Wonder if logarithmic inner radius would work? (closer the exit, bigger the radius)
Flow usually wants to separate from the short turn after the apex.

SwePatrick

5th January 2018, 08:51

When designing transfers and crankhouse.
Shouldn´t one calculate with that Aprilia is a 'closed' volume and reedengines are 'open'?

If pipe is overscavenging a reedengine, the reed´s can open at a point were a rotatingdiscsystyem is closed.
Thereby flow after 'puncturing' crankhouse when transfers is opening are different between the two?

Muhr

5th January 2018, 08:52

Wonder if logarithmic inner radius would work? (closer the exit, bigger the radius)
Flow usually wants to separate from the short turn after the apex.

With my amateur knowledge of CFD (next to none), it feels like there may be something in what your saying.

1948rod

5th January 2018, 15:07

Best of luck to ken Seeber on Monday for your plumbing operation. Be well buddy.

Twopints

5th January 2018, 16:53

Husaberg

"also tha 120mm c-c rod is very long for a piston port yam compared to others in the range
maybe its from the Longer stroke TR2 series or from an outboard do you have the numbers on the corned"

the rod i have is attached to a crank i bought on eBay as NOS for a YA6 , it has a large chamfer on one wheel for a Disk valve

the rod has yamaha on one side and the letter "C" and i think what is a japanese character that looks like a reversed F in a circle ,no numbers

Grumph

Kevin bought 4 sets of parts and i believe every thing was new, a mate of mine started his apprenticeship in 1967 he said that he was getting $16 a week so a crank half would have been 2 weeks wages for him

TZ 350

when you change rod length do you use a different piston ? or do you space the barrel up or down ? what piston do you use ?

I am keeping my eye out for YDS2 crank to measure up and a YL2 disk valve to measure up

any one recognise the Carb in this photo ?
http://collingrovehillclimb.com.au/site_files/52/Harold%20Clisby%20two%20stroke%20rotary%20valve%20 jpg.jpg
mikuni 24mm ?

Thanks every one that has replied with advice

husaberg

5th January 2018, 17:51

Husaberg

"also tha 120mm c-c rod is very long for a piston port yam compared to others in the range
maybe its from the Longer stroke TR2 series or from an outboard do you have the numbers on the corned"

the rod i have is attached to a crank i bought on eBay as NOS for a YA6 , it has a large chamfer on one wheel for a Disk valve

the rod has yamaha on one side and the letter "C" and i think what is a japanese character that looks like a reversed F in a circle ,no numbers

Grumph

Kevin bought 4 sets of parts and i believe every thing was new, a mate of mine started his apprenticeship in 1967 he said that he was getting $16 a week so a crank half would have been 2 weeks wages for him

TZ 350

when you change rod length do you use a different piston ? or do you space the barrel up or down ? what piston do you use ?

I am keeping my eye out for YDS2 crank to measure up and a YL2 disk valve to measure up

any one recognise the Carb in this photo ?
http://collingrovehillclimb.com.au/site_files/52/Harold%20Clisby%20two%20stroke%20rotary%20valve%20 jpg.jpg
mikuni 24mm ?

Thanks every one that has replied with advice
carb is a Mikuni VM
Look for kawasaki ke125/ks125 carbs on ebay.
actually is that a clip on version? so maybe early 90cc suzuki ie rv90 or a100 would be the easiest cheaply obtainable option
if you were attempting to build a repo unit or restore an old engine mock up the measurements of the origional and work from there.
If you give the the measurements of what you want i can sift through a few sites i know to give you some modern options.
The conrod is likely to be arround 100mm as it was the style of the time to run stroke times 2 for rod length.

TZ350

5th January 2018, 18:08

TZ 350 when you change rod length do you use a different piston ? or do you space the barrel up or down ? what piston do you use ?

I use single ring motor cross pistons with a crown height similar to the original GP piston and the cylinder is spaced up. For me the longer rod is about increasing the crankcase volume.

334493 334494

For even more crankcase volume the cases were spaced apart by 12mm and the insides of the crank webs were faced off until they were completely flat, without any shrouding of the big end at all.

I worked on the assumption that more volume was better and even more volume would be better still. I have no idea of how much crankcase volume there is now, it must be more than most. I will have to measure it next time the motor is out of the bike.

My motors breathing development is becoming very dependent on the suction action of the pipe.

334496 334495

Frits Overmars

5th January 2018, 22:58

Wonder if logarithmic inner radius would work? (closer the exit, bigger the radius). Flow usually wants to separate from the short turn after the apex.In principle it would work, Jannem. You'll notice that in the transfer picture I posted the other day, the centers of the inner and outer transfer radii do not coincide.
This gives a gradually reducing cross section area, building up pressure at the outer wall, which helps to prevent flow separation from the inner wall.
The advantage of this approach is that we can use constant-magnitude radii, which used to be of practical value to model makers.
Nowadays with CNC we could also use logarithmically variing radii but their effect over the restricted length of a transfer duct would be limited.

SwePatrick

6th January 2018, 02:54

I worked on the assumption that more volume was better and even more volume would be better still. I have no idea of how much crankcase volume there is now, it must be more than most. I will have to measure it next time the motor is out of the bike.

My motors breathing development is becoming very dependent on the suction action of the pipe.

