ESE's works engine tuner

[husaberg]

Like so, Smitty ?
Attachment 304110

There are several options in lengthening a pipe. You can move the end cone, or you can lengthen the header, like on the trombone pipe in the video below.

The gas pressure generates a force that is proportional to the cross section area of the moving part and proportional to the pressure difference at either side of that area. For a moving end cone this force can be up to 4 times larger than for a sliding header. That is one reason to go for the trombone system rather than the moving cone system.

The second reason: sealing. The circumferential gap that has to be sealed, is three times shorter for the trombone system. That means three times less leakage and three times less friction.

The third reason: say you wish to lengthen the total length of the pipe by 10 %. If you do it by moving the end cone, you will also enlarge the pipe volume by a little over 10 %.
But in a good pipe configuration the header length is about 1/3 of total pipe length, so in the trombone system, lengthening the pipe by 10 % will be done by lengthening the header by about 30 %. That gives a far greater variation in the pipe's Helmholtz frequency than a 10 % volume change.

It is true that the length percentages of all pipe components should be in a rather fixed relation to each other. Varying the lengths of all components by the same percentage would be the theoretical optimum, but that is not feasible.
Lengthening the belly will disturb the optimum relations, as will lengthening the header. So the pipe in its lengthened version will not be the optimum for the low resonance rpm dictated by the length. But it will be a hell of a lot better than using an exhaust power valve that spoils the 180° effective exhaust timing, necessary for true resonance.
And a pipe shortened beyond its optimum may not show the optimum length relations between its components either, but it will be a lot more effective in overrev than artificially raising the exhaust gas temperature by retarding the ignition, or by weakening the mixture strenght through closing a power jet, which has the disadvantage that not all inhaled air is used for combustion.

Trombone pipe: http://www.youtube.com/watch?v=0odVz...ature=youtu.be

This graph sticks in my mind.
Can't find it..............
it had three beautiful overlapping curves.
Later.......he does and posts it below

I had to search for this but this was pretty profound, I along with plenty of others had our thinking a little back to front.

You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.

Something to think about while the rest of the family occupy themselves with buying, boiling, painting, hiding, searching, finding and eating easter eggs: a couple of recent videos from the Dutch 50 cc scene.
http://www.youtube.com/watch?v=mvV4x...feature=relmfu
http://youtu.be/0odVzSgufjk

It was designed and built by Richard Maas http://www.adriaanmeeuwsen.nl/team-pagina.html. Hopefully we will see it in action next monday.
And if I were you, I would make it go shorter with rpm .

More news from Richard Maas. Did his trombone pipe give the desired results? O yes. At 10,000 rpm it gives 4 HP more than the same engine with a fixed pipe. It runs over 17,000 rpm without the need for a powerjet and with a fixed ignition timing. It is miles better than an engine with an exhaust power valve. And the mapping of pipe length, ignition timing and powerjet pulse width has yet to be carried out. Maybe the powerjet can disappear altogether.
Only problem so far: the piece of pipe that is fixed to the cylinder, is shrouded by the pipe that slides over it, so it gets very hot. Too hot for the Viton O-ring that is taking care of sealing. Any bright ideas, anyone?

[TZ350]

It's pouring rain here in Seattle (aka Swamptown), a good day to sit at the keyboard and try to learn from y'all. So . . .

When I do a search here, as for "torroidal heads," I invariably am directed to several 2-stoke threads with ten thousand posts apiece, and no further suggestions as to which pages have the subject term. So I'll just ask here, and know that I HAVE tried to search first

You might find these search tips useful.

Some may find this useful. Rather than use the site search which usually fails, use Google so to search this site use an ordinary search phrase and after it add

site:www.kiwibiker.co.nz

for example

Frits priceless site:www.kiwibiker.co.nz
or
Frits pisa site:www.kiwibiker.co.nz

the same will work for other sites with the appropriate site address

Mick

Here's some help on searching in these forums.

Top right hand corner of the screen, click 'advanced search'
Click the blue box 'search single content type' at the top.
Scroll down and select the forum area to buckets which is right near the bottom of the list.
Scroll down and select the dot next to 'posts' in the criteria called 'show result as'.

