ESE's works engine tuner

[Farmaken]

A Question for the wise ones :
I have a stinger 270mm long 23mm dia. with a 240 by 28mm muffler on the end.
How detrimental would it be to reduce the muffler tail pipe below 28mm ??
Seems to run fine as is with no reduction , thought maybe a smaller tip on the muffler would help with noise control but I am concerned about pushing up temps in the cylinder

[wobbly]

A larger muffler ID exposes the wave fronts to more packing material area, thus reducing noise - a step back down from the perf core to a smaller exit tube will increase the wave amplitude and make MORE noise.
Stinger/muffler lengths/diameters are very hard to analyse,only way is to cut and try, but with small dia mufflers - generally shorter is better for power, but not noise.

[F5 Dave]

Interesting idea about exposing more material, but at odds with what I have been told by a muffler manufacturer who has designed & made heaps of mufflers for MX bikes & everything else etc over last 30 years. He had stated that it was very hard to get noise down on 250s & bigger & whenever he'd made bigger tube mufflers they were louder. Small as he could get away with were quieter.

Now obviously I'm not picking sides here, but perhaps I'll suggest (in ignorance of course, why change a habit) that perhaps there is a size below which there is so little material exposed through a sweet dia spot to where the hole just gets so big the noise gets through anyway.
Heck I dunno, sounds ok.


What I do know is that you can run a reversal to quieting things down & as long as there is volume it shouldn't affect power. I have made an extn for my 50 that knocks the noise off quite a bit with a reversal & short section of more perf tube. I will add at this point that the first part of my muffler acts as the stinger, so I didn't want to increase its effective length so we made the 2nd part larger dia. Falling into Wobblies theory a bit, maybe.

either way it didn't affect power on dyno any amount. Sadly it was too unsupported so I only run it when I have to or it breaks welds (it lives tucked away under the sw). So I made a shorter revesal only which is a good compromise.

also use ally tube rather than steel for the muffler outer. carbon is in the middle.

[TZ350]

Just a small point TeeZee, the elongated oval formed around the main air corrector feed hole you will need to fit a thin wall sleeve in there, pointing directly out the bellmouth to a point where its not
affected by the venturi .

The idle air is going to be affected as well but not as drastically.
If you dont, the air corrector orifice will be subject to increasing negative pressure as the velocity increases - exactly the opposite to what is needed to lean out the fuel curve that naturally gets richer in any carb like this.

OK, used a bit of 1/4" SS tube and linished it down to 6mm, spinning the job with a battery drill makes for a fairly round finish, cleared the end with a center drill, tapped a 13mm length into the carb, Job done. The hole next to it is plugged and I may smooth it off with glue sometime.

But now I guess I have to go back and check it on the dyno again.

I may be able to use a bigger mainjet now more air will be going through the air correction jet.

Bigger main jet should mean richer down low to mid for smoother drive at the lower end of the torqe curve and then drill the air correction jet out untill the top makes best power.



On other sessions while testing different carbs the area between 8 and 9 K on the graph, the curve was much smother and sounded better on the dyno when it was richer there.



The blue line was the IE carb I tried a while back, the jetting on one of the runs didn't make much power but it drove well in the 8-9K area.

I wonder if with a bit of playing with a bigger main jet and carefully drilling out the air correction jet I can get the red line to drive as smoothly.

[wobbly]

One trick with earlyer TZ carbs was to remove the air corrector jet altogether, made them rev on way better with a slightly bigger main.

Re the muffler situation.
We have to talk apples for apples - the small engines like a 125 have a completely different sonic signature to a 250.
Anecdotal "evidence " means jack shit - you must use a DbA meter at a set distance every time.
I spent forever working weekends for the NZ Kart Federation with a Db meter hung above the track trying to find a way to quieten down the 250s.
On the meter the sound level was always less when using a bigger muffler core - to the ear it was alot "louder".
In the end we went to the ICC type muffler, with the front modified to accept the 32mm OD stinger.
This was a long 100mm tube with a 50mm core, and a 40mm outlet, thus a huge amount of absorption area, plus a resonant volume that cut high and low frequency noise considerably.
We got to the stage where the inlet was then louder than the exhaust - then we started work on carb inlet chambers and venturi nozzles etc.
The whole thing is super complex,and as usual what works to help noise - usually kills power big time - but the big diameter muffler stuck on the end of a 125 or 250 made no difference to power at all,when compared to the best small muffler, but no
way would this be practical on a bike..
A smaller muffler was always super critical on length and diameter, every change made a difference.

[husaberg]

so here in pic 1 is not the way to go (blurred) and plended ? and pic 2 is the way to go? both are cone type chambers
http://images.trademe.co.nz/photoser...70289_full.jpg
http://images.trademe.co.nz/photoser...70413_full.jpg

l know what l would use!

there is no right or wrong way its what works on your the best!

Look closely - Pic 1 has a blown or pressed header first section, the rest are segments.
Pic 2 are just a pieces of shit - I would be embarrassed to even have them in my rubbish tin, let alone have a pic of them on the interweb & no
the drastic cut angles would shag any pretence of power the design may have had initially,probably make about the same power as blown pipes would..