334496 334495

Yes, they will be very depending on the pipe.
Thereby also quite 'variable' in power.
I hade HUGE volume in case due to ~20mm spacer under cylinder because of downstroked crank and long rod.

This made it very sensitive to heat in pipe, one dynopull without 'perfect' heat could result in 48hp at the wheel.
Another with bullseye hit with temp in pipe could result in 66hp at the wheel.
No adjustments made at all.

I found it very 'hard' to reach temp also with methanol as i am running.
Therby i figure that make the engine less depending on the pipe would make it produce more heat to the pipe, and thereby the pipe will start it´s action easier and faster(important in dragracing, one need full power immediately when releasing the clutch.

And, i also figuring that with the lower crankhousecompression the more risk it is to get exhaustflow into transfers, it will be very sensitive to backpressure in pipe.
Mine were a little bit dark greyish in transfers and crankhouse(soot), and i also needed very big stingerdiam to get it to produce power.

I´m redesigning this as we speak, more crankhousecompression and a milder pipe, even still a very angry pipe it is somewhat milder then my previous one.

Rgds

TZ350

6th January 2018, 07:16

.
Very interesting, what you say makes good sense.

334520

We are close to getting this bike going, it has the same basic engine as mine but with a smaller more traditional crank case volume, it will be interesting to see how it goes on the dyno and its drivability on the track.

Nath88

6th January 2018, 11:07

I found it very 'hard' to reach temp also with methanol as i am running.

The snowmobile guys have a similar issue, they use ignition retard to heat the pipe before launch. Look for 'holeshot button', 'hot pipe button' or 'dragon button'. The ignition retard limits the RPM at wide open throttle so the clutch does not engage. The idea is to hold the button, hold full throttle, release button when you want to go, RPM goes up and the sled launches with a hot pipe.
In your case you could have the ignition retard controlled by a clutch switch. And you get to keep the angry pipe!

Muhr

6th January 2018, 11:23

This made it very sensitive to heat in pipe, one dynopull without 'perfect' heat could result in 48hp at the wheel.
Another with bullseye hit with temp in pipe could result in 66hp at the wheel.
No adjustments made at all.

That’s more den fascinating are we talking 20-50 C°?

TZ350

6th January 2018, 14:38

it's easy to take a standard T port cylinder from a MX bike or std RS125 that has like 190/195º exhaust and raise it to 200º by doing a good round chamfer raising the port 1/1,5mm.

The thing is if looking at cylinders from factory that come with 200º we don't see that chamfer, it's mostly straight plain duct on the roof, 1min in paint .....

334526

Doing this helps keeping duct volume low, the return pulse gases can follow this chanfer if big enought, or maybe not.

Would this need a dyno to confirm or is safe to say that will not be has good has a normal 200º port...

It sure will keep the duct volume small, which is always a good thing. And the radius will help both the outflow and the return flow, but the positive effect on the return flow will be small; keeping the return flow attached over the port edge would require a much bigger radius.

I'd rather say that it is better than a 'normal' 200° port, if only because you can always modify that radiused port into a 'normal' port, but you cannot modify it the other way round.

If you are lucky, the modification effect will be strong enough for a seat-of-the-pants conclusion. But then you still won't know just how big the effect was.
So, if you have access to a dyno, use it.

That is very interesting.

334523

On my Suzuki GP/NSR 110cc hybrid I radius-ed (chamfered) the front edge of the RC valves.

334524

And set the fully open exhaust port timing to 200 deg duration.

When running it up on the dyno I got a noticeable improvement in top end power when the RC valve was lowered a bit so that the radiused edge was exposed making a rounded entry into the exhaust port. This gave a few more rpm over rev and made more power than a fully open port.

Without taking the motor apart again I can't tell what the exact timing numbers are but suspect they are much like RomeuPT's diagram.

334525

This is not my NSR cylinder but it shows where I radius the RC valve.

Vannik

6th January 2018, 15:37

I did the same on a NSR250 used for racing but also built the valve halves up with brazing and filed them to get a much better fit with smaller pockets and hopefully better flow. Well, it seemed to work well, the bike dominated the championship.

TZ350

6th January 2018, 16:18

... also built the valve halves up with brazing and filed them to get a much better fit with smaller pockets and hopefully better flow. Well, it seemed to work well ...

Yes there is quite a bit of a gap at the sides of a NSR RC valve. I have been looking at it but it looked very difficult to get the re shaping of the RC valve right after building it up.

Because its very fiddly test fitting the modified valve as its filed to shape. I had been thinking of getting an un-serviceable cylinder and cutting it horizontally across the exhaust port top so that access to the RC valve pockets is much easier.

Great to hear that building the valve up to close the gap on the sides is worth the effort.

334530

334529
Building up the sides of the RC valve will be my next tuning move when the engine is apart again.

Matt@TYGA

6th January 2018, 21:49

Building up the sides of the RC valve will be my next tuning move when the engine is apart again.

This mod if definitely worth doing. When I raced the NSR back in '95/'96 I spent an excessively long time welding and grinding the valves for a pretty much perfect fit in the recess.

I'd previously done the same mod to the old '93 model NSR150R, which has a single flap valve, and this had shown a marked improvement at the top end compared to the stock valve rattling around, so it seemed rude not to do it to the 250.

Matt.

Jannem

6th January 2018, 23:16

Is there a rule of thumb about C-port sizing relative to A&B?

