ESE's works engine tuner

[2T Institute]

Has anyone tried a relocated ring peg?
Frits once informed us that there is no problem when the ring opening passes above the boost port (up to a certain width though, which I don't remember - definately more than 15-16).

I had an old piston lying around and gave it a try. Old peg was positioned 11mm from IN center and protruded -0.6mm from the piston surface. I drilled a new hole -1.5mm- and my intention is to fit in a 1.6mm drill.
Do you think it will endure the forces of the ring and that it will stay in place?



Try with a roll pin instead of a drill bit. There is one problem with moving the pin, that is getting the new peg in the hole. Many blood bilsters later I made a holder out of flat sheet that I could push a say 20mm long roll pin into, that allowed me to hammer it into the new hole. I would normaly go all the way through and hammer the pin flat and grind off excess inside the piston. I also made a height gauge off the old peg and carefully ground the outside down inside the ring groove to match the template.

[Rick 52]

Hi Rick52

This is the piston we were talking about for TF/TS's, forged piston, 1mm rings and 14mm pin.

Use one ring keep the other for a spare. The piston skirt on these forged pistons can be cut back safely.

257700257701257702

Ned Kelly got his one from Jawzys on Ebay for $82.48 plus $32.25 shipping. Jawzys seem to have a selection and are worth a look.

http://www.ebay.com/itm/Wiseco-Piston-Kit-Suzuki-TC125-70-78-57-5mm-/220616513206?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item335dc4d6b6

Wiseco 449M05600 449M05650 449M05700 449M05750 for Susuki 125 TS, TC DS replaces 449Pxx

Cheers Teezee I will get 1 sorted early next week ..

[TZ350]

When I asked if the 180 in the bottom right corner of that dyno graph was the size of the motor the graph disappeared and was then re posted with that bit obscured and I have never figured out the discrepancy between the hand written date and the one printed on the graph.



Oh, yea, 28 P.S .....is the most I have ever seen out of an....AIR COOLED, DISC VALVED 125cc TWO STROKE....
Oh, the 28 P.S is with my own exhaust as well.....
I know alot about "DISC VALVED, 130CC TWO STROKES RUNNNING 24MM CARBS…

High hp air cool ed's have been around for a while ........ 28 hp claimed by SS90 ...... posted March 09

257736

28 ps (DIN hp) with 20Nm (14.75 ft/lbs) torque and about 2.5K usable power spread.

Not everything you read on the net is true .......

That was back before I had cracked 20ps (20 DIN hp) myself, I think by claiming 28ps he was trying hard to make an impression …… if you read further on in the thread you will find the reality of his world was a bit different.


in almost 10 years of operating various Dyno's around the place, I have personally never seen more that 17 P.S and 14 N.M (at the rear wheel) on an air cooled disc valve two stroke, running a 24mm carb. I have probably done over 200 runs on that type of set up. (on various engines)

[speedpro]

Has anyone tried a relocated ring peg?
Frits once informed us that there is no problem when the ring opening passes above the boost port (up to a certain width though, which I don't remember - definately more than 15-16).

I've had ring pegs relocated by Pete Sale on Palmerston North. Always from the side never from the top. The difficulty with drilling from the top is making sure the pin isn't going to come out. As has been mentioned one method is to drill a horizontal hole that the new pin extends into and then it is bent inward making it impossible for it to come out.

My current engine has a KT100 piston with the ring peg at the rear directly over the middle of the boost port. There is so little ring free to do anything between the edge of the port and the ends of the ring that unless there is a huge force trying to rotate the ring it will just sit in the groove. If you have a problem the cause is something other than the location of the peg, say assymetrical port roof trying to spin the ring. This will cause problems for the ring peg no matter where it is.

[dmcca]

EngMod2T question...

For Wobbly, TZ, Dinamik or anyone else who can assist...

I mainly work on dirtbikes and im trying to model the air space trapped between the end of the carb bell mouth and the inside of the filter... basically the air available for the carb to suck on before it has to draw through the filter... I have today measured this volume on a KTM250exc at 2200cc (vol of the air boot and inside the filter)... and have entered this volume into engmod under the intake screen, as the volume of the air box before the carb...

My question is how do I model the entry to this 'air box' as the entry is basically the filter?? Obviously the filter offers a restriction but im not sure what equivalent size open 'pipe' would flow the same as the filter... im guessing 0.1-0.2 of the filter equivalent area?? So far I have simply entered the diameter of the filter as the entry.

To take things even further... this filter sits inside the main airbox under the seat... the volume of this is about 6000cc i think... and it has all sorts of holes and gaps that feed into it. Should i model the entry pipe above to reflect this larger volume of the main airbox... or just forget about it. Basically id really like to properly model the entire entry system, becuse up until now ive just done similar to TZ and modelled the carb with a correction factor and ignored the air box(es)

Hope this makes sense.

[dinamik2t]

Thanks for the contribution.
I've seen the blind hole on the side, in an old RS125 piston. If I remember correctly, the pin was tapered but not bent. I 'll look for the piston to confirm, because I might have just not noticed well -wouldn't be the first time..
Even if I followed this method, I think the drill bit wouldn't bend anyway.. Not trying to be stubborn, but wouldn't the tight/press fitment keep it in place?

Speedpro, your pegs are just press-fitted in a smaller hole?

I ordered a set of roll pins, as 2T suggested, so I might try that solution by the time I test the piston.

edit:
> Dmcca
I would love to help with your issue, but I 'd probably give you an inaccurate, or worse, faulty opinion.

I can think of a way to measure the fraction of X liquid that the filter permits. Place a container with no bottom over a delimited filter area and pour gasoline for, say, 30s. Then divide the amount passed with the amount pourred, in that period of time. Forgot to say, you need another container below, to collect the gasoline. :crazy:
The fraction could then be used as the mult. factor, to calculate the "true" flow diameter.
Not sure whether such an equivalent is correct or the flow/volume/area variables function (verb) proportionately to make such an assumption.

Hope Wob or Tz can enlighten you.

[TZ350]

Some old TZ pistons and someone who may or maynot be Ago

257747257748257749

To replicate the TZ pistons use Piano wire sharpened on the end for the pin, Piano wire can be bent so it stays in place.

[Frits Overmars]

Some old TZ pistons and someone who may or maynot be AgoYes, that is Agostini allright, though somehow I get the impression he has been photoshopped into that picture.



257747257748257749

To replicate the TZ pistons use Piano wire sharpened on the end for the pin, Piano wire can be bent so it stays in place.I think this is still the best way to fit the pin: from the top, with piano wire with a conical-ground tip, with a blind hole in the piston face below the groove to bend the pin.
My personal experience with roll pins: they're terrible detonation-raisers.

[2T Institute]

How do the roll pins make some deto Frits?

[Frits Overmars]

How do the roll pins make some deto Frits?I don't know. It is hard to imagine that there could be enough end gases left in them to induce uncontrolled combustion. I am not even sure it was detonation, strictly speaking; maybe they caused premature ignition. But in any case quite a number of pistons were destroyed when Elko (the Austrian branch of Mahle at the time) switched from solid pins to roll pins for the Rotax 124 engine. It happened some 33 years ago but you don't forget things like that. If anybody wants to try roll pins: fine, keep me informed.

[teriks]

EngMod2T question...

For Wobbly, TZ, Dinamik or anyone else who can assist...

I mainly work on dirtbikes and im trying to model the air space trapped between the end of the carb bell mouth and the inside of the filter... basically the air available for the carb to suck on before it has to draw through the filter... I have today measured this volume on a KTM250exc at 2200cc (vol of the air boot and inside the filter)... and have entered this volume into engmod under the intake screen, as the volume of the air box before the carb...

My question is how do I model the entry to this 'air box' as the entry is basically the filter?? Obviously the filter offers a restriction but im not sure what equivalent size open 'pipe' would flow the same as the filter... im guessing 0.1-0.2 of the filter equivalent area?? So far I have simply entered the diameter of the filter as the entry.

To take things even further... this filter sits inside the main airbox under the seat... the volume of this is about 6000cc i think... and it has all sorts of holes and gaps that feed into it. Should i model the entry pipe above to reflect this larger volume of the main airbox... or just forget about it. Basically id really like to properly model the entire entry system, becuse up until now ive just done similar to TZ and modelled the carb with a correction factor and ignored the air box(es)

Hope this makes sense.
I knew I had read something about this before, so I revisited Blair and found.. well nothing much useful..

Anyway, in chapter 8 of "Design and simulation of two-stroke engines", there's a part about modelling an intake silencer, starts mid page 570.
Basically it just confirms your thoughts about dividing the total air-box volume in two separate volumes using a flow restriction between the two.

That air-box entry of the KTM seems quite impossible to model accurately (just had a closer look on my 250sx before posting this)...

[wobbly]

I havnt used the inlet airbox volume input before with EngMod, as I have never needed to except in our open class karts where the airbox is a spec ICC item and cant be changed anyway.
So I added a 2L volume with a single inlet tube to a full noise 125.
This added (mostly) or subtracted between 1 and 2 Hp thru the range in 55 crank Hp - so an inlet airbox can be used to compliment the powerband with careful design.
One concrete example I tested years ago was a champ winning KX125 in karts, that also had to use an ICC type airbox, but this was permitted to have the inlet tubes modified.
Stock it had 2 off 20mm by 100 long tubes with inlet bells - I added 2 more, and staggered the lengths from 20 to 100 long.
This added around 2 Hp everywhere in the 44 RWHp we had at the time.
The staggered inlets was picked up in tech - though legal at the time, the buggers changed the rules immediately it was discovered.

[dmcca]

I knew I had read something about this before, so I revisited Blair and found.. well nothing much useful..

Anyway, in chapter 8 of "Design and simulation of two-stroke engines", there's a part about modelling an intake silencer, starts mid page 570.
Basically it just confirms your thoughts about dividing the total air-box volume in two separate volumes using a flow restriction between the two.

That air-box entry of the KTM seems quite impossible to model accurately (just had a closer look on my 250sx before posting this)...


I havnt used the inlet airbox volume input before with EngMod, as I have never needed to except in our open class karts where the airbox is a spec ICC item and cant be changed anyway.
So I added a 2L volume with a single inlet tube to a full noise 125.
This added (mostly) or subtracted between 1 and 2 Hp thru the range in 55 crank Hp - so an inlet airbox can be used to compliment the powerband with careful design.
One concrete example I tested years ago was a champ winning KX125 in karts, that also had to use an ICC type airbox, but this was permitted to have the inlet tubes modified.
Stock it had 2 off 20mm by 100 long tubes with inlet bells - I added 2 more, and staggered the lengths from 20 to 100 long.
This added around 2 Hp everywhere in the 44 RWHp we had at the time.
The staggered inlets was picked up in tech - though legal at the time, the buggers changed the rules immediately it was discovered.



Thanks Wobbly and Teriks...

The reason i want to do this is because i know someone who has gained some extra power in a ktm300 by simply increasing the volume of the rubber boot between the filter and the carb, so its a proven mod... but i want to correctly model it if i can to test the theory on other bikes.

I started with modeling the filter as a 10mm long pipe 150mm in diameter (close enough to the diameter and thickness of the filter) and this made no difference in power over modeling it without the airbox at all. Im now im trying an inlet pipe with a diameter of 40mm (its a guess but equivalent to 6% of the filter area, and close enough to the carb size of 36mm) with the same airbox volume of 2200cc and there is a significant drop in power at peak.

The question still remains, how do i accurately determine the density or opacity of the filter?? Once i have determined and modeled this as the inlet pipe then i can go on with what i actually want to do... model different airbox volumes to determine their effect, assuming that the filter remains the same.

Maybe an email to the filter manufacturer, maybe they know the equivalent flow rate for the filter??

[TZ350]

257809257807

Yamahas 1974 Road and Race Bikes .......

257808 Race 250 port maps.

The TZ ring peg thing and how its bent to keep it in place.

257806 257805

Ok I couldn't find any good pictures of a TZ ring peg on the net so hunted out some NOS pistons of my own from a 74 TZ350B.

[TZ350]

257813

Now that I have come by a good looking tank and seat I have a re newed interest in the 50. I am not intending to develop this to much, more just get it going and ride it.

[husaberg]

Yamahas 1974 Road and Race Bikes .......

Race 250 port maps.

The TZ ring peg thing and how its bent to keep it in place.



Ok I couldn't find any good pictures of a TZ ring peg on the net so hunted out some NOS pistons of my own from a 74 TZ350B.


You must be using the wrong bait?
5th pic on the first cast on a google search on the interwebby thingy (it is getting sort of popular, but, you know kids it won't last. They will soon get bored with it and go back to space invaders and that break dancing)

http://www.aircooledrdclub.co.uk/forum/forum_posts.asp?TID=30676&PID=234722

PS i hope you haven't put a Honda RS tank on a Suzuki that would make me cry a Bucket load of tears:violin:

Just as well Soichiro is not alive to see that.
257820

He did have quite an interest in piston rings however.

Like most other countries, Japan was hit badly by the Great Depression of the 1930s. In 1938, Soichiro Honda was still in school, when he started a little workshop, developing the concept of the piston ring.

His plan was to sell the idea to Toyota. He labored night and day, even slept in the workshop, always believing he could perfect his design and produce a worthy product. He was married by now, and pawned his wife's jewelry for working capital.
Finally, came the day he completed his piston ring and was able to take a working sample to Toyota, only to be told that the rings did not meet their standards! Soichiro went back to school and suffered ridicule when the engineers laughed at his design.
He refused to give up. Rather than focus on his failure, he continued working towards his goal. Then, after two more years of struggle and redesign, he won a contract with Toyota.
By now, the Japanese government was gearing up for war! With the contract in hand, Soichiro Honda needed to build a factory to supply Toyota, but building materials were in short supply. Still he would not quit! He invented a new concrete-making process that enabled him to build the factory.
With the factory now built, he was ready for production, but the factory was bombed twice and steel became unavailable, too. Was this the end of the road for Honda? No!
He started collecting surplus gasoline cans discarded by US fighters – "Gifts from President Truman," he called them, which became the new raw materials for his rebuilt manufacturing process. Finally, an earthquake destroyed the factory.........
<tbody>
Today, Honda Corporation employs over 100,000 people in the USA and Japan, and is one of the world's largest automobile companies. Honda succeeded because one man made a truly committed decision, acted upon it, and made adjustments on a continuous basis. Failure was simply not considered a possibility.

</tbody>





Yamaha GL750 1972 never made production and disappeared to emerge as the TZ750 later.

i guess the fuel injection must have put the frighteners on the other Japanese 3 manufacturers
.257834257835257836
http://www.classicyams.com/special-yamaha-bikes/special-yamaha-bikes/yamaha-gl750.html

[wobbly]

Cant be a TZ350 with holes in the piston.

[husaberg]

Cant be a TZ350 with holes in the piston.

Correct. I assume it is a TZ750 though.(700cc model one's i guess)

PS fixed the holes in the second pic

PPS I have watched my father make a peg out of a brass screw filed flat and peened over. For my original Villers powered James after i hastily ran my first go at an expansion chamber. I was so excited to try it. I test ran it without a stinger and lost the top of the unobtainable oversize piston. A bit of TIG welding and machining and it was as good as new. (probably better). It also had alloy fins shrunk over the iron barrel. Well it looked faster with them on.It must have had 12hp or so. Good for 80mph:yawn:

[bucketracer]

You must be using the wrong bait? 5th pic on the first cast on a google search on the interwebby thingy

Just goes to show you, use a bit of intelligence and Uncle Google will tell you about most anything ........

