New Chamber

[Sketchy_Racer]

I thought someone might be interested in seeing this so I decided to post it up.

I've spent far, faaar to long making this thing but I like the challenge (much more of one than I gave it credit for too!)

Things I learnt whilst making it:

1- Bashing 0.9mm around small pipes takes lots effort.
2- 0.9mm steel has very, very sharp edges
3- The first time you make it, you will probably cock part of it up, thus wasting about a days worth or work
4- It's very satisfying watching all your hard work turn into something cool
5- Expect to spend about 30-40 hours making your first one (including the cock up)

I'm not totally happy with the end product, but certainly not disappointed. I struggled with the welding, it's very difficult to weld around all the cones.

I got to test it today (And crash test it providing great entertainment for Fishy) and some good and not so good results have come.

It seems to make good power, but being over geared it highlighted a bit flat spot in the rev range I would guess around from 9 - 10k then it takes off to at guess about 12-13k

I'm going to attempt to get rid of the flat spot with some changes with the Jetting, timing and head volume but my gut instinct is that it is a mismatch between the transfer and exhaust port time area.

Anywhere, here are the photos feel free to make constructive criticism

Cheers,

-Glen

[AllanB]

Cool - and a lot of work!

I know what you mean about time - I spend two hours making a bracket a week or so ago!

[Buckets4Me]

Nice NICE I like it

can you make me one :blank:

[bucketracer]

It seems to make good power, but being over geared it highlighted a bit flat spot in the rev range I would guess around from 9 - 10k then it takes off to at guess about 12-13k

I'm going to attempt to get rid of the flat spot with some changes with the Jetting, timing and head volume but my gut instinct is that it is a mismatch between the transfer and exhaust port time area.

feel free to make constructive criticism

Cheers, -Glen
.



Thats a decent looking piece of work Glen.

Old TZ posted a link to a paper by Yamaha that talked about a dip before the power peak due to transfer port arrangement.

Yamaha SAE Paper on Porting:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Gold Mine 1:- http://www.2stroke-tuning.nl/media/

It can be down loaded for free and printed out. It took me a couple of nights to get my head around it.

All the best. B...

[quallman1234]

Nice work mate.
Don't forget cutting the cone's the wrong way.

[Kendog]

Was a good test and it sounded sweet as you passed me.... again..... and again..... and again.

[speedpro]

Nice bit of work, especially if it was your first. You need to start collecting bits of tapered steel and curved heavy gauge pipe for hammering the curves on.

Design wise it looks to have a pretty fat header into a not so fat centre section with a mildly tapered rear cone. It also looks a bit on the short side. Interesting to know how the design came about.

How do you find the H100 engine? Have you dropped a 6-speed in it yet? The cranks are good for 14Krpm but the rings are too fat and do lose a ring tip now and again.

[Sketchy_Racer]

Nice NICE I like it

can you make me one :blank:

Haha I'm sure something could be arranged!


Thats a decent looking piece of work Glen.

Old TZ posted a link to a paper by Yamaha that talked about a dip before the power peak due to transfer port arrangement.

Yamaha SAE Paper on Porting:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Gold Mine 1:- http://www.2stroke-tuning.nl/media/

It can be down loaded for free and printed out. It took me a couple of nights to get my head around it.

All the best. B...

Thanks for that. I had a quick look at it, but my head isn't in the right space to read into that enough tonight.


Nice work mate.
Don't forget cutting the cone's the wrong way.

Yeah, the old saying measure/check twice, cut once ring true again eh. Lucky it wasn't a big problem.


Was a good test and it sounded sweet as you passed me.... again..... and again..... and again.

Haha, yeah I tested a little more than the chambers performance though I think!

Nice bit of work, especially if it was your first. You need to start collecting bits of tapered steel and curved heavy gauge pipe for hammering the curves on.

Design wise it looks to have a pretty fat header into a not so fat centre section with a mildly tapered rear cone. It also looks a bit on the short side. Interesting to know how the design came about.

How do you find the H100 engine? Have you dropped a 6-speed in it yet? The cranks are good for 14Krpm but the rings are too fat and do lose a ring tip now and again.

Thanks Mike,
The design is off a generic chamber program. Put all the relevant info in and it spits out a plan for you. I'll try get the specs up. I did do the formula from the graham bell book, but some interesting sizes and shapes in exhaust port gave me a very wild chamber. From memory, the chamber is about 1.2m in length from piston face to the end of the stinger.