I'm working on a stud limited, single exhaust small cylinder and and it seems I need to max. out the transfers without cutting into the blowdown. If my calculations hold any water, the transfer area would be the bottleneck even without considering the less than ideal shape of the ducts. I have room to cut the c-Port area quite a bit bigger, but wondering if there's a balance of getting more appropriate total area vs. losing scavenging efficiency. In a much less than ideal situation like this, which way to compromise?

Frits Overmars

6th January 2018, 23:35

Is there a rule of thumb about C-port sizing relative to A&B? I'm working on a stud limited, single exhaust small cylinder and and it seems I need to max. out the transfers without cutting into the blowdown. If my calculations hold any water, the transfer area would be the bottleneck even without considering the less than ideal shape of the ducts. I have room to cut the c-Port area quite a bit bigger, but wondering if there's a balance of getting more appropriate total area vs. losing scavenging efficiency. In a much less than ideal situation like this, which way to compromise?Pictures, drawings and dimensions might help, Jannem.

Jannem

6th January 2018, 23:59

Pictures, drawings and dimensions might help, Jannem.

:o I'll put more effort into it and collect more comprehensive info.

SwePatrick

7th January 2018, 08:41

That’s more den fascinating are we talking 20-50 C°?

About 70-100celsius off resulted in HUGE powerloss.
It produced best power at 470-480c

And watertemp at the same time should also be quite hot, about 85-90c

Two parameters that had to be in the ballpark to get it to produce power.
And, when all was good, i could open the powerjet half a turn and it gave me about ~3hp also(at crank).
If opening to early the engine never got hot, also pipe never reached correct heat.

Muhr

7th January 2018, 09:25

About 70-100celsius off resulted in HUGE powerloss.
It produced best power at 470-480c

And watertemp at the same time should also be quite hot, about 85-90c

Two parameters that had to be in the ballpark to get it to produce power.
And, when all was good, i could open the powerjet half a turn and it gave me about ~3hp also(at crank).
If opening to early the engine never got hot, also pipe never reached correct heat.

Ok, and 90 degrees water temp never heard about anything like that.:scratch:

SwePatrick

7th January 2018, 09:30

Look at Harley dragbikes, they don´t even have cooling on the liners.
And top methanol engines (V8) have solid blocks, no cooling.
No need for any cooling.
On need to vaporize the alkohol, and the homebrewer knows that a magic number is 78.3c
But you need some more heat due to there isn´t a lot of time to do it ;)

Muhr

7th January 2018, 10:03

If anyone thinks it's interesting

It's getting closer to something, it's just the hard one left! To make the best.:sweatdrop

TZ350

7th January 2018, 11:47

It's getting closer to something, it's just the hard one left! To make the beast.:sweatdrop

Very interested. I can see that a lot of good work has gone into the design and drawing. I am looking forward to watching progress as it turns into metal.

Muhr

7th January 2018, 13:08

Very interested. I can see that a lot of good work has gone into the design and drawing. I am looking forward to watching progress as it turns into metal.

Thank you Tz
It's a few hours to wait before I get to hear the little one

JanBros

7th January 2018, 15:03

in the Bimotion Head program, the squish isn't parallel to the piston, but in some "tangetial line" to keep a constant velocity of the gases within the squish (see page 8 : https://dokumen.tips/documents/bimotion-advanced-head-manualpdf.html)

are there circumstances where this type of squish band is better than parallel to the piston ?

Buckets4Me

7th January 2018, 19:08

.

Ex-Ferrari Engineers Are Building a Carbon Fiber Two-Stroke Superbike

The (http://www.roadandtrack.com/car-culture/a14763497/ex-ferrari-engineers-are-building-a-carbon-fiber-two-stroke-superbike/)Vins Duecinquanta (http://vinsmotors.com/modelli/duecinquanta/?lang=en) is a carbon-fiber monocoque bike packing a 249cc V-twin two-stroke with electronic fuel injection. With an eye on extreme lightness, the street bike promises a curb weight of less than 210 lbs. No power figure is given, but with such a featherweight bike, it's almost guaranteed to be quick.

http://www.roadandtrack.com/car-culture/a14763497/ex-ferrari-engineers-are-building-a-carbon-fiber-two-stroke-superbike/ (http://www.roadandtrack.com/car-culture/a14763497/ex-ferrari-engineers-are-building-a-carbon-fiber-two-stroke-superbike/)

Time for a come back ;)

Grumph

7th January 2018, 19:18

Weren't there ex Ferrari engineers supposed to have been involved with the Bimota V-Due ?

I hope that they aren't the same ones - or at least that something was learned from that....

What's the engineering staff turnover like at Ferrari ? You never seem to hear of ex Honda engineers starting something up.

Jannem

7th January 2018, 19:47

Pictures, drawings and dimensions might help, Jannem.