[F5 Dave]

Nice looking RD350B, have one in my lockup waiting for the owner to lose interest & me to find some money to make him an offer.

Surely a bit more development on the 50? Say putting the top end on else it will be oversize, the cubic capacity being The Whole World.

[husaberg]

I have the updated for the 90 TZ750 with KR having a test run on it i will post later maybe.
The old man actually has none in the Shed..... Bugger.
He does have an original unrestored YDS3 though Bloody heavy for a 2 stroke.
It fell on me when i was about 4 so it Explains my disinterest in Yams and my bud spellig ass will.

I also found the pic of the Italijet. It turns out it was an 80 and way more shrouded than i thought it got me thinking Yamaha added the shrouding ala Suzuki Ram air to the Daytona special RD400 for a reason it certainly wasn't likely for looks. Well if it was they should of sacked the designer. The ugliest of RD's until the LC. i only Love the coffin tanked RD's BTW.

As well as Suzuki.
257848







http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=257856&d=1329473248

[dinamik2t]

Hey, Wob :D What's up? Need anything these days??

Could you give an idea on how someone could continue engine evolution above 14bar BMEP? :pinch:

Actually, let me ask something less stupid. Other than transmission losses, would EngMod results reflect reality if all inputs are precisely accurate? And, say, I reach a X limit of performance in engmod. What are the possibilities of post-simulator improvement without incorporating super-expensive parts or materials or processes?

[husaberg]

I mentioned the JPS it was a basic motor but cleverly done BOB.

I later pre Cosworth challange (this bike justed mounted the sterring head and the swingarm to the huge 1/4 cosworth v8)ones were monoque and Space framed one other unique feature of the of the jp nortons was the spined mounding of the disk brake to allow it to float.Yamaha copied this later for the quads.

[wobbly]

The simulation is very accurate as Neels has refined it continuously for years.
Look at his new website page, it has a result I did of the RS485 engine, straight off the sim and onto the dyno,including the ignition and PV curve programmed into the Ignitech.
All but spot on correlation with around 12% losses across the board for the drivetrain.
Only departure would be that the PV sim assumes that the blade is close to the piston thruout its stroke - which of course it isnt.

At the 14bar level you are looking for tiny improvements to the hardware,this costs a fortune no matter what the application.
As an example - 0.7mm rings, PWM powerjets,ceramic ball mains,deto sensor control of the ECU etc etc.
Getting the sim to accurately reflect performance at that level is easy - getting the parts to live there - and perform there, is not.
To exceed that level needs a quantum jump in the basic hardware,Frits has begun the process with his porting arrangement,time for you to step up and think outside the square we live in.

[speedpro]

I've had another idea, that's 2 this year.

Why are combustion chambers symetrical? Is it just for ease of manufacture? Is there any benefit to being assymetrical? I'm thinking along the lines of reducing or eliminating squish in say one section or even in areas opposite each other. My thoughts were that being loop scavenged a different shaped head may have benefits for scavenge flow whilst still having enough turbulence generated towards TDC. "We" could do it by hand but nowadays with CNC gear it wouldn't be hard to manufacture. Does anyone have simulation software that allows for something other than the normal? Possibly a bathtub shape though not so pronounced.

[dinamik2t]

I run through the last few posts very quickly, thanks for the heads up Wob!

Just wanted to add a link with several interesting info, here:

http://www.redline-ci.com/

I liked particularly the explanation on powerjet carbs : http://www.redline-ci.com/Technical%20Information/Basic%20concept%20of%20power%20jets,%20RS125R-250R.htm

It also has lots of RS and TZ manuals -like anyone here would need those.. anyway.

Some info on the deto counter that Wod mentioned too on the quest for power: http://www.redline-ci.com/Technical%20Information/SETTING%20USING%20DETONATION%20COUNTERS.htm

AH, and here's mr Neels webpage : http://www.vannik.co.za/index.htm

[Yow Ling]

Hey TZ you should ask Neels to put your bucket on his examples page then there will be 4 out of 4 kiwi developers on there

[wobbly]

Two types of asymmetric chambers have been tried, one by Doc Erlich who worked for OMC etc and sold the patent to Yamaha, simply moved the whole chamber back ,over the boost port.
This was supposed to help the loop stay attached,maybe it did but it also made the squish velocity go thru the roof on the opposite side, and it detoed its tits off.
Yamaha used it once then dropped it, maybe useful down at 7 bar bmep in an outboard, not at 12+.
The other I have seen was a teardrop shape front to rear, with wide squish on the sides - same shit, different shape.
More than happy to CAD and CNC something else if anyone comes up with something.

[richban]

I recently read a little piece on pipe design that got me thinking. One bit in particular spoke of badly matched pipes to ports. It said that any anomaly at the port end was a bigger problem than if say you had a dent further down the pipe. Due to greater force and speed at the port pipe juncture. Resulting in, as he put it ghost waves created. reversion I suppose. How important is it to have the transition seamless. I would imagine its very important. I know on my 4 stroke single the exhaust port is D shaped and does not match the header very well. I am thinking I should fix this now. Is this something you guys pay a lot of attention to?

[husaberg]

. I know on my 4 stroke single the exhaust port is D shaped and does not match the header very well. I am thinking I should fix this now. Is this something you guys pay a lot of attention to?

4 strokes, i think you are right. i don't think most people pay attention to them:innocent:
I doubt they will catch on, Unless someone changes the rules to give them an advantage in capacity then bans 2 strokes all together.:brick:


Two types of asymmetric chambers have been tried, one by Doc Erlich who worked for OMC etc and sold the patent to Yamaha, simply moved the whole chamber back ,over the boost port.
This was supposed to help the loop stay attached,maybe it did but it also made the squish velocity go thru the roof on the opposite side, and it detoed its tits off.
Yamaha used it once then dropped it, maybe useful down at 7 bar bmep in an outboard, not at 12+.
The other I have seen was a teardrop shape front to rear, with wide squish on the sides - same shit, different shape.
More than happy to CAD and CNC something else if anyone comes up with something.

DKW ran them prewar MZ postwar in the 60's.
I would hazard a guess Dr Joe got his idea from them a long with a complete engine or two.
Suzuki ran them on the 60's GP bikes as well i think.
I do remember some others in the late 70s maber 125 gp bikes euro type Motobelli or such like.

here is the DKW and The MZ.

As Wob says above there was a total elliptical shaped one basically oval buggered if i can remember what had it though.

Bear in mind that the book these came from is from the 1960's so it might as well be 50 years old :whistle:
ps have a look at the crankcase finning and the plug

[speedpro]

4-strokes :sick:

I'm pretty sure the D shape is just as important to 4-strokes as the the transition 2-strokes have between port and pipe. I would not get rid of it. I have seen that d-shaped port to round pipe transition on some serious high horsepower v8s. Ask your brother before getting the grinder out.

[richban]

4-strokes :sick:

I'm pretty sure the D shape is just as important to 4-strokes as the the transition 2-strokes have between port and pipe. I would not get rid of it. I have seen that d-shaped port to round pipe transition on some serious high horsepower v8s. Ask your brother before getting the grinder out.

I was not meaning the port shape. D shaped ports I think are supposed to help with reversion. I was meaning after the port and the transition to the pipe.

[wobbly]

D ports in a 4T are there to speed the flow up on the short turn radius, and prevent serious reversion in the area of least flow velocity,the port floor.
In a 2T we use the step at the manifold to reduce the Ex duct volume - also keeping the velocity high, and also preventing the reverse plugging wave from buggering the powerband
even more than it usually does when the pipe is too short for the rpm.
When they are designed correctly both are a useful tuning tool.
STEP AWAY FROM THE GRINDER.

[speedpro]

I was not meaning the port shape. D shaped ports I think are supposed to help with reversion. I was meaning after the port and the transition to the pipe.

The V8s had the flat floor of the D port right to the gasket surface where the headers bolted up. The shape of the port at the outlet was a D and the pipe that bolted on was an O. I wonder if there wouldn't be some advantage in a CNC oval or D to round transition like has been discussed earlier in this thread. Wondering about that sort of stuff really is for another thread.

[wobbly]

In a 4T there is very little mass flow on the port bottom,due to the tight short turn, the flat face of the 1/2 moon formed where the header bolts on, is to help prevent reverse flow
overcoming the slow velocity exiting the port at that junction.
Making a smooth transition there, would fuck the whole idea, and the power.
The Britten made a heap more power when Tim made a new pipe to my design with two reversion steps, plus one at the gasket face.

It had no problem with short turn flow, but the steps also produce a depression reflection every time you step up in dia, and if the steps are in the right place, they can reflect at peak torque and peak Hp rpm - helping to spread the usable power.
Its a similar situation with a 2T but the dynamics are way different - as is the detail of the Devil, or God, depending upon your predilections.

[richban]

In a 4T there is very little mass flow on the port bottom,due to the tight short turn, the flat face of the 1/2 moon formed where the header bolts on, is to help prevent reverse flow
overcoming the slow velocity exiting the port at that junction.
Making a smooth transition there, would fuck the whole idea, and the power.
The Britten made a heap more power when Tim made a new pipe to my design with two reversion steps, plus one at the gasket face.

It had no problem with short turn flow, but the steps also produce a depression reflection every time you step up in dia, and if the steps are in the right place, they can reflect at peak torque and peak Hp rpm - helping to spread the usable power.
Its a similar situation with a 2T but the dynamics are way different - as is the detail of the Devil, or God, depending upon your predilections.



Cool. That means we are in the ball park for sure. There is one at the gasket face from mr suzuki and I have two more steps at 100mm intervals.

[dmcca]

Two types of asymmetric chambers have been tried, one by Doc Erlich who worked for OMC etc and sold the patent to Yamaha, simply moved the whole chamber back ,over the boost port.
This was supposed to help the loop stay attached,maybe it did but it also made the squish velocity go thru the roof on the opposite side, and it detoed its tits off.
Yamaha used it once then dropped it, maybe useful down at 7 bar bmep in an outboard, not at 12+.
The other I have seen was a teardrop shape front to rear, with wide squish on the sides - same shit, different shape.
More than happy to CAD and CNC something else if anyone comes up with something.

Speaking of head profiles...

Is there a definitive answer as to whether or not a toroid is better than a bath tub shape? I believe that the RSA has a bath tub shape?? but i have heard that the toroid is good/better. Ive tried toroid shapes and they seem fine, defintiely seem to detonate less with high comp and lean mixtures, but im not testing the peak of performance like others here are, so i cant really tell too much difference.

What do others here run?

[Frits Overmars]

....I believe that the RSA has a bath tub shapeWhatever gave you that idea?

[husaberg]

Whatever gave you that idea?



Archimedes, in his defence it just slipped out:yes:

257913257914257915
http://www.absaf.nl/

[dmcca]

Whatever gave you that idea?
I thought I remembered reading it?? Are you able to elaborate/confirm?

[casal-fan]

I've been trying to think of an intelligent question to ask of our learned contributors for a while.

There have been heaps of things that have sprung to mind but I've been able to find reasonable answers myself by looking around and reading widely, asking such questions here seems a waste of a good opportunity.

So my odd-ball questions:

What is the up with the radial exhaust port angle?

I'm not sure if I have the correct term so I have attached a Picture to illustrate.

Some exhaust ports exit straight (pic on left) but I notice others, including the RS125 barrel I have sitting here, have a shape more like in the right picture.

I can guess at why this might be done but is there any general wisdom of perceived benefits/drawbacks?

I did notice one small reference to it in the large pile of books I've been working through, that was in Cesare Bossaglia's book 'Two Stroke High Performance Engine Design and Tuning' (Quite an old book but still interesting and informative, a greater scope than most) from my terrible memory he said it has been used to update old barrels to higher performance without a major redesign.


Late answer to this post, but I haven´t read somebody looking at this from this point of view.
I see the bulge as being there for exactly the same reason as there is a buldge on the trailing side of most secondary transfers ports.
It shapes the exit horizontal angle to give the max possible effective port area.
Wobbly mentions flow increase with the buldges, but lost if exagerating the buldge horizontal angles. This "flows" good with what I just wrote... maybe...

[Frits Overmars]

I thought I remembered reading it?? Are you able to elaborate/confirm?You can confirm it yourself. Some time ago I made a lot of Aprilia-documentation available to the forum. Just click the links and study the pictures.

[bucketracer]

I thought I remembered reading it?? Are you able to elaborate/confirm?You can confirm it yourself. Some time ago I made a lot of Aprilia-documentation available to the forum. Just click the links and study the pictures.

And there it is ......


Thanks, Mental; everything seems to be fine now. So here they are again:

http://www.kiwibiker.co.nz/manual/Aprilia-1.zip (http://www.kiwibiker.co.nz/manual/Aprilia-1.zip) (6.8 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-2.zip (http://www.kiwibiker.co.nz/manual/Aprilia-2.zip) (8.3 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-3.zip (http://www.kiwibiker.co.nz/manual/Aprilia-3.zip) (9.2 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-4.zip (http://www.kiwibiker.co.nz/manual/Aprilia-4.zip) (7.2 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-5.zip (http://www.kiwibiker.co.nz/manual/Aprilia-5.zip) (5.6 MB)

Collections of interesting tec links are posted on each decade page 320-310-300-290 etc to help with finding the interesting stuff, also using the "thread tools" and sorting and searching the images is another way of finding good stuff.

[timg]

I recently read a little piece on pipe design that got me thinking. One bit in particular spoke of badly matched pipes to ports. It said that any anomaly at the port end was a bigger problem than if say you had a dent further down the pipe. Due to greater force and speed at the port pipe juncture. Resulting in, as he put it ghost waves created. reversion I suppose. How important is it to have the transition seamless. I would imagine its very important. I know on my 4 stroke single the exhaust port is D shaped and does not match the header very well. I am thinking I should fix this now. Is this something you guys pay a lot of attention to? Think ya should just put in a 1/4" penny washer in there. That should make it look nice for you :innocent:

[husaberg]

You can confirm it yourself. Some time ago I made a lot of Aprilia-documentation available to the forum. Just click the links and study the pictures.

I was wondering what he meant.
but there is a ac couple of pics (pic 2 and 3) that if you look it does reassemble a elliptical shape.
A trick of the light no doubt.

While trying to find the photo i came across this (pic 4 )
What is the cast alloy piece it kind of remembles a disk valve cover design by the shock below the swing arm?It looks like the linkage is attached to it?

There is also a close up of the pin for the ring peg.(pic 1)

I also seen something i had never noticed in the transfer passage in one of the 500 pics (5th pic) a round bumper shape this may also be a trick of the angle the pic was taken as it may not be the shape it looks to me.

Yows bit below i would hazard a guess and it would be a guess is what looks like a sleeve is the coating extending over the top of the bore to limit detonation damage as per my bit i posted about Apitec

[Yow Ling]

Looking at Husaberks pictures above , is the RSW sleeved? pic 2 and 3.
What sort of material ? Any reason, run out of oversizes?

Also pretty clever piston machining for lubrication , kind of like an applicator nozzle. Cant remember seeing a 125 seize at motogp , maybe I just dont look hard enough

[dmcca]

You can confirm it yourself. Some time ago I made a lot of Aprilia-documentation available to the forum. Just click the links and study the pictures.

