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

[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

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

Get in line!! He's making me one first!!

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

[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

[Kendog]

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

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

Even bucket tyres need some time to warm up

[Skunk]

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

OK.

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

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