I love the H motor. It's the most appealing to me of the bunch of worthy bucket eligible 100cc two strokes. The H has the 6 speed in which is great, F5Dave did that when he owned it. You are right about the rings and the piston itself. I don't like it, and made some small modifications to it. The match between the piston and barrel was a joke!

What pistons do you run?

Cheers,

-Glen

[Trudes]

Nice NICE I like it

can you make me one :blank:

Get in line!! He's making me one first!!:bleh::laugh:

A work of art really Glen, you should be very proud of your labours! :niceone:

[SixPackBack]

What formula did you use to manufacture the expansion chamber?......I have had a go at manufacturing something similar for a powered skateboard, due to space requirements the wave reflective length was halved [as an experiment].......it worked well. I suspect that reducing or increasing the reflective length by a factor of two would work in most cases.

[fi5hy]

Stuff the pipe mate tell us all about your crash in the first half a lap:bleh::clap::bleh::clap::bleh::clap:

[Kendog]

Stuff the pipe mate tell us all about your crash in the first half a lap:bleh::clap::bleh::clap::bleh::clap:

You mean the one on our first lap of the day, on the fourth corner :shutup:

Even bucket tyres need some time to warm up :cold:

[Skunk]

Anywhere, here are the photos feel free to make constructive criticismOK.

Get a stand for the camera when using long exposures. It'll help avoid camera shake like you got in the second photo.

[speedpro]

What pistons do you run?

Cheers,

-Glen

I've run std honda pistons for a long time in a couple of different MB100 engines. They are good strong pistons but the rings are supposedly a bit thick for the revs the engine is capable of. I have since built a short stroke crank with a long rod and run 52mm Yamaha KT100 kart pistons. Gazilions of oversizes(.05 steps) and pretty well priced and always available off the shelf at your local kart shop.

[Sketchy_Racer]

Stuff the pipe mate tell us all about your crash in the first half a lap:bleh::clap::bleh::clap::bleh::clap:

Haha, I think Kendog would be able to give you a pretty informative description of the crash. He had the best seat in the house.

He was also excellent at reminding me that I only managed to complete 3 corners before falling off. Sadly, not the worst I have done before but always a good laugh for others eh :clap:

[F5 Dave]

Hi glen, look good, but that header section is pretty large di.

A dip in power is often too steep of a baffle cone. my original pipe suffered from this (hence the boost bottle band-aid).

But that clearly isn't the case here, I'd say that couldn't be 15deg (included). Maybe experiment with a thinner header section with a fair taper before the difficult curved section? Could blaze on the old header from my pipe, I'd have to look up what it was.

That is revving pretty high. Quite some change of plan.

I recognize Si's old RS muffler.

[Sketchy_Racer]

Hi glen, look good, but that header section is pretty large di.

A dip in power is often too steep of a baffle cone. my original pipe suffered from this (hence the boost bottle band-aid).

But that clearly isn't the case here, I'd say that couldn't be 15deg (included). Maybe experiment with a thinner header section with a fair taper before the difficult curved section? Could blaze on the old header from my pipe, I'd have to look up what it was.

That is revving pretty high. Quite some change of plan.

I recognize Si's old RS muffler.

Hey Dave,

Below is the plan of the chamber. The small black part of the header is the original off your pipe that i've used as a slip joint.

Im starting to think that Mike's conclusion of being too short is correct hence the kick in the pants at high RPM. When I can I will get on the dyno and try a few different things. One will be to extend the centre section length and see how that affects the RPM at peak power.

Also I've attached pictures of the head and piston. Apart from the fact that it was running very rich, the burn pattern shows a large washing effect from the boost port. I'm wondering if the fact that the Chamber is not working in the right rpm and the boost port is being a little to dominant combined with not enough up ward angle is blowing out the cylinder in the rpm range where the power dip is occuring?

At a guess in feeling the difference in the bike from the old pipe on the dyno giving a peak of 19.3 I would say with the new pipe it is making over 20. It is very very strong in power after the dip in the power, but only last for a short while. The other thing that has popped to my head is that I need to change is the reeds. It still has the steel reeds and I don't know how they will be affecting the rev characteristics. Is it possible to get a RPM range that suffers flutter, but then you ride through it?