... and that is a gold mine of great info thankyou, however the reason for my confusion about the RSA head shape is that i very recently heard a respected person definitively say that the RSA did not have a toriod design. There are several pics in the files you kindly posted which appear to be toroids to me, however all of these are labelled as RSW so there was still a question in my mind as to the actual design on the RSA based on the comments i had read:scratch:

[F5 Dave]

Having some carburtion issues. Does this look too lean?:pinch:

[Buckets4Me]

Having some carburtion issues. Does this look too lean?:pinch:

no it looks fine but dose have a small crack in the piston skirt

[Henk]

Looks mint, don't worry about the small crack.

[speedpro]

I'd replace the piston as a precaution, hell you have it out so why not. If you're careful taking the circlip out you could probably use it again.

[quallman1234]

Putting a new piston in a 50cc at the moment (okay its a scooter)... Idea's on getting the 10mm (im guessing) piston circlips in, bloody tiny little things anything bigger is piss easy. They are the open type, can't really use circlip pliers. Any hints?

[husaberg]

Putting a new piston in a 50cc at the moment (okay its a scooter)... Idea's on getting the 10mm (im guessing) piston circlips in, bloody tiny little things anything bigger is piss easy. They are the open type, can't really use circlip pliers. Any hints?
put a rag over the crankcase mouth:innocent: Well you did say any hints?

[quallman1234]

put a rag over the crankcase mouth:innocent: Well you did say any hints?

;) I know that one cheers :).

[Frits Overmars]

...the reason for my confusion about the RSA head shape is that i very recently heard a respected person definitively say that the RSA did not have a toriod design.Who?


There are several pics in the files you kindly posted which appear to be toroids to me, however all of these are labelled as RSW so there was still a question in my mind as to the actual design on the RSA based on the comments i had read:scratch:Fair enough. I did not post the RSA's cylinder drawings either; I don't fancy being shot the next time I visit Italy....
But I can assure you the RSA's combustion chamber is identical to the RSW's, although the outsides of the heads are quite different.

[Frits Overmars]

Having some carburtion issues. Does this look too lean?
no it looks fine but dose have a small crack in the piston skirt
Looks mint, don't worry about the small crack.
I'd replace the piston as a precaution, hell you have it out so why not. If you're careful taking the circlip out you could probably use it again.I love it! Great way to start a sunday :killingme.

[Frits Overmars]

.... the reason for my confusion about the RSA head shape is that i very recently heard a respected person definitively say that the RSA did not have a toriod design.This kept me thinking for a while. Maybe it is a misunderstanding stemming from the way you define a toroid. The decisive factor is that the radius of the combustion dome originates off-centre; its center is offset from the cylinder center line. That may or may not lead to the spark plug intruding into the combustion chamber, depending on the radius, the offset and the plug thread diameter.

The first two pictures show the Aprilia combustion chamber with a flush plug. The third picture shows a Wobbly-head with a deeply-intruding plug. The last picture shows the turbulence in a toroid head, initially caused by the transfer streams and enhanced by the squish action.
The intruding plug seemed a logical step but tests at Aprilia have shown that an intruding plug costs power, probably because it causes a scavenging shadow where spent gases are not fully removed by the incoming fresh mixture, so Aprilia-chambers have a flat area around the plug hole.

[Kickaha]

no it looks fine but dose have a small crack in the piston skirt

You could build it up with a tig and machine it back, if you do that going by personal experience it could last up to a season being revved to 12500rpm

[wobbly]

The deep intrusion toroidal head shape was developed using flat top, so called Honda A Kit pistons.
I would opine that the end result is very similar to the flat roof dome using a convex piston.
BTW there is still some differing opinions about the circular flow direction of the squish action that is created off the sharp corner
going into the bowl.
First logical reaction that would seem to be the accepted norm, and is as Frits has shown, is that the rotation is clockwise.
But a senior/clever engineer at Yamaha told me that their CFD analysis showed it was the opposite way - and he lead the development of Yamahas 250/500 flat roof chamber when unleaded fuel became mandatory in 98.

[dmcca]

This kept me thinking for a while. Maybe it is a misunderstanding stemming from the way you define a toroid.

Ah this is surely the problem... I had made the assumption that a toroid shape always involved an intruding plug. I guess that the comments I read were based on the same incorrect definition of the design. To make this more confusing the flat roof design you posted above is the design I originally thought the RSA had, however that's the one that I incorrectly referred to as a bath tub shape which is what led to this confusion in the first place. My original question therefore should have been worded... Is an intruding plug shape better/worse than a flat roof shape?? But this has now been answered.

Thanks for being patient and taking the time to explain.

[F5 Dave]

I had assumed the intrusion plug would have had most benifit as the cylinder bore & hence chamber had become larger dropping the spark plug further into the chamber where it is closer relatively on a 54mm or smaller bore. Perhaps?

[F5 Dave]

And yes thank you all for your kinds words re my poor classic YZ piston.:oi-grr:

I'll go up a jet size & see how it goes, if not I'll order a new one.

PS I think this was caused by excessive clearance, it did sound a bit slappy. No wear evident on bore, so it might have been bored too big to start with.

[Dutch Fisher]

D ports in a 4T are there to speed the flow up on the short turn radius, and prevent serious reversion in the area of least flow velocity,the port floor.
In a 2T we use the step at the manifold to reduce the Ex duct volume - also keeping the velocity high, and also preventing the reverse plugging wave from buggering the powerband
even more than it usually does when the pipe is too short for the rpm.
When they are designed correctly both are a useful tuning tool.
STEP AWAY FROM THE GRINDER.

...further to this, what's the informed wisdom on the half moon projections seen in the necks of these 2002 YZR500 pipes

http://www.blatawcm.com/redbull/images/PhillipIs2002/DSCN1996.JPG
http://www.blatawcm.com/redbull/images/PhillipIs2002/DSCN1995.JPG

[gamma500]

Here's some pics of rgv500 cylinders and pipes...hhmmm...

[wobbly]

When unleaded became mandatory in 98 most teams had a hell of a time keeping deto under control, having to run very rich and retarded.
The cylinders with the straighter pipes always gave alot more grief, untill a lowly dyno operator at Yamaha discovered that
when he stuck a large pressure probe into the header, the deto went away.
They managed to keep this secret for a couple of years but when teams like WCM got hold of the bikes, and left pipes lying about as you see in the pics,word soon got around.
The "things " intruding into the header take varying forms,but all do the same thing - the usually bottom "bent "pipes dont have the same issue, so dont need the so called deto buttons.
I have a couple somewhere from a Red Bull bike - I will pic them and post here .

Here is a shot of a cylinder I have been working on - its just come back from plating - the duct entry shape looks a bit familiar doesnt it.
The plating must have more Nickel in it, that would be why some of the previous shots on here look as though the cylinders have a liner, its the colour of the plating process.

[Dutch Fisher]

What year RGV500 are those from?

Y2K has more apparatus on the exh side

[F5 Dave]

. . .a lowly dyno operator at Yamaha discovered that
when he stuck a large pressure probe into the header, the deto went away.. .
. . .The "things " intruding into the header take varying forms,but all do the same thing -

Now that's queer. My only foray into using EGT probe (on my 50 so small header) but with probe position a good 6" away I fed it in & ran it up on the dyno. Oh dear, lost a lot of power & gee these EGT readings were higer than I thought. Jetting & ign don't help. Hmm wonder if the probe was causing the issue. Block it off & power comes back.

Thinking about it later I decided to retry with the probe only just inserted, think the metal outer was getting stinking hot & on small header was big issue. that was 2yrs ago & have got distracted since.

[Frits Overmars]

Here is a shot of a cylinder I have been working on - its just come back from plating - the duct entry shape looks a bit familiar doesnt it.Quite familiar; the only give-away is the distance between A-duct and stud. And I see no provision for a powervalve. What's it for? A kart engine?

[TZ350]

And yes thank you all for your kinds words re my poor classic YZ piston.:oi-grr:

What brand of piston were you using?

Recently we had a close call with a new PROX piston cracking up, only 20min on the dyno, pulled it out after seeing the runs losing power, it could have only been a dyno pull or two away from completely letting go.

[F5 Dave]

it was std Yamaha NOS circa 1980. Think they used ART back then which were good cast pistons. ProX used to be ART distributor under another name I think but I heard they are using Mitaka & quality is up & down. Not totally certain of any of this.

My crown was fine apart from the peppering from debris, the piston it was hard to tell where the fault started. My Std Honda piston I was running before started cracking the front of the skirt. Usually the skirt goes when there is too much clearance either through wear or incorrect bore.

But I'm guessing as there wasn't much left, clearly it fell to bits quick as I could pull the clutch.

[wobbly]

Hey TeeZee, that piston is for sure incorrectly heat treated - its faulty,take it back and demand a replacement from a different supplier or batch at the very least.
And part of the issue could be the ring width - how wide are they, and you dont need two of them bashing up and down in the ring grooves now you are reving to 13000.

Im not allowed to say whos cylinder it is Frits, this is a rapid prototyped casting as you can see by the layering marks - but it does have a two stage blade powervalve ( now ) and I "unfixed" the fixups originally departing from Jans good work.

[TZ350]

Hey TeeZee, that piston is for sure incorrectly heat treated - its faulty,take it back and demand a replacement from a different supplier or batch at the very least.
And part of the issue could be the ring width - how wide are they, and you dont need two of them bashing up and down in the ring grooves now you are reving to 13000.

The piston was in Ned Kellys bike, ring width 0.95mm, and not sure where it came from originaly as in true Bucket fashion we ratted it out of a box of oddments in the shed. Its now been replaced with a new Weisco forged piston.

[TZ350]

Wobbly put me onto this TPS, I think its from a Aprilia RS250, throttle cable, two carburettor cables and an oil pump cable what the fourth one is for I have no ideas.


258168 258169


This is going to be my new TPS (throttle position sensor) to go with the ignitech and new taper bored 24mm carb, finaly starting to get all the bits together to make a decent engine management system.

[TZ350]

Received my new pipe "kit set" from Wobbly today, 30++ hp hopefully with a bit of overreve.

258170

Not sure of the order but it makes a nice fossil fish like picture.

Anyway it will keep Bucket quite for a while rolling it up and welding it all together.

[Bert]

Wobbly put me onto this TPS, I think its from a Aprilia RS250, throttle cable, two carburettor cables and an oil pump cable what the fourth one is for I have no ideas.


258168 258169


This is going to be my new TPS (throttle position sensor) to go with the ignitech and new taper bored 24mm carb, finaly starting to get all the bits together to make a decent engine management system.

:brick::psst::wings: Same as on a RGV... I must have a couple of them sitting around under the bench (should have thought of that)... Good thinking Wobby/TZ.:2thumbsup

[wobbly]

Here is the pattern layout TeeZee with all the pieces in order, edge to edge.
Mark them as you roll them up.

[bucketracer]

:brick::psst::wings: Same as on a RGV... I must have a couple of them sitting around under the bench (should have thought of that)... Good thinking Wobby/TZ.:2thumbsup

258175 258176

So that is Aprilia RS250 and RGV250 that have cable operated TPS's, now that is very handy ......


Here is the pattern layout TeeZee with all the pieces in order, edge to edge. Mark them as you roll them up.

Thanks for the layout, TZ suggested I should stand them all on end and number them according to their length but having a proper layout plan is much better.

[crazy man]

think l would rather hydraulic my chambers out than welding that up

[bucketracer]

think l would rather hydraulic my chambers out ....

We tried that once, not a very pretty result.

[bucketracer]

For those that are interested in such things, here is a whole stack of port maps for 50-80cc performance engines.

258198

http://www.rprhosting.dk/nytsite/articles.php?article_id=8&c_start=30

[2T Institute]

The 4th cable on the TPS goes to the servo motor. Beware with the TPS as it limits slide travel on RGV/RS carbs. A conversion I helped with on a TZ250 5KE required a new quadrant to be machined up to get the full sweep of the TPS v's full movment of the slide. Before you ask you need the full sweep of the TPS because the more divisions in the sweep the more accurate the mapping.

[dinamik2t]

Proper TZ's pipe layout:

258200

[Buckets4Me]

Proper TZ's pipe layout:

258200

you forgot the big fin on the back

[TZ350]

Ha Ha ... :laugh: thats pretty good..... we need a name for the pipe, any ideas.

[crazy man]

We tried that once, not a very pretty result.there are lots of little tricks to make them right but you can get them right. l'v made over 10 rs125 ones 3 of the guys l made them for that dyno them said it went back up to the same hp as the standard ones. at the time another guy was making them the cone way and was losing 3-4 hp so some for the riders were saying

[gamma500]

What year RGV500 are those from?



2001, If I remember right. Not 100% sure though...

Here's couple of more pics.

[wobbly]

The 4th cable is to the PV servo as the man from the Institution says - it holds the oil pump open when the PV is open, but the throttle is closed ie high rpm overun into a corner.
Interesting to see in one of the Suzuki pics that it has two servo drives, one for the blade PV and another for the ATAC chamber, they too discovered you cant simply tie them together.

I recon the pipe should be named "Pirranha" looking at the fish impressions.

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.
Years ago when working with Jim at JL I tried blowing the pipe into a split mould around the mid section, but even this lost around 2-3 Hp per pipe on Hines dyno at Zip,when testing his Superkart title engines.

[TZ350]

I recon the pipe should be named "Pirranha" looking at the fish impressions.

If its OK with you Wob maybe we could call it "The Wobbly Pirranha" and if its ok with him, use dinamik2t idea for the logo ....

[dinamik2t]

You needn't have to ask...

In front of the mouth you should put a cup with the category's name.

258211

:stupid:

[crazy man]

The 4th cable is to the PV servo as the man from the Institution says - it holds the oil pump open when the PV is open, but the throttle is closed ie high rpm overun into a corner.
Interesting to see in one of the Suzuki pics that it has two servo drives, one for the blade PV and another for the ATAC chamber, they too discovered you cant simply tie them together.

I recon the pipe should be named "Pirranha" looking at the fish impressions.

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.
Years ago when working with Jim at JL I tried blowing the pipe into a split mould around the mid section, but even this lost around 2-3 Hp per pipe on Hines dyno at Zip,when testing his Superkart title engines.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/photoserver/89/206670289_full.jpg
http://images.trademe.co.nz/photoserver/13/206670413_full.jpg

l know what l would use!

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

[wobbly]

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..

[TZ350]

258237 258238

24mm OKO carb bored out to 30mm so now I have a carb to do a back to back comparison with the taper bored 24 OKO on the dyno.

258236

Surface is deliberatly left rugh, the theory is that the air flowing over it rolls up and forms little rollers for the bulk air to slide over.

[F5 Dave]

Ahh, just like those old english Anal roughbore carbs,

be interesting to see what happens.

[wobbly]

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 affcted 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.

[husaberg]

I just read an article that suggested the NSR250 (Well the MC28 at least)
has a three position RC Valve it suggests it has a fully open a closed and intermediate position can anyone confirm this?
As i always assumed it was an either open or closed scenario only.If it is a 3 postion. Is this only the MC28 or other models as well?
The MC28 i believe has a TPS which is a 4.8K linear pot (even though it has written 4K on it?)
258253258251258252

[bucketracer]

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 affcted 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.

258261 258262 258263

30mm OKO and the 24mm OKO taper bored out to 30mm on the engine side.

Thanks Wob, TeeZee and I have been playing with the taper bored 24 on the dyno and were about to try the 30 ......