Attachment 304439Attachment 304438Attachment 304437

THREAD IMAGES
Another handy tip is under thread tools (near the top of this page) click view thread images. Very! Helpful on the ESE thread

Another way to filter the wheat from the chaff is to click on the user name of the person and either view attachments by user or forum posts.

Page 1020 links list to go here:-



Hedge trimming, Isle of Man style.

Photos taken of the glory days at the IOM 61-67 http://mikepollitt.weebly.com/1960s-...-pictures.html

Hondas Golden era:- http://www.hondatwins.net/forums/8-p...-years-19.html

Chris posted some 2T Hydroplane video, you will have to follow the link back to his original post to see them.

Cable operated adjustable header on the hydroplane.
And 2T Hydroplanes In action

Seattle Smitty ... reposted here because I think they make such interesting reading, as they are written by someone who was into all out boat racing with 2T's in the 60's and I don't want them to be lost as they give a glimpse of clever people working away in their sheds pushing the boundaries of what is possible with a no holds barred racing two stroke motor.

Raced 250cc alky-burning Konigs and other oddities (Quincy, Anzani, Yamato) on hydroplanes and racing runabouts in the mid-60's thru mid-'70s. Still have some old gear, hope to get back on a racecourse and impede everyone else's progress sometime before I croak. My interest here is in 2-stroke engine tech.


Since few if any of y'all are boat guys, let me tell you a little about this. Over the decades, outboards have usually been one or two generations behind the current 2-stroke design and practices in motorcycling, esp GP racing in Europe. The outboard racing I'm talking about is jocularly referred to as "PRO," i.e., Professional Outboard Racing as practiced by the APBA (American Power Boat Assn.) or the USTS (United States Title Series), a tiny, amateur, in-crowd hobby-sport. This sort of outboard racing is not to be confused with Formula One tunnel-boats powered by big V-6 factory production racemotors, usually built by Mercury or OMC complete with starters and full cowlings, burning gasoline and often racing for actual money. By contrast, the PRO category of racing that I'm talking about uses motorcycle-sized engines (125, 175, 250, 350, 500, 700, and 1100cc displacement) completely stripped down, with unmuffled pipes and burning real racing fuels, powering hydroplanes and racing runabouts. I should say that some of the best of this sort of racing is done in Europe, up to 500cc, and in fact all of the most up-to-date racemotors we use now are coming out of Europe, mainly Italy.


My tentative understanding, based on very sketchy input, is that nothing resembling our PRO racing is being done in NZ or Oz, though there apparently was some stock outboard racing done many decades ago, and some tunnel-boat racing. That's too bad for those of you who are real far-gone 2-stroke lovers. Like you, the 2-stroke crowd in North America grieves for the loss of 2-stroke GP motorcycle racing (and the bikes didn't even get to burn fancy fuels). There's something of a 2-stroke comeback in motocross, so I hear, yet even with sleds (snowmobiles) the 4-strokes are always preferred by and often favored by the authorities-in-charge. PRO outboard racing is nearly the last arena for the most fanatical 2-stroke tuners and modifiers. The only real limits, within a given displacement, is no bottled fuels or oxidizers (nitrous is out), and no supercharging (other than that done via expansion chambers or intake tract tuning). The advantages of PRO outboard racing for our kind is that first, the 4-strokes are always going to be too heavy and especially too top-heavy to work well, and second, the 4-strokes wouldn't get any kind of traction advantage as they can on a motorcycle roadrace course. A modern racing propeller (generally 3 or 4, sometimes 5-blade) is not only quite efficient, but it HOOKS UP to the water all of the power you can find in the engine.


(Hope this will get a few of you old 2-stroke bike racers excited).


