ESE's works engine tuner [Archive] - Page 67

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adegnes

30th January 2015, 03:37

Probably gluing is going to break the magnetic path, get a pick-up that has removable iron/magnet and use one of those, the CRM125 pick-up allows that, and does the yamaha dt lc 50 one, but those might be bike models rare in where you live.

Thanks. Do you mean to use the magnet from one of those pickup as the extension?

Posted a cross section sketch, no glue between extension and pickup.

Frits Overmars

30th January 2015, 04:24

Is it possible to "extend" a magnetic pickup? Say I want to trigger from a toothed wheel behind a 5mm aluminium plate, can I drill a hole in said plate and glue a steel/iron/magnetic pin in there, then but the pickup up against the pin on the outside?Can't you use a Hall sensor? They are available in all shapes and sizes, even down to the shape of an M4-bolt, and they are indestructible.
308461

adegnes

30th January 2015, 04:29

Can't you use a Hall sensor? They are available in all shapes and sizes, even down to the shape of an M4-bolt, and they are indestructible.
308461

That would be ideal, can I use one with an Ignitech?
I mailed them months ago asking, never got a reply.

F5 Dave

30th January 2015, 06:26

Meh. I've broken one.
Used as an input on an ignitech so don't see why it wouldn't work as ign input

wobbly

30th January 2015, 06:45

To use a Hall effect as a trigger input on an Ignitech you have to order it with one input changed to suit this.
Its done with a pull up resistor already in the circuit.
I have used this on several 4 cyl car setups with a Hall Effect inside the distributor.

Re positioning the Ex sensor in EngMod - I have it at position 0 = at the port face most of the time, why and what do you want to see whats happening in the header?

adegnes

30th January 2015, 06:50

F5 Dave

30th January 2015, 11:34

ken seeber

30th January 2015, 12:11

Small ports are so hard to see in. The bits I could I was happy with. Its going to be hard to get to fix some of this stuff for access.[/QUOTE]

What we did a millennium ago was to improve the transfer passages of an ARC 100 cc kart engine. This had passages and ports the same as a Yamaha KT100S, which are miles too big and pointed in the wrong directions. We decided that the passages in a Vortex piston port engine were much better so we took Vinamoldings (or similar sort of stuff) of these. We then roughly hacked the ARC passages so the mouldings would fit and locate in. Then we slathered Devcon into the passages and then squeezed in the mouldings, effectively casting a skin of Devcon to the required internal shape. Worked out pretty well, but there were few (easily filled) pockets though.
Long story to a suggestion. As the Vinamold can be linished to a reasonable finish (taking care that it doesn't grab by linishing it in a trailing fashion), then you can reshape this to what you may want and repeating the method above. However it might be worth moulding in some string into the port end of the moulding so you can stretch the moulding to make refitting easier.
But in your case, you might need to increase the size of the moulding. Not sure on this, but you might be able to mould Vinamold onto the original moulding, after digging it out so the additional stuff is keyed into the original. The additional material being linished back to the larger desired shape.
Nary a guarantee though.

peewee

30th January 2015, 13:44

This Vinamold is great stuff for seeing

.

yep i had a hard time visualizing what the inside of the ports look like. then i put some red vinamold in there and it all became perfectly clear

Flettner

30th January 2015, 13:44

This Vinamold is great stuff for seeing what I've done wrong.

1. Oops the boost (which is modified from a reed block entry to a full length case entry) is necked & a bit too steep.

2. The bottoms of the B's actually go up a bit & in general the surface I've built up is nowhere near smooth

3. The A's kind of have a angle that's a bit odd as its triangled near the floor to follow the Ex. How (should?) I change that?.

Small ports are so hard to see in. The bits I could I was happy with. Its going to be hard to get to fix some of this stuff for access.

Well Dave, you have your shapes there, copy them into casting resin, make resin dies from that. Then cast off some fresh ones you can dick with until you have the desired shapes. Not too difficult to make a new barrel from those shapes you end up with. Imagine that your own cylinder without having to touch it with a die grinder and all the port area you want! Modern shapes / angles too.
Just what you need, more advice. Actually I'm in Wellington this weekend, don't make me come round there and do the job for you!

F5 Dave

30th January 2015, 13:59

I'll be home recovering from a hangover on sunday. I'll PM you cell if you want to come up for a beer & a nosy.

But yeah, that's a project neither of us need.:lol:

Bert

30th January 2015, 18:00

Well Dave, you have your shapes there, copy them into casting resin, make resin dies from that. Then cast off some fresh ones you can dick with until you have the desired shapes. Not too difficult to make a new barrel from those shapes you end up with. Imagine that your own cylinder without having to touch it with a die grinder and all the port area you want! Modern shapes / angles too.
Just what you need, more advice. Actually I'm in Wellington this weekend, don't make me come round there and do the job for you!

Now you have me thinking again... I have some lovely cylinders of special yamaha origin (packed away for my big toy) that could make great templates for my TZR100 all be it reducing bore size by 6mm... Need to borrow me some vinamould.
Time to get the GPR big boy furnace running and some pattern making.

F5 Dave

30th January 2015, 18:59

I can cut you off some if I ever see my PWK back.;)

mr bucketracer

30th January 2015, 19:15

I can cut you off some if I ever see my PWK back.;)bert gave that to the rubbish tip

F5 Dave

30th January 2015, 19:22

I was thinking of resurfacing that RS disc with the flapper wheel if its still lying around. Apparently some pads give that pulsing with certain surfaces.

mr bucketracer

30th January 2015, 19:44

I was thinking of resurfacing that RS disc with the flapper wheel if its still lying around. Apparently some pads give that pulsing with certain surfaces.may try that , mine was fine until my mate used it and manfeild , came back pulsing even though in the lath and dail was fine

41juergen

30th January 2015, 20:54

For the pressure trace its clear to use the 0mm position. May be I was a bit naive to think that I can use the other position to get a reasonable number for the ex temp.... :rolleyes:
Now after getting the TUbMax numbers down with lower comp I tried to use the spigot infront of the header. I used a 28mm long transition from the 75% ex area to the 100% area diameters, rest of the pipe like before. With that the power in the predicton went down about 10% and TUbMax incerased again. Could that be a sign of a kind of "over scaveging" because of better depression after EPO?

Peter1962

30th January 2015, 20:55

A question for wobbly : The 250 & 300 mx engines like the KTM stil use mechanicaly operated power valves. And they do not make use of the modern programmable ignition systems like the ignitech, neither do they use a TPS or electronic powerjet. One could say that time stood still the last 10 years or so.
In your opinion, would it be possible to modify the ktm powervalve to a servo driven unit, and change the ktm ignition for a more modern Ignitech that could operate both the powervalve as well as the ignition curve ? I know that a servo to operate the powervalve is not expensive, but can the necessary modification be done ?

Peter

Pumba

30th January 2015, 20:57

bert gave that to the rubbish tip

You guys throw nothing out so you probably need to come up with an excuse that is believable

Bert

30th January 2015, 22:03

I can cut you off some if I ever see my PWK back.;)
Yip, dug it last weekend, so it's now in the kit bag to bring down next round.

may try that , mine was fine until my mate used it and manfield , came back pulsing even though in the lathe it Dailed fine
Two of the four were fine, the rest were odd...

You guys throw nothing out so you probably need to come up with an excuse that is believable
:niceone:

F5 Dave

31st January 2015, 05:38

Yeah might be worth resurfacing as pad contaminated grooves could be the queer issue.

Will try t get into the transfers this weekend.

wobbly

31st January 2015, 06:16

Peter1962

31st January 2015, 07:19

Near on everything that increases power will increase the end gas temp - as it needs temp to create more cylinder pressure.
You need to find the combination that has the least effect on the TubMax but the max effect on power out.
Dropping the static com will drop the temp, but then raising the dynamic com with an engine tune mod will just as easily increase it again.

Re the Mx bikes with simple PV mechanisms.
Most of the Jap companies changed to digital ignitions in the early 2000s and tried electronic PJ control etc but I think only one has recently
used electronic PV servo control.
I have done many KTM and Honda 250 kart engines with Ignitech, and servo PV works really well on these highly tuned units, easy to implement and tune.
But you would be surprised that the best PV curve is usually opening around 6000 to full open at 8000 with a straight line, pretty easy to implement with
modified springs in a mechanical actuator.

I do admit that i am a little bit surprised to hear that. But is there not measurable benefit with a servo controled PV on a typical Kart track like in europe (few straight lines, a lot of corners so a lot of "on" - "of" throttle ? I would have thought that the more linear servo actuated opening of the power valve would be beneficial , when compared to the more abrupt opening of the power valve on engines with a mechanical actuator. Don't you think that there is some benefit to the electronic type under such conditions ? (I am considering this for supermoto use)

Bert

31st January 2015, 09:47

Re the Mx bikes with simple PV mechanisms.
Most of the Jap companies changed to digital ignitions in the early 2000s and tried electronic PJ control etc but I think only one has recently
used electronic PV servo control.
I have done many KTM and Honda 250 kart engines with Ignitech, and servo PV works really well on these highly tuned units, easy to implement and tune.
But you would be surprised that the best PV curve is usually opening around 6000 to full open at 8000 with a straight line, pretty easy to implement with
modified springs in a mechanical actuator.

I do admit that i am a little bit surprised to hear that. But is there not measurable benefit with a servo controled PV on a typical Kart track like in europe (few straight lines, a lot of corners so a lot of "on" - "of" throttle ? I would have thought that the more linear servo actuated opening of the power valve would be beneficial , when compared to the more abrupt opening of the power valve on engines with a mechanical actuator. Don't you think that there is some benefit to the electronic type under such conditions ? (I am considering this for supermoto use)

- by no means am I remotely a good tuner but....
We thought the same thing Peter (playing with TZR and NSR300s). But found stepped and almost almost straight line transitions produced best results (as Wobs has pointed out to us).
The theory I'm kinda working to is that the pipe is generally designed for best performance / mid to high RMP (wide open power valve) get that working well: then work backward to optimise the transition between closed and open (on the dyno)... You can even hear it in the exhaust note when your getting close (that might be me imagining things??).
Don't forget the acceleration vs how quickly the ignitech&servo combo can actually respond-keep up.
And you still need to match the carb setup and advance curve along the way.
--- no magic solution just lots of runs when first setting up a new build.

senso

31st January 2015, 12:38

I have developed a profound hate towards mechanical power valves, the freaking actuator in the Gas Gas 125 engine is so good that when it closes the valves it jams them right against the exhaust bridge and has already claimed two cylinder, now its off the bike and the valves are locked wide open :Punk:

wobbly

31st January 2015, 16:41

There is a huge amount of effort needed to get the mechanical actuator to do what you want - and even then you are
really hard pressed to put numbers to what its doing during a run on the dyno - apart from the obvious gain or loss in power.
Having the Ignitech run the ignition makes perfect sense to also run the PV as its super fast and easy to adjust.
Do a run with the PV up, do one with it down, do one with it locked at 1/2 way, then simply join the max power dots.
Job done.
PS,if the servo line ends up dead straight, the hysteresis time is minimised if you dont have any extra points doing nothing defining the line.
The microprocessor then easily ( and quickly ) interpolates the movement from min to max, extra points slow the response time quite alot.

Martin1981

1st February 2015, 00:41

Wobbly, i have a Question regarding the Crankcase Compression Ratio.

You said that you find no more power with a crankcase bigger than 1,30 on 125ccm reed valve engines.

i own a kawasaki kx 500 and i always wondered that the engine, having 4 times more cylinder volume than a 125ccm engine, is not 4 times bigger than a 125ccm engine. maybe i found at least one reason for that.

i was curious about the TDC crankcase volume of the KX 500 engine and if i have not make a huge mistake when measuring it indeed was a big surprise.

it seems that the crankcase is WAY too small. It is about 1500 ccm! that would mean a ccr of 1,5! heading for 1,30 would mean a 60(!)mm longer rod and a 60(!)mm spacer "plate" between the case and the cylinder to gain 650ccm more crankcase volume to achieve a ccr of 1,30 (and still 500ccm when taking in account that the transferports could be a little bit crappy and thus heading for 1,33). by the way this huge plate could easilie contain an intake port making a case reed engine out of it.

What do you think about that? what was the reason for the engineers making the crankcase so small? was there a reason at all? Does the 1,30 rule of thumb ccr that works for the 125ccm engines not apply for the big 500ccm engines?

On the other hand, i have heard from the honda guys that the shortrod cr 500 engines make more power than the longrod engines. so in this case it would be the smaller case that makes more power.

i am a little bit confused about that and like to hear your opinion (and of course also Frits`and all others)

peewee

1st February 2015, 06:47

hey guys can someone explain the purpose of the cross over tube on a yami twin ? im confused as to why its there or if it even needs to be there. is it because each crankcase isnt 100% sealed from each other ? if both crankcases are seperate and sealed then i dont understand why you cant just treat eash cylinder seperate and eliminate the crossover

peewee

1st February 2015, 06:54

martin i had one of them old ktm 550cc engines and if i recall i was only able to pour about 1600cc of oil in it. seems like the case ratio was around 1.5XX or so. seemed rather strange with such a small volume. installed a longer rod and 4mm spacer. never did a dyno run before or after so i couldnt say for sure if there was any power difference. on them big engines i think the manufacturer makes alot of compromises just so the engine can fit into the chassis without much trouble

Martin1981

1st February 2015, 07:17

thanks peewee, so you firgured about the same like me. yes, it might be a compromise. with a 60mm spacer i will indeed have trouble to fit the engine into the frame.

peewee

1st February 2015, 09:07

and where do you find a 200mm conrod :laugh:

Martin1981

1st February 2015, 09:46

custom made

www.crankworks.com

indeed, the stock rod is about 140mm. so when i am right with the insanely small crankcase it must be about 200mm. lets wait for wob`s opinion.

but there must be something wrong with the 500 ccm mx engines. they only make 50-60 hp stock. thats what wobblys and jan thiels 125ccm engines make...!
i often saw kx 500 cylinders with black transferducts and even inlets. and that was not black color. it was carbon residues caused by endgas that entered. nothing to do with the small crankcase but another hint that there is something wrong with the big single mx engines and plenty of room for improvement. And a 39mm carb maybe good for a 125ccm engine. but not for 500ccm.

speedpro

1st February 2015, 11:52

Ever ridden one?

senso

1st February 2015, 12:15

I know that setting the mechanical valve actuator is an art in itself, but the only thing that can be easily adjusted is the spring, there are no end-stops to adjust the allowed travel, but the valves hitting the cylinder seems like a design flaw, I have seen lots of gas gas ec 125 cylinders with broken exhaust bridges, so its not an isolated case, I have though about buying a good RC servo and make a simple linkage setup, but with the exhaust pipe passing a couple millimeters away from the valve cover its impossible to do it neatly or without recurring to a sort of YPVS approach with cables and maybe put the servo inside the air-box the only place in the bike that has a bit of free space, the fuel tank is molded in a way that only a small plug wrench can be used to turn the plug 1/8 rev each time, its molded around the carb so no easy way to even change the needle position, any work needed in the bike always ends with the side covers off, seat off, fuel tank off, just to get to the engine, oh well, lets see how it will perform with locked valves and a slightly shorter exhaust with Wobbly magic numbers.

Big cc's two strokes are "strange", I have rode a KTM 380 with a toroidal head and stock carb bored to 41mm, the torque is just crazy, but the engine is very linear, its just a beast from idling up to over-rev(it goes a wee over 11k rpm with 72 our 74mm stroke, crazy).

jasonu

1st February 2015, 12:43

F5 Dave

1st February 2015, 13:16

And on the dirt most of us would spend much of the time well off peak pipe efficiency, I know I do on my little 300.

wobbly

1st February 2015, 17:21

Using the bridge in the cylinder as an end stop for the PV travel is about as dumb as it gets, surely there is a limit in the actuator
stroke length and the pushrod ( or whatever ) drive up to the valve mechanism can be adjusted so the valve wont hit the bridge ?????

Re the case volume in the big 500 motors, I have never seriously worked on one, as those who ride them are basically shit scared of them the whole time.
So I suppose it makes no odds to the factory what they do - the things have too much unusable power as it is.
But I cant see any reason why they would not respond in the same way as the smaller engines do - but of course the rev ceiling so so much lower so
this must factor into what happens with the interaction of the reed, the case, and the transfers.