[bucketracer]

Very quickly, with fins , look at the heat path and the materials it crosses, also the air flow between the fins , and the amount of heat each fin can remove,
258259
Heres a paper on fins , hope this helps

Stephen

Very interesting paper, I see 8mm gap between fins on a moving motorcycle is the magic number .....

[2T Institute]

258261 258262 258263

30mm OKO and the 24mm OKO taper bored out to 30mm on the engine side.

Thanks Wob, TeeZee and I have been playing with the taper bored 24 on the dyno and were about to try the 30 ......

Like so(I have to make this post longer than 10 charaters, but I have SFA to say ..............)

[bucketracer]

Hi 2T any chance of a side on pic so we can see how far forward the little tubes protrude. Thanks B

[wobbly]

The NSR has a single dropping gate PV system, so saying it has "stages" is bollocks.It is servo driven up and down, and by design it is always close to the piston to work well.
The RGV has a multi blade system that pulls the valves away from the bore in stages, as in this case only the leading edge in the full down position is close to the piston.
Any value of pot in a TPS would work - all it does is vary the 5V sensor voltage sent out by the ECU.

[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.


258280258281258282

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.

258284

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.

258285

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/photoserver/89/206670289_full.jpg
http://images.trademe.co.nz/photoserver/13/206670413_full.jpg

l know what l would use!

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

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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]

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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 ......

258302

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

258303

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.

258304

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

258305

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]

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. . . .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

[bucketracer]

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


If thats 34-ish crank hp then TeeZee's 31 rwhp puts him about 33-34ish too.

And comparing TeeZees efforts with the factory racers of the sixties is not exactly apples for apples but I thought it would be interesting to check it out.

His bike compares well to the Suzuki 125 air cooleds but the 42 hp 12 speeds leave him behind untill you realise how peaky they must have been.

It looks like the golden time was for 2-3 years in the later part of the 60’s

Suzuki 125cc Racers of the 60's

1960 RT60 13ps @ 11,000 rpm air cooled

Degner is working with Suzuki about this time.

1961 RT61 15ps @ 10,000 rpm air cooled

1962 RT62 20ps @ 10,500 rpm air cooled

1963 RT63 25.5ps @ 12,000 rpm air cooled

Hugh Anderson is riding for Suzuki

1967 RT67 42ps @ 16,500 rpm water cooled and 12 speed gear box.

1968 RT68 42ps @ 16,500 rpm water cooled and 12 speed gear box.

At about this point the FIM killed of the multi cylinder tiddlers and limited the 125's to 2 cylinders and six speeds.

My source:-

http://www.suzukicycles.org/history/history_04-race-1960-1967.shtml

[twotempi]

The Suzuki 125's that you refer to are probably the 1977 air-cooled TR100 ( XR21) , TR125 ( XR24 ), plus the watercooled disk-valve 1978 RJ100 ( XR29 ) bikes.

These are documented in the Appendices of the book "Team Suzuki" by Ray Battersby. Claimed power output is 28.6 HP @ 11250 for the TR125 and 25 HP @ 11500 for the RJ100.

So TZ350's GP125 is still king !!

[bucketracer]

These are documented in the Appendices of the book "Team Suzuki" by Ray Battersby. Claimed power output is 28.6 HP @ 11250 for the TR125 and 25 HP @ 11500 for the RJ100.

Is that crank or rear wheel? hp .....

[F5 Dave]

The Suzuki 125's that you refer to are probably the 1977 air-cooled TR100 ( XR21) , TR125 ( XR24 ), plus the watercooled disk-valve 1978 RJ100 ( XR29 ) bikes.

These are documented in the Appendices of the book "Team Suzuki" by Ray Battersby. Claimed power output is 28.6 HP @ 11250 for the TR125 and 25 HP @ 11500 for the RJ100.

So TZ350's GP125 is still king !!
if you don't say so yourself.


3 posts, female, rare as hens teeth in NZ bike listed. What happened to Fred with the Manx?:innocent:


Hi Rob.


[edit] ok appears I'm wrong. this never happens to Scooby Doo.

[bucketracer]

if you don't say so yourself. Hi Rob.

:laugh: .... No not TeeZee, hopefully see some pictures of interesting 70-80's 125 and 250 Italian race bikes/engines soon.

[twotempi]

To F5 Dave,

thanks for advising me of my sex change !!

Have changed my profile to reflect what I noticed in the shower this morning !!

[husaberg]

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.

Kent Anderson was 125 world champion two years running on a modified importer suported TA125 modified yes but what proddy clubmans bike wasn't.
i doubt the Yank/Frenchman can match that.

[twotempi]

There has been a bit of historical confusion about the Yamaha 125 twin that won the World Championships

Kent Andersons bike was

1) Watercooled - TA 125 was aircooled

2) 44 bore x 41 stroke - TA125 was 43 x 43

3) Different frame - TA125 frame is considerably taller - ( Hard to believe that it could be smaller but............. )

4) 32mm forks - TA125 has 28mm

5) Was not a TA125 modified by Yamaha Amsterdam - It was a altogether totally different machine


I would commend you to also look at Ferry Brouwers Classic Yamaha website which gives the specs and images of this bike which he owns and demonstrates.

Will try to find the website with the French bike details for - The guys name is Thierry Espinay and the bike was raced very successfully in the States and is a work of art.

Fritz should know this gentleman.



:yes::yes::yes::yes:

[husaberg]

There has been a bit of historical confusion about the Yamaha 125 twin that won the World Championships

Kent Andersons bike was
1) Watercooled - TA 125 was aircooled
2) 44 bore x 41 stroke - TA125 was 43 x 43
3) Different frame - TA125 frame is considerably taller - ( Hard to believe that it could be smaller but............. )
4) 32mm forks - TA125 has 28mm
5) Was not a TA125 modified by Yamaha Amsterdam - It was a altogether totally different machine
I would commend you to also look at Ferry Brouwers Classic Yamaha website which gives the specs and images of this bike which he owns and demonstrates.

Will try to find the website with the French bike details for - The guys name is Thierry Espinay and the bike was raced very successfully in the States and is a work of art.

Fritz should know this gentleman.

:yes::yes::yes::yes:
Oh i do love an historical debate not really the place but Ferry's site you quote lists the bike as having a A wait for it..........
AS3 IE (TA125) based engine.
modified with water cooling and other mods. The real question is when does a bike cease to be the bike it started as.
I don't know or really care to guess but.......
The Brakes and forks i see as a non issue. Why have a look at the mid 90's gp glass most of the forks brakes were changed on the Hondas even the crankcases on a lot of them the cylinders were pretty much all kit ones A or B if you were lucky/Talented/or Rich.They were still a Honda rs125 though.
There no denying the kent and chas bikes received "unofficial works support" but they were production based. Hense the kickstart shaft. Why else would they have that? Not a lot of Works specials should have those? Although Yamaha did leave the autolube on a lot of bike though.
Pm me because, i don't think we should clutter up the thread with, what is on the whole, unimportant stuff.

Yamaha 623C (kent)
Although Yamaha had officially retired as Factory Team, developed of racers based on production motorcycles continued. For 1969 the YZ623 was planned, a racer based on the AS1 roadbike. 5 pcs were made for Europe. Jean Auréal won the French GP that year on one of the YZ623 machines beating Dave Simmonds on the factory 125cc Kawasaki. Lothar John from Germany saw the potential of the 125 engine and built his own 125 Yamaha racer, with some good GP finishes. To be followed by many privateers who used the 125 Yamaha engine. (Ludy Beumer pays a lot of attention to the various 125 Yamaha racers used on his website www.classicyams.nl (http://www.classicyams.nl/)

For the 1971 season Yamaha had developed a real racer from the YZ623, the frame was drastically changed, front and rear suspension and brakes of the RA31A 125cc 4 cylinder, lightweight frame parts, the AS3 configuration engine, CDI ignition, were all used. Riders selected to ride the bikes were Yamaha Motor NV supported rider Kent Andersson and Rod Gould. After a sighting lap Kent decided that he did not want to race at the Isle of Man, at the spot Chas Mortimer was recruited by the Irish Yamaha Importer Mr Danfay and proposed to Mr.Minoru Tanaka the responsible Japanese person from Yamaha Motor NV . Winning the TT secured Chas a machine for the rest of the season to ride, also because Rod did not like the 125 at all. Chas finished 5th in the Worldchampionship.
For 1972 the machines were updated to water-cooling, dry clutches and increased horsepower. Riders Kent Andersson, Chas Mortimer. Chas finishing the season with most gross points (121), and equaling Kent (gross 103) on nett points 87 finishing 3rd . Should he have been the Worldchampion?
For 1973 Kent got a new machine, with improved power. Main difference was larger transfer ports. The same applied again for 1974, when new team mate Bruno Kneubühler also got a new OW15. Both riders replaced the drum frontbrake by twin “scarab” disc brakes. They finished 1st and 2nd in the Wolrdchampionship. For 1975 Yamaha supplied new improved engine parts and tuning information, but the machine were the 1974 machines.
The YCRT machines are the genuine 1972 YZ623C machines, the OW15 is a replica.
http://www.yamaha-classic-racingteam.nl/site2/index.php?page=125cc_623c2 (http://www.yamaha-classic-racingteam.nl/site2/index.php?page=125cc_623c2)
http://www.yamaha-classic-racingteam.nl/site2/index.php?page=125cc_623c2_tech

Turns out TZ is in the hunt for HP with the works bikes though admittedly piston ported and liquid cooled twin cylinder ones from 1970's.

(http://www.yamaha-classic-racingteam.nl/site2/index.php?page=125cc_623c2)

[twotempi]

Fair call Husaberg.

Would be good to catch up one day.

Have a look a this website for the details of the "GCS" special at the bottom of the website page.

This guy was in the fine tradition of "bucket" style bikes, and deserves an honorable mention.

http://www.tsrfcars.com/toys-full_size_morbidelli.htm

Some good ideas as well


cheers

:yes::yes::yes:

[TZ350]

Interesting about the Factory air cooled race bikes from the 60's and 70's. I didn't know I was doing so well ..... :laugh:

258333258334

Suzuki RS67 1967
February 1967 - August 1967
Engine type: Water-cooled 125 cc square-four 2-stroke.
Bore x Stroke: 35.5 x 31.5 mm
Compression ratio: 8.4
Carburetor: VM24
42 hp / 16,500 rpm (350 bhp per liter), 145 mph.
Transmission: 12 speeds

But the real hero in all of this is Speedpro with his Wobly designed 30 rwhp MB100, with water cooled head as its making near 350 crank hp per liter, so there truly is a Bucket that foots it performance wise with the big factory boys from the golden era of GP racing.

Speedpro has built a Bucket that pretty much makes the same power per liter as the RS67, now thats a real achevement.

[husaberg]

Well seeing as we are not all ridding SPX engined bikes i guess it didn't set the world on fire.
But then again it did take Norton a while with the Norton rotary so who knows.

But there are some interesting bits with the design as well. ESP as to why the uninspired can find the music produced by a 2 stoke on the pipe as iritating.
As well as these designers solution as to a way around the problem. Hooper was a clever guy.
There was a bit in the article i was planing to keep to myself, but it it is well shrouded i doubt most people would pick up on it.
It is in fact a real clever tuning aid.:blink: I will just keep plugging away on it myself if no one else does.
I have also seen other articles which discuss the actual engine in more detail. but not the whys.
Oh by the way i posted in in a random order after i fixed my inadvertant mirror image posting of one page now it will not post the attachments in the correct order
Why is that?

[Frits Overmars]

O yes, the Wulf. The stepped pistons require that the cylinder bores are perfectly in line. But the sideways-poking exhaust ducts cause a very uneven heat distribution so those bores are anything but round during operation. What can you do about that? Use air cooling.....:facepalm:.

Here is a little principle sketch; it may be easier to understand than the pictures with the many streamlines in the publication above.

[husaberg]

O yes, the Norton Wulf. The stepped pistons require that the cylinder bores are perfectly in line. But the sideways-poking exhaust ducts cause a very uneven heat distribution so those bores are anything but round during operation. What can you do about that? Use air cooling.....:facepalm:.

Here is a little principle sketch; it may be easier to understand than the pictures with the many stream lines in the publication above.

Always pushing that new fangled water cooling Frits:innocent:
It was the prototype the production engine was to be water cooled.
Was it a lot cleaner re emissions.It looks like it should have been. i also see the transfers could be modified by increasing the thickness of the plates, and it was to be fuel injected.Dribble feed though.
Zero balance factor interesting lubrication system. 4 stroke annular discharge mufflers. Al Alloy rods plain big ends.
Is there merit in the engine design or just for a slugger commuter?
Shame the Brits never did seem to invest much in R&D.


Thanks for the diagram.

[TZ350]

258366258371258372


Pictures of an OW15 sent to me by twotempi

258367258368258369

And the GCS



Have a look a this website for the details of the "GCS" special at the bottom of the website page.

This guy was in the fine tradition of "bucket" style bikes, and deserves an honorable mention.

http://www.tsrfcars.com/toys-full_size_morbidelli.htm

Some good ideas as well

[bucketracer]

Oh i do love an historical debate .....

Turns out TZ is in the hunt for HP with the works bikes though admittedly piston ported and liquid cooled twin cylinder ones from 1970's.

TeeZee Suzuki GP125 commuter bike engine is from the 70's too .......

[wobbly]

I think its a good time to remind everyone that the whole reason we heard about the possibility that 30 Hp was feasible from a 100 bucket was due to the software I was
using at the time.
Now, we plug TeeZees 125 Aircooled engine into the latest version of EngMod and voila we get a result.
Gaining the experience to run the software effectively is time consuming - but nothing like the time it would take to learn the hard way, what not to do.

[husaberg]

I think its a good time to remind everyone that the whole reason we heard about the possibility that 30 Hp was feasible from a 100 bucket was due to the software I was
using at the time.
Now, we plug TeeZees 125 Aircooled engine into the latest version of EngMod and voila we get a result.
Gaining the experience to run the software effectively is time consuming - but nothing like the time it would take to learn the hard way, what not to do.

Your post got me thinking about a thought i had the other day, Which is something (2 thought per week) i generally avoid for obvious reasons.

The sim's are fantastically awesome tools. Indeed Great predictive models of what can happen if you do this or that etc.
The writer's of the programs are fiendishly clever people and so are the people who can get them to work accurately but i can see one major limitation.
They only will express known parameters. Like a Map really or a recipe

Is the 2 stroke a the stage when there is nothing new to discover with the two stroke. I don't think so .....yet.
But how will the new discoveries be made if all the clever people are using them to test theories.
I do understand that Neel's is updating the sim regularly. But is there new ingredients available or missing to create a new spicy dish

I for one will be using Wobs experience with the Sim to design the engine and his real world experience that he has also attained. for my part...but
How will we know if we are missing something with 2 stroke development?

Also does it mater that most of the people under 20 think 4 strokes are faster than 2 two strokes. and yet they have never ridden a modern two stroke.

[Bert]

.....
The sim's are fantastically awesome tools. Indeed Great predictive models of what can happen if you do this or that etc.
The writer's of the programs are fiendishly clever people and so are the people who can get them to work accurately but i can see one major limitation.
They only will express known parameters. Like a Map really.

Is the 2 stroke a the stage when there is nothing new to discover with the two stroke. I don't think so .....yet.
But how will the new discoveries be made if all the clever people are using them to test theories.
I do understand that Neel's is updating the sim regularly.