Blowing a pipe,except for the initial header shape, looses power big time,as the angle changes are blurred.
HRC has the trick method of pressing the pipe in two halves, and welding the seams, as a press tool can imprint distinct "corners" where for example the mid joins the rear cone.

I would Plumb for both.
As (but not always) what functions best also concidently often has the best form.But depends how you choose to look at it.
I do have an article on forming pipes by ther Hydraulic method (Rob Becket i think), but f'ed if i can find it.
The article expanded on the construction of the blown style chambers.But even the author conceded he believed Fabricated was best for power.
But when Wobs exhausts are so beautiful and it is how he makes a living. Not to mention he is kind of good at it. Why look past them.
Crazymans i think may have got the numbering mixed up on the photos too.
Honda's method Wob mentioned while very nice is hardly practical unless they were planing to make thousands of them.Maybe there were?
pic to be added later.But there was a reason Honda did them that way. Likely to show off and because the hard changes in section indeed worked better.
I also note honda often had the more visible sections form as described while the rear cylinders pipes were fabricated by convention means.
BTW Crazyman does a beautiful frame to replace the RS125. Using the std rs running gear seats tanks etc.
So more Honda RS125's need not face the ignominy of being powered by Yamaha Kawasaki and Suzuki engines.


Please Humour me and take the time to read the Cameron article.

[crazy man]

I would Plumb for both.
As (but not always) what functions best also concidently often has the best form.But depends how you choose to look at it.
I do have an article on forming pipes by ther Hydraulic method (Rob Becket i think), but f'ed if i can find it.
The article expanded on the construction of the chambers.
But when Wobs exhausts are so beautiful and it is how he makes a living.Not to metion he is kind of good at it. Why look past them.
Crazymans i think may have got the numbering mixed up on the photos too.
Honda's method Wob mentioned while very nice is hardly practical unless they were planing to make thousands of them.
pic to be added later.But there was a reason Honda did them that way. Likely to show off and because the hard changes in section indeed worked better.
I also note honda often had the visable sections form as desrbed while the rear cylinders pipes were fabracted by convention means.
BTW Crazyman does a beautiful frame to replace the RS125. Using the std rs running gear seats tanks etc.
So more Honda RS125's need not face the ignominy of being powered by Yamaha Kawsakis and Suzuki's.


Please Humour me and take the time to read the Cameron article.

l dont want to get into it with anyone anymore we all have are ways of doing things. l was

Hydraulicing them out 19 years ago at the age of 18 and made heaps of them

[Frits Overmars]

A larger muffler ID exposes the wave fronts to more packing material area, thus reducing noise - a step back down from the perf core to a smaller exit tube will increase the wave amplitude and make MORE noise.
Stinger/muffler lengths/diameters are very hard to analyse,only way is to cut and try, but with small dia mufflers - generally shorter is better for power, but not noise.

The most effective silencer I once made for a 125 cc kart had a length of 400 mm, an outer diameter of 80 mm and a core diameter of 35 mm.
Smaller core diameters did nothing for engine power and were worse in silencing. An end cap with a smaller exit diameter made more noise, just like Wobbly says.

[bucketracer]

.

Time to Compare apples with apples ......



and acknowledge how well TeeZee has done by wringing 31 rwhp out of his 1978 Suzuki 125 commuter engine.



In 1978 the Honda over the counter 125 factory racer made 25 and then later 28 hp and was the for runner of the RS125.



The Honda wasn't limited to a 24mm carb.



And the Honda also had a bridged exhaust port, while TeeZee has to contend with the limitations of a single exhaust port.

Info scraped of the net about the Honda MT125R

- Bike was produced and modified by Honda RSC (Racing Service Corp., the forerunner to HRC)
- Three versions were made MKI, MKII, MKIII from 1977-78
- Approx 200 imported into US each year.
- Bike Dry weight 165lbs.
- Engine configuration is factory modified version of the 1977 Elsinore motocross based engine
- Narrow power band with road race porting - "on the pipe" from 9,500 - 13,000rpm
- 6-speed with "ultra close" road race internal gearbox ratios - shifter mounting rearwards
- Road Race specification porting and factory 34mm carb - 25.5hp @ 12,5000rpm for MKI, MKII
- MKI had a mechanical activated disk brake from a CB200
- MKII & MKIII had upgraded front hydraulic disk brake
- Final MKIII in '78 had additional porting, pipe changes for 28hp peak
- RSC offered a special factory water cooling kits in 1978, including pipe, cylinder., head, radiator, mounts, and special side cover with external water pump.
- Water Cool kit avoided the heat-induced power loss form running at 13,500 rpm in a long race.
- Top Speed (with a light rider!) approx 115 mph.
- I have achieved 108mph at Daytona with 185lb rider.