The crossover tube on the twins is there to help augment the intake flow when there are small reeds and small carbs.
As each cylinder draws on its intake some flow is available from the other side ,down the crossover tube.
When you hotrod the things with big reeds and carbs, then the tube becomes redundant.
But what does work is individual " boost bottles ", with short 16mm hoses onto the reed manifold with a volume no less than around 1.5 X the cylinder from memory.
Individual bottles work alot better than a single volume connected to both.

husaberg

1st February 2015, 17:36

I still have a CR500, I have had others previously. The power output is what Rolls Royce describes as adequate.
The biggest issue (other than the speed they exhaust us lesser mortals. ) I can see (that aside) with seriously tuning one would have to be carb size. as carbs generally don't come bigger than 40mm which is only 125gp bike size.
In general handling, They turn far slower than Cr250's (Larger gyro forces)and only have a few extra hp.
They have (as have been mentioned) serious power off idle, yet conversly actually have a narrower operational speed range than most other two stokes on account of their lower redline.
They also have no counter balancer.
A modern kTM300 would piss all over one in real workld power and ridability, and still leave the rider in a fit state to still turn fast laps, lap after lap.
The CR500 engine shares a lot in common with the early cr250's basic design. Which likely accounts for the small crankcase.
later fitting in a decent pipe would be a bit hard but not impossible

here is the lectron carb
Golly 53mm big boy
http://www.lectronfuelsystems.com/carburetor/lectron_50mm_power_jet_pro_carburetor.html
http://www.lectronfuelsystems.com/carburetor/images/50mmPJ250.jpg

Frits Overmars

2nd February 2015, 01:43

Ever ridden one?That's what it's all about. A 500 cc MX two-stroke may have hardly more power than a good 125 cc roadracer, but using that power off-road will demolish its rider in no-time. Like Wob says, the last thing you want to do is give it more power.
My friend Jan Schäffer of Langtuning is not only a gifted tuner but also a gifted rider, on both asphalt and dirt. He rides a 250 cc KTM and a 250 cc Yamaha, and he tried new pipes to make them more rideable. He went looking for laptimes instead of horsepower and he came up with a solution that makes you think.
Looking at the power graph (red=stock, blue=new) you'd say he castrated the bikes. But the resultant power delivery leaves his opponents standing.
308570308571308573

I think the ultimate goal should be to achieve the improved throttle resonse and linear power delivery without taking away the power peaks of those bikes. So the power will be there when you want it, but only when you want it.
Two-strokes have a mind of their own and domesticating them requires some out-of-the-box thinking. A solution might be throttling the exhaust.
Richard Maas, the guy who built the trombone pipe that I showed here some time ago, found out that a simple exhaust throttle slide, not at the cylinder but further downstream in the header, gives a beautiful linear power delivery (half open = half the power) without causing any overheating problems.
I think we'll try it for the Zabel next. That is an MX engine too, but it's not a 250... http://www.zabel-racing.de/zabel-motor-2010-2011

adegnes

2nd February 2015, 04:57

That's what it's all about. A 500 cc MX two-stroke may have hardly more power than a good 125 cc roadracer, but using that power off-road will demolish its rider in no-time. Like Wob says, the last thing you want to do is give it more power.
My friend Jan Schäffer of Langtuning is not only a gifted tuner but also a gifted rider, on both asphalt and dirt. He rides a 250 cc KTM and a 250 cc Yamaha, and he tried new pipes to make them more rideable. He went looking for laptimes instead of horsepower and he came up with a solution that makes you think.
Looking at the power graph (red=stock, blue=new) you'd say he castrated the bikes. But the resultant power delivery leaves his opponents standing.
308570308571308573

I think the ultimate goal should be to achieve the improved throttle resonse and linear power delivery without taking away the power peaks of those bikes. So the power will be there when you want it, but only when you want it.
Two-strokes have a mind of their own and domesticating them requires some out-of-the-box thinking. A solution might be throttling the exhaust.
Richard Maas, the guy who built the trombone pipe that I showed here some time ago, found out that a simple exhaust throttle slide, not at the cylinder but further downstream in the header, gives a beautiful linear power delivery (half open = half the power) without causing any overheating problems.
I think we'll try it for the Zabel next. That is an MX engine too, but it's not a 250... http://www.zabel-racing.de/zabel-motor-2010-2011

Wow! That pipe doesn't really need to perform, it wins on looks alone!
And that Zabel is just insane!

Martin1981

2nd February 2015, 07:44

Ever ridden one?

Hi speedy,

i said i own a kx 500. so yes, i guess i have ridden it a few times already. :msn-wink:

of course i am also scared by the power of the engine. but i like it in spite of that (or because).
i was just curious about that big singles and their small crankcases and wanted to know what the experts think of it.

the zabel has 700ccm. even more a monster. but the borexstroke ratio is not so good maybe. i like the 86x86 ratio of the kx.

Flettner

2nd February 2015, 09:20

Hi speedy,

i said i own a kx 500. so yes, i guess i have ridden it a few times already. :msn-wink:

of course i am also scared by the power of the engine. but i like it in spite of that (or because).
i was just curious about that big singles and their small crankcases and wanted to know what the experts think of it.

the zabel has 700ccm. even more a monster. but the borexstroke ratio is not so good maybe. i like the 86x86 ratio of the kx.

A KX 500 would be a good candidate for EFI, perhaps make it a little less monster.

Frits Overmars

2nd February 2015, 09:21

Wow! That pipe doesn't really need to perform, it wins on looks alone!I think so too. Using titanium wouldn't have been necessary but the guy who builds these pipes, does it just for fun. He is an engineer at BMW Sport and he likes to get away from the four-strokes from time to time. With a day job like that he doesn't need to take any orders; he puts a 'MAX' sticker on his pipes but other than that he prefers to remain anonymous.
308581308582

And that Zabel is just insane!You can say that. The first time I laid eyes on it, we had it on the dyno at the Technische Hochschule in Zwickau (were the Trabants were built).
The owner brought the bike (a world championship MX-sidecar) and a right boot; starting the monster was as challenging as riding it.

Frits Overmars

2nd February 2015, 09:26

A KX 500 would be a good candidate for EFI, perhaps make it a little less monster.The Zabel dearly needs injection. Momentarily it is being fed by a 50 mm Bing carburettor. Not because it's such a fine instrument, but simply because it's the biggest carb available. Starting is a nightmare; so is riding because it won't run decently below half-throttle. And half-throttle is about 60 HP.

Tim Ey

2nd February 2015, 09:38

A friend of a friend has a Zabel too.
308583

This is a power curve of a Zabel Engine. I do not know which type of engine it is exactly.
The lower curve is "as it is", the upper curve is with NOS injection.
I think a good point to prove Frits argument about the bigger carb in need :-D

So the question would be - why in the world would someone put nitrous oxide in such a monster?!
Because the shovel tire needs such an amount of power to crawl up the mountain :weird:
308584

Martin1981

2nd February 2015, 09:48

Momentarily it is being fed by a 50 mm Bing carburettor. Not because it's such a fine instrument, but simply because it's the biggest carb available.

Frits, as far as i know there are 58mm carbs made by lectron. but i think for 700ccm this is still too small. and the big lectrons are very expensive.

Frits Overmars

2nd February 2015, 10:28

Frits, as far as i know there are 58mm carbs made by lectron. but i think for 700ccm this is still too small. and the big lectrons are very expensive.Expensive is relative if you're going for a world championship. But don't tell them; I don't want them to go in that direction; I prefer injection.
Or maybe they just need a bigger pipe :rolleyes:.
308586

jasonu

2nd February 2015, 10:42

http://articles.superhunky.com/4/52
https://www.youtube.com/watch?v=-GiRtQZlnbw

Martin1981

2nd February 2015, 10:45

wow, this is a good photoshop job! or is this pipe really real? :shit:

Frits, another question regarding the crankcase volume....

you said that when using the 24/7 inlet one will have to use a really big crankcase. on the pictures of the modena engine of Roland Holzner you posted once, the crankcase does not seem to be very big. have you talked about that with Roland and did he tested out that it works with a small crankcase also?

F5 Dave

2nd February 2015, 10:57

peewee

2nd February 2015, 11:12

this is my ktm550 92x82 that uses methanol. it has cr500 rod (can see 4mm spacer under the cylinder) and fuel pump mounted in the airbox. space was limited so you mount things where ever you can . i have a ktm 500cc 89mm barell that im going to put on and use a cr500 piston for 89x82

F5 Dave

2nd February 2015, 11:12

http://articles.superhunky.com/4/52
https://www.youtube.com/watch?v=-GiRtQZlnbw

Thanks for posting
I had heard of those, reading the article I still couldn't help wonder if it was an elaborate send up knowing the authors other work.

peewee

2nd February 2015, 11:42

wobbly on that aluminum welding brazing rod. just ordered 3 different brands to try. im hoping it will do the job for these aux tunells. anyways i read it doesnt stick to steel. thinking maybe i can put some steel plugs in there and weld over the top then pull the plug out. you ever did anything like that ?

wobbly

2nd February 2015, 14:25

Dont know about steel, but I have alloy tig welded around brass before with no problems.
I know others have tig welded on the Ex floor on cylinders right up to the sleeve.

Larry Wiechman

2nd February 2015, 15:39

Carbon can be used as a "core" when welding with aluminum filler rod. Easy to shape and remove after welding. Check with plastic mold tool shops for EDM electrode material.

husaberg

2nd February 2015, 16:00

Frits, as far as i know there are 58mm carbs made by lectron. but i think for 700ccm this is still too small. and the big lectrons are very expensive.

53mm at least well I never knew that anyway...by the wording it looks like they may even go bigger to special order.

http://www.lectronfuelsystems.com/carburetor/images/50mmPJ250.jpg

Lectron 50-53mm Power Jet Pro carburetor

The Lectron 50mm- 53mm Power Jet Pro carburetor is the ultimate for large air flow requirements. This carburetor has been proven as the leader from NHRA Pro Stock Motorcycles, UTV & AVT Racing, Snowmobile Racing and so on…..
This Carburetor comes completely set up with Billet Bell, Billet Bowl and all machining mods!

Price: 50mm $625.00 each
http://www.lectronfuelsystems.com/carburetor/lectron_50mm_power_jet_pro_carburetor.html
52mm and 53mm $775.00 and up.

peewee

2nd February 2015, 16:07

Carbon can be used as a "core" when welding with aluminum filler rod. Easy to shape and remove after welding. Check with plastic mold tool shops for EDM electrode material.

ah yes why didnt i think of that. we use carbon blocks at work when welding against rail tracks. im not actually the welder but ive worked with them and seen how they do it. that stuff is pretty soft and could be easily grinded to the desired plug shape then easily grinded out for removal. hek they probly got a old chunk i can take home

Frits Overmars

2nd February 2015, 23:15

Frits, as far as i know there are 58mm carbs made by lectron. but i think for 700ccm this is still too small.The '50 mm Bing' was a typo; actually it's 55 mm. And you are right, it's a bit on the small side. If we were to go for all-out power, the standard Zabel should have a 65 mm carb and the projected new engine a 71 mm one. But maybe it is wise to not go for all-out power...

Frits Overmars

2nd February 2015, 23:26

Frits, you said that when using the 24/7 inlet one will have to use a really big crankcase. on the pictures of the modena engine of Roland Holzner you posted once, the crankcase does not seem to be very big. have you talked about that with Roland and did he tested out that it works with a small crankcase also?Roland has one huge handicap: the rulebook. The carburettor diameter is restricted to 30 mm. That of course influences all other dimensions in his inlet system.
A second handicap is that none of these kart engine manufacturers has unlimited funds. Roland had to avoid upsetting the beancounters so he worked with what he had.
Besides, even if money would not be an obstacle, Kart engine manufacturers cannot change an engine at will because of homologation issues.
Rolands primary goal is to get his fuel injection approved, which won't be easy because he already rubbed some stone-age officials up the wrong way with the synthetic inlet inserts in the present Modena engines. These were homologated all right, but subsequently the officials let Modena know that these inserts won't be accepted in future engines. Why? All I can think of is envy.

adegnes

3rd February 2015, 01:29

seattle smitty

3rd February 2015, 05:00

Martin1981

3rd February 2015, 05:30

Roland has one huge handicap: the rulebook. The carburettor diameter is restricted to 30 mm. That of course influences all other dimensions in his inlet system.
A second handicap is that none of these kart engine manufacturers has unlimited funds. Roland had to avoid upsetting the beancounters so he worked with what he had.
Besides, even if money would not be an obstacle, Kart engine manufacturers cannot change an engine at will because of homologation issues.
Rolands primary goal is to get his fuel injection approved, which won't be easy because he already rubbed some stone-age officials up the wrong way with the synthetic inlet inserts in the present Modena engines. These were homologated all right, but subsequently the officials let Modena know that these inserts won't be accepted in future engines. Why? All I can think of is envy.

thanks Frits! so i guess if he could like he would, we would make the case bigger...

yes....the rulemakers. :facepalm: i already heard the inlet insert story and only can shake my head.

F5 Dave

3rd February 2015, 08:21

I can understand why air cooling is appealing to some... Not a looker!
308608

Speaking of lookers, here's a shot with the dweeb mounted.
308607
Would fabricating a more aerodynamic "racing seat", one that takes over where my back ends, make any noticable difference? We're not talking face melting speed here, hopefully around 130-140kmh.
Yes road seats are terrible to race with, that will be the biggest improvement in being able to move around and not fighting foam. Aerodynamically you are just starting to make a diff at that speed. Rear is more important than one would think. Old RS125 seat would do. Older the better.

you might want to consider some hose clamps. Just saying.

adegnes

3rd February 2015, 08:46

Yes road seats are terrible to race with, that will be the biggest improvement in being able to move around and not fighting foam. Aerodynamically you are just starting to make a diff at that speed. Rear is more important than one would think. Old RS125 seat would do. Older the better.

you might want to consider some hose clamps. Just saying.

Didn't even think about the fighting foam part, makes sense, it shure is sticky. Thanks for the rs125 tip!

Clamps are for losers. No, the picture was taken while I was routing all the hoses.

Here's how you can get some proper damping and adjustability in the rear cheap if you have friends with flashy bike parts addiction - Mtb third shock.
308610

Video of rebound adjustment with the third shock
http://youtu.be/VbS1NZvA_HA

twotempi

3rd February 2015, 10:43

"Face-melting speed," . . .

For fun, google "Lt. Col Paul Stapp rocket sled" for YouTube videos of a NASA researcher of the late-40s/early-50s who was called "The fastest man on earth" in my early youth. On our black-and-white televisions, we got to watch 16mm movie footage of this insanely brave man, a doctor doing research to determine the maximum speed at which ejection seats for then-new jet fighters could be deployed.

Here's another human test dummy from those days: www.youtube.com/watch?v=9V49oBXCEEY (if the link doesn't work, go to YouTube and search "Human Tolerance to Wind Blasts"

Wasn't this test the orgin of Murphys Law where the person in charge of the data off the poor sucker in the chair was a Colonel Murphy. The patches attached to the sucker were wired up back-to-front so after a 20G deaccelaration no data was collected. Hence Murphys Law became "if it can be done wrong it will be done wrong" !!

wobbly

3rd February 2015, 12:59

Re the Modena and Rolands problems with the CIK.
I can tell you now that the 24/7 inlet will never get thru,as what is the difference between a mechanism that allows the reed block "to move "
and a mechanism that moves PV blades.
And getting the injection system approved, would in the end mean that ALL the other engine building manufacturers would have to have access to exactly the same part.
So what point would that be for Modena to spend a heap on R&D of a part that would have to be available to all.
Exactly the same issue arose with Rotax Max - Tillotson developed a pumper carb that was a bolt on and made better power everywhere.
Did that get thru the CIK, no, and it would have been an off the shelf part available to all.
Development of KZ2 engines is still WAY behind what can,and has been done already, in GP125 racing - especially regarding transfer and Ex duct geometry.
Cooling is another area with big gains to be made due to the straight line ignition affecting badly the current almost non existent squish action.
The mods I am playing with recently, destroy the best World Cup engines from Eric Savard, so I believe Modena really are wasting their time concentrating on
clever but ultimately no go technology when scrutinised by the CIK for homologation.
Sad but true I believe.

TZ350

3rd February 2015, 15:28

Here's how you can get some proper damping and adjustability in the rear cheap if you have friends with flashy bike parts addiction - Mtb third shock.

308614

Video of rebound adjustment with the third shock
http://youtu.be/VbS1NZvA_HA

That shock idea looks good and I like the tail light, we have to run a rear light in bad weather too so your idea looks a good one, thanks.

husaberg

3rd February 2015, 15:54

That shock idea looks good and I like the tail light, we have to run a rear light in bad weather too so your idea looks a good one, thanks.

The Japanese Pavement speedway bikes used to run twin adjustable steering dampers on each fork leg.
http://livedoor.blogimg.jp/autoraceblog/imgs/7/1/71c00e65.jpg

F5 Dave

3rd February 2015, 16:35

peewee

3rd February 2015, 18:16

hey guys what material is the high performance conrods made from. is it usually 4340 steel ?

adegnes

3rd February 2015, 18:49

Hmm that's either the biggest stinger I've ever seen or the smallest muffler. Might need some work meeting noise control if you have such a thing, and if you don't you will have soon running that:crazy:

That is the stinger, but there's a 13.5mm venturi at the end of the cone. The stinger will be perforated and used as the innards of the muffler, but I want to get it running and see how the pipe performs before i finnish it.

TZ350

3rd February 2015, 18:52

Injectors turned up from Ecotrons today, four days from date of order and two of them were weekend days, pretty good service in my books.

308623

I fitted a smaller injector and did a bunch of runs at different throttle settings. Interesting that the 60, 50 and 40% runs carry on out to close to 13,000 rpm.

308625

Blue line is the TPS. 100-90-80-70-60-50-40% throttle settings. It is certainly throttling and coming back onto the power much better. I will have to analyse the data to see if I can use an even smaller injector.

308624

Just by changing the central injector (and the injector size in the EFI software) I got the Blue line, I am not sure what that means as by rights, it was the same Alpha-N map so I was expecting the curves to be the same..... :scratch:

adegnes

4th February 2015, 08:44

I've never really known exactly why the crank should have some axial play, thought maybe it was because of different expansion rates between metals and torque between the casehalves, and maybe to allow for some misalignment.

Found this:
http://husaberg.org/mechanical/17170-definative-main-bearing-thread.html

From the first post:

"what causes the oem roller bearings to fail ?