There are so many variables with these things, and they all have to work together. Frustrating but also very satisfying when you get it right!

Oh and yes that's parts of Si's old muffler. It's about half the length it used to be (Concrete wall and manfeild claimed that...) and the part that bolts to the chamber is new and ally instead of stainless.

Cheers,

-Glen

[Sketchy_Racer]

What formula did you use to manufacture the expansion chamber?......I have had a go at manufacturing something similar for a powered skateboard, due to space requirements the wave reflective length was halved [as an experiment].......it worked well. I suspect that reducing or increasing the reflective length by a factor of two would work in most cases.

Hey mate,

In the above post it shows a picture of a basic chamber program. You put in all the relevant information and it spits out a plan. It's a simple math calculation from known figures.

I have no idea how changing the wave reflective length would affect the power curve, but it is something I plan on experimenting when I get a chance to get on the dyno.

Cheers,

-Glen

[SixPackBack]

Hey mate,

In the above post it shows a picture of a basic chamber program. You put in all the relevant information and it spits out a plan. It's a simple math calculation from known figures.

I have no idea how changing the wave reflective length would affect the power curve, but it is something I plan on experimenting when I get a chance to get on the dyno.

Cheers,

-Glen

Cool programme. I did all my calculating the old fashioned way hehe...
Wave reflection length is questionably one of the most important aspects of chamber design and should be the first aspect of design to set.
Angle of the rear reflective cone also makes a big difference, and can change peak power and spread of torque. I found that a shallower angle created a broader spread and steeper a higher overall 'peaky' delivery.

[F5 Dave]

That piston pattern looks okish to me. The pipe design however is queer as buggery. There's no header to speak of & all section one diffuser. The fact that it is tuned for peak power at 9500 & then takes off after that means that it is all up the booie.

Is that really 100mm di, looks smaller, 100 is small for a 100, but that is not ness a good measurement of a pipe.

Was just wondering about the reeds. Steel are the business up to 10,000, but after that I'd worry. But you don't originally seem to have been tuning the bike that fast. Pistons will be fine up to 10,000. Short stroking the engine to fit thinner ringed pistons is mondo work. There is very little else in a legal piston size that will allow heap of revs & stay together. My MB50 was very prone to losing piston ring tips when revved hard. Fortunately RD50 pistons would fit & stay within legal size, but needed several mods to work.

[fi5hy]

Buy a diesel then you can just sit down and drink beer:beer:

[Skunk]

And lap valves, and replace pistons, and tweak carbs, and modify ports, and, there's just too much to list. And in the end it's still a diesel.

[Sketchy_Racer]

Buy a diesel then you can just sit down and drink beer:beer:
Yeah, desiels are real cool until a two stroke comes past. I hope you have the nos sorted... :headbang:

[Sketchy_Racer]

That piston pattern looks okish to me. The pipe design however is queer as buggery. There's no header to speak of & all section one diffuser. The fact that it is tuned for peak power at 9500 & then takes off after that means that it is all up the booie.

Is that really 100mm di, looks smaller, 100 is small for a 100, but that is not ness a good measurement of a pipe.

Was just wondering about the reeds. Steel are the business up to 10,000, but after that I'd worry. But you don't originally seem to have been tuning the bike that fast. Pistons will be fine up to 10,000. Short stroking the engine to fit thinner ringed pistons is mondo work. There is very little else in a legal piston size that will allow heap of revs & stay together. My MB50 was very prone to losing piston ring tips when revved hard. Fortunately RD50 pistons would fit & stay within legal size, but needed several mods to work.

From what I have noted with different figures in the program is that the RPM range that you pick dictates the total length of the chamber, and each part gains length (diffuser, mid section, baffle) The part that seems to make the most significant differences to the diameters is the original size of the exhaust port.

The revs that I mentioned before are a seat of the pants feeling I have. To be fair I may be well out of the ball park as the new chamber sounds much 'zippier' than the old one, so may sound like it is reving higher. The dip in the power still existed with my RS125 chamber but was very small on the dyno sheet, and I couldn't feel it riding. I would like to keep the RPM range about 12ish, more for longitivity than anything else.