Ok, here we go:

44mm bore
39mm stroke
11krpm targetmax. torq.
Durations:
ex 192,5 with radiused upper edge, radius included in the duration
blowdown 33
ABC 122,6

Roof angles:
ex 15
A 22
B 10
C 51

Shapes:
ex elliptical @70% with small bulges in port within blowdown area, floor stuffer planned.
A Rectangular
B Rectangular
C Rectangular

Angle corrected chordal areas:
Blowdown 305mm^2
A 143 mm^2
B 162mm^2
C 91mm^2, maxed out c-port would be 153mm^2
Transfer total 701mm^2, with maxed out c-port 764mm^2

Port directios:
A-port: ex. port side wall "extension line" crosses exhaust centerline at cyl center
A-port: B-port side wall "extension line" crosses exhaust centerline at midpoint between cyl center and c-port wall

B-port: A-port side wall "extension line" crosses exhaust centerline at 2mm from cyl center towards c-Port
B-Port: C-port side wall "extension line" crosses exhaust centerline at midpoint between cyl center and c-port wall

C-port: wall "extension lines" cross exhaust centerline at cyl center

Thoughts:
If my calculations are reasonably ok, existing transfer and blowdown areas should be reasonably balanced, although somewhat limited from ideal. However, transfer flow coefficients in this case will be relatively worse due to shapes, so thinking adding 10% area might not be a bad idea.

Twopints

7th January 2018, 20:33

carb is a Mikuni VM
Look for kawasaki ke125/ks125 carbs on ebay.
actually is that a clip on version? so maybe early 90cc suzuki ie rv90 or a100 would be the easiest cheaply obtainable option
if you were attempting to build a repo unit or restore an old engine mock up the measurements of the origional and work from there.
If you give the the measurements of what you want i can sift through a few sites i know to give you some modern options.
The conrod is likely to be arround 100mm as it was the style of the time to run stroke times 2 for rod length.

Thanks that would be great, scaling from the drawings i have the centre line of the crank to head gasket line is 158mm so from the information i have gathered from you guys 25mm from the throw of the crank ( half the stroke) plus 100mm rod and a piston with 30mm compression height gives me 155 mm or with a 103mm rod 158mm

as i only have the crankcase ,all this scaling is done from grainy photos, so there is a margin of error

with the assistance i have got here this is much clearer to me, i am starting to lay out the ports to the timing figures i have

I am keeping my eye out for a Suzuki GP 125 crank ,rod and piston to mock things up

and i have worked out how to attach photos

Muhr

8th January 2018, 05:07

Ok, here we go:

44mm bore
39mm stroke
11krpm targetmax. torq.
Durations:
ex 192,5 with radiused upper edge, radius included in the duration
blowdown 33
ABC 122,6

Roof angles:
ex 15
A 22
B 10
C 51

Shapes:
ex elliptical @70% with small bulges in port within blowdown area, floor stuffer planned.
A Rectangular
B Rectangular
C Rectangular

Angle corrected chordal areas:
Blowdown 305mm^2
A 143 mm^2
B 162mm^2
C 91mm^2, maxed out c-port would be 153mm^2
Transfer total 701mm^2, with maxed out c-port 764mm^2

Port directios:
A-port: ex. port side wall "extension line" crosses exhaust centerline at cyl center
A-port: B-port side wall "extension line" crosses exhaust centerline at midpoint between cyl center and c-port wall

B-port: A-port side wall "extension line" crosses exhaust centerline at 2mm from cyl center towards c-Port
B-Port: C-port side wall "extension line" crosses exhaust centerline at midpoint between cyl center and c-port wall

C-port: wall "extension lines" cross exhaust centerline at cyl center

Thoughts:
If my calculations are reasonably ok, existing transfer and blowdown areas should be reasonably balanced, although somewhat limited from ideal. However, transfer flow coefficients in this case will be relatively worse due to shapes, so thinking adding 10% area might not be a bad idea.

Is it looking something like this?

To me it seems like you have more than enough tans area for 11krpm targetmax. torq. 14m/s and peak hp at 16-17m/s.

I would focus on exhaust

Jannem

8th January 2018, 05:52

Is it looking something like this?

To me it seems like you have more than enough tans area for 11krpm targetmax. torq. 14m/s and peak hp at 16-17m/s.

I would focus on exhaust

Seems I have probably goofed up my calculations entirely... If those areas are uncorrected, It would seem I have even more than that.

Do you mean 14Krpm & 16-17Krpm? Or am I missing something? Piston travel/s? Wouldn't that equal max.torq @10700 max hp @ 12300?

Exhaust height is purposefully conservative at this point and easier to tune afterwards, once I see if it falls on it's face after the peak. Just would like to get the transfers into ballpark with one royal pain with this iron cylinder, aged eyesight and less than professional tools...

How did you evaluate the required area / rpm in general?

Muhr

8th January 2018, 07:47

Seems I have probably goofed up my calculations entirely... If those areas are uncorrected, It would seem I have even more than that.

Do you mean 14Krpm & 16-17Krpm? Or am I missing something? Piston travel/s? Wouldn't that equal max.torq @10700 max hp @ 12300?

Exhaust height is purposefully conservative at this point and easier to tune afterwards, once I see if it falls on it's face after the peak. Just would like to get the transfers into ballpark with one royal pain with this iron cylinder, aged eyesight and less than professional tools...

How did you evaluate the required area / rpm in general?

yes i was referring to piston speed.

I have not done any calculations just went on feeling:mellow:

or maybe i misunderstood.