1) crank spread under its own weight is the main problem

2) misalignment of the bearing bore, seems rare, search lineaweavers posts

3) insufficient crank axial play (end float) with crank spread

what is crank spread?

when the crank spins, its own weight causes it to spread outward opposite the pin
when you add in the combustion forces they contribute further to the spread.

sorry for the crappy pic there is a better one i will add later

http://2.bp.blogspot.com/-2Jn0rR9ZdjM/Ukjvn6REP9I/AAAAAAAABNI/w_IJFQeTY0A/s1600/Truing+the+crank_C.jpg

in this condition while running the axial play of the crank reduces until the forces deforming the crank outward are matched by the crank resisting deformation (a function of its stiffness)

if you don't have enough end float or stiffness for the weight of the crank and the rpm its doing your end float (axial play) will become zero

with zero axial play the NJ series roller bearings will experience side loads as they are now subjected to some of the force causing crank spread."

wobbly

4th February 2015, 09:12

Where we are talking "normal " cranks and not idiot huge things like the KTM - or Triumph twins for that matter, axial end float on the crank
simply makes more power.
As the axial clearance of the stock bearings is taken up by differing expansion rates or crank flex, the normally fitted ball races see a huge increase in end wise friction.
Using C3 as you should ,does help, but when using balls you have to polish the crank axles to alow a slip fit with 0.3mm end float in a 125.
This ultimately causes wear on the slip fitted journals.
Using rollers means that the axial clearance can be arranged to be within the bearing end faces, and the inner race can still be a slight press fit.
As a side effect the rollers are capable of twice the radial load so last much longer - though they do have slightly higher rolling friction.
The only issue with the rollers is they dont like any axial angular misalignment, and in really dumb designs like a Triumph twin, where the axles of a 750 are the same size as that
we use in a 125, of course they bend like hell with 15Kg of pig iron flailing about.
So they developed a special line of rollers called " SuperBlend " that have a slight radius tapered end on the rollers to allow some axle flex.
Many designs have one bearing locked onto the crank - but floating the other end still works well to reduce axial friction.

peewee

4th February 2015, 15:47

well i rounded up some carbon blocks from work. also got some spare pieces of the sand molds used for thermite welding. between these im hoping i can make a plug and weld over the top, thus creating a tunell. both will be easily removable. ill report back if it works or not

wobbly

4th February 2015, 17:51

Re conrods, most Asian manufacturers use CRM415, there is no direct correlation in US types to this but its closer to 4140 than 4340.
Its called 15CrMo5 .The different spec gives a more ductile core when case hardened to 60-62RC as is needed to support needle rollers.
This gives a stronger forging able to withstand shock loading better.

husaberg

4th February 2015, 18:20

Frits Overmars

4th February 2015, 23:05

I was looking at a pic the other day (a cutaway drawing of a RSW crankcase)I mused to myself... if one of the benefits of the roller bearing in this application was also a better smoother straighter inlet port due to a potentially smaller outer id of the bearing. Maybe I was overthinking it or its just a happy coincidence.You weren't overthinking and is was not a happy coincidence either, but a necessity. When working at the first Rotax-256 tandem-twins in the winter of 1980,
I substituted the standard 34 mm carburettors with 38s. When adapting the rotary-side cases to the bigger carbs the outer ball bearing races started peeping through!308655

The later roller bearings allowed fitting 42 mm carbs. As an added benefit they made splitting and closing the cases a whole lot easier.
The first ball-bearing tandem-twins were real pigs, with both inner bearing races press-fitted to the crankshaft and both outer races shrunk into the cases.

wobbly

5th February 2015, 08:46

Thanks for reminding me Frits about how much we hated those early Rotaxes,I spent many cold nights at ZipKarts in England
grinding and dyno testing them.
Polishing the journals was the first thing I did and having slip fitted bearings was a godsend when pulling them apart all the time.
Hines 83 championship wining Superkart engine made 84Hp at the sprocket, and boy did we think we were clever - not.

FastFred

5th February 2015, 09:04

spark plug thread sizes and pitch http://www.mrcycles.com/page/sparkplugspecguide

Martin1981

5th February 2015, 09:12

84Hp at the sprocket, and boy did we think we were clever

come on wob.... 42 sprocket hp/125ccm in the early 80s..... this is not that bad!

F5 Dave

5th February 2015, 11:33

A mates one with std 82 barrels in a GP bike makes 60hp at the rear wheel. its got size smaller Mikunis & pipes for short ccts and a very nice curve at conservative revs (all the cranks could take with those size pins & without Wobs hand selected rollers). These were pre powervalve, so that's pretty impressive for the time.

wobbly

5th February 2015, 12:35

Ha, I had forgotten about the rollers - I spent a fortune back then buying a 4 digit micrometer and went thru boxes of big end bearings
to find enough to make sets of needles that were all the same within 0.001mm.
They varied up to 0.008mm in one cage set from the factory, and the rod bores varied 0.005,so if you were keen you could match them all together.
Hines championship year we were able for the first time to run the same cranks all season,previously we would be lucky if they lasted the first all gear run on the dyno even with 16:1 on 747.

Frits Overmars

5th February 2015, 21:48

Ha, I had forgotten about the rollers - Hines championship year we were able for the first time to run the same cranks all season,previously we would be lucky if they lasted the first all gear run on the dyno even with 16:1 on 747.I did all my Rotax development work on the Rotax124 single (the one with the teflon inserts holding the crankshaft bearings in the magnesium cases).
The teflon had to go but after that I never experienced any crankshaft problems. I ran the engine to 14.500 rpm on 25:1 Castrol with 0,4 mm quish gap.

Hines 83 championship wining Superkart engine made 84Hp at the sprocket, and boy did we think we were clever - not.In 1980 my single gave 34 HP at my Heenan & Froude brake. Meanwhile Jan Thiel was working at Reggianis Rotax tandem-twin in Italy and he too extracted 34 HP at his Borghi & Saveri brake from a 125 single. These Rotax tandem-twins would run circles around the Yamaha TZs until the primary coupling gears shed their teeth.
So you weren't doing all that bad, Wob.

wobbly

6th February 2015, 10:01

The 83 engine had special cylinders that Hines got the factory to cast with alot more material around the Aux ducts ( it was easy for them to scrape
material off the moulds prior to casting ) so I could make the Aux ports and ducts WAY bigger right down to the flange.
That is where I begun to learn about NOT making the exit size bigger as I ruined a perfectly good set of cylinders, and waisted JLs time building a special
set of pipes with 42mm headers.
This made a whole lot less power,so I wasnt too popular at the time, but if only I had done some testing with the stock small duct, and the big pipe.
In the end the new way fat belly JL pipes I did made big power gains,and they made a fortune selling these as you HAD to have them or simply got blown away.
The factory didnt believe what we were saying about the power numbers we got off our Borghi ( so basic I had to write down the numbers as the run progressed )
until we sent them one of the spare development sets.
Then it dawned on them why Hines had set new lap records at every track that year - near on a full week grinding one barrel.
But it was several years before we could replicate that power in production cylinders as the factory would not do " specials " for just anyone.

husaberg

6th February 2015, 11:16

You weren't overthinking and is was not a happy coincidence either, but a necessity. When working at the first Rotax-256 tandem-twins in the winter of 1980,
I substituted the standard 34 mm carburettors with 38s. When adapting the rotary-side cases to the bigger carbs the outer ball bearing races started peeping through!308655

The later roller bearings allowed fitting 42 mm carbs. As an added benefit they made splitting and closing the cases a whole lot easier.
The first ball-bearing tandem-twins were real pigs, with both inner bearing races press-fitted to the crankshaft and both outer races shrunk into the cases.

Seeing as I m now batting near one in 600.:innocent:
The other thing that occurred to me was the other long rod advantage, in that there was a lot more room for a more gently radiuses more straight inlet as well as the many other advantages.

308683
If I may ask does anyone know the dimensions of the rsw main bearings? I tried a quick google
They are only listed as a part number in the rws part manual that doesn't seem to cross reference.
but I think it maybe approximates this
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=304386&d=1413875767
25 x 52 x 15 mm

http://www.maranello-engineering.com/sgm/cuscinetto-di-banco-speciale-a-rulli-p-1868.html?language=en

peewee

6th February 2015, 14:16

wob i was thinking of something like this for carb angle. maybe i cant get a straight on shot into the cylinder but anything should be better than the large kink of the common aftermarket and oem manifolds. as the carb is tilted farther forward is it better to use a deep float bowl rather than a wide shallow one ? another question on crankshafts. been trying to locate a +4 set of new webs. only thing ive found is fully assembled +4 cranks, so ill have to pull them apart i guess. most are welded at the manufacturer so its going to be a pain. almost thinking of some billet webs from crankworks as theyre sold in unassembled sets but $1000. you got any ideas on this ?

wobbly

6th February 2015, 14:33

That carb angle is right at the limit, and is about what I end up with when machining 7* off the face of TZ350 cylinders.
The issue is the proximity of the fuel level to the pilot jet, you have to lower the floats at least 3mm or under brakes the slosh dumps
petrol straight thru the pilot drilling in front of the slide, and into the intake.
I have a few +4 cranks that are welded in the centre axle only, makes it easy to split the outside wheels off if needed.
Pm me re this.

Grumph

6th February 2015, 15:38

If the pilot jet is a plain orifice jet, like a dellorto for example,you can make up a male/female extension to lower the jet well down into the bowl. this removes most of the "slosh" effect.
If it's got an emulsion tube incorporated, you're on your own...But a piece of brass tubing slip fit over the jet, and long enough to be trapped against the bottom of the bowl will do much the same thing. Cut some slots in the bottom end of the tube of course for fuel entry.
If you think you've got a problem under braking, try speedway TQ's with bike carbs and Methanol. High sideways G's which the carbs were never intended for.

wobbly

6th February 2015, 16:06

Makes no difference whatever where the jet itself is situated, the rising fuel level at the front of the bowl simply runs up the drilling.
As soon as the bowls liquid level is higher than the pilot drilling into the carb bore, fuel will spill.
The only carbs that dont do this have the bowls sitting horizontal, and the bore downdraft, like FCRs,or the other is the Lectron that has
no pilot circuit at the front of the bowl.
Some Dellortos have the pilot behind the emulsion tube, so dont suffer from the level rising at the front of the bowl under brakes.

richban

6th February 2015, 16:17

The only carbs that dont do this have the bowls sitting horizontal, and the bore downdraft, like FCRs,or the other is the Lectron that has
no pilot circuit at the front of the bowl.

With the FCR's you've run on the 2 strokes wobbly. Have you run into the problem I have, where the needle rounds out the top of the emulsion tube / Needle jet and kills all half throttle fuel control?

F5 Dave

6th February 2015, 20:08

S`common problem and why I run an `orribile mikuni RGV carb on the 100. Pity there isn't a real downdraft pwk.

Frits Overmars

6th February 2015, 22:13

Pity there isn't a real downdraft pwk.Build your own; start with foul-stroke stuff and replace what doesn't suit you. We did it in 1992, so why not now? Maybe because now injection would be a better bet...
308702308703

F5 Dave

7th February 2015, 07:21

Yeah they tend to be a little as the a`mercans say; spendy. And the last thing I need is another project but thanks for the thought.

wobbly

7th February 2015, 08:19

The needle clips in the FCR are locked into the slide but the needle is free to slop about - a real design fault as yes the big 4Ts that run them always end up with worn tubes.
The carb on the Rumi is an FCR,thats the first time I had seen the idea used,the "Great Leader " should have taken note somewhat later and used the idea instead of
putting a 45* bend in his upsidedown creations intake - instantly loosing a couple of Hp.
Re downdraft PWK, the carbs on NS400s etc are exactly that,some had D slides but they would work really well in a 100.

jasonu

7th February 2015, 11:18

Re downdraft PWK, the carbs on NS400s etc are exactly that,some had D slides but they would work really well in a 100.

Good luck finding any of those that don't cost more than the bucket you want them for...unless you and 2 mates can split them.

http://www.ebay.com/itm/Honda-NS400R-NS400-NOS-Carbs-Carburettors-TA09A-/370885751936?pt=UK_Motorcycle_Parts_13&hash=item565a837480&vxp=mtr

husaberg

7th February 2015, 13:03

Good luck finding any of those that don't cost more than the bucket you want them for...unless you and 2 mates can split them.

http://www.ebay.com/itm/Honda-NS400R-NS400-NOS-Carbs-Carburettors-TA09A-/370885751936?pt=UK_Motorcycle_Parts_13&hash=item565a837480&vxp=mtr

The NS400 carbs are pretty much the same as the NSR250 carbs.......
Which come in sizes between about 28mm and 34mm.
308716

Also there is always the TDMR Mikuni but as Dave said a bit spendy........
http://www.braigasen.com/TDMR40-B14_500.jpg

Oh it looks like there is a down draft PWK (Well it looks like one with the slide body)
The YD-MJN28
Yoshimura Downdraft - Multiple Jet Nozzle
Hate to think what it costs
http://www.yoshimura-jp.com/en/products/engine/yd-mjn.php
buggger only 24mm and 28mm
308713308714308715
http://shop.yoshimura-jp.com/syouhin/syousai.php?id=16682

TZ350

7th February 2015, 13:56

Hate to think what it costs
http://www.yoshimura-jp.com/en/products/engine/yd-mjn.php
buggger only 24mm and 28mm
308713308714308715
http://shop.yoshimura-jp.com/syouhin/syousai.php?id=16682

30,000 yen = $342 NZD

husaberg

7th February 2015, 14:55

30,000 yen = $342 NZD

you sure? because the Small TDMR's are between 500 and 900 US
it seems a bit odd doesn't it....... Hard case but sized more for a 50 (or restricted 125:msn-wink:)
he googles and comes up with the same answer as Rob though..........bugger its not a little bit bigger...

https://www.youtube.com/watch?feature=player_embedded&v=APq5jz4T_08

dark art

7th February 2015, 15:21

Wouldn´t the Mikuni TM SS series work? Several bikes had those carbs from stock, the yamaha DT125R model comes to mind, in 28mm I believe.

F5 Dave

7th February 2015, 15:27

husaberg

7th February 2015, 15:44

Having some NSR carbs here (thanks yowling) and an old mvx carb they are the same body and 25mm mvx. 28 NSR. But I believed that 28 was as big as they got.

I've got a 32 RGV carb and a matching one I've bored to 35 that has worked better but had issues also home mod for PJ solenoid but needs more time and I've had other issues to sort.

I have a pair of NSR carbs here that's a bit bigger than that.
They have the air correction solenoid and TPS not sure which model though, but it came from Rob......
He goes upstairs to measure........
Typical keihin 36mm at bore but more like 30x 32 closer in at the venturi (think of a XR200 carb if you don't know what I mean)

It's a TA22a I have here so I'm guessing Daves one he has is a TA10 or suchlike off a MC16 or earlier.....maybe even mc14 or whatever the ns250 was called
According to the NSR World site the nsr MC28 had TB model carbs so I guess mine are MC21 or 18 (later they are early MC21)

He fumbles about the NSR world site ...oh here are the std settings
http://tech.nsr-world.com/nsr250/all-nsr250/nsr250-stock-carb-settings.php
they list them as 32mm but that's a venturi measurement.
according to the blurb they have a pj..........

Wouldn´t the Mikuni TM SS series work? Several bikes had those carbs from stock, the yamaha DT125R model comes to mind, in 28mm I believe.
yeah we got them here on the tzr250.. decent carb but a bit small, they only bore out to 29mm

peewee

7th February 2015, 17:24

Re downdraft PWK, the carbs on NS400s etc are exactly that,some had D slides but they would work really well in a 100.

if i need a downdraft style for this yami engine then whats my choices in 36mm-39mm range ? will be mainly for drag racing. mostly up sand hills

tomorow im gonna take a look at the pwk on my ktm 300 and see what kind of angle its sitting at. maybe they can be used with alittle more forward tilt without much trouble. it only has to work well going up the hill :laugh:

if nothing else i guess i could use some lectrons. dont they work fine at a fairly steep forward angle ?

F5 Dave

7th February 2015, 17:41

if i need a downdraft style for this yami engine then whats my choices in 36mm-39mm range ? will be mainly for drag racing. mostly up sand hills

tomorow im gonna take a look at the pwk on my ktm 300 and see what kind of angle its sitting at. maybe they can be used with alittle more forward tilt without much trouble. it only has to work well going up the hill :laugh:

Ahh ya bugger, I was just about to crack that joke.

Tim Ey

7th February 2015, 22:04

It did; it circulates 60 liters per minute for an engine that produces about 60 hp at the crankshaft: there's your rule of thumb.

A friend of mine measured a Suzuki GSXR 600 K4 Pump, mounted on the bike.
308730
Like this one http://www.ebay.de/itm/Suzuki-GSX-R-600-K4-K5-Wasserpumpe-Motor-/390287894464?pt=DE_Motorradteile&hash=item5adef8a7c0
I do not now the crank to pump ratio but I think this might help a few of you guys as the pump is good seperated from the engine.

Cheers!

oktrg500

7th February 2015, 23:43

Hi, I'm a 48 year old (Or, is it young?) Norwegian. I've been lurking around this thread for some time now. I'm currently in the process of building a tuned Rotax 122 engine. The bike will be used mostly for fun on road and track days. My only concern is getting as much power as possible from the engine.

The cylinder has been reworked by a known UK tuner. To go with this I've got a VHM head for use with flat top piston. And a good selection of different reeds, carbs, std and custom exhausts, different ignition CDI's, etc.

I just can't make up my mind if I should go for a 1 or 2 ring piston. It seems to me both have their pros and cons and I would appreciate very much any advice. For now, I'm thinking 1 ring is the best.

Thank you.

Martin1981

7th February 2015, 23:54

hello. 1 ring! there is no need for a second ring. good 1 ring pistons with the ring peg at "18 o clock" position (so you can widen the b ports) are easy available for this engine.

i dont know why but i doubt this vhm heads a little bit. i think it would be better to not use a flat piston and have a stock head machined to desired specification.

oktrg500

8th February 2015, 03:56

hello. 1 ring! there is no need for a second ring. good 1 ring pistons with the ring peg at "18 o clock" position (so you can widen the b ports) are easy available for this engine.
It seems I just can not let go of the thought of the rings dissipating heat from the piston. Thus - two rings should dissipate more heat than one ring. At the same time, I've got the impression the ability of the heat dissipation from the rings might be overrated.

i dont know why but i doubt this vhm heads a little bit. i think it would be better to not use a flat piston and have a stock head machined to desired specification.
I've had a std head machined down as much as possible (0,5mm), but this only brought down the squish band from the usual 1,8/1,9mm to 1,3mm. The VHM heads are said to dissipate heat much better than the stock 122 heads. Maybe I should get a VHM head for domed piston and machine it to the desired specification. Thanks.

Frits Overmars

8th February 2015, 07:04

Hi, I'm a 48 year old (Or, is it young?) Young, definitely. Velkommen, ung mann.

It seems I just can not let go of the thought of the rings dissipating heat from the piston.I can't let go of the thought that a ring rubbing against a cylinder bore generates heat :rolleyes:.

wobbly

8th February 2015, 08:17

The most powerfull 125 known to man quite happily got rid of the heat generated thru a single ring.
There have been cases of huge overbored ie oversquare cylinders that had piston heat trouble and twin rings
did help in this particular scenario, but that was a special case where the real issue was lurking elsewhere and the rings just
ameliorated the symptoms.

F5 Dave

8th February 2015, 10:38

Ohh fancy word for the day.