To be honest, I'm feeling a little dumb right now. I did research and have a good think about the chamber before building it, but I'm starting to think I didn't do enough. It's a lot of hours to say "well at least it was a learning experience...."

Cheers,

-Glen

[fi5hy]

[QUOTE=To be honest, I'm feeling a little dumb right now.
Cheers Glen,[/QUOTE]

Thats ok mate drink more beer and you get smarter think of it as a herd of cattle, When the herd is being attacked by loins the weaker or the slower get killed by the loins in that way saving the rest of the herd or making them faster. A bit like your brain by drinking lots of beer you are killing off the slower cells in your brain and in doing so making your brain faster.

Cliff Cheers 1988 ish :clap::apint:

[sonic_v]

Nice bit of fabrication. Your seam welds on the bend sections are all on the inside of the bend. Are you using a programme to draw each individual bend section?

[CookMySock]

I did research and have a good think about the chamber before building it, but I'm starting to think I didn't do enough. It's a lot of hours to say "well at least it was a learning experience...." Glen, it's important to remember that the software will just get you in the ballpark. Also, consider that if you made five of these exactly the same there will be one that magically goes better than the rest anyway, so don't worry too much.

When building this sort of stuff, it's important not to spend a lot of time worrying about making it look pretty, when it will possibly be hiffed in the corner as a dud. Someone on trademe will pay top bux for something like that too, as a hot up for their road bike.

Looks like you are using the same software as I. I'm just waiting on some TIG gear before I get started on B1 and Daytona chambers. I tried welding thin steel with my gasless MIG but it just tore everything apart.

Nice work.


Steve

[Trudes]

But it's gotta look pretty!!!:innocent:;)

[F5 Dave]

Software is all very well, & draws a pretty picture, but I have never seen a header only 55mm long. It just don't make sense.

My original pipe had a 276mm header at 2.75 degrees, followed by a 9 & 15 diffuser with a mondo 23 Baffle, 20 would have been better (think I have right file, it was 1997 when I laid it down). Bit of a queer design, but I was after supercross power for kart tracks. There was a bit of a mismatch to transfer Height for the super aggressive baffle, but it was a 'bit of a laugh' wheelie bike so I never tried to redevelop it.

[TZ350]

Hey mate,

In the above post it shows a picture of a basic chamber program. You put in all the relevant information and it spits out a plan. It's a simple math calculation from known figures.

Cheers,

-Glen

Hi Glen, is that the Mota Pipe programe?

Can you post the basic data you used so others can have a play and see what comes up?

.

[koba]

\ There was a bit of a mismatch to transfer Height for the super aggressive baffle, but it was a 'bit of a laugh' wheelie bike so I never tried to redevelop it.

I imagine it may have got even worse with the KTM chamber Ola put on it, I was crying more than laughing when I rode it!

[Skunk]

Software is all very well, & draws a pretty picture, but I have never seen a header only 55mm long. It just don't make sense.
You're reading it wrong Dave. The header is well over 400mm long...

Hi Glen, is that the Mota Pipe programe?
Can you post the basic data you used so others can have a play and see what comes up?It's not MOTA. It's IWT Racing. The figures used are all in this post's (http://www.kiwibiker.co.nz/forums/showpost.php?p=1129302629&postcount=17) images.

[F5 Dave]

ya know I don't think I am, looks like 1st section is port LX 45mm (which is correct for the H from my old notes). Then a parallel section of header 54.8mm & then Diffuser 1 is L1. It is 409 long & 4.76 degrees (included). That is no header.

Actually it is a queer angle for a diffuser too. 9 & 14 may have been more suitable for a 2 stage diffuser.

[ajturbo]

well done matey..

last time i saw it, you were just drawing on the 0.9....

now this.. well done!!!

[speedpro]

ya know I don't think I am, looks like 1st section is port LX 45mm (which is correct for the H from my old notes). Then a parallel section of header 54.8mm & then Diffuser 1 is L1. It is 409 long & 4.76 degrees (included). That is no header.

Which leads to the skinny looking centre section. It'll be interesting to see how it shapes up on the dyno.

[Sketchy_Racer]

Hi Glen, is that the Mota Pipe programe?

Can you post the basic data you used so others can have a play and see what comes up?

.