TZ350

8th January 2018, 15:23

334584

My pressure sensor has turned up. I think it is a pizeo resistive type. It is 5Volt in and 0.5 to 4.5 analog Volt out. Perfect for the Arduino. Hopefully have it all wired in, in a couple of nights ready for the big test. I am unsure what the pressure range should be but figure that the cylinder pressure at exhaust port opening is about 10% of maximum combustion pressure, so maybe about 150 to 200 psi. The sensor is rated for 3 times over pressure so should be good.

Jannem

8th January 2018, 16:59

Speaking of sensors, found this cable operated TPS, which could be useful for others too. Haven't figured out the connector type yet. These are Citroen/Peugeot/Suzuki 2.0HDI sensors, some Fiat's as well.

334615334616

TZ350

8th January 2018, 17:13

Great, thanks, I have been looking for TPS like that.

peewee

8th January 2018, 17:52

hey guys I need some help from the masters. I have a common cr500 steel exh spigot (not the exact one in the photo but similar) and I need to narrow it down closer to 75% or so. I have to first say that theres no reasonably easy method (or even reasonably hard method) I can water cool it, without a huge undertaking and I don't have time for that now, so ill make do with what I can at the moment. maybe you fellers have even a better solution :wings:

my amateur ideas are simply to get some flat steel plate which I already have in the garage and weld it in the spigot, creating the roof and floor ( like in the pics), and of course weld caps over the ends at the exit so its sealed from the pipe side , the other end may not need a cap since its mated against the cylinder. but this method leaves a hollow void below the floor and above the roof (arrows in pics)

my other Idea is to get a chuck of 6061 or 7075 (assuming it can be fairly easily machined as I have no experience with 7075). then have a local shop machine the outside spigot dimensions then ill hand grind the inside of the passage. t6-7075 would be more appealing since I think it would have a higher wear resistance between the spigot and pipe, as this engine vibrates quit alot

heres were im stumped, im thinking the steel method is the better of the two situations. wouldn't the steel spigot idea heat up slower and put less radiant heat back into the washed through mixture ? and the hollow cavities might even help this alittle ? aluminum seems like it soaks up heat so fast and would radiate it back into the mixture a lot

Jannem

8th January 2018, 18:01

yes i was referring to piston speed.

I have not done any calculations just went on feeling:mellow:

or maybe i misunderstood.

I think you caught up an error in my spreadsheet regarding the t-port heights. I need to dig up my old mm-paper portmaps and take a look at it. Thanks.

The ex. port in your pic matches pretty well, although the width you show is what I have as chordal width. The rod length I have is 85mm.

EssexNick

8th January 2018, 20:22

Peewee,
I think aluminum is the way to go because you want to get the heat to the outside world as quickly as possible. Steel will hold heat for longer, (and having a void like a vacuum flask making things worse), means the heat can only go back into the washed through mixture.
If your local firm can turn the outside of a spigot then they can certainly bore the centre nice and round, leaving you less work opening it out to the size and shape you want.

Matt@TYGA

8th January 2018, 22:58

my other Idea is to get a chuck of 6061 or 7075 (assuming it can be fairly easily machined as I have no experience with 7075). then have a local shop machine the outside spigot dimensions then ill hand grind the inside of the passage. t6-7075 would be more appealing since I think it would have a higher wear resistance between the spigot and pipe, as this engine vibrates quit alot

7075-T6 is very strong, but is prone to corrosion cracking. If you can source 7075-T73 this would possibly be a better choice of material.

I recently made a oval-round transition manifold for the NSR150 out of some scrap 6061-T6, and to be honest it was showing unacceptable wear after just the day's dyno session. Didn't leak or anything, but don't think that I'd want to use it for an actual part.

Matt.

Haufen

9th January 2018, 02:57

my other Idea is to get a chuck of 6061 or 7075 (assuming it can be fairly easily machined as I have no experience with 7075). then have a local shop machine the outside spigot dimensions then ill hand grind the inside of the passage. t6-7075 would be more appealing since I think it would have a higher wear resistance between the spigot and pipe, as this engine vibrates quit alot

heres were im stumped, im thinking the steel method is the better of the two situations. wouldn't the steel spigot idea heat up slower and put less radiant heat back into the washed through mixture ? and the hollow cavities might even help this alittle ? aluminum seems like it soaks up heat so fast and would radiate it back into the mixture a lot

Don't worry about heating the washed through mixture with the spigot. The EGT will always be above the temperature of the spigot, hence heat will always be transferred from the exhaust gas to the spigot and not the other way round.

To maximize the cooling effect, aluminium would be the material of choice (copper would be even better still). Personally, and having hand grinded 7075 before (pita), I would choose another aluminium and have the pipe sit an an all around o-ringed flange (two radial and one in the direction the pipe is stuck on to rest the pipe against). And btw, I don't know if you planned to, but 7075 can not be welded.

Frits Overmars

9th January 2018, 04:55

Don't worry about heating the washed through mixture with the spigot. The EGT will always be above the temperature of the spigot, hence heat will always be transferred from the exhaust gas to the spigot and not the other way round.The temperature of the washed-through mixture will always be below the temperature of the spigot, hence heat will always be transferred from the spigot to the mixture. The hotter the spigot, the more it will heat up the mixture. I don't think that's what we want.

breezy

9th January 2018, 08:00

just watched a few you tube videos showing plasma sparks on spark plugs..... cant remember how to down load here, but has anybody had a go? power enhancers? or engine killers? looks pretty easy to set up to experiment. i would say the spark produced looks like something you would use to cut through steel, not sure what it would do to a piston!

katinas

9th January 2018, 08:18

my other Idea is to get a chuck of 6061 or 7075

Best 2618 ( high Cu and temperature plus Fe ) and 2014, 2024 ( high precentage of Cu ) much stronger than 6061.