--Smitty

When I started racing Stock Outboards forty-five years ago, the engines for all of those classes (250/322/500/700cc) were Mercury factory racemotors, meaning production engine powerheads on short towerhousings with small, low-drag, direct-drive lower units and light flywheels. No modifications allowed. I believe that these small stock Mercury engines were what got raced Down Under, long ago. Most outboard racers here start out in the stockers, learn to read the water, to make starts against a clock, and to race. The competition is close and the speeds are not insane, and many race drivers (as opposed to tuners, men with shop skills, and 2-stroke tech enthusiasts) prefer to stay with the Stocks. Some of the old crossflow Mercurys of the '50s and early '60s still are enthusiastically raced, no longer in the Stock or PRO categories, but in a semi-modified category, burning gasoline and running open megaphones. Moreover, there have been a runabout and a hydro class for old twin-opposed cast-iron block motors first raced in the 1930s. These Antique C (500cc) classes burn methanol and nitro, are run by themselves at PRO races, and limited to the original open-exhaust configuration of eighty years ago. Old alky racers who keep at it often end up in the Antique C boats because they aren't too fast, make good sounds, and are raced by men who have been pals for life.


Crossflow 2-strokes actually were a pretty good design for small, low revving outboards. I have a 1956 5 1/2hp Johnson that is as smooth a motor for trolling hour after hour for salmon as anything built today.


(EDIT) ellipsis, when you get around to doing something with that Anzani, if you're interested I can impart a ton of obscure and otherwise useless info on that engine.

Thanks all for getting me into the 21st century (well, I guess; so far I think that overall the late-'50s/early-'60s were the best of times, at least in this part of this country).


I've been slowly working through the ten thousand pages of those threads, bliss for 2-stroke lovers. Looks like a couple of posters were near or right at the top of 2-stroke GP racing in its heyday (is "kel" who I think he might be??). Any possibility one of them would lower himself enough to take PM questions from an outboard racer on applying modern tech to our lower-tech engines?


Again, I think fellows like them, or any far-gone 2-stroker who lives to carve on ports and roll cones for pipes would have a blast working on engines with almost no limits to modifications or fuel. Actually, two such men, both Italians, have got into outboards, and are manufacturing the first up-to-date racemotors our little sport has seen in a long time. Giuseppe Rossi, a many-times European champion outboard racer, builds the GRM 125/175/250/350/500cc engines which are winning most of the races in those classes here and in Europe. Carlo Verona, who I understand has done contract work for some of the motorcycle factory teams, makes the VRP engines that are fully competitive with the GRMs. A slightly sad consequence of the competition between these two well-informed men is that their engines are so good out-of-the-box that ordinary outboard racers know they aren't knowledgeable enough to improve on them, which used to be half the fun of PRO outboard racing. However, there are still possibilities for getting an edge . . . heh, heh, heh.

Very slowly plodding through it due to time constraints.


Need another term, what is a "spigot"? Is that the intake tract from the carb, or is it the venturi in the carb, or what?


I'm not far into the thing, still reading 5 year old posts, but wondering how "TZ350" made out with his experiments on cylinder cooling. I've always thought that the front wheel of any motorcycle is a terrible obstruction to engine cooling, and that big ugly air ducts would be the solution (for air-cooled barrels anyway). I Also think you can help the situation a bit by welding some cooling fins to the first several inches of the exhaust header-pipe, right after the monting flange. As we all know, the megaphone section of the expansion chamber draws some fresh air/fuel charge some distance into it, and this is then crammed back into the cylinder at exhaust-closing by the positive return wave from the baffle cone (in Seattle, in the first days of expansion chambers, we boatracers called them "bounce-pipes.). This column of air/fuel picks up heat while it is in the exhaust tract; I'm guessing it would pick up less of this heat if the header-pipe had cooling fins.


I did this, welded some cooling fins to the header pipes, on my '76 Yamah RD400C when I made a new exhaust system. But I did no before-and-after testing of that feature in isolation. I don't race it, and ride it like an old lady (I'm old, I never raced bikes, only boats, and I don't mind a splash but don't want to crash), so can't tell you anything about the practical effect of the fins, sorry.