Right its a sunny day so I`m off down to the garage to ameliorate my transfers.

senso

8th February 2015, 12:16

My two year old crm 50 cylinder retired after running for 30 minutes with no cooling and still managing not to seize, so for science I cut him in half(sorry buddy) to see and measure in fact how much wall thickness I still have to play around with in the new cylinder, the conclusion is: not much.
I talked with a machinist friend about the possibility of welding the exhaust duct to gain a couple mm's but he doesn't want to do it, he says it might crack, so I will resort to a maximum of 190º of exhaust timing at 80% piston diameter.

About the duct shape, it should be straight or is it ok to leave it like it was, sort of a deLaval nozzle(more or less expected I grinded the exhaust with the burs in steep angle and very slowly due to the known limitation of the wall thickness)?

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TZ350

8th February 2015, 12:33

maximum of 190º of exhaust timing at 80% piston diameter.
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What is the transfer timing (STA)? I know low and wide is the prefered option for transfers but to improve the exhaust timing can you raze the cylinder a little without upsetting the transfers and spigot the head into the cylinder to get the correct squish clearance. And if you are widening the exhaust a lot it may only require grinding it up just a little to get 194 - 196 duration to get a satisfactory STA for blowdown. Anyway looks like it was a very good idea to have cut the old cylinder.

senso

8th February 2015, 12:40

Unfortunately the transfer timings from stock are atrocious, almost 130º if I remember correctly, but you are in the right direction about raising the cylinder, its common to do that with this engines, there is not a lot of cylinders for them and sadly almost all of them are expensive copies of the original cylinder, almost all of them in cast iron too.

I will look to the STA values and report back, I don't have a goal for maximum power, just would like to have a bit more, she was fun all right, but could be even better.

peewee

8th February 2015, 14:28

hey guys what you think. i was sucessfully able to fill in the front side of B with low temp rod and straighten it. kind of tricky but it was my first time so it should get easier. next is try to see if i can get a outer wall over the aux and create the passage

TZ350

8th February 2015, 15:38

hey guys what you think.

Very clever, looks good to me.

wobbly

8th February 2015, 15:56

A far bigger issue with that 50cc is the HUGE idiotic size of the duct exit - looks real easy though to counterbore it and fit an insert to get
the exit area down near 90% of the effective port size.
This will pick up a major amount of power with a new pipe having the way smaller entry size, that then creates naturally steeper diffuser etc.

F5 Dave

8th February 2015, 18:45

S' ' funny I was just thinking that 50 could do with some low temperature filler on the waterway and peewee posts about it.

Frits Overmars

8th February 2015, 22:16

... how much wall thickness I still have to play around with in the new cylinder, the conclusion is: not much... I will resort to a maximum of 190º of exhaust timing.I'd say you stopped grinding just in time. But radiusing the port's upper edge may still give you a bit more timing and quite a bit more flow.
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About the duct shape, it should be straight or is it ok to leave it like it was, sort of a deLaval nozzle?Your duct may look like a DeLaval nozzle, but to the exhaust gases it isn't. A DeLaval nozzle should offer the outflowing gases a nicely guided duct for controlled expansion. In the case of an opening exhaust duct the bulk flow occurs while only the top part of the duct is open, so the gases dash into the deep without any guidance at the bottom. Take Wobs advice.

senso

9th February 2015, 03:49

I think the stock exhaust diameter duct is already in the 26 to 27mm when stock, but machining a bit of the cylinder and sticking a plug is not a bad idea.

I was mistaken, the maximum I can go is 22mm from top of cylinder to top edge of the exhaust port, with the stock 91mm con-rod and 41.4mm its just shy off 186º, the transfer all sit at 32.5mm from top, about 124º timing for A and B, being the C a bit lower with around 117-118º.
That gives 31º of blow-down, but with limited area.

In that cut cylinder I was trying do give it a radiused edge but its a tight spot for my limited tool to put a radius on it, but I will try to do it, worse case scenario I will do it by hand with sand-paper.

The engine was also running with 1.1mm squish, now I dropped it to 0.8mm(the minimum allowed by the gasket, and the head is to thin and breaks when o-ringed so its no an option).

I still don't like a lot of the idea of raising the cylinder and machining the top, because I just gain timing in all the ports, so the blow-down remains the same and 1mm will leave the cylinder with almost 130º in the transfers.

I don't have an accurate port-map with me now, but the exhaust port with 80% width has about 575-600mm^2 total area, following the 90% rule from Wobbly it would need at max an exhaust duct with 27.6mm in diameter, I think that cylinder has 28mm so not far off.

I found a couple pictures of the cylinder in one piece, I think there is still a bit of exhaust area to be gain, but I'm kinda shy to square the exhaust port and then have the piston rings stuck in it, what is your opinion about the shape Frits?

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Thanks for the advice.

adegnes

9th February 2015, 03:55

...worse case scenario I will do it by hand with sand-paper..

One big advantage of doing it by hand with sand paper or small files - it's slow, very hard to screw up.

adegnes

9th February 2015, 03:59

Playing with the belt tensioner.
Whats better? Both pictures are with the variator in "low gear"

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vs

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Yeah, pipe is ugly I know...

senso

9th February 2015, 04:15

The first one seems to provide a smaller footprint, less pulley to put your feet into, but I don't think the skate bearings will be up the task, maybe using a belt tensioner from a car might be a better option, from some small 1.1 to 1.5l engine will be compact and have everything included(bearing, rolling surface, eccentric adjuster, spring/hydraulic tensioner) in a ready to mount piece with 2 or 3 bolts, the best part is that you get all that for 30-40€.

adegnes

9th February 2015, 04:21

Belt tensioner from a car is a good idea, thanks!

TZ350

9th February 2015, 05:48

I was mistaken, the maximum I can go is 22mm from top of cylinder to top edge of the exhaust port, with the stock 91mm con-rod and 41.4mm its just shy off 186º, the transfer all sit at 32.5mm from top, about 124º timing for A and B, being the C a bit lower with around 117-118º.That gives 31º of blow-down, but with limited area.

I still don't like a lot of the idea of raising the cylinder and machining the top, because I just gain timing in all the ports, so the blow-down remains the same and 1mm will leave the cylinder with almost 130º in the transfers.

The degrees of blowdown may remain the same but if you are widening the exhaust port, the blowdown STA increases, its the STA (Specific Time Area) that is important.

The timing of the exhaust port becomes important because of the all important pipe resonance reinforcement you get around 190-194 duration of the pressure waves in the pipe.

breezy

9th February 2015, 06:01

Playing with the belt tensioner.
Whats better? Both pictures are with the variator in "low gear"

308794

vs

308795

Yeah, pipe is ugly I know...

hello, just an obserevation, shouldnt the front pulley be turned the other way so that the rollers push against the sheave to grab the belt, or am i seeing it wrong. yeah seeing it wrong.. rollers still push sheave

adegnes

9th February 2015, 06:08

hello, just an obserevation, shouldnt the front pulley be turned the other way so that the rollers push against the sheave to grab the belt, or am i seeing it wrong.

It does exactly that, the outer moving sheave is pushed towards the inner stationary sheave by the rollers. It's just mounted inside out compared to most scooters.

breezy

9th February 2015, 06:22

yeah sorry just edited post... does anyone know the dimention from the center of the front variator shaft( crankshaft) and the clucth wheel shaft on a piaggio zip 50cc 2t.

wobbly

9th February 2015, 07:50

From the 50cc pics its easy to see that you can get into the waterjacket and firstly bead blast then secondly metal spray the cast iron above the EX.
This works very well, we have been metal spraying the cast iron bore cylinder tops on KT100 Yamahas for years, then spraying the alloy fins as well to
get the rule book legal overall cylinder length dimension after machining the base to drop the port timings.
And its the effective port area you need to use ie is that 600mm2 times the down angle cosine ?

lodgernz

9th February 2015, 08:45

[QUOTE=adegnes;1130828775]Playing with the belt tensioner.
Whats better? Both pictures are with the variator in "low gear"

I don't know about variators, but if they were toothed or fixed pulleys, the first option would be the one, since it provides the belt with more wrap-around on each pulley

adegnes

9th February 2015, 08:49

Drew

9th February 2015, 09:21

[QUOTE=lodgernz;1130828838]

That makes sense.

To a point. But the extra 'drag' is less than desireable, one would think.

I'd get a shorter belt, and let it tension with the pulleys like it's meant to.

adegnes

9th February 2015, 10:12

[QUOTE=adegnes;1130828842]

To a point. But the extra 'drag' is less than desireable, one would think.

I'd get a shorter belt, and let it tension with the pulleys like it's meant to.

The drag thing makes sense to.
It's single variated, originally the whole engine was the tensioner - spring loaded and swinging back when the variation was happening, the rear pulley is just that; a pulley, no moving sheaves.

jasonu

9th February 2015, 10:28

hello, just an obserevation, shouldnt the front pulley be turned the other way so that the rollers push against the sheave to grab the belt, or am i seeing it wrong. yeah seeing it wrong.. rollers still push sheave

I would have thought no tensioner was appropriate as the moveable sheave increases and decreases the amount of belt needed as it moves in and out. That is how it works on my Polaris Sportsman 700 twin quad anyway.

https://www.google.com/search?q=polaris+sportsman+700+cvt+drive&espv=2&biw=1280&bih=915&source=lnms&tbm=isch&sa=X&ei=T-PXVKeNMZShoQTZqYKIDQ&ved=0CAcQ_AUoAg#imgdii=_&imgrc=RLcu9nahbcRwJM%253A%3BJvm2Mk6geo6l5M%3Bhttp% 253A%252F%252Fi.ytimg.com%252Fvi%252FO_jbUTQyoms%2 52Fhqdefault.jpg%3Bhttp%253A%252F%252Fwww.youtube. com%252Fwatch%253Fv%253DO_jbUTQyoms%3B480%3B360

lodgernz

9th February 2015, 10:31

Ocean1

9th February 2015, 10:55

I don't know about variators, but if they were toothed or fixed pulleys, the first option would be the one, since it provides the belt with more wrap-around on each pulley

As long as the belt's designed to flex backwards...

TZ350

9th February 2015, 13:04

Page 1110 progress on the EFI thing.

I have made three basic mistakes.

1:- using the biggest injectors, I should have used the smallest injectors that will support maximum power. Because the smaller injectors can be dialed back by the CPU for a wider range of tunability. The big injectors are forced to stay on for the minimum injection time and flood the engine.

2:- Had even spacing between the columns of the Alpha-N map. I needed to reduce the number of columns in the fat areas of the map and use them in the steep areas to reduce the size of the steps between them.

3:- Similar thing with the rows on the Alpha-N map, I had to many rows in the power area where things don't change much and not enough in the lower (below 50% TPS) area where things are changing rapidly and wound up with steps that the CPU found difficult to bridge especially while it was also trying to decide when to swap between high and low injectors.

:doh: I think I have shot myself in the foot again.

After the poor showing at Taumarunui where the bike would not come back on the throttle I thought I had better run it up on the dyno with the Ecotrons Procal tuning program displaying the Gauge monitoring screen in the hope of seeing what was going on.

The bike would start and trickle out onto the track easily enough and it would fly like a cut cat when it was shown a bit of stick. But it had two real bad faults, at about 8,000 rpm it would jump around like a demented kangaroo and when it was shut off at high rpm it would not come back on the throttle until the rpm had dropped under 7,000 rpm or so.

I thought it may be to rich/lean at lower throttle settings on over run at high rpm or it needed some adjustment to the throttle blip virtual fuel pump. But no amount of Map fiddling improved things.

Sorry about the jerky video but that is the bike shaking me around as I was recording the gauges. Its not dangerous to run a bike up full tit on the dyno by yourself with one hand while trying to record video with the other - yeer right its not dangerous.

Top left gauge is rpm and it tops out close to 13,000. Top right is the TPS and the two gages on the bottom right are for the injectors. Injector 1 to the left, Injector 2 to the right.

<iframe width="420" height="315" src="http://www.youtube.com/embed/tXP6aUKbzcE" frameborder="0" allowfullscreen=""></iframe>

You can see injector 1 increasing in pulse width until it switches over to injector 2 at about 8,000 rpm, just where it starts to jump about. Then Injector two stays at 1.7ms right up to 13,000 ish rpm.

Close the throttle and injector 2 stays at 1.7ms until the rpm drops back below 7,000rpm and the system switches back to the smaller injector 1 at which point the engine will respond to the throttle again.

On over run above the changeover point the engine won't respond to small and medium throttle openings but at higher rpm it will jump back into life when given full throttle.

Previously I had been wanting to get as much fuel in as possible in the shortest amount of time and I had made injector 2 as large as possible and injector 1 was much smaller and only for starting and off pipe running below 8,000 rpm. The smaller the injector the more adjustable it is with the fuel map.

Both injectors have a minimum open time of 1.7ms and what I think is happening is that the big injector is too big and even at its minimum open time it drowns the motor at anything less than near full throttle.

And the jerking at 8,000 rpm is the EFI being confused about whether to use the injector that is to small or the injector that is to big.

I think Injector 2 needs to be smaller so it gets held open over a greater range of time from say 1.7ms at small throttle openings and high rpm to 3.5ms for full throttle at high rpm.

At the moment the EFI works well with injector 1 but it has no adjustment with injector 2, its all or nothing, actually injector two is virtually full on all the time above 8,000 rpm because it can't be run any slower than 1.7ms it needs more adjustment and we can only get that by going to a smaller injector because a smaller injector would need to be held open for longer than the minimum 1.7ms.

To get the greatest range of adjustment out of a fuel injector you need one that is only just big enough to do the job. I think I have been running one that is way too big for the job and even on minimum open time it is drowning the motor on overrun.

Instead of thinking big injector to get loads in quickly I think to get best throttle response I need to think smallest injector possible that is only just big enough to do the job at max fuel demand (max torque).

Tomorrow I will swap out the big injector 2 for a smaller one and see how that goes, here is hoping .... :)

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Ok after months in the wilderness I finally figured it out. I was right about needing smaller injectors.

So it looks like, to maximize tune-ability you need to minimize the injector size......... in hindsight its so obvious really .... :facepalm:

<iframe width="420" height="315" src="http://www.youtube.com/embed/0lMT2GLtKsg" frameborder="0" allowfullscreen=""></iframe>

Now that I have smaller injectors fitted, on the bottom right gauge you can see the number 2 injection pulse width increasing and decreasing and it is coming back onto the throttle much better now that the EMS has some pulse width range to play with.

Not perfect yet but very very promising.

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Making progress with mapping the fuel injection.

Did a series of runs at different throttle openings 100-90-80-70% etc and it fell apart at 40%.

I will have to sit down now and look at the recorded run data to see why, it may just be to rich or something else, like the injectors are still to big or not crossing over nicely at 8-9,000 rpm.

Injectors turned up from Ecotrons today, four days from date of order and two of them were weekend days, pretty good service in my books.

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I fitted a smaller injector and did a bunch of runs at different throttle settings. Interesting that the 60, 50 and 40% runs carry on out to close to 13,000 rpm.

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Blue line is the TPS. 100-90-80-70-60-50-40% throttle settings. It is certainly throttling and coming back onto the power much better. I will have to analyse the data to see if I can use an even smaller injector.

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Just by changing the central injector (and the injector size in the EFI software) I got the Blue line, I am not sure what that means as by rights, it was the same Alpha-N map so I was expecting the curves to be the same..... :scratch:

The EFI lesson I learnt last month was, that to get the greatest range of tune ability I needed to use the smallest injectors possible that will still do the job. I know, pretty obvious, but there you go.

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I read the Ecotrons EFI manual and saw that the map must have as many even steps as possible and I thought that meant dividing the rpm range up as evenly as possible, seemed logical, but wrong again.

The bike bucked around swapping between the staged injectors as the EFI struggled to jump from one cell to another on the steeper parts of the fueling curve.

I guess what they really meant was that the changes between cells need to be as even as possible.

So I don't need even spacing between the rpm break points and can have big or small gaps between them so long as there are no big steps between adjacent cells.

That means I can straight line it between say idle and where the fuel demand just starts picking up around 7,000 rpm. And once again use a straight line after peak torque where the fuel demand is relatively steady again.

The straight line does not have to be horizontal, it can tip up or down, its just a line between two points on the map that may be several thousand rpm apart but covers an area of relatively similar fuel demand.

By straight lining where I can, I now have spare rpm break points to use to smooth out the map where the fuel demand is rapidly increasing with increasing torque.

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From left to right on the model, the first cell covers 4,500 rpm the next 1,500 rpm and the next only 250 rpm but the steps between the cells are relatively the same, ie a smoother map. Anyway I hope this is what they meant.

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I can now throttle on/off pretty well and do a series of part throttle runs, the last one is at 30% TPS, it looks a bit lean.

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Its not perfect but is running a lot better, so for what its worth here is the current Alpha-N map.

Yep, just like a large house party with interesting people.

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The EFI is going better than ever but :doh: the evening ended in a woopsie .....

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I was able to do several really good all gear runs with the bike coming back onto the throttle very nicely.

But my dreams of being the first persion to run an EFI 2T in a real F4 race on Sunday vanished when I felt the familiar overrun death shudder,

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Getting pretty hot, interesting stain at the top of the combustion chamber where it looks like the transfer streams sweep up into the head.

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Very dry in the bore and scratches that look like evidence of the ring ends butting up from over heating and the ring scraping the bore clean. Know more tomorrow when I get the cylinder off. It will be interesting to see how much oil there is in the crank case.

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Bit of quick work with a file and a light hone and everything is all good, even re used the piston ring, 2T's are so easy to work on

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Dyno runs from from 100 to 20%, looks OK so hopefully back on for Sunday.

Not sure about the ring gap now, looked good when I took it apart, I think you are probably right about the lean seize as it was definitely getting no fuel at closed throttle.
There is a software switch in Ecotrons where you can turn the fuel off on over run..... and I had to try it just to see what it did, as you do.:Oops:

You were on the money, I have been dialing in more fuel, heaps more fuel in the area of the Map that if it was a carb it would be the pilot and slide plus the very first bit of the needle.

Comes back on the throttle much better now, hopefully get to ride it tomorrow.

