New Chamber

[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

[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

Yeah, desiels are real cool until a two stroke comes past. I hope you have the nos sorted...

[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

[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!!!

[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?

.