Suzuki 2 Strokes

TZ: By using JKL block you Refer to the barrels right, i mean they where ported more for low end right? And dont worry about weight, the diet is called the grinder, i makes weight watchers look like amateurs

Tomorrow is the big day for picking her up, cant wait.

BTW, right now she is wearing dunstall body / tank fairing kit. Is that worth something on ebay?

Yes, barrels = block = Cylinders

Angle grinder diet is a good place to start but there are other things that can be changed for example front disk rotors are ridiculously heavy. Modern disks will save a couple of kilos. And the stock exhaust system is thick walled and very heavy.

Lower radiator mounts are redundant. Cut them off and just use the top ones.

Dunstall tank fairing kit don't seem to get good money but I really like the way they look.

Yes, J/K/L porting is more mild on the intake and exhaust. The shorter intake makes a significant difference to low to mid range compared to late M/A/B port timing. Of course if you use a barrel spacer, that lifts and corrects the intake timing a little....

tz375 wrote:I wonder how well they worked compared to some of the other options available.

Tz, how critical is the length of the tail pipe? The Straders & Pipers are quite a bit shorter than mine, and wondered how it might affect performance? Is the tailpipe purely for silencing?

Good question and one I'd like to understand better. There are guidelines as to diameter and length and in general longer/smaller raises pressure and temperature which raise top end power at the cost of meltdown if you go too far. Aprilia RS250 Cup Race bikes have very long stingers and they make 65 hp from 250cc, so there's some room to experiment I think.

I spent a couple of hours with sled exhaust guru Olav Aaen recently and he recommended a much larger pipe that I was planning on using but he's assuming that Strader is twice as large as it really is. Their 3 into 1 sled pipes are huge. I mean close to 8" diameter.

The plans Bill sent me for the FI cylinder had a body 6" across i couldnt use the plan as they wouldnt fit under the bike

As was posted, the stinger/tailpipe is essentially a bleed tube. To keep a certain amount of heat in the pipe. And like any pipe, you can vary the flow by it's length and diameter. A long large tube can act like a shorter smaller tube. So the pipes with very long stingers, just have a larger diameter.

John,

Have you seen any dyno tests that provide concrete data? MOTA gives me all manner of answers that suggests that there's a lot of flexibility in stinger dimensions without a huge change in output, but I suspect that's only true at a relatively low state of tune.

No dyno stuff, never did comparisons personally.

ja-moo wrote:As was posted, the stinger/tailpipe is essentially a bleed tube. To keep a certain amount of heat in the pipe. And like any pipe, you can vary the flow by it's length and diameter. A long large tube can act like a shorter smaller tube. So the pipes with very long stingers, just have a larger diameter.

Why do you need to keep heat in the pipe? Surely, if the pipe was freezing cold, the charge from the piston would contract, thus allowing more to be withdrawn, and more blown back in? Kinda reverse NO2, if you will. Or am I exposing myself as a clueless numpty here?

Nick.

Although a bit vintage with some of the theory this is good reading and will teach you a lot about 2 strokes http://edj.net/2stroke/jennings/2stroke ... ndbook.pdf" onclick="window.open(this.href);return false;

Hey numpty,

Just kidding. All questions are good, but if you are exposing yourself, we don't need to know about that.

Actually it works almost the other way round. The issue is speed of sound which is higher in a hot pipe than a cold one and the faster the pressure wave moves, the stronger the pipe works.

We are less concerned about the gas contracting or expanding that we are with the waves moving through the gas. Gas moves at around 300 feet per minute and pressure at around 700 miles per hour (over 60,000 feet/minute). Pipe design is basically about waves first and flow a distant second where a 4 stroke is more about flow than waves.

On a 2 stroke, we want to keep the pipe hot but not so hot that pistons melt. We are looking for mean temps around 1,200F in the center of the pipe at peak load. EGTs above that tend to lead to excessive piston heat and that leads to holes appearing where metal used to be or to pieces of metal becoming intimate and occupying the same time space coordinates and that generally is considered to be sub-optimal.

tz375 wrote:Hey numpty,

Just kidding. All questions are good, but if you are exposing yourself, we don't need to know about that.

Actually it works almost the other way round. The issue is speed of sound which is higher in a hot pipe than a cold one and the faster the pressure wave moves, the stronger the pipe works.

We are less concerned about the gas contracting or expanding that we are with the waves moving through the gas. Gas moves at around 300 feet per minute and pressure at around 700 miles per hour (over 60,000 feet/minute). Pipe design is basically about waves first and flow a distant second where a 4 stroke is more about flow than waves.

On a 2 stroke, we want to keep the pipe hot but not so hot that pistons melt. We are looking for mean temps around 1,200F in the center of the pipe at peak load. EGTs above that tend to lead to excessive piston heat and that leads to holes appearing where metal used to be or to pieces of metal becoming intimate and occupying the same time space coordinates and that generally is considered to be sub-optimal.

Jeez, cheers tz. It has only taken me about 30 years to understand how spannies work, and now you throw this at me. I thought that the whole idea of a spanny was the expansion & contraction of gas, but do remember once hearing about pressure waves & the speed of sound............so now need to understand more. Is there a bible to read on this? Zen & the Art of Expansion Chamber Science perhaps?

Suzukidave wrote:Although a bit vintage with some of the theory this is good reading and will teach you a lot about 2 strokes http://edj.net/2stroke/jennings/2stroke ... ndbook.pdf" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Cheers mister, will print this & study. Funny, isn't it, how you think that you have a grasp of something, then you realise that you know bugger all!

A comparative I use, is it's like standing in front of a big bass speaker. You can feel the (sound) pressure pulses of the beat. The bang (sound) coming out of the EX port travels down the pipe until it hits the baffle/reverse cone where it reverses, and that sound pulse pushes the gas back down the pipe, pushing the gasses back into the cylinder. The hotter the gas, the faster the sound waves move. Too hot and not enough heat gets out and pistons melt.

BTW, I was on vacation two weeks ago with the Family, and what a perfect spot to read a book. I had Graham Bell's two stroke tuning with me, and did chew my way through it. Is there a "this book you must read" ? Both Gordon Jennings and Graham Bell are from around the same period back in days. Is there anyone that have read both and could comment?

Cheers