I for one will be using Wobs experience with the Sim to design the engine and his real world experience that he has also attained. for my part...but
How will we know if we are missing something with 2 stroke development?


valid points Husaberg; like all sims/models the quality and understanding of the back end calculations & required parameters are critical to the success of the generated information. It great the Wobby can apply his real world knowledge in enhancing his sims and Neels also continuing improvement to his product. must get me a copy (it must be more interesting than spending time fixing fluvial Hydraulic models...)

I'm guessing as long as people continue to play with Two strokes and can relate there "new" developments to calculable parameters then there will be endless improvement to Sims. I Think we are only at the start of two stroke development...


.....
Also does it mater that most of the people under 20 think 4 strokes are faster than 2 two strokes.

Hummm well that's what they are brought up on... and I blame MX (well Honda really). gee I'd hate to be a MX dad these days... $$$$$$... whats wrong with a scruffy RM80??

What we really need here is for Mira motorcycles to produce a road going water-cooled 100cc "non race" 6 speed close ratio, two stroke...
Come on Wobby push them in the right direction :innocent:
http://www.miramotorcycles.co.nz/motorcycles.html

[speedpro]

Good points.

Pete Sales told me a long time ago that he could build a 25rwhp Honda MB100. He actually did it and it had nice power, evidently. The knowledge to do that was all gained through trial and error over a lot of years. Anyone who knew him when him and Penny were still living in Blenheim will know how much time he put into tuning 2-strokes. He still holds the NZ land speed record for a 50 with his GT50 bucket. To get to 30rwhp by trial and error will take more time than one person who has to earn a living has in this world. His Suzuki TM400 was a sight to behold as well. It'd be real interesting to see what the simulation software could make of that.

The knowledge needs to be condensed and disseminated in a manner that is accessible to all. Which is where the simulation software comes in. Users of the software then need to spend time getting good with it, or pay someone who is.

[koba]

How will we know if we are missing something with 2 stroke development?


When you have the fastest bike you think is possible and some other sod comes and blows your wheels off.

[koba]

Is the 2 stroke a the stage when there is nothing new to discover with the two stroke. I don't think so .....yet.
But how will the new discoveries be made if all the clever people are using them to test theories.
I do understand that Neel's is updating the sim regularly. But is there new ingredients available or missing to create a new spicy dish


I'm just spit-balling here, not really agreeing or disagreeing, just adding some more thoughts to the mix.

I think those at the cutting edge of the technology need, and do have, a very clear and thorough insight into what's going on inside the engine.
If they didn't that wouldn't be pushing boundaries and making gains.

Those who progress past the known limits will do so regardless of whether or not they use a sim to get to that point.
They get there by identifying the limiting factors and finding a way past them (as we have seen in this thread, but we are still really in in sim territory)
Those that just use the sim will still have a winning engine in all but the most fierce competition.

Physics is the only firm boundary, still we (collectively, man) manage to find new ways of making this better within these limits.

Abel Tasman would have had a map up to a certain point, it's how it goes and what is discovered after the map runs out is the tricky bit.
Cook did 'better' as technology and understanding of scurvy improved (and they took a sensible approach!)

Just as 'we' will do 'better' than those who were making fast bikes in the 60's.

(Except Frits, because he was probably making fast bikes in the 60's and is still contributing now!)

[TZ350]

With EngMod2T's help and a few valuable tips from Wobbly we have cracked 30+ but behind that is a lot of hardwork, considered study and dyno work.

[Frits Overmars]

I think those at the cutting edge of the technology need, and do have, a very clear and thorough insight into what's going on inside the engine.I wish! I may know more than some, but not nearly as much as I'd like to know. And that's just about the things that I'm aware of.


If they didn't that wouldn't be pushing boundaries and making gains.It is quite possible to blunder into new discoveries, unhindered by any knowledge. Although you have a better chance if you have some idea of what you are looking for.


Those who progress past the known limits will do so regardless of whether or not they use a sim to get to that point.Just ask Jan Thiel what he thinks of sims: not much. I must add that I have a bit more confidence, but having written my own sims, I remain very aware of their limitations.


Abel Tasman would have had a map up to a certain point, it's how it goes and what is discovered after the map runs out is the tricky bit.Everyone who tries to discover unknown territory, goes to the boundaries of what he knows. Beyond that, the guessing begins. Because no matter how much you studied, it will never be enough.


Just as 'we' will do 'better' than those who were making fast bikes in the 60's.(Except Frits, because he was probably making fast bikes in the 60's and is still contributing now!)In hindsight, what I did back then, is a collection of blunders, with a hit every now and then. Looking back, I knew nothing then.
Looking back in ten years' time, I will probably say the same about now :p.

[TZ350]

Onwards and upwards towards the goal of a useable race bike. My interest at the moment is learning about air correction and how to use it to improve drivability in the lower part of the torque curve.

At the moment to get best power at the top I have to use a 110 mj but best drive in the lower part of the torqe curve is with a 118-120mj. My plan is to fit the mj main jet that works best at the lower end and then adjust the air correction jet and emulsion tube untill I get the top end back, anyway thats the plan but first I need to find out all I can about air blead jets and emulsion tubes and how they work.

You would have to be an idiot, not to use Google for researching this sort of stuff, there is so much info out there. Below is Weber and VW stuff and with a bit of intelligence its possible to relate it to tuning motorcycle carbs.

http://www.aircooled.net/gnrlsite/resource/articles/jetting.htm

Carburetors are simply devices that meter fuel depending on the amount of air that is entering the engine. There are a couple problems though! Air and fuel have different viscosities, and since air and fuel do not flow the same, the metering of fuel is NOT LINEAR. What this means (if this didn't make sense to you) is that you can have a correct metering for a while, and then at certain RPMs it goes off. So, you have another set of jets to "correct" it and one more set to correct the correction!

Idle jets operate from idle to 2500-3000rpms or so. Main jets are primarily from 2500-4500rpms, and Air jets affect the engine from 3500/4000 on up. Lastly, you have emulsion tubes to change "where" it's rich, lean, etc. The complexity of jetting is that the operating range of the carburetor's jets OVERLAP, so a change in one area often MUST be accompanied by another change somewhere else,

Air Corrector Jet: The air jet jets AIR, not fuel! So, if you want to lean it out, you go BIGGER on the air jet, and smaller on the air jet if you want to richen it up! The air jet affects the engine from about 4000rpms up. You really have to wind it out to use this one, so be careful! Start with a baseline jet of 200. If it starts spitting and sputtering at high rpms, you need to richen it up, so change it to a 180 air jet. You are following the same procedure as the main jet, but your "operating window" is now 4000 RPMs up instead of the main jet's 2500-4500. I have seen air jets in the range of 160-240. If you are out of this range, you need to go back to the 200 air jet, and change emulsion tubes.

Emulsion Tubes: The Emulsion Tube mixes air from the air corrector jet with fuel from the main jet, and controls the mixture from the discharge nozzle at all engine speeds that the main jet is working! Basically, the Emulsion Tube changes the diameter and location of small holes in it's body. For Weber IDF carbs, the F7 or F11 is usually what you need. The F "series" has no rhyme nor reason to the numbering system, so you can't tell anything by the number unless you look it up! But, with these two examples, the F7 richens the mixture up at the bottom of the RPM range and under acceleration, while the F11 leans the mixture out on the top end a little bit, and is usually used (high RPMs) when you use air jets larger than 200.


258382 258385

http://www.rhinoracing.com/yaw/carb_tuning.htm

Air Bleeds
The air bleeds, or air correction jets, control the mixture mostly at mid to high rpm. The air bleeds are best described as a controlled air leak in the main circuit. The air bleeds work by "bleeding off" this vacuum which draws fuel through the main jets. A larger air bleed will make the mixture leaner at high rpm by bleeding off more vacuum or "signal." A smaller air bleed will richen the high rpm mixture by bleeding off less signal.

Emulsion Tubes
The air from the air bleeds enters the main circuit through the emulsion tube. The emulsion tube has a series of small holes from top to bottom, and it is through these holes that air enters the main circuit. At low engine speeds, when fuel demand is low, these holes are submerged in fuel, and so no air can flow through them. As engine speed increases, the fuel level in the float bowl drops, uncovering these holes, and allowing air from the bleeds to enter the main circuit, thus leaning the mixture. As the engine speed increases further, the fuel level in the float bowl continues to drop. This uncovers even more of the holes in the emulsion tube, which makes the air bleed have a greater effect on the mixture.

More from the net on Weber emulsion tubes:-

Emulsion tubes affect the shape of the fuel curve across a wide RPM range where a air corrector has effect at high speed.

258389

Holes towards the bottom
low rpm enrichment or acceleration enrichment

Holes towards the top
low rpm leaning or acceleration leaning

More holes
high rpm leaning with air corrector larger then 2.0 mm

Smaller diameter tube low rpm acceleration with larger air corrector ( it does not say OD or ID smaller. I think increasing the liquid fuel in the emulsion well before the main circuit gets flowing causes this effect, so a smaller OD sounds likely ).

[wobbly]

Dont get all involved with the primary emulsion tube correction data from Webber etc - no 2T carbs use this system of air bleeding into the tube body.
All you have to tune with, is the main air corrector jet size dumping into the well at the top, more air = progressively leaner top end, along with the primary shield height around the needle.

[TZ350]

Dont get all involved with the primary emulsion tube correction data from Webber etc - no 2T carbs use this system of air bleeding into the tube body.
All you have to tune with, is the main air corrector jet size dumping into the well at the top, more air = progressively leaner top end, along with the primary shield height around the needle.

My Suzuki needle jets are like you discribe but the RD250/350 Yamaha and all the Kiehin ones I have, have a series of small air bleed holes like the Webers.

[husaberg]

Dont get all involved with the primary emulsion tube correction data from Webber etc - no 2T carbs use this system of air bleeding into the tube body.
All you have to tune with, is the main air corrector jet size dumping into the well at the top, more air = progressively leaner top end, along with the primary shield height around the needle.

The top section of the 2 stroke needle jet (the bit in the carb the needle passes through)
I have noticed that on Mikunis there is generally a large projection with the opening open towards the air entry of the carb with reed and piston ports. But with rotary valve and four strokes it is flat. Bell mentions it also but why is it the case.
Is it to do with intake velocity or is it to stop fuel enrichment from the signal passing back over the mainjet. I realise with Dynojet kits the glue in shroud i it increase the depression over the jets. I am sure generally most Keihins are not replaceable in the needle jet as well. Do the OKO's.

I have often thought this is the main difference between 2 and 4 stroke mikuni's and why it is problematic sometime to get mid range fueling right ion a Four stroke with a 2 stroke carb I always thought ah they need a four stroke needle jet with those holes in it.

[TZ350]

Air Bleeds
The air bleeds, or air correction jets, control the mixture mostly at mid to high rpm. The air bleeds are best described as a controlled air leak in the main circuit. The air bleeds work by "bleeding off" this vacuum which draws fuel through the main jets. A larger air bleed will make the mixture leaner at high rpm by bleeding off more vacuum or "signal." A smaller air bleed will richen the high rpm mixture by bleeding off less signal.

Emulsion tubes affect the shape of the fuel curve across a wide RPM range where a air corrector has effect at high speed.

258389

Holes towards the bottom
low rpm enrichment or acceleration enrichment

Holes towards the top
low rpm leaning or acceleration leaning

More holes
high rpm leaning with air corrector larger then 2.0 mm

Smaller diameter tube low rpm acceleration with larger air corrector ( it does not say OD or ID smaller. I think increasing the liquid fuel in the emulsion well before the main circuit gets flowing causes this effect, so a smaller OD sounds likely ).

I can make more power (31rwhp) with a smaller mj but these two curves illustrate my point nicely. Insted of leaning it out on the mj and losing the bottom end of the torqe curve, I should look at changing the fuel curve to get the best at both ends.

258395

Red line 150mj, Blue line 120mj, now what I wan't to do is use the air correction jet to lean the 150mj off towards the top end and the emulsion tube to tailor the curve so the two curves combine.

[wobbly]

From memory only a couple of RZ models used primary bleed tubes,then factory changed back to "normal" with a completely different setting.
All the Keihin 2T specific carbs like PJ ,PWK have no tube to remove, and only have air correctors.
The OKO must be used on 4T as well, but I do remember reading that 4T and rotary valve engines work best with the bleed hole setup.
Never seen one used though on any rotary valve 2T production engine.

[TZ350]

258397

My rotary valve Suzuki ones are the primary type and look like how you discribe them.

258398

All my Keihin carbs from 28-38mm came from read valve 2-strokes and the OKO's have the bleed type too and they all look like this.

258399

My RD's 250/350's and 400's and some 24mm Kawasaki carbs I have all had bleed ones that look like this.

258400

And the jets cant be removed from some of my other carbs.


The OKO must be used on 4T as well, but I do remember reading that 4T and rotary valve engines work best with the bleed hole setup.

The original Suzuki carb was a primary type and as my OKO is the bleed type I hope your right.

[twotempi]

The Dellorto carbs I use have the option of either a bleed type with a flush nozzle, or a primary type with shrouded nozzle.

Which type should be used for a piston-ported engine ?? Most seem to use the primary type.

Or would a bleed type with a shrouded nozzle be even better ??

To achieve this I would have to make the shrouded nozzle part the the nozzle jet screws into from the underside of the carb.

I have read various info on this subject but haven't got a definitive answer although some immediate previous posts by Wobbly say that that a primary type with shrouded nozzle are the ones to use.

Any opinions on a bleed type with a shrouded nozzle ??

[TZ350]

Any opinions on a bleed type with a shrouded nozzle ??

258459

The Honda MC18 does it that way ...

[TZ350]

Something else I scraped off the net:-

I should point out here how the air jets and fuel jets interact. I can do this most easily with a little graph.

258460

This graph is 100% a figment of my fevered imagination, and is only to be used as a general guide, not an absolute definitive end all be all word of truth. That said..

1. air jet way too small
2. air jet a little bit too small
3. air jet just right
4. air jet a little bit too big
5. air jet way too big

So basically what happens is if you have the mixture right at low rpm, and it's too rich at high rpm, the air jet is too small and you need a bigger one. Or if you have it just right at high rpm and it's too lean at low rpm, you have an air jet that's too small and you need a bigger one. Or if you have the mixture just right at low rpm and it's too lean at high rpm, the air jet is too big and you need a smaller one. Do I really need to type the fourth combination? When you put in a bigger air jet, it leans things out everywhere, but more at higher engine speeds. And when you put in a smaller air jet, it richens things up everywhere, but more at higher engine speeds. Then when you get the right air jet, it might be too rich or too lean everywhere, so now you have to go and put in a smaller or bigger fuel jet to fix things up again. So you control the shape of the graph with the air jet, and move it up and down with the fuel jet.

I scraped it from here:- http://www.braigasen.com/fcr_tuning.htm

[koba]

In hindsight, what I did back then, is a collection of blunders, with a hit every now and then. Looking back, I knew nothing then.
Looking back in ten years' time, I will probably say the same about now :p.

That whole post drips wisdom.

[wobbly]

I think that as time progressed the 2T carb manufacturers realised that you can very easily tune the fuel curve to suit by simply changing
the needle, the tube diameter and the air corrector.
Dellorto,Keihin and Mikuni offer both for differing applications.
Having to deal with a myriad of bleed holes, there size and position and number of them all make a difference, and ends up being a full on nightmare to make every variation needed.
Keihin led the way and for years have deleted the removable tube altogether,as do many of the Mikuni 2T carbs.
The OKO carb will for sure have a range of tubes and needles available,and with luck you may be able to track them down.
You can for sure tune both types of system, but the bleed type really is brian damage.