Actually, there is some evidence seemingly supporting my idea, from the sled (snowmobile) racers (who have some interesting 2-stroke tech, if you want to check that out). When the pipes on a sled get hit by a big load of snow, they cool off, the wave-speed slows, and they go out-of-tune until the snow melts off. Same thing can happen with racing outboards. The sled guys sought to prevent this by wrapping their pipes with thermal-insulating wraps. They soon found that it was best to leave the first several inches of the header-pipe uncovered, no thermo-tape, because of what I'm talking about, an over-heated slug of air-fuel getting shoved back into the cylinder.

Since I came into this in the middle of things, I don't know what kind of thing you are racing (roadracing? motocross?). Are you restricted as to octane?


I still think you should try any/all of the other things before putting water in your fuel. This is sort of basic, so don't be offended if you've done this long ago, but have you got the squish-height down to near the minimum recommended by the experts on your particular engine? That's very important. If you still get detonation with minimum squish (and have ruled out too much ignition advance), don't ever try to reduce compression by means of shimming up the head with a thicker gasket or whatever. Once you get a squish-height that's tight but never lets the piston actually touch the head, leave it alone, and if you have to reduce compression, do it by taking material out of the combustion chamber pocket. A little drop in compression won't hurt performance noticeably, but increasing the squish-height will tend to worsen detonation, even if it reduces compression at the same time. I learned about squish from a couple of smart engineers who raced outboards in the Sixties; this was at least fifteen years before the motor-racing magazines first began talking about it; today it's almost a buzz-word.


Is there some anomalous glitch in your ignition that makes it over-advance in some circumstances? Remember, the better the cylinder-filling (usually at peak torque), the less spark advance is needed to light the fire at the right time, as long as it keeps up with rpm.


How about fabricating a lightweight, custom-looking air-scoop atop the front fender or in whatever fairing you might have, and duct that air to right above the exhaust port exit?


Some guys look at big old air-cooled aircraft engines, and observe the finely-machined, closely packed cooling fins, and think their bike should have that. But the cowling of those engines, of all air-cooled engines, is a hard-won science that was needed to make those closely-packed fins shed heat. An aircraft cowling is built to pressurize the air to make it run between the fins. High velocity ram-air comes in the front of the cowling, is slowed as it comes into a higher-volume area, converting velocity to pressure, and is closely ducted to make sure it gets between the cooling fins. By contrast, a motorcycle has a few big fins that are just radiators of heat to turbulent air that passes in random, ever-changing eddies, mostly over the tops of the fins. A few of the bike makers (Suzuki, for one, with their old two-stroke 550) made what were supposedly ram-air ducts over the top of the head, and they might have helped a little, but how do you get any real ram-air effect when there's a front tire shoving the air to either side and making it wildly turbulent? So bike motors can't be like airplane motors without good control of the airflow (which we don't want to do because really effective air-ducting would hide our pretty engines, right?).

(I CAN'T TELL WHETHER THIS PM IS ACTUALLY GETTING SENT TO YOU . . . .????)

Yes yes five times :-)


Dang, I was afraid of that.

As to water, I know some of the real old-time outboard racers tried small amounts of it, but this was in combination with the methanol-based fuel they used. In the Thirties, outboard racing in the US was at least a semi-professional sport, and on the amateur (I think) side there was even an inter-collegiate outboard racing circuit. I don't think there was any Stock racing then, and modified engines running fuel blends was the rule. Methanol base with about 12:1 to 16:1 castor oil lubricant. Additives included acetone, toluol, gasoline, nitromethane, benzol, . . . and in one blend I read about, 5% water as an anti-detonant. Kind of funny that nowdays guys are very concerned about their methanol absorbing moisture. But water is only useful if you have a detonation problem that you can fix in any other way, and it does cost some power. That's why guys who put water injection systems in their gasoline-fueled cars sometimes mix the water half-an-half with methanol, which restores most of the lost power. If this is in a racing context, however, class rules may prohibit the methanol. Some people have the idea that water injection gives you a steam engine, which sounds like an advantage. But any push from the steam doesn't match the power lost from the cooling of the burn by the water. So unless you have detonation you can't fix, or you are so close to the ragged edge than you want the water for insurance against going over the edge, I think water is a last resort. The old outboarders who use the 5% water were doing it so that their engines would live under big loads (20-40%) of nitro without melting off the big piston dome deflectors in their crossflow engines. And the highly-developed aircraft piston engines of WW2 and the Fifties had water-alky ADI (Anti-Detonation Injection) systems that only cut in at high manifold pressures only used on take-off or in combat.