As with any 125 cc roadracer, it was best suited for smaller riders. After bump starting the engine a good start required patience and finesse. To characterize the personality of the 125 cc two-stroke look at the RSC factory tachometer. It did not move or display engine rpm until 5,000 rpm and registered up to 14,000 rpm. With the tall gearing needed for top speed performance it would not pull its own weight until the tachometer was showing at least 9,000 rpm. The engine was in its peak powerband or, "on the pipe" from just below 10,000 rpm and went out of the powerband a little past 11,000 (depending on jetting and modifications).

To achieve a good start the rider needed to hold the throttle wide open and begin feathering the clutch as fast as possible while keeping the rpm between 10,000 and 11,000 rpm. If the tachometer dropped below 10,000 RPMs the rider needed to pull the clutch in, rev the motor and begin the process again. If the clutch was engaged too quickly the engine could "bog" or even stall while the rest of the starting field rode away. Even with the lightest of riders, the MT125R required slipping the clutch for 40 or more feet. The rewards for a successful launch were full throttle with quick shifts (approximately every 1,000 rpm) up through the six gears. At the end of sixth gear the hard-working 123 cc engine would be pulling along a straight stretch between 110 and 120 mph.

The last Hondas made 28 hp and had a 2.5k power band, TeeZees Suzuki is 31 hp with a 4kish power spread and that beats the Honda factory made racer hands down.

Compared to the Honda 2-stroke racer TeeZee's efforts with a commuter bike from the same period would have made a competitive ride back in 78, it could have been done, if only we knew.

I wonder if in the late 70's or early 80's if any one built a road racer using the Suzuki GP 125 engine and what it was like.

[F5 Dave]

. . .
On the meter the sound level was always less when using a bigger muffler core - to the ear it was alot "louder".
. . . .

well I'm glad I worded it like I did about not picking sides. I'll tuck that info away for later thought & trial. Think we have a db meter at work somehwhere.

[F5 Dave]

. . . .Please Humour me and take the time to read the Cameron article.

Ha! - I haven't read that article since. . . last night. Amazon will sell you the TDC books 1 & 2 & I'm rereading them. That article is included in these 'best of' books. He's not always right, but his writing style is entertaining & makes an effort to try & understand everything he can & put it to text in a way the general muppet can understand..

[husaberg]

.

Time to Compare apples with apples ......



and acknowledge how well TeeZee has done by wringing 31 rwhp out of his 1978 Suzuki 125 commuter engine.



In 1978 the Honda over the counter 125 factory racer made 25 and then later 28 hp and was the for runner of the RS125.



The Honda wasn't limited to a 24mm carb.


The last Hondas made 28 hp and had a 2.5k power band, TeeZees Suzuki is 31 hp with a 4kish power spread and that beats the Honda factory made racer hands down.

Compared to the Honda 2-stroke racer TeeZee's efforts with a commuter bike from the same period would have made a competitive ride back in 78, it could have been done, if only we knew.

I wonder if in the late 70's or early 80's if any one built a road racer using the Suzuki GP 125 engine and what it was like.

With 9000 pound's prize money that would buy over 10 cb400f's back then or a three bedroom house.
I am guessing they would have chosen to run the Honda anyway Bucketracer.

If you like compare the Gp125 to the Yamaha TA125 esp Kent Andersons one. 80 odd percent DNA shared with the AS3.
I am Not repeat Not taking away anything from TZ and the rests of the teams acheivements mind you.

PS Performance bike built a GP125 or 100 back in the late 80's or early 90's custom monoshock tz250 fairings and seat unit etc 20 odd HP If i recall corectly they claimed with the std carb.
I will dig it out sometime.

[bucketracer]

MT125R vis TeeZee's GP was a good apples with apples comparison, the early factory racers from the 60's are something else, I had forgotten about the TA125.

The Yamaha Two Stroke Twins book lists the TA125 as having 24hp at 12,500 rpm and 1.36 kg/m torqe at 12,250 rpm but it would be interesting to know more about the TA's and Kent Andersons one.

[twotempi]

The customer TA125 was approx 24 hp claimed and this seems abouit right with a top speed of about 110-115 mph. Power was/is between 9500 min to 13000 max. Very little below 9500.
Kent andersons bikes were a completely different animal and I don't have any info on what power they produced but i would guess at mid 30's. Say 34-ish

Another guy in America ( relocated Frenchman ) created a very sucessful 125 based on a 125 AS3 engine called a GBS ?? which equalled or exceeded the Andersons bikes. The acronym was " Garage Bin Special" or similar.

The TA125 gearbox had 5th gear a bit tall for the engine to bridge the gap. A slightly lower 5th gear from the RD125 will fit and allows the engine to still accelerate when changed from 4th to 5th.

Although a nice little bike it comes standard with a hinge in the middle of the frame, and a rear swing arm on rubber bushes allowing movement in all 3 axes directions rather than just up and down !!

the article on air-cooled cylinders was very interesting, is there any info available on side-by-side twin cylinder engines where the airflow between the cylinders is restricted. Some intelligent ducting must help in this instance.

[2T Institute]

Suzuki built a water cooled disc valve 125 race engine (basicaly 1 cylinder off a RGB 500) was only raced a few times in Japan and Malaysia. There is a pic of it but do you think I can find it