Reed valves and torque pipe

[bahramu]

I'm still torn between getting the reed valve or not.

You've made it clear that a reed valve+torque pipe is the most torquey, and that an intake extension would probably be more torquey than a reed valve without a torque pipe. What I'm still wondering is what is the performance difference between a reed valve+torque pipe and an intake extension+torque pipe. Is it really worth the extra $$$ if I already have an intake extension and a torque pipe?

Also if anyone has noticed fuel consumption differences with a reed-valve I'm curious about that too.

 

[Deleted member 12676]

try the cheaper combo first and see how you like it.
things to do that cost practically nothing-
1. plane down the head for more compression (using glass & sandpaper)
2. plane the top of the cylinder so it matches the head and loses less pressure
3. redirect the transfers rearwards
4. extend the standard exhaust pipe
5. jet the carb as perfectly as is possble

mods that prevent unwanted loss of delivery ratio increase power without increases fuel consumption.

>What I'm still wondering is what is the performance difference between a reed valve+torque pipe and an intake extension+torque pipe. Is it really worth the extra $$$ if I already have an intake extension and a torque pipe?

Also if anyone has noticed fuel consumption differences with a reed-valve I'm curious about that too.[/QUOTE]

 

[Fabian]

Just get the reed valve intake and be done with messing around. Honda spent a bunch of money in the early days of 500cc Grand Prix racing to improve 2-stroke engine response and powerband usability.
They never went back to a non reed valve system.

Another way of explaining the function of a reed valve is a bit like the concept of opening and closing a window in your house, in sync or in time with wind gusts. Every time the wind wants to blow through your house, you simply close the window. It doesn't matter how hard the wind blows, it can never enter your house if the window is shut. The same concept is applied to a reed valve intake, but this time the wind is on the inside and it's trying to get out, but the reed valve snaps shut as soon as the air/fuel mixture tries to make it's way out of the crankcase.
It's a mechanical method of keeping the air/fuel charge inside the crankcase whereas a longer intake tube is a passive method and it only becomes effective when intake air speed is moving at high velocity. At lower and midrange rpms, a longer intake simply cannot match the positive crankcase seal of a reed valve intake.

 

[lazylightning@mail.r]

I'm still torn between getting the reed valve or not.

You've made it clear that a reed valve+torque pipe is the most torquey, and that an intake extension would probably be more torquey than a reed valve without a torque pipe. What I'm still wondering is what is the performance difference between a reed valve+torque pipe and an intake extension+torque pipe. Is it really worth the extra $$$ if I already have an intake extension and a torque pipe?

Also if anyone has noticed fuel consumption differences with a reed-valve I'm curious about that too.

Hi, I've made a Jaguar all rpm range pipe and cant wait to make a reed valve system too. Have you made a pipe using his calculator? It's really worth it. With the 44 tooth sprocket on it goes to full speed in just a few seconds. It roars like a bat out of hell and sounds really sporty with no muffler. All the drivers notice me and it's made driving much safer. I can move out really fast now too. It's on the pipe all the time at speeds above like 4 - 5 mph. I have removed material from the head though to make the compression higher and have worked the cylinder over too. A 16mm Dellorto carb is better than the stock one for me...

 

[bahramu]

I've already done all steps except 4 Jag.
That's nice to know about Honda and their decision to stick with reed valve. I love Honda
And I haven't used Jags pipe calculator but will soon for my new build

 

[HeadSmess]

disc or drum induction is the best. bit hard to set up on a ht.

honda gave up on twostrokes altogether, remember? the nsr500 was an insane bike, but after trying to squeeze four tuned pipes in there somewhere... sense took over and they started working on the fourbangers.

dont be too brainwashed by all this reed valve nonsense.

quote"""Originally, these early Yamahas employed reed valves in order to cure the perennial problem of piston ported two-strokes, namely their symmetrical port timing which leaves just as much time for an incoming charge of mixture to escape via the exhaust ports, as to pump it in from the carbs. The growing dominance of the Suzuki RG500, whose rotary-valve design’s assymetrical timing meant it didn’t suffer from this handicap, persuaded Yamaha to take a year off from 500cc GP racing in 1976, in order to develop an all-new four-cylinder machine code-numbered OW35, which broke with the company’s four-year tradition of promoting rideability as opposed to the pursuit of outright power, by jettisoning the reed valves in order to remove their inherent barrier to clean intake flow, and thus top end numbers. Powerjet carbs also made their debut, on a bike which for the first time adopted the short-stroke 56 x 50.6 mm engine dimensions of later 500 Yamahas. But even in the hands of Steve Baker, Johnny Cecotto and Ago, the OW35 was no match for the Sheene/Suzuki combo - a fact the unfortunate Baker paid for by being dropped from the team for the following season, in favour of Yamaha’s new American superstar, Kenny Roberts.""" end quote.



take note JETTISON THE REED VALVES TO REMOVE INHERINT BARRIER TO INTAKE FLOW.


back in the days when twostrokes were racing gp... honda was never really that big.

it was always zuki, yami and kwaka...