Hi again Smitty


I quoted one of your posts here:- http://www.kiwibiker.co.nz/forums/sh...post1130778618


Rob

Hard to see whether anybody else thought much of the idea, but I'm interested to see that you think it might have merit.


Fellows are talking there about polishing piston crowns (to considerably reduce surface area, as detectable on a microscopic level), something some of us were doing in outboard racing forty-five years ago, and about ceramic coating the pistons for the same reason but with greater effect.


But then they talk about polishing or coating the exhaust port and passage. I'm not so sure about that idea, partly for the reason I want a finned exhaust header: to keep from heating the portion of the new air/fuel charge that gets that far. I want the exhaust port and passage to be transferring heat as fast as it can to the cooling fins or water jacketing immediately behind the port. Polishing or coating the port drastically reduces the heat transfer to the outside, and that's the hottest part of the engine, and often the area where you get pistons sticking and melting, so I wouldn't want anything that impedes heat transferring out to the outside.


On my old outboard racemotors I always reworked the factory water inlet arrangement (these engines got water from the lake rammed in the front of the lower unit, no water pump) to get the water-in streams flowing across the metal directly behind each exhaust port, with the intent of scrubbing off steam-bubbles as they formed.


Besides adding fins to the exhaust header, AND devising an air-duct or two (surely the best fix) that will blast air directly at the cooling fins on the cylinder and the exh. header, I would also be looking at the various "black-body" coatings that claim to increase heat transfer from the surface of the fins to the air.


This last might only provide a marginal increase in heat transfer, but then most advances come from incremental improvements. You Kiwis probably are familiar with the old "Hundred Pound Rule of Motor Racing," which states, "There's no place you can take a hundred pounds out of the car. But there might be a hundred places you can take out one pound." A goofy little fix like my cooling fins on header pipes won't make much difference in isolation, but three or four such little fixes might add up to something worthwhile.


Gosh, Rob, you quoted me and made me somebody; flattering! I was just going to be a lurker for a while, and not barge into a long-running thread. But I don't mind you quoting me if you think I actually say something of any value, LOL.


(I CAN'T TELL WHETHER THIS PM IS ACTUALLY GETTING SENT TO YOU . . . .????)

Thanks for the photos, looks like you guys are having a blast! Unfortunately, I can't make out how the ducts run on bike #38. But I did notice some of the bikes had their number plates set so close to the top of the fender as to completely block any airflow between the forks. That area would seem to me to be the FIRST place to think airflow. Rules permitting, rather than have an absolutely flat number plate, I'd want to roll the outer edges back, at least the lower edge, and continue that rolled lower edge with some sheetmetal that takes the airflow through the forks and then diverts it down toward the engine.


Suppose the rules require a 10" by 10" absolutely flat number plate. Obviously the edges of that flat plate create lots of turbulence (and drag). The fix is to add four rolled pieces of sheetmetal to the four edges, each having a radius of one-quarter of the width of the flat plate, in this case 2 1/2". So even though your number plate is now 15" wide, and still has a 10" flat plate in the middle, it's now has a lot less drag . . . especially if you can continue some of your rolled edges farter back as far as you can to make a classic aerodynamic teardrop. Any time you have to drag a big box shape through the air (in my case, the box on my outboard racing trailer), radiusing the outer 1/4 of the front of the box (or as near as you can get to that) takes care of the aerodynamics of the front of the box. Of course, it's a lot more trouble to build than a plain square box, LOL.


A '76 Yamaha RD400C like I have came with a little plastic vanity cover over the lower fork clamp/steering thing (I think it's called a triple clamp)(I know little about bikes). This cover had no function, and I didn't like the sharp lower edge which hung into the area where the air comes through the forks above the fender. So I got rid of it, and then made a sheetmetal replacement that's intended to carry air smoothly under the triple clamp and then get it going about 40 degrees downhill. Whether it actually does so I can't say, and it's only a start in the direction of what you'd want for racing. Probably it mostly has been just a source of comments and speculation, over the years.