No, because it ran very well every where with 50% plus TPS. It was easy to get the EFI running in the "main jet" area. But tuning the lower parts of the Map is taking a bit of patience.

It would rev out real hard, shut the throttle and it would not light up again until the revs had dropped below 8 or the throttle was opened past 50%.

I had no idea what a Map should look like or if it was rich or lean until I put the O2 sensor back on it.

Been taking lots of dyno runs at part throttle and comparing them as I make changes to the Map.

Carburetors are great because of their analog ability to change the fuel delivery with changes in air flow at the same throttle setting.

EFI, well EFI is not forgiving at all.

309236 16 Alpha-N map lines with most of them concentrated in the upper power area of the graph.

Back to the EFI thing. The Ecotrons Alpha-N map has 16 rows to work with and I had concentrated them in the area where the power is, as you do. Well that turns out to be a mistake because there is not much difference in fuel demand per cycle between 100% throttle and 90 or 80 or even 70 at max power and virtual no difference at all above 40% in the 3 to 6000 rpm range.

The big jumps were between the lower throttle settings where there was not much excitement happening, well the mistake is that the CPU has a hard time bridging the big gaps below 40% especially when it is also trying to swap between low and high injectors at the same time.

309235 16 Alpha-N map lines more evenly spread so as to not have any big jumps between them.

Under 35% throttle is pretty unexciting power wise but on the track its a big deal as far as on track drive-ability is concerned. So for the next attempt I am going to use more Map lines in the lower area where things are changing rapidly with throttle position and less in the upper area where things are not changing so much, the power at 80% throttle is not very much different to 100%.

As it turns out, it was a mistake to concentrate my map in the power area, but I guess I will forgive myself..... :laugh:

senso

9th February 2015, 13:33

Senso, now that you have cut your CRM50 cylinder, is it possible to measure the thickness of the sides of the exhaust port near the cylinder wall?
I am wondering how wide we can go at the top of the port before breaking through

Sure, next weekend I will cut it a bit more, measure and post here the results, its a pleasure that I can help someone!

Wobbly, the 600mm^2 are a direct measurement from the port-map, so no downdraft angle included.
I forgot about the magic that happens with 190º of exhaust, I will see how much it cost to skim 2mm off the top of the cylinder.
Regarding the metal spraying, I know the technic but I don't know how thick it can go, because I would need about 3mm to be on the safe side, maybe some silicon bronze welded with an oxi-acetylene torch, or maybe stick welding might work?

Regarding the exhaust duct size, I measured a 100% original cylinder and it measures 27mm wide and 24mm tall, or in other words, it as an oval exit.

In any case, my next cylinder is already bored so I can't do any welding to it.

wobbly

9th February 2015, 14:14

You can build up as much as you want with metal spray - but yes bronze weld would work.
Stick welding i would not recommend in cast iron as the localised heating can make it crack very easily.
The Ex bore area must be multiplied by the duct down angle cosine as this is the true port area.
Your 600mm2 at 30* down becomes 519mm2 times 0.9 = 419mm2 exit = a 24.4 round exit.
An exit ellipse at 27 by 24 is 509mm2 - still way too big.

peewee

9th February 2015, 14:51

well im starting to get the hang of this stuff alittle better. still far from a professional though :laugh:. had trouble yesterday because i wasnt quit getting enough heat into the work area so i got a different torch that seems to work better. put a nut and bolt in there so that stuff wouldnt fill up the nut pocket

Ocean1

9th February 2015, 15:47

. had trouble yesterday because i wasnt quit getting enough heat into the work area t

If you're using oxy acetylene then try turning the oxy almost off, so you get soot from the flame. Coat the cleaned work area with soot. Retune the flame to neutral. Before starting to weld heat the whole piece but concentrate progressively more and more on the weld area. At some point the soot will start to vanish, you'd just a couple of degrees from hot shorting, turn the heat down a tad and start applying filler.

peewee

9th February 2015, 17:15

seattle smitty

9th February 2015, 17:55

Peewee, how about oxy-hydrogen (rent a bottle), which is what the old-timers used when welding aluminum in the days before TIG was widespread. It's clean, and burns somewhat cooler than oxy-acetylene. I'm really interested in your commentary on this! Some of the low-temp rod I've tried seems to work well on beer cans, which are nearly pure aluminum, but don't want to "tin" very well on anything else (beer cans are what the fellers selling this rod at swap-meets always use). Keep it coming.

From the excellent photos from Senso, it appears to me that there's just enough metal that he could pick up a few degrees of exhaust-open timing by grinding a small 45-degree bevel in the upper edge of the port. Not only is this less work than making a radiused corner (or opening up the whole upper surface of the port), my notion (subject to anyone's correction) is that a bevel creates a more well-defined edge than a radius, and thus maybe a crisper exhaust signal. Yet it's less likely to catch on the ring than a port cut back at its existing 30-degrees or whatever. This was the thinking among some of us Seattle-area outboarders forty years ago so I suppose it is hopelessly primitive, but there you are.

peewee

9th February 2015, 18:07

smitty the little mapp torches will get it hot enough, just takes alittle longer than a big full size torch. also i wasnt using oxy, just straight mapp. they have a mapp oxy set up at the local home depot down the street which im sure gets quit a bit hotter than straight mapp. problem is the oxy bottles are only 1.4 lb and only last about 10min according to the video i watched, and they cost $10 a bottle. im not concearned about the money but i need to get alittle faster first. maybe after i get more practice and can get alot of work done in 10min then i might give it a try but right now im still trying to learn the ropes of this stuff. gonna play with the torches i have alittle more untill i get the hang of it

husaberg

9th February 2015, 19:10

I'd get a shorter belt, and let it tension with the pulleys like it's meant to.

I would have thought no tensioner was appropriate as the moveable sheave increases and decreases the amount of belt needed as it moves in and out. That is how it works on my Polaris Sportsman 700 twin quad anyway.

https://www.google.com/search?q=polaris+sportsman+700+cvt+drive&espv=2&biw=1280&bih=915&source=lnms&tbm=isch&sa=X&ei=T-PXVKeNMZShoQTZqYKIDQ&ved=0CAcQ_AUoAg#imgdii=_&imgrc=RLcu9nahbcRwJM%253A%3BJvm2Mk6geo6l5M%3Bhttp% 253A%252F%252Fi.ytimg.com%252Fvi%252FO_jbUTQyoms%2 52Fhqdefault.jpg%3Bhttp%253A%252F%252Fwww.youtube. com%252Fwatch%253Fv%253DO_jbUTQyoms%3B480%3B360

Is it one of these set up though........

In the first picture you can see the horizontal spring, nested in the frame. The complete engine, including the pipe, is hung by the head (they do that to engines in France; for humans they have the guillotine).
The spring keeps the V-belt in tension. And in case you want to kick the revs up a bit when exiting a corner, there's a foot pedal with which the rider can put a bit more tension on the belt and thus force the primary heaves wider apart and lower the gearing.

But you don't want to go there, TeeZee. Only one heave of the front pully moves axially; the other front heave and both heaves of the rear pully are fixed.
That not only means that the range from shortest to longest ratio is only half of what it could be on a decent vario; it also means that the belt is forced to run skew most of the time.
click on the arrow after Frits to see the pics if I can't be assed bring them through
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adegnes

9th February 2015, 19:16

Is it one of these set up though........

click on the arrow after Frits to see the pics if I can't be assed bring them through

Yep, same system, thats why I need the tensioner now that my engine is stationary (it's mounted with sliding bushings to let it move side to side - eliminates the belt misalignment with just one variable pulley)

Is it "heave" or "sheave"?

Ocean1

9th February 2015, 19:43

i was using just straight mapp gas. got 2 different burner attachments and one gets hotter than the other i believe. was gonna try some mapp gas and oxy but figure i would give these burners a try first. still might try the mapp and oxy. i got quit a few junk cylinders i can practice on and see what works good. also i did preheat the cylinder in the bbq to about 300f or so. problem is its in the backyard and wind blowing etc. soon as you open the lid you lose a ton of heat. still its was better than no preheat. might turn the bbq up a notch next time also. ill get it figured out sooner or later

i could be wrong but i thought i read you werent supposed to use acetalyne with this low temp rod. something about acetalyne being to dirty or something. again i could be wrong

Not sure what rods you're using but alloy "braizing" rods have been around for a while and I used to use oxy acetylene quite successfully.

If you're managing with MAP gas but are a bit short of grunt then track down a half a dozen refractory bricks and build a little wall, (and roof?) around the work-piece leaving just the weld area exposed.

Just be careful of getting it too hot, may even be a good idea to track down some thermo-crayons or similar from your local welding supplier.

Frits Overmars

9th February 2015, 23:35

I think there is still a bit of exhaust area to be gain, but I'm kinda shy to square the exhaust port and then have the piston rings stuck in it, what is your opinion about the shape Frits?
is it possible to measure the thickness of the sides of the exhaust port near the cylinder wall? I am wondering how wide we can go at the top of the port before breaking throughYou don't need to go any wider, Senso. In fact you've already gone to wide. With your 80% port width you need huge radiuses in the corners in order to keep the piston ring alive (and you would need the same size radiuses at the port bottom, so it looks as if you've been lucky so far not to break a ring).
70% port width is optimal. The total port area will be less but thanks to the tighter corners that it will allow, you'll have more area above the transfers, where it counts.
To be precise, it's not the area that counts, but the product of each mm² of area, multiplied by the number of crank degrees that it is open before the transfers open. You've guessed it: the blowdown angle.area.
308837

Frits Overmars

10th February 2015, 00:19

In case you're wondering what you can get away with: the top and bottom of each window where a piston ring passes over, should have an elliptical shape.
Below you see the formula with which you can establish these shapes yourself, and the minimum safe limits for the optimal port width of 70%.
But since elliptical shapes are difficult to produce and measure, I've also converted the 70% port-ellipse shapes to multi-radius shapes for you.
308844

wobbly

10th February 2015, 08:24

One thing I would add re port widening is that it is a mistake to go directly to the straight sides ( even as shown in Frits drawing).
In the vast majority of cases the best way forward is to simply widen to the max above the transfers, leaving the bottom of the port completely stock.
There is no gain at all making the port wider below the transfers and alot to gain by reducing the duct volume, and helping to prevent direct short circuiting from the A
port front edge.
If you are going all out,then raising the floor to get it several mm above BDC and increasing the bottom corner rads does both - reduces the volume and the short circuiting.
Near on every cylinder made to date will benefit greatly from this approach, from a Banshee to all the KZ2 engines - ( if you can get away with adding material to the casting,as that is actually illegal under the CIK regs )

senso

10th February 2015, 09:01

Thanks for that image Frits, I had already spent a lot of time in search of it(or a similar one), I will print a template in paper and also follow what Wobbly said, and I will only grind it above the transfers.
In fact, the first time I touched the cylinder it was almost straight, but after the cylinder stood alive for 1.5 years, I decided to put a new ring on, I hogged the intake to try CR80 reed cage(saddly its the 2 reeds version) and I carefully measured how much the casting had from the exhaust duct to the cylinder top(its around 22.2 mm in that one), then allowed 2mm of wall thickness and went mad, the idea was just to see how much time it would live, it still went through 60-70l of gas before the frame gave up, but the piston never seized.

So now I want to squeeze the little crm engine a bit more, and I'm loving all the ideas that have sprung, so next weekend I will talk with my machinist to shave 2mm off the top of the cylinder so I can it the magical 190º exhaust timing.

Wobbly, about the exhaust area, yes, its without the angle of the duct, after all those factor counted, it seems really small..
Regarding the metal spraying, can it be done after final machining(I assume not, so I can't do it in this cylinder)?

And again, thanks to all of you.

TZ350

10th February 2015, 11:30

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Start of the mighty Team ESE super RG50 project. Sketchy made this head insert for us to try, maybe we could have done it on the lathe but we wanted at least three the same with a variety of insert profiles. In the end CNC is the only way to get repeat ability and like Flettner, Sketchy makes a really good job too.

The drawings were done by Kel and are a copy of the Aprilia bath tub head, Kel has also drawn a RG50 head insert based on Wobs toroidal design. There will also be a 14mm and 10mm plug version so we can do a back to back test to see what plug size is best.

If anyone wants to try a head insert for their own RG50 then they are welcome to have Sketchy run one off using our drawings.

F5 Dave

10th February 2015, 11:55

Very nice, those RG heads warp if you remove too much from them. Mine ended up being a slab of metal, but that would be great for testing. Anyhoo that engine is on the shelf for the time being.

jonny quest

10th February 2015, 12:54

Running a domed piston? You should try the Yamaha hybrid flst top with chamfered edges. Yz125 style. I'd guess .5hp gain over domed.

Frits Overmars

10th February 2015, 13:23

One thing I would add re port widening is that it is a mistake to go directly to the straight sides ( even as shown in Frits drawing). In the vast majority of cases the best way forward is to simply widen to the max above the transfers, leaving the bottom of the port completely stock.There is no gain at all making the port wider below the transfers and alot to gain by reducing the duct volume, and helping to prevent direct short circuiting from the A port front edge.
If you are going all out,then raising the floor to get it several mm above BDC and increasing the bottom corner rads does both - reduces the volume and the short circuiting.You're quite right Wob. I drew the top and bottom shapes identical to keep things simple but in reality the shapes should look more like the ports below.
(I know it's still not a perfect drawing, but hey, what can you do with MS-Paint).

peewee

10th February 2015, 14:56

Not sure what rods you're using but alloy "braizing" rods have been around for a while and I used to use oxy acetylene quite successfully.

If you're managing with MAP gas but are a bit short of grunt then track down a half a dozen refractory bricks and build a little wall, (and roof?) around the work-piece leaving just the weld area exposed.

Just be careful of getting it too hot, may even be a good idea to track down some thermo-crayons or similar from your local welding supplier.

i stand corrected. was reading the hts website and it says oxy acetalyne will work fine. im assuming most of the low temp rods dont use any type of flux but i seen some that was self fluxing or is all the low temp rod self fluxing ? http://www.ebay.com/itm/Hobart-Low-Temperature-Aluminum-Brazing-Rods-8-pk-1-8in-Dia-Model-770206/400802752518?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D777000%26algo%3DABA.MBE%26ao%3D1%2 6asc%3D29171%26meid%3D1bd1039cb6834dc79da92ae0af31 183b%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D2617 54892020

ordered a bunch more of the hts stuff today as i had ran out yesterday.

TZ350

10th February 2015, 15:09

My two year old crm 50 cylinder retired after running for 30 minutes with no cooling and still managing not to seize.

That is very interesting, virtually air cooled. I am trying to convert a water cooled cylinder to air cooling and would like to know more about the circumstances around how yours was being run, was it being thrashed? was there any water left at all or was it dry? I would love to know more.

TZ350

10th February 2015, 15:13

Running a domed piston? You should try the Yamaha hybrid flat top with chamfered edges. Yz125 style. I'd guess .5hp gain over domed.

Yes domed piston, a piston with champhered edges would definitely be worth a try. Do you know how the head is shaped? does it match the champhered edge of the piston?

TZ350

10th February 2015, 16:07

The EFI lesson I learnt last month was, that to get the greatest range of tune ability I needed to use the smallest injectors possible that will still do the job. I know, pretty obvious, but there you go.

308855308856

I read the Ecotrons EFI manual and saw that the map must have as many even steps as possible and I thought that meant dividing the rpm range up as evenly as possible, seemed logical, but wrong again.

The bike bucked around swapping between the staged injectors as the EFI struggled to jump from one cell to another on the steeper parts of the fueling curve.

I guess what they really meant was that the changes between cells need to be as even as possible.

So I don't need even spacing between the rpm break points and can have big or small gaps between them so long as there are no big steps between adjacent cells.

That means I can straight line it between say idle and where the fuel demand just starts picking up around 7,000 rpm. And once again use a straight line after peak torque where the fuel demand is relatively steady again.

The straight line does not have to be horizontal, it can tip up or down, its just a line between two points on the map that may be several thousand rpm apart but covers an area of relatively similar fuel demand.

By straight lining where I can, I now have spare rpm break points to use to smooth out the map where the fuel demand is rapidly increasing with increasing torque.

308853308854

From left to right on the model, the first cell covers 4,500 rpm the next 1,500 rpm and the next only 250 rpm but the steps between the cells are relatively the same, ie a smoother map. Anyway I hope this is what they meant.

308859

I can now throttle on/off pretty well and do a series of part throttle runs, the last one is at 30% TPS, it looks a bit lean.

308857

Its not perfect but is running a lot better, so for what its worth here is the current Alpha-N map.

kel

10th February 2015, 16:13

a piston with champhered edges would definitely be worth a try. Do you know how the head is shaped? does it match the champhered edge of the piston?

Something like this http://www.pit-lane.biz/t118p20-gp125-caracteristiques-ktm-frr

Can anyone tell me what the acceptable minimum distance would be from spark plug to piston crown at top dead centre for a 50cc cylinder with 41mm bore?

wobbly

10th February 2015, 17:24

I tested all this to death ( of pistons ) at BSL and the best power was had from a piston that had an angled squish ( at 7* ) then a flat top.
On the 59.6mm piston the squish was at 50% ie 8mm wide and this was how wide the angled area was on the piston.
The toroid chamber always made better power and was much more deto resistant than the domed pistons once I established that the optimum
distance from the tip of the fine wire earth electrode to the piston flat was 5.5mm.
This put the tip dead in line with the highly turbulent end gases exiting the squish band.
The idea of the angled edge came from the factory YZR 500 as this is what they used at the time, and was developed when they got themselves a Czech CNC anemometric flow test machine.
I just extended the idea to having the flat angled piston area the same width as the squish width.
And the piston and the chamber were then ceramic coated inside of the squish area only.
The angle on the piston edge would determine the distance of the plug tip from the flat piston would vary with the bore and plug chosen.
The idea works exactly the same as having a domed piston with a flat roofed bathtub ( ie as Jans Aprilia ) but better again.
So now ESE are making CNC inserts there is NO reason not to use the 7376 type 3/4", proper race, fine wire plugs from NGK.
VHM have started making flat top pistons with a radiused edge that make better power than the domed variations - but I dont know how clever they really are in that a domed piston with a radiused edge
may also do exactly the same thing.
BUT - I know for sure that a flat top WILL NOT make more power without a toroid.