Hi TZ,

Yeah it's the (edit) sorry its not the Mota, it's program Skunk mentioned. All the info is in the screen shot but here is the info that are knowns from my specific motor;

Exhaust port ATDC = 84 degrees
Effective exhaust port Dia = 32mm
Exhaust port Dia at barrel flange = 34mm
Length from piston face to exhaust flange = 45mm

There was a link posted up in your thread to a online version of the Graham Bell book, I had a look for it, but gave up after 50 or so pages. I don't suppose you have it save somewhere?

Cheers,

-Glen

[Str8 Jacket]

I imagine it may have got even worse with the KTM chamber Ola put on it, I was crying more than laughing when I rode it!

OI! HTFU! Jeebus, I loved that bike. You just needed to know how to ride it smoothly! :rolleyes:

[Buckets4Me]

Hi TZ,

Y
There was a link posted up in your thread to a online version of the Graham Bell book, I had a look for it, but gave up after 50 or so pages. I don't suppose you have it save somewhere?

Cheers,

-Glen

and we wondered why he posts that link so often :P

http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf (1st page of E.S.E tuning page)

[Buckets4Me]

Graham Bell

http://www.kreidler.nl/artikelen/per...raham-bell.pdf

Gordon Jennings

http://www.vintagesleds.com/library/...20Handbook.pdf


http://toostroke.blogspot.com/2007/1...-handbook.html

Engine Formulas

http://members.bellatlantic.net/~vze...es/engine1.htm

Reading Plugs.

http://www.dragstuff.com/techarticle...ark-plugs.html

Rate of fuel burn and how it affects power output

http://www.factorypro.com/tech_tunin..._vs_power.html

and more

[fi5hy]

For F**k Sake buy a Diesel and drink more beer:wari::wari::wari::wari::wari:

[Buckets4Me]

I've seen your Diesel mechanic and it's stunts your groth :innocent:
by the look of him he couldn't even buy bear :P

or is that the trick buy a diesel and get your kids to work on it ;P
no wonder your swing arm fell apart :2guns:

[Buckets4Me]

here you go

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Motorbikes/Sports/auction-229232177.htm
and I can drop it off to you at Taupo :Punk:

[F5 Dave]

Which leads to the skinny looking centre section. It'll be interesting to see how it shapes up on the dyno.
106mm isn't skinny, but it isn't like 115/120 one might expect on a 100. I don't think it is the volume of the pipe at all (but I know you're aware of that), that is a function of the diffuser cone angles, often 2nd is usually steepest & longest for a race pipe. A tamer pipe would have a longer 1st diffuser which by course would result in smaller center section.

Modern pipe designs on older engines don't always wash, on less curved transfers are supposed to overscavenge, the H not being too bad, but not tremendous. I might presume that with only 30deg blowdown I over cooked it on the original design pipe.

[fi5hy]

I've seen your Diesel mechanic and it's stunts your groth :innocent:
by the look of him he couldn't even buy bear :P

or is that the trick buy a diesel and get your kids to work on it ;P
no wonder your swing arm fell apart :2guns:



:Punk: To right got to start them young

http://www.youtube.com/watch?v=9t_bmvmSCkw

:laugh:

[Bren_chch]

:Punk: To right got to start them young

http://www.youtube.com/watch?v=9t_bmvmSCkw

:laugh:

Whats his hourly rate?

[fi5hy]

Hes on a good wicket food, roof, all expenses paid till hes 18

[Kendog]

Hes on a good wicket food, roof, all expenses paid till hes 18

16 for bad behaviour?

[Buckets4Me]

16 for bad behaviour?

or a droped valve :bye:

[TZ350]

It might be Karts, but there is a bit of interesting reading here.

www.kartweb.com/TechArt/2Stroke/chapter1.doc

www.kartweb.com/TechArt/2Stroke/chapter2.doc

www.kartweb.com/TechArt/2Stroke/chapter3.doc

chapter 3 is on chambers.

[Kendog]

How did the chamber testing go this afternoon? :devil2:

[Sketchy_Racer]

How did the chamber testing go this afternoon? :devil2:

Mumble-fuckit-mumble...

I swear my bike has a thing against gravity..... :argue:

[quallman1234]

Mumble-fuckit-mumble...

I swear my bike has a thing against gravity..... :argue:

Haha :D. Again Man!

[Ivan]

Buy a diesel then you can just sit down and drink beer:beer:

good call.

God call indeed