I try 7075, its good, but some scuff spots from vibration ( high precentage of zinc not good for high temperature )

Stay away from 6000 grade (soft cheese), but 6026 would be most suitable from 6000 grade .

husaberg

9th January 2018, 16:29

Great, thanks, I have been looking for TPS like that.
Pretty sure flettner had troubles with the Suzuki one he used to run, is that what you used to use as well?

Pursang

9th January 2018, 16:47

hey guys I need some help from the masters. I have a common cr500 steel exh spigot (not the exact one in the photo but similar) and I need to narrow it down closer to 75% or so. I have to first say that theres no reasonably easy method (or even reasonably hard method) I can water cool it, without a huge undertaking and I don't have time for that now, so ill make do with what I can at the moment. maybe you fellers have even a better solution :wings:

my amateur ideas are simply to get some flat steel plate which I already have in the garage and weld it in the spigot, creating the roof and floor ( like in the pics), and of course weld caps over the ends at the exit so its sealed from the pipe side , the other end may not need a cap since its mated against the cylinder. but this method leaves a hollow void below the floor and above the roof (arrows in pics)

my other Idea is to get a chuck of 6061 or 7075 (assuming it can be fairly easily machined as I have no experience with 7075). then have a local shop machine the outside spigot dimensions then ill hand grind the inside of the passage. t6-7075 would be more appealing since I think it would have a higher wear resistance between the spigot and pipe, as this engine vibrates quit alot

heres were im stumped, im thinking the steel method is the better of the two situations. wouldn't the steel spigot idea heat up slower and put less radiant heat back into the washed through mixture ? and the hollow cavities might even help this alittle ? aluminum seems like it soaks up heat so fast and would radiate it back into the mixture a lot

We want the heat & energy from the exhaust pulse to go out into the chamber. The spigot & duct should absorb, hold and re-transfer as little heat to the charge as possible.
Make your reducer from stainless steel, pull the air out the cavities before sealing them, if you can. Polish the surfaces. Just like a Vacuum flask.

and a Happy New Year to All. Cheers, Daryl.

TZ350

9th January 2018, 18:23

Pretty sure flettner had troubles with the Suzuki one he used to run, is that what you used to use as well?

No I have been using the TPS that came with the Ecotrons system but looking for something else for others because no one else on the team is crazy enough to run EFI on their 2T.

flyonly

9th January 2018, 20:22

Frits

I was talking with the bucket guys and one of them suggested you might know the answer to my question

If I have a piston port 50cc two stroke and the reed cage is in the crankcase. Do you think it's possible to run with out the reed block?

I am using the bike for land speed racing in Australia. It's a TZR50 R 4EU so not the AM 6 engine

Sent from my iPhone using Tapatalk

husaberg

9th January 2018, 20:30

No I have been using the TPS that came with the Ecotrons system but looking for something else for others because no one else on the team is crazy enough to run EFI on their 2T.
I am having problems finding a pic of the RGV one but they work much like this with a splitter cable providing the location fotr the potentiometer.
https://blog-001.west.edge.storage-yahoo.jp/res/blog-34-42/xj750e2/folder/766632/72/26563272/img_13?1368183296 (https://blogs.yahoo.co.jp/xj750e2/GALLERY/show_image.html?id=26563272&no=13)
but the best set up itp use would be a KX keihin or a Keihin off a NSR.
the push pull makes it easy on the NSR set up
Pretty sure the mikunis on a 97-98 CR125 had a TPS as well (they has some electricy gubins if memory serves anyway)

tedspeed230

9th January 2018, 22:03

Best 2618 ( high Cu and temperature plus Fe ) and 2014, 2024 ( high precentage of Cu ) much stronger than 6061.

I try 7075, its good, but some scuff spots from vibration ( high precentage of zinc not good for high temperature )

Stay away from 6000 grade (soft cheese), but 6026 would be most suitable from 6000 grade .

Hi Can anyone recomend the best aluminium for a weld on packer to extend my cylinder ?
Thanks Neil

Frits Overmars

9th January 2018, 23:26

just watched a few you tube videos showing plasma sparks on spark plugs..... cant remember how to down load here, but has anybody had a go? power enhancers? or engine killers? looks pretty easy to set up to experiment. i would say the spark produced looks like something you would use to cut through steel, not sure what it would do to a piston!The plasma principle is not that complicated. The diagram below shows how it's done. At the left is a conventional ignition system. At the right the low-tension coil input and the high-tension coil output are connected through a series of diodes that prevent the high tension from returning to the input side.

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The spark starts in the normal way. A high tension between the plug electrodes is needed to create an ionized path through the mixture. That path is conductive and a spark will occur. But once that conductive path is established, it can also conduct the primary low-tension, high-current flow, which then does not have to travel through the primary coil windings anymore, but can jump the spark plug gap directly.

A high-tension spark in itself is not a very good igniter; you may have seen videos of people handling million-volt Tesla discharges without getting hurt.
But bring in a high current and things change...

