Yamaha pipes

Taft Racing said:
Lee
The other aspect is stinger diameter and length. This also controls back pressure that assist in pushing the charge back by controlling the bleed off rate. Too small or too long a stinger and you'll build too much heat in the piston crown.
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So how do you explain the Hartman blimp and my Mayko shark pipe? Neither of which had a stinger.
Draw, pretty much the same as suck, and there’s no such thing as suck, at least in the context that we are talking about. There is only pressure differential.
A stinger controls the temperature and pressure of in the pipe. And this can lower or raise the average temperature in the pipe. This has a very significant effect on the wave speed, (sound) in the pipe. The wave speed will change with the temperature, about 1 ½ ft. per second per degree. Pressure has little effect on the speed of sound. The sound wave is what does all the work. The speed of the sound wave thus changes with changes of temperature in the pipe.
The term, “back pressure” is a colloquialism used by many in their attempts to explain the expansion chamber.
I did a post a few days ago explaining the whole process, so I won’t do it again. You can easily look it up and see how everything works.
Comments compliments criticisms and questions always welcome. There are
If the data does not support the theory, get a new theory.
 
The Hartman blimp pipe is not used in any modern pipe design. Why not? There are allot of old exhaust systems that 2 cycle will run on. Heck they'll run with no expansion chamber at all. Why bother making one. Oh wait. Cause they've found that using the most modern principles of physics develops more power. I won't say hp. Cause some people don't like that term used when describing a form of force.
I never used the term draw or suck. The conversion cone creates a log jam at the exit of the pipe. This builds pressure on the mass of gasses trying to escape. Pressure = heat. The stinger controls bleed off of that pressure which in turn controls heat. I hope you can grasp that concept
Are you saying that stinger length and diameter have nothing to do with bleeding off the pressure built up in the pipe Al? Just curious. Why do all the current pipe designers use them?
 
Taft Racing said:
The Hartman blimp pipe is not used in any modern pipe design. Why not? There are allot of old exhaust systems that 2 cycle will run on. Heck they'll run with no expansion chamber at all. Why bother making one. Oh wait. Cause they've found that using the most modern principles of physics develops more power. I won't say hp. Cause some people don't like that term used when describing a form of force.
I never used the term draw or suck. The conversion cone creates a log jam at the exit of the pipe. This builds pressure on the mass of gasses trying to escape. Pressure = heat. The stinger controls bleed off of that pressure which in turn controls heat. I hope you can grasp that concept
Are you saying that stinger length and diameter have nothing to do with bleeding off the pressure built up in the pipe Al? Just curious. Why do all the current pipe designers use them?
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your saying, "are you saying" is just a cheap trick and I would expect more from you.
you know I think you could be a little more respectful. And I didn't say you said draw, but the term has been used several times in this discussion.
It's called "2 cycle exhaust theory", and I have mine. Dr. Blair, (Belfast University) has his theories, and I built my very 1st expansion chambers using his theories, but over time, with experimentation, I found his theories to be a little flawed. A pipe designed to his specifications, works better with no stinger. (Interestingly, his formula describes a much shorter stinger than most pipes in use today) A pipe designed to his specifications, (by the way, his design uses 2 angles on the diverging cone) but with a bigger diameter, works better. My Mayko bullet pipe, although built to the same length, and still without a stinger, but the cones were spun with parabolic curves, worked even better. In the end I had 3 different bullet pipes. The L, the M, and the S. Each one being 1 inch shorter than the other. I also found that Blair's formula for determining the diameter of the stinger, was a little off.
Theories are great, yours being no exception, but they are still just theories. Build it, test it on the dyno, run it on the track, make modifications and then tell me what's best!
If the data does not support the theory, get a new theory.
Something else I found very interesting; the brother of a guy who worked for me fit one of my bullet pipes to his 125 scrambler. His report, with track testing, the bullet was much better than the factory pipe.
The fact that new pipes, better pipes, have come along since my bullet was made, surprises me not at all. And I'm pretty sure, in the future, newer better pipes will come along.
Comments compliments criticisms and questions always welcome.
 