PS - I discovered a bit later that the Pulse ( ie last version Swiss Auto ) used A kit RS125 pistons that had the domes machined flat,leaving the squish radiused, so that ended up as effectively the same thng.
But sadly they hadnt used a real toroid so lost alot of the big power advantage to be had with that scenario.

adegnes

10th February 2015, 18:14

Something like this http://www.pit-lane.biz/t118p20-gp125-caracteristiques-ktm-frr

Can anyone tell me what the acceptable minimum distance would be from spark plug to piston crown at top dead centre for a 50cc cylinder with 41mm bore?

Me to. What is too close?

Ocean1

10th February 2015, 19:16

i stand corrected. was reading the hts website and it says oxy acetalyne will work fine. im assuming most of the low temp rods dont use any type of flux but i seen some that was self fluxing or is all the low temp rod self fluxing ? http://www.ebay.com/itm/Hobart-Low-Temperature-Aluminum-Brazing-Rods-8-pk-1-8in-Dia-Model-770206/400802752518?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D777000%26algo%3DABA.MBE%26ao%3D1%2 6asc%3D29171%26meid%3D1bd1039cb6834dc79da92ae0af31 183b%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D2617 54892020

ordered a bunch more of the hts stuff today as i had ran out yesterday.

I don't recognise those, but that's hardly surprising, it's been a while.

It's worth getting a local supplier involved for some free expert advice in which rods to use for your particular application. You can get flux powders but flux coated rods have the advantage of a using a flux optimised for the application of that particular rod.

Probably the most common cause of local failure is inclusions in the original casting. Particularly sand cast stuff, a single grain can make a mess over a surprisingly large area. Take some time to inspect the cleaned weld area for wee craters and excavate them out.

Luck.

F5 Dave

10th February 2015, 19:45

The EFI lesson I learnt last month was, that to get the greatest range of tune ability I needed to use the smallest injectors possible that will still do the job. I know, pretty obvious, but there you go.

308855308856

I read the Ecotrons EFI manual and saw that the map must have as many even steps as possible and I thought that meant dividing the rpm range up as evenly as possible, seemed logical, but wrong again.

The bike bucked around swapping between the staged injectors as the EFI struggled to jump from one cell to another on the steeper parts of the fueling curve.

I guess what they really meant was that the changes between cells need to be as even as possible.

So I don't need even spacing between the rpm break points and can have big or small gaps between them so long as there are no big steps between adjacent cells.

That means I can straight line it between say idle and where the fuel demand just starts picking up around 7,000 rpm. And once again use a straight line after peak
From left to right on the model, the first cell covers 4,500 rpm the next 1,500 rpm and the next only 250 rpm but the steps between the cells are relatively the same, ie a smoother map. Anyway I hope this is what they meant.

I can now throttle on/off pretty well and do a series of part throttle runs, the last one is at 30% TPS

Its not perfect but is running a lot better, so for what its worth here is the current Alpha-N map.
Yeah yeah all very well. But what if you put some BIGGER injectors in there. Surely that must be better:banana:

speedpro

10th February 2015, 19:57

Yeah yeah all very well. But what if you put some BIGGER injectors in there. Surely that must be better:banana:

Yeah, because putting in bigger main jets always makes more power, eh?

jonny quest

10th February 2015, 19:58

I've found cast piston make more power than forged pistons.

The link that Kel posted of the KTM is exactly what I was talking about. Great info by Wobbly too.

I've wondered why Frits and Jan didn't run that piston design, I feel it's the best.

lodgernz

10th February 2015, 20:45

TZ350

10th February 2015, 21:18

If you make inserts with 10mm plugs, don't forget to change the insert profile to keep the water near the plug. Otherwise it's 2mm further away on each side. Just sayin'...

Good tip, thanks.

senso

10th February 2015, 21:26

That is very interesting, virtually air cooled. I am trying to convert a water cooled cylinder to air cooling and would like to know more about the circumstances around how yours was being run, was it being thrashed? was there any water left at all or was it dry? I would love to know more.

Good morning TZ350, it was in fact an accident, my brother went for a ride with some friends(another 50cc bike and a 1980 kx250), the other 50cc guy got tired and went away, so my brother keep going and playing catch up with the 250.
He thinks that it was after a jump, the lower frame(the part that goes under the engine) broke, and the back engine mounts moved enough that the radiator tubes disconnected from the water pump, he says that he noticed the engine reving up slower, but he didn't notice any lack of power, so after at least 30 minutes after the said jump they arrived at my friends house and they noticed a horrible burning smell(it was the head gasket sort of roasting with the heat).

They connected the tubes, but as soon as a sit on the bike they would disconnect again, and the engine was still running so he came home ridding her(another 15 minute travel distance).

He arrived home, told me what happened and I didn't believe, but its true, the next day I still put the engine working, there was still a good compression feeling in the kick-starter.

I have some photos of the piston, that is burned a lot in one spot and the cylinder also got yellow/reddish in some places.

In the end, after pulling the cylinder off the engine he sort of dropped the cylinder in the work bench and broke the back(intake) skirt, also a lesson learned, I can't remove a lot of metal in the intake because the back skirt loses almost all its support.

adegnes

10th February 2015, 21:30

Frits Overmars

10th February 2015, 21:58

Yeah yeah all very well. But what if you put some BIGGER injectors in there. Surely that must be better
Yeah, because putting in bigger main jets always makes more power, eh?Right, like big-diameter exhaust ducts and headers and diesel-like compression ratios :p.

...the best power was had from a piston that had an angled squish ( at 7* ) then a flat top.... The idea of the angled edge came from the factory YZR 500 as this is what they used at the time, and was developed when they got themselves a Czech CNC anemometric flow test machine.But the idea did not originate at Yamaha, Wob. The flat pistons with a beveled edge that you saw in the YZR 500, were designed by a friend of Harald Bartol, the late Martin Ziegler, who lived across the street from Mahle in Stuttgart. He supplied them to Team Roberts if I remember correctly, and in his office he had a certificate, thanking him for his contribution to the world title (from Wayne Rainey, I think it was).

I've found cast piston make more power than forged pistons.We found the same outcome about cast versus forged pistons. But for the next ten years 'everyone' will still be convinced that forged is better.

The link that Kel posted of the KTM is exactly what I was talking about. Great info by Wobbly too. I've wondered why Frits and Jan didn't run that piston design, I feel it's the best.I wonder why you think that Jan didn't. He tested everything you can think of, and then some.
Keep in mind that both the transfer layout and the combustion chamber shape have an influence on the results, so there were a lot of combinations to test.
From the tested shapes the flat top piston was worst; flat with a bevel, like Wobbly describes, was better; domed with the squish area turned conical was about the same; domed with the center turned flat was about the same; just domed was best.
Domed with an edge radius was unbelievably good on the flowbench but not on the dyno, probably because of the influence of the radius on port timings. I still want to get to the bottom of this but test facilities are not what they used to be. Didn't you have plans to look into this too, Wob?

F5 Dave

10th February 2015, 22:10

Yeah, because putting in bigger main jets always makes more power, eh?

Hmm, I hear what you're saying. It must be MORE injectors he needs.

TZ350

10th February 2015, 22:31

Good morning TZ350, it was in fact an accident, my brother went for a ride with some friends(another 50cc bike and a 1980 kx250), my brother keep going and playing catch up with the 250.

Thanks, leaves me feeling hopeful that I can make the RGV250 cylinder work as an aircooled one.

adegnes

11th February 2015, 05:21

Please excuse me for the OT, I just can't figure out what these weird things I found are, and thought I'd check if you guys have seen anything like it.

I found a box with ten of these under my porch. No marking on the box except for a "danger corrosive" triangle.

308863308864

White plastic box with clear plastic fluid container on top. Says "push" on top of container, to let the fluid drop down into the plastic box I presume (added som black so it would show up on the pic) . One red and one black wire connected to the white box, pins with big head on the end of the wires sitting in a small piece of styrofoam.

Could it be some kind of weird battery with separate acid container, so that it can be stored for a long time without going bad, and when you want to use it you push the button, the acid drops down and the battery is ready to be charged?

F5 Dave

11th February 2015, 06:05

Heavy water?

WMDs?

adegnes

11th February 2015, 06:08

Heavy water?

WMDs?

Maybe call up the germans and hear if they still want some then...

I'm hoping it's a battery - need the sulfuric acid for anodizing.

jonny quest

11th February 2015, 07:23

Frits, did not mean to imply that RSA testing did not cover all the bases. But what makes the RSA like a dome vs other designs.

On a warmed over bridged exhaust YZ125, same CR, the chamfered edge flat top was worth a full HP more than a dome. That's huge on a 125.

And yes, just a traditional flat top I've found to put it subtle. .. shit. That little chamfer (with corresponding head design) is pretty amazing.

I'd hazzard a guess as to the rounded edge piston just traps too much fuel above the ring that doesn't get a chance to heat the air.

wobbly

11th February 2015, 07:49

Too many variables to make an informed idea about why the VHM flat top with edge radius design makes more power in a KZ2.
I know the head shape goes around the corner, so there is no extra trapped end gases in the ring crevis, but then
the piston is fully machined from billet material - so maybe as has been found when comparing cast with forged,its simply the alloy type that makes the difference.
And maybe the real difference comes down to the machining - because its the shape the piston becomes when its hot in the bore that is all important, and all the different materials will
have quite different expansion rates.

The radius edge piston is on the list of possible projects to be completed as a thesis subject at Canterbury Uni - just needs a candidate thats interested in using
Fluent as well as the dyno to validate the results.

peewee

11th February 2015, 14:48

The radius edge piston is on the list of possible projects to be completed as a thesis subject at Canterbury Uni - just needs a candidate thats interested in using
Fluent as well as the dyno to validate the results.

regarding flat tops. do you meen like the red line or orange ? then cut the outer corner of the head at the same shape ?

then use a head shape like the rsa, but with flat squishband ? (TZ350's RG50 head appears to be just that). should the band be paralell or have some diverging angle like 1 or 2 degrees ?

F5 Dave

11th February 2015, 15:22

At some stage there has to be a compromise between increasing flow over a sharp surface of a constantly moving port duct to chamber interface
vs the increase of port timing, decrease of blowdown, increase of squish area trapped at the bore edge.

wobbly

11th February 2015, 16:47

The VHM pistons have a radius like the orange corner.
But in answer to the squish questions, the head should follow the piston shape ie dead flat with no taper except a tiny divergence of just 0.1mm.
As I discovered with a flat top the piston will hit the squish inner edge first if running real close to clipping at peak rpm.
And as i have already said several times, in my testing a flat top is completely useless without a toroidal chamber.

seattle smitty

11th February 2015, 17:53

What a great site! Four separate discussion topics running concurrently, jumping from one to another, all interesting.

TZ350

11th February 2015, 19:05

What a great site! Four separate discussion topics running concurrently, jumping from one to another, all interesting.

Yep, just like a large house party with interesting people.

308890

The EFI is going better than ever but :doh: the evening ended in a woopsie .....

308889

I was able to do several really good all gear runs with the bike coming back onto the throttle very nicely.

But my dreams of being the first persion to run an EFI 2T in a real F4 race on Sunday vanished when I felt the familiar overrun death shudder,

308891

Getting pretty hot, interesting stain at the top of the combustion chamber where it looks like the transfer streams sweep up into the head.

308888

Very dry in the bore and scratches that look like evidence of the ring ends butting up from over heating and the ring scraping the bore clean. Know more tomorrow when I get the cylinder off. It will be interesting to see how much oil there is in the crank case.

adegnes

12th February 2015, 01:50

Another subject for the party-people...

I've ordered one of these for testing:

CE-i 100 with sensor SE-1
http://www.power-spark.de/images/Lieferumfang_Verpackung_800p.jpg
http://www.power-spark.de
Manual here http://www.power-spark.de/downloads/Bedienungsanleitung_PowerSpark_engl_2011_1.pdf

Seems like a good unit, has it's limitations, but for my use (variated engine) it should suffice.

Some features and limitations:

- 4 programmable ignition maps (and 10 preprogrammed maps - non of them seemed very useful, maybe for small rc engines)

- no computer needed, programming is done with a magnet(!), seems slow and weird but hey, no computer needed.

- Four adjustable rpm-points only (actually just three, the first point has to be 0rpm), this is very limiting for most, but for my variated setup it's ok.

- Easy setup; there's a "sensing mode" where it notifies you when it senses the magnet - just lock the crank at 75° btdc (what the manual say's it should be) and rotate the flywheel until the magnet is sensed - tighten up, done. If you manage to fuck up, you can adjust the 75° to something else, but anything under 75 limits how much advance you can run at high revs. (they give an example; if you set it to 70° btdc you can "only" run 35° advance @ 26500rpm, yeah thats gonna be a problem.)

++

I also asked Ignitech what they would charge for a dccdip modified to be used with an hall sensor - same price as the regular unit. So if this Power-spark is no good, I'll just get the tried and true Ignitech, and reuse the hall sensor pickup.

I'll post a small review when I get it up and running, if anyones interested.

TZ350

12th February 2015, 05:46

Interesting Ignition, I would like to know how it goes when it is up and running.

peewee

12th February 2015, 13:16

And as i have already said several times, in my testing a flat top is completely useless without a toroidal chamber.

that was my plan. do you have any guess what the radius should be ? while im thinking of it do you have a guess where to start with comp ratio ? 50% band should be good for starters eh ?

peewee

12th February 2015, 15:32

im gonna give this a shot and see if i can fill up the kicker and roof alittle. if its sucessful it will be permanent and impervious to any fuel because i want to use methanol. if it doesnt work ill weld the door back on and use epoxy

TZ350

12th February 2015, 17:11

im gonna give this a shot

I like your style.... very Bucketish..... :yes:

adegnes

12th February 2015, 17:48

I like your style.... very Bucketish..... :yes:

+1
.....
.....
....

seattle smitty

12th February 2015, 18:02

Ditto that! Peewee, are you using the low-temp rod for all of these operations? What specifically is this rod, what is the working temperature, what pre-heat do you use? I was skeptical of the idea of using a low-temp rod when you first brought it up, just because I have seen erratic results with some (more than one brand) of that stuff myself, but you could make me a believer if this holds up. I'm even more skeptical of using epoxy fillers inside an engine (esp. one that runs real racing fuel rather than parts-cleaner:violin:) but again, people are making it work, amazing.

FWIW (repeat repeat), you should be able to buy pre-fluxed (external) aluminum gas-welding rod at a welding supply house. You couldn't use it to re-contour ports, but it's stronger than the low-temp stuff and has its uses (building tanks?) once you learn to gas-weld aluminum, if you aren't TIG-equipped. The old-timers had to flux-coat their own rod, a dull chore, and I was delighted to discover the pre-fluxed rod.

peewee

12th February 2015, 18:20

Ya lowtemp rod. Melts around 730f or so according to the packaging. So far im liking it

Hts2000, durafix, alumalloy. I think theyre all pretty similar or maybe the same. I been getting it from ebay. Used the bbq for preheat

adegnes

13th February 2015, 01:41

TZ350

13th February 2015, 21:53

308969308970

Bit of quick work with a file and a light hone and everything is all good, even re used the piston ring, 2T's are so easy to work on

308968

Dyno runs from from 100 to 20%, looks OK so hopefully back on for Sunday.

adegnes

13th February 2015, 21:56

308969308970

Bit of quick work with a file and light hone and everything is all good, even re used the piston ring, 2T's are so easy to work on

308968

Hopefully back on for Sunday.

Always nice when it works out like that!

Tim Ey

14th February 2015, 11:52

308891

Is your squishband included in the copper gasket? It looks that way...

senso

14th February 2015, 12:09

I think the squish is indeed done in the cooper sheet, TZ made it that way to pull more heat out of the head, he also has one(or more) heads that where cooper plated/blasted.

F5 Dave

14th February 2015, 12:59

So was the ring too tight in bore? If not conclusive I'd be adding some more gas at closed throttle. Looks like a lean seize type of thing when pilot is too small or inlet leak.

TZ350

14th February 2015, 13:57

So was the ring too tight in bore? If not conclusive I'd be adding some more gas at closed throttle. Looks like a lean seize type of thing when pilot is too small or inlet leak.

Not sure about the ring gap now, looked good when I took it apart, I think you are probably right about the lean seize as it was definitely getting no fuel at closed throttle.
There is a software switch in Ecotrons where you can turn the fuel off on over run..... and I had to try it just to see what it did, as you do.:Oops:

speedpro

14th February 2015, 14:05

There is a software switch in Ecotrons where you can turn the fuel off on over run..... and I had to try it just to see what it did, as you do.:Oops:

Pretty cool effect on the twin, when you closed the throttle it went quiet then at whatever revs I'd set the fuel to restart it got noisy again.

TZ350

14th February 2015, 14:12

Is your squishband included in the copper gasket? It looks that way...

Yes and extends out to form some large fins.

I think the squish is indeed done in the cooper sheet, TZ made it that way to pull more heat out of the head, he also has one(or more) heads that where cooper plated/blasted.

True, metal sprayed 1.5mm but the polished copper combustion chamber tarnished and became a heat absorber instead of reflector, I tried good quality silicon car polishes, they helped slow down the oxidation but now I find it more practical to have a hybrid arrangement where the squish is copper and the combustion chamber is aluminum. Copper transfers heat twice as fast as aluminum so is worth using if you can. You can use it to pick up heat in the combustion chamber area and transfer it quickly to the outer fins. Unless the motor gets over heated, copper in the squish area remains relatively clean and shiny.

peewee

14th February 2015, 17:47

Ocean1

14th February 2015, 18:17

hey guys has anyone had sucess plating a iron liner ? ive heard its possible but never really investigated it much. not sure if nikisil can be used or something else. im looking to do some aluminum sleeves or maybe plate the iron liner if its possible

When I freshened up the 525 I found that the cylinder had been sleeved. There was also a minor trench up one side. I sent it down to NZcylinders and they filled the trench, nicasil plated it and honed it to spec.

Not my preferred fix, (biggest issue is the thermal barrier at the sleeve/cylinder boundary), but with my less than fully demanding riding it's been just fine.