Plasma ignitions do not harm the piston, but they can eat spark plug electrodes for breakfast. Martijn Stehouwer (www.emot.nl) has been racing such a system: http://www.youtube.com/watch?v=7BfQuxyWN90 , winning the European 50cc championship twice. He actually had to reduce the current in order to make the plug survive long enough. He reports better engine performance, especially in damp conditions.

Frits Overmars

9th January 2018, 23:31

If I have a piston port 50cc two stroke and the reed cage is in the crankcase. Do you think it's possible to run with out the reed block?Running it: yes. Starting it: no.
That is why my 24/7 inlet system has a hinged reed that can be shut for starting the engine in the conventional reed-mode, and that can be swung out of the way, once the engine is running in the power band and the exhaust pipe suction is taking care of things.

flyonly

10th January 2018, 06:43

Running it: yes. Starting it: no.
That is why my 24/7 inlet system has a hinged reed that can be shut for starting the engine in the conventional reed-mode, and that can be swung out of the way, once the engine is running in the power band and the exhaust pipe suction is taking care of things.

Do you have a picture of the 24/7 setup?

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seattle smitty

10th January 2018, 06:43

The temperature of the washed-through mixture will always be below the temperature of the spigot, hence heat will always be transferred from the spigot to the mixture.

Frits, I'm just a dumb liberal arts major, and I don't get how that could be. The interior surface of the spigot (not a term we use here, but I gather that it refers to the extension of the exhaust port, to which the header section of the pipe is bolted) didn't get hot on its own, but from the exhaust gases passing through. How can it get hotter than those gasses?

Frits Overmars

10th January 2018, 07:01

Do you have a picture of the 24/7 setup?Yep, posted several of 'm here. Look for "Modena 24-7".

The interior surface of the spigot... didn't get hot on its own, but from the exhaust gases passing through. How can it get hotter than those gasses?I never said that it does, Smitty. The interior surface of the spigot gets hotter than the washed-through unburned mixture.

Haufen

10th January 2018, 10:52

The temperature of the washed-through mixture will always be below the temperature of the spigot, hence heat will always be transferred from the spigot to the mixture. The hotter the spigot, the more it will heat up the mixture. I don't think that's what we want.

Nope, I don't think so. I am with the simulation software on this one, have a look:

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wobbly

10th January 2018, 13:07

Here is how you cool the spigot,this made more power and also enabled leaner jetting with no deto.
I am just about to get a cylinder Exhaust duct coated with ceramic to see who is right or wrong about the trapped charge overheating
and causing deto, or more heat energy being transferred to the pipe,thus making more power.

katinas

10th January 2018, 18:46

Hi Can anyone recomend the best aluminium for a weld on packer to extend my cylinder ?
Thanks Neil

Best 2219 (Weldural) very good weldability and high strength under heat stress, but its hard to find.

All 6000 series have very good welding properties, but 6026 highest strength, when treat gone after welding,

katinas

10th January 2018, 20:14

Running it: yes. Starting it: no.
That is why my 24/7 inlet system has a hinged reed that can be shut for starting the engine in the conventional reed-mode, and that can be swung out of the way, once the engine is running in the power band and the exhaust pipe suction is taking care of things.

Once testing engine with trimmed reed petals ( open area 40x6mm ). Starting engine just after "high speed run" with the bike. From 0 to 6000 rpm no power at all ( very similar to my rygerised engine, maybe too soft reed petals ) just terrible sound from carb. When pipe is on, more power than with normal reeds, but not much ( maybe with fully open area would be more ).
But it was very unstable carburation. Between lean and rich very thin line and maybe with adjustable reed block would be better open at last 1000-2000 revs.

TZ350

10th January 2018, 21:22

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Got the chance to try my new pressure sensor tonight.

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Bottom line is the ignition pickup, top line is the in cylinder pressure sensor. There was not much of a signal from the sensor, nothing usable anyway.

The hole in the wall of the cylinder is exposed before exhaust port opening for about the same number of crank shaft degrees as the positive side of the ignition triggers wave form.

I suspect the new pressure sensor is too slow reacting, I was hoping for a signal that looked like the positive side of the ignition triggers pulse but I guess the cylinder pressure sensor is electronically damped to cut out noise. Mechanical pressure sensors are often damped with fluid so I guess its logical that an electronic one could be damped too.

Its very hard to get a good photo, so here is a video clip of the oscilloscope screen:- https://youtu.be/Hnqeh5jNtfE

diesel62

11th January 2018, 07:47

How come you don't have a continuous flat line on the pressure sensor?. Are you only measuring it over x degrees?

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Muhr

11th January 2018, 08:38

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Got the chance to try my new pressure sensor tonight.

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I suspect the new pressure sensor is too slow reacting,

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I suppose pipe length to the sensor is devastating for reaction time!?
something more that came to mind was Bernoulli's principle :dodge:

seattle smitty

11th January 2018, 11:03

Dang! Sorry Frits, it was clear enough.

peewee

11th January 2018, 14:48

We want the heat & energy from the exhaust pulse to go out into the chamber. The spigot & duct should absorb, hold and re-transfer as little heat to the charge as possible.
Make your reducer from stainless steel, pull the air out the cavities before sealing them, if you can. Polish the surfaces. Just like a Vacuum flask.

and a Happy New Year to All. Cheers, Daryl.

hey mate i never thought of stainless steel. would 304 be suitable ? if so then ill just get a small chunk and machine the whole spigot as one piece and forget about them hollow voids and forget about any welding

TZ350

11th January 2018, 20:26

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Made myself a little pressure sensor from a cheep piezo disk. Gave a reasonable signal at least 2-3 Volts at idle.

https://youtu.be/bHCxhSV_6hw

I still have to work out if the collapse in the signal when I blip the throttle is on over run or actually during acceleration at which time I would have expected the signal to be stronger??? ... :scratch: maybe need to get it on the dyno so as to hold the acceleration load/pressure for longer.