 

[Deleted member 12676]

**** Honda!
they only care about money. When it was profitable to introduce two strokes they did, and when it was profitable to drop two strokes, they did.

rotary valves are the absolute best design. But it wears out too quick and the seals it mates to have to stay in perfect condition. Not really reliable unless you have a rigid maintenance schedule which Joe public has never been too keen on. But it definitely increases the powerband and has excellent flow (not restricted like a reed valve) at high RPM. Really big case reed induction mostly makes up for reeds inherent flaw though.

 

[HeadSmess]

ive noticed the original versions of these motors, the russian ones... they have drum induction.

comes in through the crank much like on a small rc nitro.

one advantage? the circumferental speed of the seals is less on smaller diameters. sealing is much easier.

unfortunately theres only so much air you can stuff down a 10mm hole, especially if it has a right angle bend in it!

tip number 6 to add to jags list? port matching! the exhaust port is square, not round like 99% of exhaust manifolds.

im yet to see a(commercial) "high performance exhaust" with a matched port as standard... and with the pipe squashed into a rectangle where it joins flange...

same goes for the intake manifold. port is square. and those stock steel intakes have a LOT of material to remove, from around the flange/port and at the welded join. ive seen one where it was blocked to 1/3 of its size with weld!

aim for maximum airflow. a simple task that doesnt cost ANYTHING and makes a big difference depending on setup...

number 7? if you have the stock pipe still, pull the end out, replace the 10mm outlet with a 16mm one. you have to either drill the baffles to take the new pipe, bust them out completely, or cut the tube fairly short.

hot air expands...so why have the carby at 16mm bigger than the exhaust outlet? unless its a stinger on a tuned pipe which needs to be fairly small... thats different.

 

[Fabian]

honda gave up on twostrokes altogether, remember? the nsr500 was an insane bike, but after trying to squeeze four tuned pipes in there somewhere... sense took over and they started working on the fourbangers.

Completely untrue. Honda has always been a company pushing 4-stroke technology, even though 2-strokes make more power per engine unit size. Honda's social dominance in the Japanese automotive business world has always required the other Japanese manufacturers to respect their hierarchy. When Honda pushed for the change to the 4-stroke MotoGP formula, after perfecting the 2-stroke 500cc platform, none of the other other Japanese manufacturers opposed the changes. Shame really, because 2-strokes always have and always will be the piston engine of choice at the elite end of motorcycle racing, given an "open" engine formula.

dont be too brainwashed by all this reed valve nonsense.

It's far from nonsense. Reed valves are used to smoothen the power delivery; making the engine more tractable, thereby making the engine more rideable mid corner which improves corner exit speed.

The growing dominance of the Suzuki RG500, whose rotary-valve design’s assymetrical timing meant it didn’t suffer from this handicap

A disk valve induction system has proven to be the optimal solution for maximum power, and it always will be, barring supercharging. Suzuki simply copied the disk valve research and technology and manufacturing techniques of the MZ factory and it's GP racing motorcycle prototypes when they were racing back in the 50's and 60's.

back in the days when twostrokes were racing gp... honda was never really that big.

The 2-stroke Honda NSR 500 dominated everything and anything that the other Japanese and Italian manufacturers could throw at it. It was the simply untouchable and was the pinacle of 2-stroke GP technology. To further improve tractability Honda introduced water injection into the expansion chambers to alter the speed of the reflected wave; boosting midrange torque.

Honda was untouchable!

 

[HeadSmess]

no.

mick doohan was untouchable.

honda loved all these fancy new innovations thought up by overpaid engineers who had to produce something to keep their salary, whereas their best rider ever, the only "innovation" he demanded be fitted to his bikes was that funky brake lever cus the maniac broke his leg countless times and wanted to WIN.

stick him on a postie bike and he would have won! thats hondas claim to fame. stepthrough 90cc putt putts that dominated the world in sheer sales volume.

interesting that stoner rode, and won for quite some time, on ducati... with an engine that doesnt have the same peak power as a similar honda, nor has the redline of the honda... and wait, didnt yamaha whup honda too? stoner moved to honda, then quit cus he got a few grazes. lil girly boy, not like doohan.


sure, dukes and fireblades maynt be 2 strokes...

but neither is a ht66 an nsr500.

its not even going to come close to a morini or denardis, no matter how much money you throw at it.

my thoughts on aftermarket reeds on a piston ported motor?

gotta convince someone that it was money well spent