The FCR carb was designed for 4T racing, and is considered a real bitch to tune correctly, but it has a primary shroud and all the same circuits as a normal 2T Keihin, with one extra.
Its idle circuit has FOUR adjustments, idle fuel jet, idle fuel screw, idle air jet, idle air screw.
I use them as a down draft on several 2T engines to get the carb dead straight on the manifold and they work a treat.

[husaberg]

To get the result you are after with a number of differing methods.
The nature the overlaping curcuits of the traditional carb is why some people turned to the Lectron EI type.:eek::msn-wink:

The sudco site and cataloge used to offer some great info Haven't been there for a while.
It sounds like these Oko carbs might actually be better than the original Keihin they were based on.

I noticed on the RS125 nf4 the Keihin (Which i guess is a PWK) seems to handle a fair amount of downdraft anyone know how much?
or if it is just a the angle of the pics i have looked at?.

Copied links from when i was ridding the cr500 of the old Keihin spooge.


Also Robinson covers fueling with the airjet and differing needle jet types posted below

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif][if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} </style> <![endif]--> Jetting the Pilot:
http://www.cr500riders.com/cgi/yabb/YaBB.pl?board=Tech;action=display;num=1067267855

The jets to buy:
http://www.cr500riders.com/cgi/yabb/YaBB.pl?board=Tech;action=display;num=1132092467

2-Stroke Tuners Handbook:
http://www.edj.net/2stroke/jennings/2stroketunershandbook.pdf

PJ Carb exploded view:
http://www.sudco.com/vol33/129-130.pdf

PWK Carb exploded view:
http://www.sudco.com/vol33/125-128.pdf

Sudco Needle Jet cross reference chart:
http://www.sudco.com/vol33/135-136.pdf

Oxygenated fuels:just for fun
http://www.cr500riders.com/cgi/yabb/YaBB.pl?board=Tech;action=display;num=1066795536

[husaberg]

Now i Can't find that much about the engine but i do note the updraft on the carb.
The frame is Mg alloy.

It was later Water cooled.
The rider (Santiago Herrero) was yet again leading the 1970 250 world Championship when he died.


Although the single cylinder Ossa had 20 HP less than the powerful V4 Yamahas of Phil Read and Bill Ivy, the Ossa was 45 pounds lighter and its monocoque frame was much stiffer, giving it superior agility. The Yamahas swept the championship but, Herrero left no doubt that the little Ossa was quick and dependable. He finished seventh in the championship and claimed a third place in the final race of the season at Monza. He would once again take the 250cc Spanish National Championship.
1969 would be a big year for Herrero. He began the year winning his first Grand Prix at the opening race of the season in front of his countrymen at Jarama. After retiring from the German Grand Prix with mechanical problems, he returned with a victory at Le Mans. He followed this with third place at the Isle of Man TT, a considerable accomplishment considering his horsepower deficit on the infamous Snaefell Mountain Course. He triumphed again at Spa and was leading the championship points race when he was beset by bad luck. He crashed in the rain at the Ulster Grand Prix and suffered a broken left arm. Most observers considered his championship hopes dashed, but Herrero showed true grit by coming back to finish in a remarkable fifth place at Imola. At last race of the season in Yugoslavia, he held a one point lead in the championship. He started the race in the lead but crashed on the seventh lap, ending his championship hopes. He would finish third in the World Championship. He repeated as Spanish 250cc champion for a third consecutive year. http://ozebook.com/wordpress/archives/2033

<tbody>

250cc
Ossa (http://en.wikipedia.org/wiki/Ossa_(motorcycle))
ESP (http://en.wikipedia.org/wiki/Spanish_motorcycle_Grand_Prix)
1
GER (http://en.wikipedia.org/wiki/German_motorcycle_Grand_Prix)
DNF
FRA (http://en.wikipedia.org/wiki/French_motorcycle_Grand_Prix)
1
IOM (http://en.wikipedia.org/wiki/1969_Isle_of_Man_TT)
3
NED (http://en.wikipedia.org/wiki/Dutch_TT)
3
BEL (http://en.wikipedia.org/wiki/Belgian_motorcycle_Grand_Prix)
1
DDR (http://en.wikipedia.org/wiki/German_motorcycle_Grand_Prix)
2
CZE (http://en.wikipedia.org/wiki/Czech_Republic_motorcycle_Grand_Prix)
DNF
FIN (http://en.wikipedia.org/wiki/Finnish_motorcycle_Grand_Prix)
6
ULS (http://en.wikipedia.org/wiki/Ulster_Grand_Prix)
DNF
NAT (http://en.wikipedia.org/wiki/Italian_motorcycle_Grand_Prix)
5
YUG (http://en.wikipedia.org/wiki/Yugoslavian_motorcycle_Grand_Prix)
DNF
83
3rd
3

</tbody>



By guest writer Richard Fowler of Motorsport Retro (http://www.motorsportretro.com/). This amazing little OSSA (http://en.wikipedia.org/wiki/Ossa_(motorcycle)) 250cc Grand Prix bike finished 3rd in the 250cc World Championship in 1969. Its revolutionary monocoque stunned the Grand Prix paddock, yet the clearly superior design never found favour with the big manufacturers. Designed by Eduardo Giró, the son of OSSA founder Manuel Giró, the bike featured a six-speed gearbox mated to a single cylinder, 250 cc two-stroke rotary valve engine. It produced a modest 30 hp. The engine was no match for the fire-breathing V4 Yamahas of Phil Read (http://www.philread.org/) and Billy Ivy, but with its clever magnesium monocoque chassis, the bike weighed a full 20 kg (44 lbs) less than the class-leading Japanese competition. Riding the bike was young Spanish superstar Santiago Herrero (http://www.motorsportretro.com/2010/03/santiago-herrero-ossas-favourite-son/), who soon showed the world that despite its power deficit, the advantages of the innovative chassis were sufficient to bring the small team Grand Prix victories. Herrero reveled in the OSSA’s superior cornering and braking ability, throwing the OSSA into corners like it was a 125 cc lightweight. He was able to carry more speed whilst being super-accurate, and slice up the inside of his competitors under braking. It was all due to the monocoque superior chassis stiffness and weight. The 1969 campaign saw Herrero and the team win three Grands Prix against the previously unbeatable Yamahas and he led the Championship going into the final race—until a crash ended his title hopes. The tiny Spanish OSSA team again led the Championship in 1970, until Herrero crashed (http://www.iomtt.com/TT-Database/Events.aspx?era=3) fatally at Isle of Man TT. Devastated by his death, the OSSA team immediately withdrew from road racing, never to compete again.

Read more: http://www.bikeexif.com/ossa-motorcycle#ixzz1nTHVoSxU

[husaberg]

Second lot of Pictures,
Someone must know a bit more about the engine. It must have still been bloody fast.

[Frits Overmars]

....Someone must know a bit more about the engine. It must have still been bloody fast.See for yourself. It wasn't the engine that was bloody fast. It was the rider. And the handling of the bike.

[husaberg]

Thanks Frits it contrasts nicely with the Yamaha approach of the times.
Note of course this is the 125cc. Rather than the 250

Yamaha’s first 4-cylinder racing bike: Yamaha RA31 & RA31A (1966-1968)

…water-cooled two-stroke V4 125cc.
With rotary valves, magnesium engine case and Mikuni 22mm carbs, 9-speed gearbox, dry clutch,
201 lbs, 44HP @ 17,300 rpm, 140 mph top speed.


Yes that does say 17300rpm.

258586

[gamma500]

http://www.youtube.com/watch?v=ODH2nwWO-ds


turn up the volume! :cool:

[Frits Overmars]

Thanks Frits it contrasts nicely with the Yamaha approach of the times.Note of course this is the 125cc. Rather than the 250. Yamaha’s first 4-cylinder racing bike: Yamaha RA31 & RA31A (1966-1968). …water-cooled two-stroke V4 125cc.
With rotary valves, magnesium engine case and Mikuni 22mm carbs, 9-speed gearbox, dry clutch, 201 lbs, 44HP @ 17,300 rpm, 140 mph top speed.Now I suppose you want to see that from the inside as well, don't you?

[TZ350]

I checked my 38mm Keihin PWK carbs and they were like Wobbly said, no removable emulsion
tube. Which leaves me a bit confused because amongst my collection I am sure I have seen big Kiehin 2-stroke carbs with emulsion tubes, Oh well I will have a bit of a better look later. I also have a carb (actually a complete moter) from a Kawasaki F81M 250cc rotary valve MX engine, so I will have a look at its jets when I find it.

258595

The OKO/Keihin emulsion tube and needle jet. The Suzuki primary type on the right.

258596

The well around the top of the Suzuki primary type needle jet.

258598

The complete main jetting arrangement.

258597

I have cut the side away on one of the Keihin neddle jets to see if I could use it to richen up the bottom end of the 31hp curve.

258594

The blue line is a 150mj, The red line is with a smaller mj. You can see why I am so keen to find a way to combine them.

I hopefull will get a chance in the next night or two to try drilling out the air correction jet and hopefully keep the 150mj's low end drive with it leaning out on the air correction and get the red lines top end.

[Bert]

something a little different:

http://www.youtube.com/watch?v=NNJkYIE3PYY&feature=related

I take it that the 80cc class is still strong over that side of the world.

[bucketracer]

258604

TeeZee I can see why your so keen to combine the two graphs, and with a power jet cut off as well, there is every chance the power spread could go from 8-13.5K, thats a massive 5,500rpm power spread. Thats unheard of from a stroker that makes any real power.

31 rwhp and 5,500 power spread now that would be a stroker with the same power spread as a std FXR150 and twice the power everywhere.

[husaberg]

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

Not the one you were talking about I thought there was a pic of it on this thread but i can't seem to find it.
but this below is similar ilk to quite a few local buckets.

Brent Jones in CHCH had something similar made in the late 70's early 80's pretty sure this UK version, has been posted before at of the start of the thread though somewhere
258605258606258607
SCITSU
The bike was built by Nick Carpenter UK, it is one of only two produced.
The engine uses a Kawasaki motocross engine, disc valve with Suzuki RG500 cylinder.
Sounds a bit familar doesn't it.

Nice frame though.
Don't know about the carb poking out the side though i doubt it will catch on:wait:


Also seen this US one Suzuki 125 . I guess it is a RM125 motor though.
258610
This bike is all hand built in 1978 to compete in the 125 gp wars against honda mt 125r, yamaha td and tz in southern california. it wound up being a skunk works project out of suzuki. world champion eddie lawson once rode this bike. (although never raced as he was under contact by kawasaki) the frame is all hand made out of 4130 cromoly and the tank and tail are hand formed aluminum. every part on this bike has been hand formed for the lightest possible weight and function. dry wight is 159 pounds! picture provided by jeff allen.

[Farmaken]

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.

Cheers Wobbly,(and Frits ) makes sense about the increased surface area. No end cap reduction for me then !!

[F5 Dave]

TeeZee I can see why your so keen to combine the two graphs, with a power jet cut off, there is every chance the power spread could go from 8-13.5K, thats a massive 5,500rpm power spread. Thats unheard of from a stroker that makes real power.
. . .
pah! my GG Trials bike has easily that spread, - the secret is no expansion chamber.

. . .by real power, I hope ~8 or 9 qualifies.

[dinamik2t]

Hey, TZ, your primary transmission gears are heli or straight cut?
I remember reading over the net a long time ago, that straight cut gears produce more noise, while heli are quieter, thus used in mass production 'civil' engines.
I don't remember seeing heli on any race engine. Straights must eliminate the side loads on bearings I believe.

Anybody has an opinion, performance wise?

[F5 Dave]

on something like a twin or triple with a long crank it is a good idea. On a single I wouldn't get too worked up about it. theoretically you should lose less power, but I doubt you would notice it on the dyno even if you did cleverly engineer a straight cut set onto an engine with helicals. . . . well at least I didn't see it.

[dinamik2t]

Actually I have found that my clutch basket is the same with Cr80, which has straight cut gear (same teeth too). I found a few crank gears and one fits the distance and tooth pitch, but needs some machining to fit the crank. So I wondered whether it's worth it..
Clutch basket and gear is lighter than the stock one, perhaps that could improve something.

ps. your post is devilish 6666 OUU :devil2: OUUU

[wobbly]

Straight cuts only make more noise if they are not cut properly - too much backlash and they will chatter,also being in an oil bath helps heaps as in a RZ sidecover.
They do reduce side load on the crank bearings, the graph shows a couple of Hp gain up to peak, nothing dramatic.
The real gain is in reducing the ratio and dropping the torque load on the clutch.

[F5 Dave]

So those two runs were done on different days? Just looks like curve is affected by conditions, or otherwise one could draw the conclusion that straights will lose power after 10,000 rpm compared to helicals. Looks like a jetting or ign movement.

[husaberg]

Straight cuts only make more noise if they are not cut properly - too much backlash and they will chatter,also being in an oil bath helps heaps as in a RZ sidecover.
They do reduce side load on the crank bearings, the graph shows a couple of Hp gain up to peak, nothing dramatic.
The real gain is in reducing the ratio and dropping the torque load on the clutch.

My guess it the Poms got it a bit wrong with the Morris's then. Not that i am complaining I would hate to sound like a winy bitch:clap:

One of the engine selection criteria for Vanessa was straight cut gears.

I am not sure if she does have them in her as they seemed to mix and match depending on the market.
but they are available on differing models.(non competition as well i might add) as well as different gear ratio's as well.

I doubt weather there is much in it but every little bit helps.

Most all Honda's have straight cut gears and they are not loud. Where as most of the other makes use Helical gears on primary drives on there road/trail and straight cut on the competition models.

Very few competition engines have gears that are not straight cut. They also have very narrow contact patches as well.
I love those beautiful knife edged gears you see in competition engines of yesteryear ESP the Italians.

Virtual Chocolate fish to anyone (bar Frits or Wob) that can name this engine i am pretty sure we have one still in NZ and it does have a New Zealand as well as a Italian connection.

Note it has a cassette box I didn't realise that before. Also a interesting center joint for the crankshafts.

[F5 Dave]

yeah old Hondas & Kawis seem to run straight cut. Must be cheaper to hob.

[marsheng]

Hi Husaberg

Which Robinson book is the last attachment from ? (page says 109)

[husaberg]

Hi Husaberg

Which Robinson book is the last attachment from ? (page says 109)

It the er... 2 stroke one.

A lot of people don't like it but it has some relevant info if you read between the lines.
The carburetor section which i admit i had never seemingly taken that much head of does describe a lot of stuff.

Are you starting to think those four strokes are a bit boring?
Anyway this is the book. Is Hitech books still in CHCH.

[Grumph]

Straight cut Vs Helical....if you've got helical primaries, don't stress, they can probably be narrowed as they'd have been designed for long life. If you're building a motor from scratch, by all means use straight cut.

I've been through this with a 4 stroke which comes with helical primaries. Substituting straight cut gears led directly to regular crankcase cracking. And yes, they were very well engineered gears. Checking with experts in the field revealed that you swap the small end thrust of helicals for a greater "separating force" between the shafts. Sometimes it can be surprisingly large.
On the motor in question I now narrow the std helicals from around 22mm wide to approx 15mm - haven't broken one yet, so I could probably go narrower again.