I still like a big air-scoop built into the top of the fender. Big issue there is adding a bunch of unsprung weight. Wait, I gotta go back to the photos and see if you get to remove the fender; back in a sec. . . .

Back; okay, some of you retain the front fender, some don't. If this is optional, maybe you can fabricate whatever you like, and make something very functional. And if you make it of carbon fiber, lightweight. You could bolt it on to the fork brace like the fender bolts on, or avoid any unsprung weight at all by hanging it from that lower triple clamp. Let's see, that would still follow the steering, so if you wanted to avoid that, you could suspend it from the frame, immediately behind the steering head.
Again, I know zip about bikes, and probably I have said little of nothing that you haven't considered long ago. Well, it has been fun for me to think about!

[TZ350]

Welcome to the piston side.
Below you will find brands such as:
Barikit, Kitaco, Wiseco, Pro-X, Polini, Mahle and others.
I stocks normally pistons that you see below.
, there are other pistons in stock,
which can be a bit odd sizes etc..
If you can not find what you are looking for, write and ask,
so we'll see if I can help you!



http://www.pvlsverige.se/vrm/kolvar/kolvar.html

[husaberg]

Welcome to the piston side.
Below you will find brands such as:
Barikit, Kitaco, Wiseco, Pro-X, Polini, Mahle and others.
I stocks normally pistons that you see below.
, there are other pistons in stock,
which can be a bit odd sizes etc..
If you can not find what you are looking for, write and ask,
so we'll see if I can help you!



http://www.pvlsverige.se/vrm/kolvar/kolvar.html

Rolffe is the Mad Swede who did the Debri cylindered MB50 with a disk valve.
What happened to the piston rod spreadsheet Brent was going to do.
this site is a great one in particular as it gives the oclock position of the ring pegs'.

[jonny quest]

Frits, instead of Viton... piston rings.

Might want to look into shock piston seals... like those on newer dirtbikes. Don't know what they're made of, but pretty amazing stuff.

[wobbly]

What would work well I am sure would be a multi groove labyrinth.
You would need a parallel section, maybe a thin sleeve over the header.
I am still amazed every time I rebuild a crank that 4 small grooves over a shaft works as well as a lip seal with no contact at all.

[husaberg]

What would work well I am sure would be a multi groove labyrinth.
You would need a parallel section, maybe a thin sleeve over the header.
I am still amazed every time I rebuild a crank that 4 small grooves over a shaft works as well as a lip seal with no contact at all.

its a puzzle that one............

[ken seeber]

I think Wobbly's on the case here. I was thinking of a circlip style groove towards the end of the female tube. Into this groove would be a metal seal, one suitable type being the multi strand retaining rings (see www.spirolox.com ). Alternatively, an oversize piston ring could be fitted into an undersize steel sleeve such that its end overlapped and its inside diameter was less than the outside diameter of the male header tube. This would be then annealed in this position (oxy or propane flame up the guts), such that when removed it would be a light fit over the header. Then it would be gapped to suit. Not sure about the assembly into the groove though. In either case, the header would need to have its outer edge chamfered to allow easy(ier) assembly.

Downsides are more friction, but with possibly improved sealing and less oily "weeping".

Wobbly's labyrinth is much simpler though with zero friction.

[husaberg]

I think Wobbly's on the case here. I was thinking of a circlip style groove towards the end of the female tube. Into this groove would be a metal seal, one suitable type being the multi strand retaining rings (see www.spirolox.com ). Alternatively, an oversize piston ring could be fitted into an undersize steel sleeve such that its end overlapped and its inside diameter was less than the outside diameter of the male header tube. This would be then annealed in this position (oxy or propane flame up the guts), such that when removed it would be a light fit over the header. Then it would be gapped to suit. Not sure about the assembly into the groove though. In either case, the header would need to have its outer edge chamfered to allow easy(ier) assembly.