F5 Dave

14th February 2015, 20:52

TZ350

14th February 2015, 22:27

I'd be adding some more gas at closed throttle. Looks like a lean seize type of thing when pilot is too small.

You were on the money, I have been dialing in more fuel, heaps more fuel in the area of the Map that if it was a carb it would be the pilot and slide plus the very first bit of the needle.

Comes back on the throttle much better now, hopefully get to ride it tomorrow.

husaberg

14th February 2015, 22:50

You were on the money, I have been dialing in more fuel, heaps more fuel in the area of the Map that if it was a carb it would be the pilot and slide plus the very first bit of the needle.

Comes back on the throttle much better now, hopefully get to ride it tomorrow.

Rob did it "hang"at higher revs, before returning to low rpm off throttle?

TZ350

14th February 2015, 23:06

Rob did it "hang"at higher revs, before returning to low rpm off throttle?

No, because it ran very well every where with 50% plus TPS. It was easy to get the EFI running in the "main jet" area. But tuning the lower parts of the Map is taking a bit of patience.

It would rev out real hard, shut the throttle and it would not light up again until the revs had dropped below 8 or the throttle was opened past 50%.

I had no idea what a Map should look like or if it was rich or lean until I put the O2 sensor back on it.

Been taking lots of dyno runs at part throttle and comparing them as I make changes to the Map.

peewee

15th February 2015, 03:35

Yes its been a secret for a decade. US chrome Nickle NASCAR engines. I had it done in Aussie first . Lasted 1/2 of one meeting.

The etch kills ally so you have to put in an inflatable and then latex coat. Then etch with evil stuff, then nickel with 4x more current than with ally. 10 years on same bore before performance dropped off.

ok so you tried the plating on a iron bore and it worked good ? the uschrome webpage says they can do it. would be far cheaper than having aluminum sleeves made, installed and plated

one other question since im not familiar with the plating process. it doesnt require high heat does it ? what do you meen inflatable and latex coat ?

Frits Overmars

15th February 2015, 05:06

Copper transfers heat twice as fast as aluminumDid you consider silver? Great heat conductor, much better than copper. You know the old saying "Speed costs money; how fast do you want to go? "

has anyone had sucess plating a iron liner ? ive heard its possible but never really investigated it much. not sure if nikisil can be used or something else.
Yes its been a secret for a decade. US chrome Nickle NASCAR engines. I had it done in Aussie first . Lasted 1/2 of one meeting.Which decade was that?
I raced an aircooled 500 single with a hardchromed cast-iron liner in 1973-1974. It seized about twice a weekend but the chrome still looked like it would last forever.

TZ350

15th February 2015, 06:28

Did you consider silver? Or gold? Both great heat conductors, much better than copper. You know the old saying "Speed costs money; how fast do you want to go?

Yes I have, and silver heat transfer paste has its place.

309007

Gold fins, well maybe and if it didn't go fast at least it would have bling bling .....

seattle smitty

15th February 2015, 08:33

I'm confused (it's a chronic condition with me). I can't tell who wants to plate what, the inside or the outside of an iron sleeve. The old-timers used to get their bores, or rings, hard chrome-plated, but that was mostly because the aircleaners of the time were nearly useless. Makers of small aircraft cylinders tend to be the experts at plating now, though there's a difference in that their cylinder liners are alloy steel, often nitrided for hardness, even nickel and carbide coated for wear.

What I want to know about is copper or silver-plating the OUTSIDE of iron sleeves. Frits has said he doesn't like iron sleeves, that the differential expansion of aluminum clylinder and iron sleeve leaves gaps, esp. in the vicinity of the exhaust port, and that those gaps tend to accumulate carbon soot, an excellent thermal insulator, which is not whats wanted there. With due deference to Frits, I think there are ways to address that problem starting with a good tight press, and also providing better ways (via more surface area) for the aluminum cylinder to cool. I like iron sleeves. But in the racing outboards I knew long ago, we had cooler coolant available, in unlimited supply, than is the case for bikes and karts.

Back to plating the outside of iron sleeves, Ocean has pointed out my concern, the thermal barrier between sleeve and cylinder. My dumb-welder understanding is that this junction would have some resistance to heat transfer even if you pressed an aluminum sleeve into a tight-fitting aluminum cylinder; in other words, the discontinuity itself is a big issue, not just the lower heat transfer through cast iron. But you do what you can. Ocean, even though my iron sleeve is to be shrink-fitted in place, don't you think a plating of heat-conductive material on the O.D. of the iron sleeve would help move those BTUs along? One advantage might be that if you had to press a sleeve OUT, a copper-plated surface would help enough that you could slightly increase the tightness of the shrink fit . . ???

senso

15th February 2015, 09:28

Regarding the plated iron liners, I can also confirm that, I have one CRM cylinder that is chrome plated, its much harder than the iron that composes the cylinder, and every machine shop that I take it to bore it out want to charge me twice, because has they say the chrome chews up the boring bars they use for the iron liners.

Never rode with that cylinder, but it should have a bit less drag than a iron liner.

peewee

15th February 2015, 10:23

smitty im not worried much about heat transfer or lack there of, with a plated iron bore. for drag racing with methanol i dont think it will matter much. my reason for plating the bore is so i can always use standard readily available pistons. plus when you have a ton of hours devoted to porting the cylinders you want to keep it intact as long as possible.

husaberg

15th February 2015, 11:04

Did you consider silver? Great heat conductor, much better than copper. You know the old saying "Speed costs money; how fast do you want to go? "

.

Ages and ages ago I posted that the works Nortons actually had silver alloy heads.......:innocent:
Yes I realise your post was in mirth........
http://www.classicsportbikesforsale.com/wordpress/wp-content/uploads/2011/10/KGrHqRhE5oVwYz3BOi3MgZL760_12.jpg

Ocean1

15th February 2015, 11:15

Ocean, even though my iron sleeve is to be shrink-fitted in place, don't you think a plating of heat-conductive material on the O.D. of the iron sleeve would help move those BTUs along? One advantage might be that if you had to press a sleeve OUT, a copper of silver plated surface would help enough that you could slightly increase the tightness of the shrink fit . . ???

I remember sleeving an alloy cylinder many years ago and deciding a taper fit was a good idea. By the time I'd worked out the maximum shrink the cylinder would take without exceeding the materials' elastic limit I needed a new cylinder. It worked OK, but on striping it much later I found the liner wasn't anywhere near as tight as it had been, presumably the many heat cycles since had some effect in relieving some of the stress in the alloy...

I'm not now in a position where I've got the sort of constraints that would require me to use an iron liner in an alloy cylinder for competition, so it's not a problem that keeps me awake at nights. If you're considering plating the outside of a liner for thermal continuity then why not just use a silver thermal paste? If it's a water cooled application and you've got room maybe make it a wet liner?

seattle smitty

15th February 2015, 17:56

The idea of the taper being that the upper half of the sleeve and cylinder are running hotter and expand more, right? I was thinking of that too. But why not try to draw the heat out of the aluminum (upper cylinder) faster so that it's not trying to expand itself away from the sleeve? Okay, there's a water jacket; okay, we look at pumps and flow-rates and radiator capacity and such. But it evidently is not enough to just put water in and take it out. The coldest water would seem to need to be DIRECTED at the hottest regions, so that it is moving fast and scrubbing off steam bubbles as they form. And if cooling fins work on air-cooled engines by increasing the radiating surface area of the hot parts, some form of fins INside a watercooled engine, doubling or tripling the surface area of the metal over and around the exhaust port ought to do some good in engines prone to problems there. Similarly, as TeeZee and I have been telling each other in a PM, those cylinder head inserts he has shown us in photos have room for at least one good cooling fin, that might nearly double the area exposed to coolant. Then maybe you could run a hotter plug, a little less likely to foul . . . .

And if we find we have over-cooled an engine, just "tip the can" (add some nitro)!!

Ocean1

15th February 2015, 19:42

The idea of the taper being that the upper half of the sleeve and cylinder are running hotter and expand more, right?

The idea of the taper was a slightly misguided attempt to get a tighter fit than I thought I'd achieve from a simple interference fit on a parallel liner. Misguided because I thought I could get enough pressure to begin to get some actual mechanical bonding between the two surfaces. I didn't. Turns out the limit was the strength of the cylinder, which you could exceed either way.

I did get there with just a couple of ton on the press, though.

TZ350

15th February 2015, 22:50

Well todays attempt to ride the first EFI 2T to compete in and finish an actual race did not turn out so well. The bike ran better and stayed strong all day but the throttle response was not good enough to race. Such a small area on the graph, such a large effect on the track.

309031309033309032

The technical high light of the day was seeing this very cleaver idea for adding some heat sinking to the crank cases. On the clutch side the copper extends into the clutch/crank case area where it is bathed in oil. A very neat and effective way to add some extra cooling.

Another great day of racing in the sunshine at Mt Wgtn. After round 4 I suggested that a "sub-30 second lap on a 50cc bike is looking distinctly possible". And at his next serious attempt, Nathanael Diprose has done it. I must extend my congratulations to Nathanael for his 29.831-second lap in F5 race 1 today. I'd be even happier if I wasn't the poor sod in second place watching him disappear into the distance.

Mylaps: http://www.mylaps.com/en/events/1108317

Tim

Frits Overmars

16th February 2015, 00:24

Makers of small aircraft cylinders tend to be the experts at plating now, though there's a difference in that their cylinder liners are alloy steel."Define small aircraft cylinders, Smitty. I was able to contribute a bit to the design of the 6,5 cc (.40 cubic inch to you) MB40 engines that have ruled F3D pylon racing for the past 15 years or so. My first concern was to get rid of those ridiculous sleeves altogether and switch to hard-chromed alu cylinders.
It worked; they just don 't wear out at all. And the pistons are happy too; finally they have got a relatively cool surface to lean against.

Frits has said he doesn't like iron sleevesI never said that; I said that I hate any form of sleeve: iron, steel, alu, unobtainium, whatever.

Ocean has pointed out my concern, the thermal barrier between sleeve and cylinder. My dumb-welder understanding is that this junction would have some resistance to heat transfer even if you pressed an aluminum sleeve into a tight-fitting aluminum cylinder; in other words, the discontinuity itself is a big issue, not just the lower heat transfer through cast iron.You've got that absolutely right, Smitty.

don't you think a plating of heat-conductive material on the O.D. of the iron sleeve would help move those BTUs along?Do you think adding another layer of whatever between sleeve and cylinder will improve conduction? Only if it's a good conductor and the contact between the sleeve and the cylinder was imperfect to begin with. But then you will probably have that same problem with your added layer.

309034
The high light of the day was seeing this very cleaver idea for adding some heat from the exhaust pipe to the crank cases.Fixed that for ye :devil2:.

Here is a picture of my little German friend (116 kg) winning a 50 cc aircooled race by keeping his 'porcupine' engine cool while the competition looses one-third of their power during the race. It is amazing how even the cooling fins on the ignition cover get extremely hot. Just don't touch the fins on the clutch cover.
309035

Frits Overmars

16th February 2015, 00:49

as TeeZee and I have been telling each other in a PM, those cylinder head inserts he has shown us in photos have room for at least one good cooling finOr two. Front and side views of a double-finned insert and cover: 309036

And if we find we have over-cooled an engine...You won't. You can't.

seattle smitty

16th February 2015, 06:33

(For some reason, my computer won't bring up that photo, just endlessly indicates it is loading).

By small aircraft engine makers I meant outfits like Lycoming, though I do not diminish anything that can be learned from model airplane racing (quite a few older outboard racers have flown in control-line speed and combat meets, including Jim Hallum who engineered that Anzani outboard I've referred here; Jim's planes had pulse jets and went 150mph in the early Fifties)(at 80, Jim has returned to flying some of his slower ones).

However, a current top-level outboard racer and engineer/machinist who does lots of paid engine-building and boat-building for others, in talking about today's Rossi and VRP methanol-burning outboards states that the Nikasil plating in these engines is only good for 15-20 heats . . . and our heats are very short sprints, say about 5 miles per heat, average. He suggests that serious racers keep spare cylinders, and cycle them through the re-plating service on a schedule that gets you fresh cylinders in time for the Nationals race. Add to that Jan Thiel's observation that his re-plated cylinders were never as fast as before.

husaberg

16th February 2015, 07:18

(For some reason, my computer won't bring up that photo, just endlessly indicates it is loading).

.

Right click on the inmage then save it to your computer. Then open it out of your computer file, Since i went to Windows 8 point whatever, I can't bring up PNG files off a message board , no idea why either. I guess its a Browser setting issue.

F5 Dave

16th February 2015, 07:24

Yeah I must try Firefox again

wobbly

16th February 2015, 07:49

Re the question about plating a cast liner - i have done this on several builds all for the same reason, to keep the same piston size
for the life of the engine.
The first was done by Millenium, the others by NZ Cylinders, all have worked out just fine,with a couple of silly seizures and no damage to the bore at all.

The other issue for comment is cylinder head cooling.
Mr Thiel gave us one really "cool" pointer about keeping the plug body temp under control, by allowing water close to the threads.
But in theoretical terms we dont want to cool the chamber surface, as this increases the temp delta, and simply pulls heat out of the expanding
combustion charge - throwing away Hp.
So what we dont want to do is add fins to the back side of the chamber and allow the water to cool that area more.
Without simply giving away a really successful secret, what we do want to cool as effectively as possible is the squish band area, to keep the end gases away from
the killer deto heat range.
TeeZee does it by having a copper fin connected directly to the squish in the head, so think about applying Jans plug body water cooling idea to the squish area only.
Then add another method for keeping heat in the combustion charge and ceramic coat the inside of the chamber only.

Frits Overmars

16th February 2015, 07:50

a current top-level outboard racer and engineer/machinist who does lots of paid engine-building and boat-building for others, in talking about today's Rossi and VRP methanol-burning outboards states that the Nikasil plating in these engines is only good for 15-20 heats . . . and our heats are very short sprints, say about 5 miles per heat.The nikasil plating that I know is also good for 15 heats, a heat being three days of practising followed by a Grand Prix, maybe 600 km per weekend, 15 times a year.
Not on cool-running methanol but on hot-burning petrol. Were do you boat people get your nikasiling done, Smitty?

Haufen

16th February 2015, 08:35

The other issue for comment is cylinder head cooling.
Mr Thiel gave us one really "cool" pointer about keeping the plug body temp under control, by allowing water close to the threads.
But in theoretical terms we dont want to cool the chamber surface, as this increases the temp delta, and simply pulls heat out of the expanding
combustion charge - throwing away Hp.
So what we dont want to do is add fins to the back side of the chamber and allow the water to cool that area more.
Without simply giving away a really successful secret, what we do want to cool as effectively as possible is the squish band area, to keep the end gases away from
the killer deto heat range.
TeeZee does it by having a copper fin connected directly to the squish in the head, so think about applying Jans plug body water cooling idea to the squish area only.
Then add another method for keeping heat in the combustion charge and ceramic coat the inside of the chamber only.

Thanks for the tip, wob. What's the minimum wall thickness for a dome you'd recommend in the plug and squish area?

F5 Dave

16th February 2015, 09:33

I had my steel bore plated in Auss a decade or so ago, & it lasted. . .well it didn't last the meeting.

US Chrome did it next & it has only recently worn a bit too oval on a 50cc turning to 14.

Clearly the others have learnt how to do it.

Kept the same piston size which needed a plated bore for soft rings.

It lost 0.3hp, which I put down to another thermal barrier, but it could also have been the transfer ports were a little more messy at the exits (harder to work than a huge 54mm bore) where they had cleaned them up a bit averagely & I was a bit scared to remove plating. But it was a good trade off.

Kickaha

16th February 2015, 10:38

I had my steel bore plated in Auss a decade or so ago, & it lasted. . .well it didn't last the meeting.
When I was racing my TZ250 a decade or so ago we were told not to get anything done in Oz, the guys I knew shipped their stuff to Langcourts in the UK

speedpro

16th February 2015, 12:15

309034Fixed that for ye :devil2:.

In practice the copper got hot closest to the clutch cover and was cold at the end closest to the pipe. Hard to say if it made any real difference but it can't have hurt. It certainly hurt less than whatever caused the ceramic to come off the centre electrode of the plug.

wobbly

16th February 2015, 14:54

The only way to spec what thickness will be OK for a head insert is to do a FEA analysis on it with 80 Bar or so of peak cylinder pressure
acting as a UDL over the inner surface.
Using whatever head cover restraints and clamping studs etc this will tell you if the UTS is exceeded.
But a simple way to get away with pretty much murder in this scenario is to use brass, it doesnt seem to have any better thermal effects but is shit loads stronger in bending.

The only thing that will make a plug ceramic crack and fall off is deto.
In an ordinary Iridium even a few light deto pings will make it happen instantly.
A whole large batch of B9 or 10 EGV plugs the ceramic fell off for no reason, and NGK have acknowledged this in writing but I bet the importer will deny all culpability ( lawyer word for the day ).
But none of this dumb shit would ever happen if you wankers would listen to me and use a RACING plug in a RACING engine - B7376 has never once lost a ceramic or a fine wire laser welded
earth strap due to any tuning issue.
This is why they cost a bit more, still,its less of a piss off than loosing a race, and way less than the cost of a new piston etc.

speedpro

16th February 2015, 15:29

, still,its less of a piss off than loosing a race, and way less than the cost of a new piston etc.

The happy place we were in was that we had a spare competitive bike in the van, and I have a box of KT pistons that cost $6ea

seattle smitty

16th February 2015, 16:28

Where do you boat people get your nikasiling done, Smitty?

I thought you knew Rossi, Frits. For my part, all my boxes of stuff is Pleistocene Era with iron sleeves.

dont[/U] want to do is add fins to the back side of the chamber and allow the water to cool that area more.
Without simply giving away a really successful secret, what we do want to cool as effectively as possible is the squish band area, to keep the end gases away from
the killer deto heat range.