[twotempi]

Husabergs' Quiz question answer

Engine is a Harley Davison / Aermacchi RR250 or RR350


Please send chocolate fish by virtual mail.

[twotempi]

and for two virtual fish

The bike was ridden in NZ by Murray Delacy, & Ginger Molloy in the Malboro series and is currently seen at the Pukekohe Classic Festival events

[husaberg]

and for two virtual fish

The bike was ridden in NZ by Murray Delacy, & Ginger Molloy in the Malboro series and is currently seen at the Pukekohe Classic Festival events

That was quick and so was the bike for a Harley it's probably the best bike they never made.
258656258657258658

[2T Institute]

Not the one you were talking about I thought there was a pic of it on this thread but i can't seem to find it.
but this below is similar ilk to quite a few local buckets.

Brent Jones in CHCH had something similar made in the late 70's early 80's pretty sure this UK version, has been posted before at of the start of the thread though somewhere
258605258606258607
SCITSU
The bike was built by Nick Carpenter UK, it is one of only two produced.
The engine uses a Kawasaki motocross engine, disc valve with Suzuki RG500 cylinder.
Sounds a bit familar doesn't it.

Nice frame though.
Don't know about the carb poking out the side though i doubt it will catch on:wait:


Also seen this US one Suzuki 125 . I guess it is a RM125 motor though.
258610
This bike is all hand built in 1978 to compete in the 125 gp wars against honda mt 125r, yamaha td and tz in southern california. it wound up being a skunk works project out of suzuki. world champion eddie lawson once rode this bike. (although never raced as he was under contact by kawasaki) the frame is all hand made out of 4130 cromoly and the tank and tail are hand formed aluminum. every part on this bike has been hand formed for the lightest possible weight and function. dry wight is 159 pounds! picture provided by jeff allen.

No that's not it, the RM engined bike a pushbike frame builder fabricated the frame. There is a KX/RG cyl bike running out here but it isn't the fastest, was half way through building one and the the owner got bored with the project and on sold it. Plus I got hold of 2 Rotax 124 engines:msn-wink:

The Suzuki 125 in question is pictured here No22 and a earlier model can be seen down the line a bit. I'll have to get my Japanese operative to snap some better pics next time he visits the museum
http://www.suzukicycles.org/All-Suzuki/all_suzuki_models.html

Click on "Suzuki Vintage Racing" then "GP racer in Hammamatsu" on the left.
The website I'm thinking of was half Japanese/half English but had some great pics

[bucketracer]

Here TeeZee I found Robinsons book in the lunch room library, these are the relevant pages. I think the book is worth having in any ones collection as it seems to cover carburation quite well.

TeeZee, it looks like your on the money.

[husaberg]

Here TeeZee I found Robinsons book in the lunch room libary, these are the relevant pages. I think Robinsons book is worth having as it seems to cover this part of carburation quite well.

TeeZee, it looks like your on the money.

I just spend 20 minutes scanning and putting that together in a neat formatt for Wallace.(Marsheng)
20 minutes at my age is something i will never get back.:nono:

Put in the first page for you though.

Random order though sorry, but if you can read the text i am sure the numbers at the bottom so they will give a clue to the order:rolleyes:

[bucketracer]

Please post them up, your scans are always easy to read, much better than my effort.

[Kickaha]

but I doubt you would notice it on the dyno even if you did cleverly engineer a straight cut set onto an engine with helicals. . . .

I was quoted $500 to have a pair made to replace the helical gears on the mighty GN, back then it would have bought two more Buckets

[nadroj]

That was quick and so was the bike for a Harley it's probably the best bike they never made.
258656258657258658

Is this the rebadged Airmacchi? (sp)

[husaberg]

Is this the rebadged Airmacchi? (sp)

Yes but as they were owned By Harley so it kind of is a Harley.(even thought the Yanks would have had very little to do with it. Other than maybe the colour scheme and the font for the Harley logo.
I think they brought Aermacchi in about 64ish.There was a aircolled version prior to this.
the Italian wing of the company was sold of to Cagiva in the late 70's.Probably Harley got sick of winning world championships by then (6) and wanted to build bikes for cashed up lawyers and Dentists who thought Harley's were BAD ASS. either that or Harley was broke or something.

Wiki

In 1978 Cagiva entered the motorcycle business with two racing motorcycles ridden by Gianfranco Bonera (http://www.kiwibiker.co.nz/wiki/Gianfranco_Bonera) and Marco Lucchinelli (http://www.kiwibiker.co.nz/wiki/Marco_Lucchinelli). In the same year they bought a factory in Schiranna (http://www.kiwibiker.co.nz/w/index.php?title=Schiranna&action=edit&redlink=1), Varese (http://www.kiwibiker.co.nz/wiki/Varese) from AMF-Harley Davidson (http://www.kiwibiker.co.nz/wiki/Harley-Davidson) and went into motorcycle production. By 1979 the company reached an annual production of 40,000 motorbikes, with eight models with two-stroke (http://www.kiwibiker.co.nz/wiki/Two-stroke) engines ranging from 125 cc to 350 cc.

Many of the Harley-Davidson models were continued in production as Cagivas, and the off-road motorcycle division was improved and expanded, eventually producing their own race-winning WMX series of moto-cross motorcycles.
In 1983 Cagiva also sourced Ducati four stroke (http://www.kiwibiker.co.nz/wiki/Four_stroke) v-twin engines from 350 cc to 1000 cc and entered the big displacement market. Cagiva bought Ducati (http://www.kiwibiker.co.nz/wiki/Ducati_Motor_Holding) in 1985, but kept the Ducati name that was better recognized outside Italy. Ducati motorcycle production continued in Bologna (http://www.kiwibiker.co.nz/wiki/Bologna), while the Varese (http://www.kiwibiker.co.nz/wiki/Varese)-built Cagiva Ala Azzurra (sold under the name "Alazzurra") and Elefant were introduced, both featuring Ducati engines.[2] (http://www.kiwibiker.co.nz/forums/#cite_note-1)
Cagiva continued with strategic buyouts of Moto Morini (http://www.kiwibiker.co.nz/wiki/Moto_Morini) in 1985 and Husqvarna (http://www.kiwibiker.co.nz/wiki/Husqvarna_Motorcycles) in 1987. In 1991 Cagiva also bought the trademarks for the MV Agusta (http://www.kiwibiker.co.nz/wiki/MV_Agusta) brand.
In 1996, the Ducati and Moto Morini brands were sold to Texas Pacific Group (http://www.kiwibiker.co.nz/wiki/Texas_Pacific_Group).
In 1999, for strategic purposes, the company was restructured. MV Agusta Motor become the main brand comprising Cagiva and Husqvarna.
In 2000, production of the Cagiva roadster (http://www.kiwibiker.co.nz/wiki/Cagiva_roadster) ended
In 2008, Harley Davidson bought MV Agusta Motor, the parent company of Cagiva, thereby regaining some control of their old Aermacchi factory.
In October 2009, Harley-Davidson informed that it will put Cagiva on sale.

The Harley 2008 buy out well i didn't realise that.

Aermacchi Wiki bit
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See also: Harley-Davidson Hummer (http://en.wikipedia.org/wiki/Harley-Davidson_Hummer) and Harley-Davidson Topper (http://en.wikipedia.org/wiki/Harley-Davidson_Topper)

As part of war reparations (http://en.wikipedia.org/wiki/War_reparations), Harley-Davidson acquired the design of a small German motorcycle, the DKW RT 125 (http://en.wikipedia.org/wiki/DKW_RT_125), which they adapted, manufactured, and sold from 1948 to 1966.[29] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-HummerClub-28) Various models were made, including the Hummer (http://en.wikipedia.org/wiki/Harley-Davidson_Hummer) from 1955 to 1959, but they are all colloquially referred to as "Hummers" at present.[30] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-HummerDotCom-29) BSA (http://en.wikipedia.org/wiki/Birmingham_Small_Arms_Company) in the United Kingdom took the same design as the foundation of their BSA Bantam (http://en.wikipedia.org/wiki/BSA_Bantam).[31] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-EncycMoto37-30)

In 1960, Harley-Davidson consolidated the Model 165 and Hummer lines into the Super-10, introduced the Topper scooter,[32] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-EncycMoto252-31) and bought fifty percent of Aeronautica Macchi (http://en.wikipedia.org/wiki/Alenia_Aermacchi)'s motorcycle division.[32] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-EncycMoto252-31)[33] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-MotoClassicsSprint350-32) Importation of Aermacchi's 250 cc horizontal single began the following year.[33] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-MotoClassicsSprint350-32)[34] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-EncycMoto74-33)[35] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle187-34) The bike bore Harley-Davidson badges and was marketed as the Harley-Davidson Sprint.[34] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-EncycMoto74-33)[35] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle187-34) The engine of the Sprint was increased to 350 cc in 1969[33] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-MotoClassicsSprint350-32)[36] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle215-35) and would remain that size until 1974, when the four-stroke Sprint was discontinued.[36] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle215-35)
After the Pacer and Scat models were discontinued at the end of 1965, the Bobcat became the last of Harley-Davidson's American-made two-stroke (http://en.wikipedia.org/wiki/Two-stroke_engine) motorcycles. The Bobcat was manufactured only in the 1966 model year.[37] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle193-36)
Harley-Davidson replaced their American-made lightweight two-stroke motorcycles with the Aermacchi-built two-stroke powered M-65, M-65S, and Rapido. The M-65 had a semi-step-through frame and tank. The M-65S was a M-65 with a larger tank that eliminated the step-through feature. The Rapido was a larger bike with a 125 cc engine.[38] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle218-37) The Aermacchi-built Harley-Davidsons became entirely two-stroke powered when the 250 cc two-stroke SS-250 replaced the four-stroke 350 cc Sprint in 1974.[39] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-Chronicle247-38)
Harley-Davidson purchased full control of Aermacchi's motorcycle production in 1974 and continued making two-stroke motorcycles there until 1978, when they sold the facility to Cagiva (http://en.wikipedia.org/wiki/Cagiva).[32] (http://en.wikipedia.org/wiki/Harley-Davidson#cite_note-EncycMoto252-31)


When Husqavana was sold to Cagiva some of the engineer's and designers didn't want to leave Sweden. So they formed their own Company they did all right too. You may have heard of the company HUSABERG I think there first factory was in a old Cowshed. They too sold later to KTM in the early 2000's.
But they were built to their own designs.
If you have seen one in pieces you can see why they are beautiful handmade sandcast cases billet this and that's and hand-balanced cranks. Well they were anyway.

A couple of pages missing sorry. They will be somewhere i guess.
And Wow they brought a stake in Aemacchi way before i thought, but not a full amount until later intersting.

Second lot of Attachments
Is an Eric Gorr article on jetting. i am guessing there will be somewhere where not everone agrees with Eric on a point.

[F5 Dave]

Bearing in mind that Eric's article is based on riding MX bikes in the dirt & MX bikes start off as competition models so mods are limited I don't see any problems with generalised comments + also he had a shit load of experience on the MX GP cct & runnnig his business for years.

[TZ350]

258752

F81M Kawasaki's Rotary Valve MXer, early 70's.


258755

250cc 2-stroke Rotary Valve.

258754258753

Carb has a primary type needle jet with a low nozzel height and removable air correction jet.

258751258756

Rotary valve cover ..... 30mm carb, carb area 707mm2, port window area 965mm2, 1.4:1 carb/port window ratio.

So now we know that Kawasaki used primary type needle jets in their rotary valve MX racers.

[F5 Dave]

that is trick. Just tickle it up till it looks like the one in the pics & I'll store it for you;)

[2T Institute]

I'll have to drag my Big Horn engine out.......................:lol:

[husaberg]

258752

F81M Kawasaki's Rotary Valve MXer, early 70's.

250cc 2-stroke Rotary Valve.



Carb has a primary type needle jet with a low nozzel height and removable air correction jet.

Rotary valve cover ..... 30mm carb, carb area 707mm2, port window area 965mm2, 1.4:1 carb/port window ratio.

So now we know that Kawasaki used primary type needle jets in their rotary valve MX racers.

I was looking for something today and came across this site it is all about the Kawaskis that TZ mentoned.

Also a page of pressure testing engines and air leaks
http://klemmvintage.com/airleaks.htm

The 350 had the 30mm carb as well and a three ringed piston,

but what was interesting to me was the Decomp.
I had obviously seen them before on old villiers etc and two stroke trials bikes i always thought they were to soften the power and stop stalling plusaid starting.

But this site suggests they are effective engine brakes.
http://klemmvintage.com/Bighorn-Bison-recreational.htm

One thing i always wished a two stroke had was 4 stroke engine braking character.
So i guess one potential downside is it has to be manually tripped and i guess i could swallow the bits as the site sugests
but is this an answer or just creating another potential problem.
What are the downsides to one have they been tried in a GP style engine?
Should i just harden up and stay on the throttle more. Should pull finger and finish my bike.

[TerraRoot]

i wish my fourstrokes had less engine braking, i hate having to brake, gear down and have the hold the throttle open a touch to stop the rear skipping/locking.

[F5 Dave]

Yeah there's a whole industry based around reducing diesil engine braking; slipper clutches, blipper electronics.

Engines aren't brakes!

[bucketracer]

Yeah there's a whole industry based around reducing diesil engine braking; slipper clutches, blipper electronics.

Engines aren't brakes!

Because of the poor gear ratios on the GP's I know TeeZee clutches it on the down changes and slips the clutch going into the corner if the engine has buzzed up and the back is skipping around from the induced engine braking, poor mans slipper clutch I guess.

[Frits Overmars]

i wish my fourstrokes had less engine braking, i hate having to brake, gear down and have the hold the throttle open a touch to stop the rear skipping/locking.Set the idle rpm above 3,000 rpm.

[F5 Dave]

So just a rambling question while I was out walking & while Frits is online or perhaps I missed him, but why is it that the RSA ex port is canted downward at 30 deg? I can see that it makes p/v packaging easier and perhaps the key is the water cooling of that area is clearer, - so without a powervalve one might have a straighter passage?

Or is it something to do with the opening & closing port when piston near top of port, although I can't see quite how that helps.

Further if I may, I wonder how effective the PV is at racing speeds, ie: is it still tracking after 10,000 and if so does it keep up in the lower gears?, or is it just full open by then, & if so - why bother?

thank you.

[Frits Overmars]

why is it that the RSA ex port is canted downward at 30 deg? I can see that it makes p/v packaging easier and perhaps the key is the water cooling of that area is clearer, - so without a powervalve one might have a straighter passage? Or is it something to do with the opening & closing port when piston near top of port, although I can't see quite how that helps.The exhaust port isn't canted downward 30°. The flange mounting face is canted downward 30° but the roof of the exhaust duct exits the cylinder at 25°.
The reason is that this angle gives the best flow.


I wonder how effective the PV is at racing speeds, ie: is it still tracking after 10,000 and if so does it keep up in the lower gears?The power valve starts opening at 10,000 rpm and it is fully open at 12,000 rpm. It can keep up with acceleration in any gear. And when you blip the throttle in neutral, the power valve servomotor moves almost as quickly as the revcounter needle.

[F5 Dave]

Ah, yes I casually glanced at the drawing but I see that the roof is a bit off. 25 deg gives best flow; I can accept that but I'll still have to ponder why that is.

ok PV action quick-as & effective at race revs. Nice. I'm too used to road & dirt stuff.

Thanks for the reply.