Taft Racing said:
The Hartman blimp pipe is not used in any modern pipe design. Why not?
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the blimp pipe, even after RLV bought him out, was made for several years with only minor modifications. In 1985 they changed the converging to a double angle, trying I think, to match the parabolic converging cone of the Bullet pipe. Recently they have changed the diverging cone to better match the parabolic diverging cone of the Bullet pipe. And I don't know for a fact, but I doubt it has a stinger on it.
And I have a new design too, I’m just waiting to find somebody who wants to build.
Comments compliments criticisms and suggestions always welcome.
 
As far as respect. You show none you receive none. I'm not the only guy here on bobs you disrespect.

Now I agree that theory's are just theory's. But most are based in some sort of physics. You make statements that contradict your own statements. IE. Your dispute with the term "Back pressure". The expanding gases in the combustion chamber create "pressure" the exhaust port opening releases "pressure" and a sound wave. This sound wave also creates "pressure". The 2 forces expand down the pipe until they reach the conversion cone at which time they are reflected BACK. Now what's being reflected BACK?. Oh yeah "pressure". In the form of a sound wave and in the form of heat and mass of "pressure". So the term back pressure is accurate in every way.
I enjoy conversations on the physics of all things . why not engage in conversation with out constantly challenging every one else in your usual disrespectful way.
A stinger is used to control the release of pressure. Its a very tunable aspect to pipe building. Its just a fact. Its not the only way
 
Heres a good theory about pipes. I could care less about building one, the theory about how they work is good basic knowledge. But the reality of the fact is I buy a pipe based on the engine mods. You must know what mods have to be done to make this the best preformer for that build. Most experiment with lots of different designs trying to find the one that works best with their mods. I try and find out what mods are required to the engine for that particular pipe to be the best to use.This is why most manufactors with hold or dont even know what mods will work best. They sell more pipes that way. If the pipe has been designed for lots of intake mods and few exhaust mods then they should let you know that. Not just this pipe should work best in midrange or top end,or low end thats pretty vaqgue.I discussed with Kermit about what pipe with what engine mods will preform best under a given set of criteria.He told me this is whats needed for the intake port duration and area and this is what needed for the exhaust port duration and area, fuel type, compression ratio, to get the best overall preformance for that type racing, example max torque, preferred rpm band to ahieve max torque, short overall top end runs.Lets say an 1/8- 1/4 mile track with a KT100 engine. The corner radius and strait away lentghs are not that important, thats more final gear ratio adjustments. I just want to know what engine mods will preform best under those given conditions and the best pipe for that engine design on that type of track. A enduro and a sprint engine are total different designs than a oval track racer and their pipes should be also. The bottom line is design the engine for the type of track to be race at and use the correct pipe for those engine mods and know this information before buying a pipe.
 
ttownwideglider said:
You must know what mods have to be done to make this the best preformer for that build. The bottom line is design the engine for the type of track to be race and use the correct pipe for those engine mods and know this information before buying a pipe.
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the stock Yamaha is pretty much fixed as far as ports and everything else is concerned. All Yamaha’s, regardless of what pipe you put on them, reach peak torque at pretty much the same RPM. You can change the curve some with different pipes, like my Bullet pipe, I had a lower range, a midrange and a high range. But all 3 reached peak torque at about 10,300 RPM. Depending on the track, you might choose any one of them.
Dr. Blair has a formula for calculating the length of the pipe. His formula uses the exhaust port opening in degrees and the RPM where the engine reaches peak horsepower. And it’s a good formula. Thing is you do need to know where the engine reaches peak horsepower. Once you modify an engine, and find out where it reaches peak horsepower, (this means dyno testing) Dr. Blair’s formula will give you a total length and a header length that are pretty close.
I’m pretty sure everybody that builds pipes would just love to have a formula that could give them all the right stuff just knowing the mods of the engine, but I have never heard of that formula.
The motorcycle people spending a lot of time and money designing pipes and the fact that my friend could run my bullet pipe and get better performance than the factory pipe tells me a lot. Do you know of Erve Kanamoto? He used to be the chief mechanic for Kawasaki’s American racing effort. He told me when he visited their facility in Japan, they had this huge building where they would do dyno tests on pipes. He said the walls of the warehouse were covered with pipes they had tested. Now I would think, with all the money they had, they could hire someone to do what you want to do, and save a lot of money. The fact that they didn’t/couldn’t should tell us something.
I’ve built a lot of pipes, and I was concentrating on the KT 100 only, and are while some worked, many more didn’t.
While I don’t want to discourage you, you have some good ideas, in my experience, it’s a lot tougher than you might think.
Comments compliments criticisms and questions always welcome. There are
If the data does not support the theory, get a new theory.