Assume you have addressed the exhaust port area cooling aspect. Now if you are getting detonation, the region of interest becomes the combustion chamber, right? If you want to draw heat from the metal around the plug body, instead of making the water jacket thinner there per Jan Thiel, with structural integrity becoming an issue, it would seem to me better to have a cooling fin at that point, with lots of surface area from which to draw heat, and structurally stronger as a side benefit. And/or, to cool a squishband (to my dumb welder's intuition this sounds right-on, Wobbly!!), again how about a cooling fin configurated as a vertical ring in the water jacket directly above the squishband, again to add a lot of surface area (and strength) exposed to coolant.

In days of yore, I fabricated a couple of heads for Konigs with vertical mill and lathe. Has to be two-piece: you machine the combustion chambers on one side of your head, and shape the water jacket on the opposite side, and cap the water jacket with your second piece. Simple to do even for a very modestly-skilled amateur machinist like me. I didn't think of it then, but when carving the water-jacket side of the head, it would be dead-simple to form an annular (I think that's the word) cooling fin or two above/opposite the squishband, . . . and easy enough to do one for the the metal around the sparkplug hole. Given a lot better knowledge than I had 45 years ago, a guy could make himself a head in which the coolant flows in a directed pattern rather than they appear to me to do in even modern engines' water jackets I've seen.

I did this stuff with ordinary machine shop tools and would still do it that way, but understand that you can make pretty tricky internal passages with modern lost-foam foundry techniques, and have a one-piece head. OTOH, the photo of the combustion chamber insert that TeeZee posted intrigues me; maybe I'll make a THREE-piece head on my new (to me) Bridgeport mill. Computer-ignorant old man that I am, I've gotta get a pad of paper and pen, and start sketching . . . .

Wobbly, as I said and you say, the combustion chamber is where the engine makes power, so I imagined a possibility that one could over-do the cooling fins in the head and lose power. Frits says you can't over-cool (but I might misunderstand exactly how he meant this; Frits?).

(EDIT) For reasons known only to software engineers, the program has ignored the way I laid out this post. I hope you can decipher the original emphasis and order. The little pencil-necked dorks keep yammering about "user-friendly;" what a damned LOAD that is!!!

RAW

16th February 2015, 22:08

Frits Overmars

16th February 2015, 23:28

309064309065309066309067
A couple of head designs. The finned one is from the current benchmark in superkart engines. DEA & the other with the passages about the plug may be a Thijs Hessels design.
Frits the DEA head seems to go against what has been described for performance, however this engine is extremely powerful. Given your friendship & confidential nature with Andrea I hope it wouldn't be asking to much to have you explain how / why this style is employed within the DEA inline engines.You are more or less right about the Thijs Hessels inserts. Thijs produced them, but they were designed by Dolph van der Woude (who also designed the original Aprilia 250 cc V-twin race engine).
The DEA insert is completely in line with my ideas about cooling. I suppose you are referring to Wobbly's remarks?

RAW

17th February 2015, 00:19

Yes Frits, Wobbs remarks may to some degree contradict the DEA insert. As such would you explain the reasons for the DEA insert and how it fits with your views on insert designs. This I'm sure would assist us all in better understanding the 2 stroke principals & requirements.

Frits Overmars

17th February 2015, 02:18

would you explain the reasons for the DEA insert and how it fits with your views on insert designs.I tried to be explicit before and I don't know how to say it any clearer: cool it.
Wobbly is right in that a cooler chamber surface conducts more heat away from the burnt gases, lowering both their temperature and their pressure.
But in our experience that's what it takes to allow optimizing the mixture strength and the ignition timing without running into the deto zone.
The cool chamber is already important before combustion even begins; the fresh charge should not pick up too much heat from the surrounding metal during the compression phase.

wobbly

17th February 2015, 07:07

In all current designs ( exactly like the two shown for Superkarts ) there is NO attempt to do anything clever about explicitly cooling the squishband.
The cutaway design gets water up to the threads,no better or different than Jans original,the step design is just bulk cooling everything in site, and this probably helps pull heat away from the
end gas area, by default - not design.
As I said the theoretical best scenario is to have as cool a squish as is possible and then have a reduced temp delta across the chamber area.
A possible solution is to have 2 cooling circuits, one that keeps the transfers and squishband coolest, and a second hotter one that surrounds the chamber.
But this seems an impossible pipe dream to implement.
Im not giving away the solution to this, but it is possible to do exactly as the theoretically best scenario suggests and in a KZ2 this allows way more advance and a leaner mixture
without the spectre of death deto ,constantly looming over the piston edge trapped in the squish.
I am, as everyone should be, very wary of contradicting what Frits has to say, but in this case he is citing the result gained from the DEA head as being exactly what he found in practice works best.
That is, cool the hell out of everything - the carpet bombing approach.
What I am suggesting is slightly more elegant, in that the next step to what we really want cooled the most is the end gases trapped between the piston and the insert.

seattle smitty

17th February 2015, 07:07

. . . I don't know how to say it any clearer . . .

I beg your pardon, Frits. Certainly what you wrote was clear, but when our two chief experts appeared to me to disagree on a point and I am citing one of them to the other, I thought it just good manners to suggest that I might have missed something. Besides that, I thought I shouldn't ignore that you are advising a readership comprised overwhelmingly of motorcycle racers, and probably some kart racers; for both of them, the coolant enters their engines already twice as hot as the water entering a racing outboard engine, AND they are burning gasoline rather than methanol having a "refrigerant effect" that a student like me would guess might (?) make you modify your straightforward assertion, were you addressing outboard racers.

2T Institute

17th February 2015, 10:37

The only thing that will make a plug ceramic crack and fall off is deto.
In an ordinary Iridium even a few light deto pings will make it happen instantly.
A whole large batch of B9 or 10 EGV plugs the ceramic fell off for no reason, and NGK have acknowledged this in writing but I bet the importer will deny all culpability ( lawyer word for the day ).
But none of this dumb shit would ever happen if you wankers would listen to me and use a RACING plug in a RACING engine - B7376 has never once lost a ceramic or a fine wire laser welded
earth strap due to any tuning issue.
This is why they cost a bit more, still,its less of a piss off than loosing a race, and way less than the cost of a new piston etc.

As proof was ever needed on this but the life expectancy of a shitty ES style plug in a TZ 250 is about from 9000-11,500 once. Moral is if your using ES, EV, EG or EGV your tuning has a long way to go.

lodgernz

17th February 2015, 12:14

But none of this dumb shit would ever happen if you wankers would listen to me and use a RACING plug in a RACING engine - B7376 has never once lost a ceramic or a fine wire laser welded earth strap due to any tuning issue.
This is why they cost a bit more, still,its less of a piss off than loosing a race, and way less than the cost of a new piston etc.

Wobbly, I've had B9HCS plugs recommended to me, and I currently use BR9EGV to try and save the engine in case of detonation.
Do you have any experience with these plugs? Any comments?

TZ350

17th February 2015, 12:26

I've had B9HCS plugs recommended to me, and I currently use BR9EGV Any comments?

The NGK B9HCS is a 14mm x 1/2" reach plug while a BR9EGV is a 14 x 3/4" reach plug.

speedpro

17th February 2015, 12:40

What I am suggesting is slightly more elegant, in that the next step to what we really want cooled the most is the end gases trapped between the piston and the insert.

An insert within an insert would seem possible at 1st thought, with 2 seperate cooling circuits. O-rings would handle sealing and the boundary between inserts would create a step in temperature between the inserts. One insert being the squish and the other the actual combustion chamber bowl. Have to be careful with hot edges in the combustion chamber.

Re the damaged motor, I pulled it down last night and detonation was the problem. The piston has a slightly furry patch in the centre and on the exhaust side in the squish area there were 2 chips knocked off the crown and other fuzzy sort of damage. Time to take it out to the next oversize, 52.15 from 52.1 and only because I got the pistons. the bore is good(ish). Love those kart pistons and their .05 oversizes.

ken seeber

17th February 2015, 13:36

Smitty,
Have been reading the latest round on cooling discussion, but with the mind focussing on more pressing matters, haven’t had the opportunity to comment of late.
My take on cooling a 2 stroke is that, as Frits says, you can never over cool a 2 stroke. This is a very general statement, generally applying to the overall engine. Cold air passing thru equals:
• Higher charge density – more power
• Cooler temps mean better lubrication control and durability(less oil breakdown/carburizing)
• Cooler temps mean less opportunity for detonation
You are fortunate with boats in that you have the world’s biggest radiator at your disposal, with typically a 15 – 20 deg C inlet flow temp, compared to bikes/karts where the ambient temp can vary from whatever in the northern hemisphere to over 40 in Oz. From this potentially high ambient temp we need to cool the coolant down to as low as possible maybe as a guess, even with a huge radiator, that this might have delta T of 10 deg over ambient. Passing through the engine, I seem to remember that a fairly normal increase was around 5 deg, this being obviously dependent on the flow rate. The higher the flow rate the better the actual heat transfer rate, giving a smaller overall temp differential across the engine. If the 5 deg is in fact the case in current racing 2 strokes (will bow to Frits and Wob on these matters), then the need for a separate circuit is hard to justify, but who knows…I don’t. The downside to higher flow rates is the power required to drive the pump and its heat input into the cooling system (previously discussed).
However what Wob is saying, I am sure, that overall cooling is good for all the obvious reasons, HOWEVER in certain areas there are specific needs for power and engine durability. Specifically:
• We want the spark plug to remain as cool as possible
• We want the two surfaces (head outer circumference and piston crown edge) that form the squish zone to be as cool as possible to avoid detonation
• We want the combustion zone to be as warm as possible tor maximum Carnot cycle efficiency, consistent of course with detonation and even pre-ignition control.
There have been some attempts at detonation control (other than the more subtle methods that are being currently employed), one of these being Warren Willing’s Yamaha sprung loaded cyl head combustion chamber that after a certain cylinder pressure was attained, the whole insert would shift outwards, allowing the pressure to drop. Dunno if it was ever successfully used though.
Back to combustion chambers. I think the ideal shape for a combustion shape is a sphere, which offers a minimum surface area to volume ratio, thereby minimizing heat transfer, allowing maximum combustion temps and efficiency. By employing squish zones, this allows a more compact combustion chamber shape. Not perfect, but clearly the way to go. And as Wob has been saying, the toroidal shape within the head is desirable as (I think) it places the spark plug gap towards the centre of the zone (obviously more so in the case of the flat top piston) so the flame kernel can radially progress. My understanding anyway.
If you want to see a shit combustion chamber, have a look at this: https://www.youtube.com/watch?v=0SiRqmo5Onc It can be clearly seen at the 3 minute stage.
In recognition of this, a direct fuel injection system was developed that, under the generic terminology of the day, DISC (direct injection stratified charge) which allowed the fuel (and a small quantity of injection air) to be injected late in) the compression cycle such that no fuel entered the acres of squish area. In that case, we were chasing fuel consumption and low unburnt HC emissions.
As a digression, this fuel injection system was very successful, particularly so when applied to a 2 stroke engine. (both crankcase or externally scavenged). The system is still being commercially manufactured today with applications such as marine (Mercury Optimax) to small drone engines (spark ignited running on jet fuel).
Personally I wish that some of the dumb arse controlling bodies, particularly in karting (which in my understanding is the largest (numerical) arena for competition 2 strokes) where they stick to archaic/ill considered rules (possibly for pecuniary reasons) and don’t allow any significant technical advancement opportunities, would use their imagination.
That’s what is great about this bucket thing. Lots of regulation freedom and cultural freedom, allowing guys like Neil and TZ350 and many others experiment, hopefully leading to the advancement of 2 strokes and their rightful and justifiable place in the future.
My thoughts anyway.

Larry Wiechman

17th February 2015, 13:54

Seems that we've been pumping the coolant the wrong direction, all these years. Wouldn't it be better to have the biggest temperature delta in the head instead of the cylinder?

Yow Ling

17th February 2015, 14:41

What I am suggesting is slightly more elegant, in that the next step to what we really want cooled the most is the end gases trapped between the piston and the insert.

Could always put a mask , like when you etch a pcb, over the combustion chamber part of the dome on the water side. Use a material like an epoxy paint that has a known thermal resistance. Leave the squish bit unpainted and allow the water up to the plug threads

wobbly

17th February 2015, 15:13

There are two issues in the cylinder that need the most attention from the coolest water available.
Over the transfer duct outer walls, and the Ex duct outer walls.
The first as this keeps the inducted charge as cool as possible, the second is to keep the trapped slug of fresh ( ish ) fuel air in the Ex duct
also as cool as possible.
The slug gets stuffed back past the closing piston ,thus this contributes to the combustion process - and if overheated it creates deto very quickly.
Wrap your header with glass insulation tape - and quickly find out what not to be doing.
We have a trade off situation in the cylinder/head interface.
As Frits alludes to we dont want a "hot " head contributing heat to the cool charge being compressed prior to ignition, but on the other side of this coin we dont want
cold alloy pulling heat out of the ignited mixture.
As DEA etal have found the tradeoff currently works in the favour of the carpet bombing approach of cooling the hell out of everything in the head.
But as I have found dozens of times if you ceramic coat the chamber only, power goes up.
When you ceramic coat, two things happen.The coolant temp drops, always a good thing, and this cooler water in the head then possibly has a chance to do more good by
dropping the end gas temps, thus helping to keep deto at bay.
Jan found a very simple way of keeping the plug cool, you guys wanting to tune to the edge of available power need to think of your own solution to effectively
cooling the squishband, in a better way than the current carpet bomb approach.

seattle smitty

17th February 2015, 16:34

(Quote=Wobbly) ". . . you guys wanting to tune to the edge of available power need to think of your own solution to effectively cooling the squishband, in a better way than the current carpet bomb approach." (end quote)

EASY, when the answer is handed to us, gift-wrapped! Dang, Wobbly, if you were in Japan they'd declare you a "Living National Treasure," and put a giant medal on your chest, with crossed bounce-pipes on a backqround of chrysanthemums and castor beans.

This is an especially easy thing to do in an outboard. You don't particularly want water leaks to the outside, just as a matter of pride in workmanship, but if you do have odd water-jacket seeps past home-designed gasketing and o-ringing, it doesn't matter! Your coolant all goes over the side anyway after it has done its job (flow through the engine is controlled by restricting water-out). An extremely simple modification to the head design I carved from billet long ago will do exactly what you advocate. Nothing in the rules says you have to put all the coolant into the engine at a single point and trust it to flow around just as you hope; you can make a water manifold that puts the water in at a number of points. This manifold can have big lines going some places and small lines going elsewhere. In outboards, we frequently let the water OUT of the engine at multiple points as well.

(I just wish my personal road to enlightenment didn't have to be paved with my endless long-winded and doofus questions in between the "AHA!!" moments!!)

TZ350

17th February 2015, 19:15

.... what is great about this bucket thing. Lots of regulation freedom and cultural freedom to experiment ....

Yes we are very lucky, and the class structure makes it affordable too and competitive enough to keep skilled riders happy, I love it.

Frits Overmars

17th February 2015, 22:23

I shouldn't ignore that you are advising a readership comprised overwhelmingly of motorcycle racers, and probably some kart racers; for both of them, the coolant enters their engines already twice as hot as the water entering a racing outboard engine.Smitty, basing your opinion about my experience on the prevailing type of readership here may not be the way to go.
As long as 30 years ago (yes, I'm an old sod) you would not find any form of radiator on Jan Thiel's Garelli test bench. There was a hose from the cold water tap to the engine and a hose from the engine to the sewer. And Jan was not afraid to measure a stone cold engine at full throttle. It made him realize were the power is, and how important cooling is.

I am, as everyone should be, very wary of contradicting what Frits has to sayThanks for the flowers Wob. I hope everyone here realizes that we all owe you the same courtesy.

in this case he is citing the result gained from the DEA head as being exactly what he found in practice works best. That is, cool the hell out of everything - the carpet bombing approach.There's two ways to look at this.
A: You can't argue with measured results, provided that these results include all the variables that played a role during the measuring.
B: Those results will not prove that they are the optimum. There may always be better, or as you put it, more elegant ways to advance. You made me curious...

what we really want cooled the most is the end gases trapped between the piston and the insert.That's where detonation occurs, so your desire is logical. But around here a quote from yours truly has become well-known:
"Squish it till the doctor comes; try to get your dynamic squish gap down to zero. Mixture that isn't there anymore, won't detonate".

There are two issues in the cylinder that need the most attention from the coolest water available. Over the transfer duct outer walls, and the Ex duct outer walls.Don't forget the transfers' inner walls. That brought another HP or so for the RSA. Yes, I know, that will require some casting skills. Or the Selective Laser Melting that I used for the FOS cylinder.
309096

husaberg

17th February 2015, 23:06

Yamaha during the sixties found a correctly fuelled air cooled engine HP fell from 30 cold to 23 HP when tested hot.
Where as a over rich mixtured one began with only 27 yet when hot still made 25hp.
Of course the figures were not as good as a water cooled ones lesser power fade.

Re the damaged motor, I pulled it down last night and detonation was the problem. The piston has a slightly furry patch in the centre and on the exhaust side in the squish area there were 2 chips knocked off the crown and other fuzzy sort of damage. Time to take it out to the next oversize, 52.15 from 52.1 and only because I got the pistons. the bore is good(ish). Love those kart pistons and their .05 oversizes.

I don't understand the furry bits in the middle? Wouldn't damage or erosion their not also suggest pre ignition?

Martin1981

18th February 2015, 02:48

From time to time one just has to say thank you to wob frits and all the other 2 stroke builders and tuners for that awesome thread. Wayne and Frits are sharing their lifework with us. one can not appreciate that enough. if only we could meet all together in New Zealand someday and talk about that simple looking but so complex and complicated 2 stroke engines (and:drinknsin and eating bratwurst). kicked ass by politicans unfortunately for to me no obvious reason:motu::mad:. fortunately there are some people left on earth paying the 2 stroke the attention it deserves. thanks Jan Thiel, Wayne and Frits and all the others!!!!!!!!

Mentioning Jan Thiel.... Frits, one remarkable issue, at least to me.... it seems that Jan realized just from the Beginning that the rotary inlet is the best for power. there are not many pictures showing Jan with piston port or reed valve engine. maybe a stupid question but is that the only reason (power) that he so to speak started straight off with the rotary inlet system or are there other reasons that makes him prefering it?