Downsides are more friction, but with possibly improved sealing and less oily "weeping".

Wobbly's labyrinth is much simpler though with zero friction.

Hey guys go back to the original posts.........
http://www.kiwibiker.co.nz/forums/sh...post1130298456

[Frits Overmars]

Hey guys go back to the original posts.........
http://www.kiwibiker.co.nz/forums/sh...post1130298456

You said it, Husa. Those posts are 30 months old and the sealing issues have been fully solved since then. But thanks for the tips anyway.

[RAW]

You said it, Husa. Those posts are 30 months old and the sealing issues have been fully solved since then. But thanks for the tips anyway.

Success Frits, congratulations, any hints for the rest of us mere mortals on sealing.

[chrisc]

I couldn't find the actual solution when going back but I might be blind.
I was going to suggest water cooling the spigot after reading recent discussion about cooling the first bit of the header.

Frits, where can we find more information/pictures/videos of that trombone set up? EDIT: Answered my own question: http://www.adriaanmeeuwsen.nl/team-pagina.html

Cable operated adjustable header on the hydroplane



In action




I did some searches on this variable header that Kel found a while back and found some more information:

How about a variable exhaust header. This one allows 25mm adjustment

Attachment 241299
Attachment 241300

Google translate says "a new control to include inflammation of RTD and the like" Thanks Google.

"HE-YES. VARIO EXHAUST

Making an expansion outlet is no sinecure. Let there be no doubt that it is a very complicated matter. Indeed, there are very many things that influence the final form and the result. It comes down to the fact that you're never done with it. Even in an advanced stage is often called a small improvement. Even at the major racing teams are still minor changes. This involves literally millimeters. To even approach the matter differently, we at He-Ja R & D at us engrossed in fabricating a vario outlet. Here's a design Henk hunter that is operated by a servo motor. This includes whether a new control in RTD, including inflammation and the like. This kit is "Not for Sale" and only for their own use and testing. The whole is fit to a He-Ja type B kit for more bottem power.'s vario outlet work in a way that at low speed, the length of the entire exhaust route is longer than 25 mm at a speed above 11,500. therefore, may be a result of engine speeds with the same adjustment."

From: http://www.he-ja.nl/news.htm

[husaberg]

I couldn't find the actual solution when going back but I might be blind.
I was going to suggest water cooling the spigot after reading recent discussion about cooling the first bit of the header.

Frits, where can we find more information/pictures/videos of that trombone set up?

Not Frits but Carbon ring from memory relayed i think via Raw from another forum maybe the british 50 site?

Anyway this is worth a look even if it has some silly halftime valve thingies.
http://thekneeslider.com/jlsp305-300...-luc-borgetto/

Homemade Honda 5

[TZ350]

Links to some Ruapuna B track and 2014 BOB video

This thread needs more good stuff, so untill somebody posts some video, here is one we made earlier

Video from yesterdays F4 cup, filmed from GPR bike no 11

Here is the first 15min of the BOB , Riding with Mr BucketRacer

[husaberg]

The late model SA500 had shields but a cutaway slot allowing A/F to be "flung" upwards from crank rotation.
The latest TM125 kart engines have exactly the same idea.
I will have one apart soon so will pic this, as according to my info from Maxter its worth at least a Hp in 40ish.
Yes the cranks were Hirth assembled.
Funny how the SA case has a striking resemblance to this model.

Shields and a cut away slot, a bit like this?
Attachment 302867

Things are moving along, ports only need a couple of degrees onthe exhaust , and 1 degree on the a and b ports so getting a bit closer
Attachment 302868

Here is the sideways slot on a TM125KZ10B

Here is the front tunnel.
The crank spins forward as normal, so the ramps over the crank shield the intake flow from the turbulent boundary around the wheels.
The rear slot lets "flow" from around the crank up under the piston.
Mr Thiel tried the shields on the Aprilia and found some power as well, but dont know if the sideways slot was tested at the time.

I found this pic from another angle whilst looking for something else.
Must be a different model?