 
Al I was not talking about a KT100 in a stock comfiguration. Sorry that I did not state that. I was talking about modified engines. Kermit Buller has done a lot of modified engines and has designed his pipe to achieve max torque in a range that is usable and non destructive mainly for oval raving, he does have a few for enduros. He has done the engine mods and has designed a pipe, Iam sure with much duno testing to achieve max results that he could achieve specifacly for those exact mods. Thats why I consulted him when I was engineering my engine design from the start. I did use some of Gordon Jennings theories and expanded on his basic guidelines to suite my application. This is what Iam talking abot. Just as with the KTs Kemit has also do his homework to specific mods on the sudans and his pipes. For a stock engine KT or sudan the parameters for pipe designs a much are much more finate than the modified parameters. The preformance differences from one new designed low end to midrang pipes are very small compared to the gains acheviable with the modifieds.
 
Hey Tim ya got me there I idin't know Alexander was into to 2 strokes, guess thtas how he powered his light bulbs back then. LOL Your right got um mixed up Thomas Edison made the worlds fasted light bulbs. Both powered by highly modified 2 strokes.
 
Interesting stuff.

Al, when you tested pipes that you built that "didn't" work, what are you regarding as didn't work?

Were they terrible or just 5% or so less than what was already available? Reason I say % is because it would of course depend on what port configuration and rpm band and engine type you were trying to achieve higher performance for.
 
pipe

AL, since I have some of your pipes, what length would you suggest for stock appearing Yamaha/gas and Stock appearing Reed/alky. Clutch slip. Thank You
 
Re-read all post and still don't want to rock the boat BUT, has anyone expeiremented with different headers , same pipe? I see many variations of headers,some real short , some longer, with double taper or single taper. Some neck down at entry like a torque tube.what I'm asking is will short header with flex at 9 inches act the same as long header with a shorter peice of flex still at 9 inches?any other info on subject is greatly apprieciated! Thanks to all Shawn
 
The taper in the header reduces flow resistance So the wave and gases can flow out and expand and on the return wave the gases can flow back in with less constriction. Length would again be a timing issue. Just my understanding of the principles and use. The shorter the flex piece the better due to the fact most flex pieces are straight tube.
 
has anyone experimented with different headers
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We did once we built an inertia dyno. The smallest diameter headers performed best for us with IKF KT100 rules.

With all the discussion here I am surprised there was none about wet line tuning with flex. We always tuned flex to 3/4" to 1" wet line for reliability. With this we would tune down very lean without sticking pistons.

DK
 
Don K said:
We did once we built an inertia dyno. The smallest diameter headers performed best for us with IKF KT100 rules.

With all the discussion here I am surprised there was none about wet line tuning with flex. We always tuned flex to 3/4" to 1" wet line for reliability. With this we would tune down very lean without sticking pistons.

DK
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Thanks Don, what is wet line tuning?
 
With all the discussion here I am surprised there was none about wet line tuning with flex. DK[/QUOTE]

don, i was thinking the same thing. before gauges were readily available/affordable that's how it was done...or at least the way i learned, along with the fine art of plug reading and overall color of the inside of flex from header to pipe. even today with modern data acquisition, these are still a part of tuning for me, old habits i guess.
 
the wet line is visible outside the aluminum exhaust port and inside the steel header as a result of the separation cooler fuel air charge and the hot exhaust flame front. We would watch the indication when cutting flex length. Under 3/4' flex too short and over an 1" flex too long. Maybe our tuning was simplistic but, once we set the flex length for a given pipe we didn't change it.

DK
 
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