Piezo sensor is the top trace, the ignition trigger pulse is the bottom. The gaps in the traces are due to the difference in sweep speed as apposed to engine rpm.

<iframe src="https://www.youtube.com/embed/bHCxhSV_6hw?ecver=2" width="480" height="360" frameborder="0" allow="autoplay; encrypted-media" style="position:absolute;width:100%;height:100%;left:0" allowfullscreen=""></iframe>

Pursang

12th January 2018, 01:26

hey mate i never thought of stainless steel. would 304 be suitable ? if so then ill just get a small chunk and machine the whole spigot as one piece and forget about them hollow voids and forget about any welding

A chunk of SS in the port might be a good thing.....or a disaster.
SS has thermal conductivity around half of steel and perhaps a 10th of cast alum.

Maybe it will absorb less heat during the exhaust flow and transfer less to the 'flow through' charge. (Win/Win):woohoo:

Or....It might just heat up and up and transfer huge quantities of heat to the new charge (Lose/Deto/Lose):bash:
Far too many factors to consider just at the moment.

The reference to the vacuum flask is for a purpose.
There are 3 factors to be combined for a Thermos to work, miss out on any one and all you have is a bottle.:drinkup:

Shiny surface to reflect heat transfer by radiation. (Like Wobbly's piston crowns).
Vacuum (or air) gaps to prevent transfer by convection. (or bubbles in foam or some ceramics)
Long, thin, pathways and materials to reduce conduction, (SS better than steel and alum. not as good as glass & some ceramics)

Do some experiments and report what happens. Might be the next 'Big Thing' in 2T technology. :corn:

Cheers, Daryl.

Muhr

12th January 2018, 01:49

A chunk of SS in the port might be a good thing.....or a disaster.
SS has thermal conductivity around half of steel and perhaps a 10th of cast alum.

Maybe it will absorb less heat during the exhaust flow and transfer less to the 'flow through' charge. (Win/Win):woohoo:

Or....It might just heat up and up and transfer huge quantities of heat to the new charge (Lose/Deto/Lose):bash:
Far too many factors to consider just at the moment.

The reference to the vacuum flask is for a purpose.
There are 3 factors to be combined for a Thermos to work, miss out on any one and all you have is a bottle.:drinkup:

Shiny surface to reflect heat transfer by radiation. (Like Wobbly's piston crowns).
Vacuum (or air) gaps to prevent transfer by convection. (or bubbles in foam or some ceramics)
Long, thin, pathways and materials to reduce conduction, (SS better than steel and alum. not as good as glass & some ceramics)

Do some experiments and report what happens. Might be the next 'Big Thing' in 2T technology. :corn:

Cheers, Daryl.

if you go that way why not Invar:scratch:

lodgernz

12th January 2018, 09:19

What if you water-cooled the SS?

DoldGuy

12th January 2018, 14:43

What to expect with the Sub/Auxiliary Exhaust Ports opening at TDC (approximately 3mm on a 76mm stroke) ?

Main Exhaust open at TDC (1mm-2mm on a 76mm stroke) ?

wobbly

12th January 2018, 17:37

Aux ports open at TDC you loose a ton of power, main port open works to make power on a 180* twin with a common pipe, but would be impossible to jet without
pumper carbs and a shitload of jetting change.

jonny quest

13th January 2018, 05:37

Does anyone have any experience with the Aprilia Ditech SR50 scooters, 2001 year?

More specifically the fuel injection system. Looking to build a big bore stroker... around 100cc. I'd like to use the fuel injection system on it already, but don't know if I can modify it to work

peewee

13th January 2018, 09:54

What if you water-cooled the SS?

im sure that's a great idea if you already have water up near the spigot and can tie into the water source, like wobbly has shown several times. but like many older cylinders, mine has water only around the bore. if I didn't have fairly fresh nikisil I would see if it was feasible to weld on some water channels to the spigot. on the side of the cyl I could install some nipples and small water hose connected to the spigot but I don't think the pumping action would be very effective and the center portion of the exh passage would still be air cooled so how much would I really gain :laugh:

tjbw

13th January 2018, 14:36

What to expect with the Sub/Auxiliary Exhaust Ports opening at TDC (approximately 3mm on a 76mm stroke) ?

Main Exhaust open at TDC (1mm-2mm on a 76mm stroke) ?

Not sure if I understand the question, as I can't imagine why anyone would want to do this.

If you take a conventional two stroke, but move the exhaust ports up to near the top of cylinder, then when exhaust ports close just before TDC most of the mixture will have been pushed into the exhaust pipe. Compression would be very low, so very easy to kick over, if it fires expect flame exiting the exhaust pipe. Power would be very low.

Well that's what I think, anyone else have any thoughts on this?