[wobbly]

As a side point to what Frits was saying re 25* down angle giving the best flow.This also reduces the duct area by the cosine of the exit angle,thus reducing the duct
volume.
And this then also allows steps and transitions in the flange to promote the flow exiting the Aux Ex ports,helping blowdown efficiency.
The main handbrake at the limits of power production.
The flow exiting into the duct, just as the piston cracks open the port,is dropping over a cliff - the piston face.
This is why the down angle helps flow,it is " pointing " the exiting gases toward the duct centre,not keeping it attached, normal to the piston dome.

[F5 Dave]

ok now I'm getting brain damage, but I was looking at the port floor shape.

[edit] Ahh see what you are saying about the piston & what I was pondering in original post.

I think I need to go on another walk.

[husaberg]

Yeah there's a whole industry based around reducing diesil engine braking; slipper clutches, blipper electronics.

Engines aren't brakes!

Yeah but i am not after full on compression braking just the character.
Although as i doubt it will be that much of a problem as the 2 stroke has no where near as much reciprocating mass friction and a shorter pause between the compression strokes so i kind of sincerely doubt it will behave exactly as a four stroke does anyway.


I Mentioned the VP of HRC and the NR500
The NR500 had something i believe was the first use of something that all the Moto gp bikes, i think now have, Virtual choc fish for anyone who can guess what it was?
ps it is not carbon or USD forks or Valves cams etc either:shifty:
Hint it is to do with the fact it had virtually no flywheel effect.
It failed, but a least they tried to do it as an even match 500cc vs 500cc

The first use of a slipper clutch i am aware of is the Honda NR500.
Allegedly if you were to shut the throttle it would just lock up. After a while the riders got kind gf sick of falling off it.
So they persuaded the engineers to sort out a solution or have a go at riding it themselves. This was the question no one got right a while back, or not bothered to answer if they knew.


splitters

It is interesting look what he says the effect is i guess what you are looking for in a round about sort of way?
I have also looked at these with a bit of suspicion esp as the Mikuni and Keihin aren't exactly rushing to fit them.
so are they just another bolt on goodie.


The carb spltter allows the air flow to be smooth, drawing into the carburettor without turbulence and with a much higher pressure accross the fuel nozzle.
The splitter mainly improves Throttle response and off idle to midrange power, but you can run out farther on top after leaning out the main jet.
Re-jetting will be required to maximize performance but often the main jet can be dropped as the fuel atomization is greatly increased..


258815258816258817258818

Heck check out his price i hope it is four all four of them!!!!

http://www.suzuki-rg500.com/carb.htm

It would be pretty easy to test and make a spiltter and a factory squad with the unlimited resources such as Team ESE should be able to whip one up over smoko?
Other two are out of interest one is a needle jet rg500 and other is how to do a air bleed mod to a TMX.


http://homepage.mac.com/rg500delta/d...bleed_mod.html (http://homepage.mac.com/rg500delta/deltaphasetwo/Frames/air_bleed_mod.html)

http://www.bdkraceeng.co.uk/RGV500 Conversions.html

Below is a nice little air box made for RG500 very Aprilia looking
(http://www.bdkraceeng.co.uk/RGV500 Conversions.html)

[TZ350]

Those are some pretty interesting ideas Husaburg has posted, in due course I will try them.

258845

I think I may have made a mistake in my previous post, the realy good 150mj low end drive (blue line) may have been when the Ex opened 80deg ATDC and now its 78.5 (red line) so not quite apples with apples and the later 80 deg opening probably accounts for some of the good low end and 78.5 the loss. Anyway I tried a 150 main again with a bigger air correction drilling and it was hopless but things got going when I went to a 135.

258820

135 main jet and air correction drilled out to 1.45, nice consistant results.

258819

the 135mj improved the bottom end but I could not get the bigger main jet with air correction (blue line) to give as much top end as the old 112mj did.

The graph does have a little better bottom end so it looks like playing with the main jet and air correction can pay off, maybe if I fiddle with the air correction to lean out the top a little more.

If you are generous and take the very extremes of the torqe curve it looks like its a good 4,000rpm power spread, 30+ hp and 4k power spread, now that has to be good.

[Ocean1]

i wish my fourstrokes had less engine braking, i hate having to brake, gear down and have the hold the throttle open a touch to stop the rear skipping/locking.


Yeah there's a whole industry based around reducing diesil engine braking; slipper clutches, blipper electronics.

Engines aren't brakes!

I like engine braking. The 1125 has a very clever vacuum-actuated arangement controling the main clutch, progressively slipping it. Very cute. I hate it, it's one of the features I miss from the XB12. You could just roll off the throttle, tip it in and the back would step out a tad. It was very predictable, reasonably self correcting and seemed to keep the bike stable.

But then, I wasn't stomping it down 3 gears for corners...

[quallman1234]

Rotary Valve 4 strokes...

http://www.coatesengine.com/csrv-system.html

[husaberg]

The progress of jet engine development overtook that of the Crecy and replaced the need for this engine. As a result the project was cancelled in December 1945 at which point only six complete examples had been built, however an additional eight V-twins were built during the project. Crecy s/n 10 achieved 1,798 horsepower (1,341 kW) on 21 December 1944 which after adjustment for the inclusion of an exhaust turbine would have equated to 2,500 horsepower (1,900 kW).[11] (http://en.wikipedia.org/wiki/Rolls-Royce_Crecy#cite_note-10) Subsequent single-cylinder tests[12] (http://en.wikipedia.org/wiki/Rolls-Royce_Crecy#cite_note-11) achieved the equivalent of 5,000 brake horsepower (3,700 kW) for the complete engine. By June 1945 a total of 1,060 hours had been run on the V12 engines with a further 8,600 hours of testing on the V-twins.[13] (http://en.wikipedia.org/wiki/Rolls-Royce_Crecy#cite_note-12) The fate of the six Crecy engines remains unknown.

Seen this i was actually looking for the areo engine that ran a rotary sleeve valve kind of like a cup shaped spinning disk it was a ww2 engine and came across this.
better than a Crecy?. Certainly less moving parts.

Oh yeah it mentioned the planes that had in in WW2 not the design i was looking for though.


Little history of the Sleeve Valve Engine The basic design of the sliding or sleeve valve engine has been around since 1909 when English Daimler used it in their 1909 automobile models. Other companies like Voisin, Stearns-Knight and Willys-Knight also incorporated this engine technology. The Bristol Engine Company's Centaurus, sleeve valve, 18-cylinder two-row design radial aircraft engine delivered over 3,000 hp! This engine was used in some of the Blackburn Firebrand, Hawker Tempest, Hawker Sea Fury, Vickers Wellington, Supermarine and Vickers Warwick RAF fighter aircraft in WWII. The Napier Sabre 24-cylinder sleeve valve aircraft engine used in some of the Hawker Typhoon and Tempest during WWII developed over 3,500 horsepower!
http://www.rcgroups.com/forums/showthread.php?t=567998



Rotary Valve 4 strokes...

http://www.coatesengine.com/csrv-system.html


I remember reading about a guy who though he had solved the problems of the overheating or top end seizing ,or if they are lubricated adequatly to stop those both. Oil burning.
The guy was an Aussie he had one running on a i think Honda 125 and a old Pommy banger.
As it was never seen again i guess not. He had a lot of piston rings arranged around the sphere i think.

It was however able to run a much higher comp ratio than a poppet valve motor. 15;1 on pump fuel or so. It was also ment to be ecomical and quiet.So with modern ceramics and so forth who Knows
the first time i saw the pic on the link you posted was about 93 in a car mag.So i guess devolpment has been slow.

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=258867&stc=1&thumb=1&d=1330505450 (http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=258867&d=1330505450)

[dinamik2t]

Guys, just want to add a way of measuring axial port angles.

What is needed is a pair of these (angle measuring-protractor):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p3984.m1497.l2649&item=390390190782&viewitem=&sspagename=STRK%3AMEWNX%3AIT#ht_1665wt_1270
Unfortunately one must be modified..


The long ruler must be shortened to about 5-6mm from one side and 10-11mm from the other. In this particular one, I cut the semi-circular angle plate base too, because it was too wide to fit into my 54mm bore.

258876

The straight side of the semi-circular plate -if cut- must remain parallel to the original straight line, because it will be used as the vertical plane for measurements. Like this:

258877

Finally, after you determine which side (short or long) to use in the port roof/floor and you tighten the screw, you can measure the angle like this:

258878

As a tip, you can tighten the screw frow the start and carefully apply pressure to the protractor until it is aligned with the duct.

In this measurements most attention has to be paid when aligning the ruler side to the port roof. If that's done perfectly right the instrument can provide easily one degree accuracy.

That's it! :drinknsin



ps Ah, excuse the logo, I used the photos in our local forum too..

[Frits Overmars]

No need to buy two angle protractors and mess up one of them. One protractor, two metal strips and a bolt with a spring washer work just as well.

[dinamik2t]

I like to mess with things a lot!:sweatdrop Actually, the original idea was to use the whole protractor as is, with a small metal ruler like now. Eventually, it didn't fit the 54 bore and as a waster greek I am, I destroyed the second. (sorry, cynical political comment)
But sure, I stand corrected Frits. Mine looks more fancy though.

[teriks]

quallman1234, husaberg:
The Bishop (+Illmor-Mercedes) take on rotary valves.
258882

"To demonstrate the credibility of Bishop Innovation’s new rotary valve technology it joined
forces with Mercedes-Ilmor to develop the technology for use on their V10 Formula One
engine only to have its strategy destroyed by a change in engine regulations. "

"By late 2000 back to back testing with the poppet valve
single cylinder engine demonstrated a 10% power advantage and improved durability."
258883
Source: http://home.people.net.au/~mrbdesign/PDF/

Four-stroke I know, but if you split that rotary valve in half, you basically have what I use for intake valving. -See, I managed give it some two-stroke angle ;)

[twotempi]

A couple of questions for comment.

1) Why do 14mm spark plugs get used. In a 125 twin or 50cc the spark plug takes up a fair part of the head area. Does anyone use 10mm or 12mm dia plugs ?? NGK appear to have a reasonable range of 10mm fine-wire plugs of the desired heat ranges. Assuming they are actually available

2) Carb primary or emulsion nozzle jets. What type would be better for methanol fuels. Would a shrouded emulsion type give better atomisation for this application with the increased fuel flow requirement of 2 - 2.5 times that of petrol ??


thanks

[TZ350]

The Wobbly Pirranha ....

258897

Laid out all the pieces in order and the right way round and numbered them so that they are easier to sort when welding them.

258898

Cleaned the ends and started a small lead on them so they go through the roller easily.

258899

Fed them all the same way up into the roller and rolled them into more or less a circle.

258896

Not perfectly round but I made sure the edges where they butt together are sitting flush.

Next move is to fusion weld and hammer the joints then roll the again so they are nice and round.

I should have left this job for Bucket, he has more patience than me ...... :yes:

[Grumph]

A couple of questions for comment.

1) Why do 14mm spark plugs get used. In a 125 twin or 50cc the spark plug takes up a fair part of the head area. Does anyone use 10mm or 12mm dia plugs ?? NGK appear to have a reasonable range of 10mm fine-wire plugs of the desired heat ranges. Assuming they are actually available

2) Carb primary or emulsion nozzle jets. What type would be better for methanol fuels. Would a shrouded emulsion type give better atomisation for this application with the increased fuel flow requirement of 2 - 2.5 times that of petrol ??


thanks

14mm spark plugs are the common size for road motors as they are cheaper and less subject to damage from ham fisted owners...
In NZ there's a good range of 10mm available, probably better available in 12mm, and a limited range of 8mm. Ask Darbi's...

I can't say from experience which style of needle jet nozzle will suit bulk methanol flow best - I'd think it may depend on the application...ie cylinder size. Plain nozzles have worked fine with meth for me.
Vizard quotes a problem with fuel not emulsifying in a car carb which he solved by putting a knife edge on the nozzle - the ragged edge acted to break up fuel droplets better than a plain square edge.

[Gigglebutton]

The Wobbly Pirranha ....

258897

Laid out all the pieces in order and the right way round and numbered them so that they are easier to sort when welding them.

258898

Cleaned the ends and started a small lead on them so they go through the roller easily.

258899

Fed them all the same way up into the roller and rolled them into more or less a circle.

258896

Not perfectly round but I made sure the edges where they butt together are sitting flush.

Next move is to fusion weld and hammer the joints then roll the again so they are nice and round.

I should have left this job for Bucket, he has more patience than me ...... :yes:

Im working on my buckets tomorrow night & hopefuly Saturday morning. Pop in and ill weld it up for you if you want

[dinamik2t]

Wob, may I ask an EngMod question. I want to simulate a Vforce reed valve.
What I do, is measure every dimension as a normal reed valve and for the angle I measure & use this one:
258932

It looks obvious, but I am not sure. Vforce pyramidic triangles are not isosceli (greek plural of greek word isosceles :D), like most reed valves.
The above angle measures 23.5 degrees and eff. diameter is ~41 over 43.5 of the conventional equivalent valve.

Furthermore, would you care to give an insight on why we don't see vforce on road race bikes?

--------

Can't wait to see the piranha ready TZ! :cool:
I liked the small description on the manufacturing. Please add more on the next phase.

[wobbly]

Here is a Banshee VF3, all you can do is measure the angle between the reeds as you say.
Any small inaccuracy in the geometry isnt worth worrying about.
VF reeds work really well on road race bikes - an RS125 Honda makes better mid and top end with a CR125 VF2, we have done dozens of tests on this.
The VF3 for this model isnt as good and chips petal tips.
All the sprint and road karts here use them, but only a few road race bike riders seem to know.

[dinamik2t]

I see..
Me too saw a clear difference in favor of the VF in EngMod, that's why it seemed odd.
Mine comes from Arctic Cat 500/600 Twins and here's a shot if anybody needs the dimensions:
258935

[quallman1234]

All the sprint and road karts here use them, but only a few road race bike riders seem to know.

Thanking you sir. Next upgrade for my RS then!

[speedpro]

An advantage i see with the VF reeds is the tuned length of the reeds. In a conventional reed block if the free length is restricted for tuning purposes the effective area is reduced which is compensated for by going wide. With the VF reeds they are stacked so I see a better shaped reed block and port.

[richban]

Hey Guys

What's the stuff you have been using to build up ports etc. I had a look through but could not find it. Am making a manifold and need to match carb spigot nice.

Cheers Rich

[bucketracer]

Devcon F, you can get it from Blackwood Paykles in small tubes like 5min Araldyte ($25) or big tins of putty ($175). I think Fishy sells it or something similar too, but cheaper.

[F5 Dave]

JB weld is good too (bought on TM ages back) & better for self leveling stuff, Devcon better for forming shapes as its thicker. Copes with inlet temp just fine. Not so much on ex side, maybe for several min.

[wobbly]

RS Components sells Devcon F in the tins for around 1/2 what Paykels want.

[richban]

RS Components sells Devcon F in the tins for around 1/2 what Paykels want.


Great stuff thanks Guys.

[Gigglebutton]

The filler in Tz's piston is Belzona 1111. Its dam expensive but can handle loads of punishment.

[F5 Dave]

Really? RS are usually hella expensive. hmm I only see plastic steel in my '11 cattledog.

Either way if you don't need much I can spot you some small tubes of JB weld for a after meeting beer or two .

[edit] http://www.trademe.co.nz/motors/car-parts-accessories/tools-repair-kits/repair-kits/auction-453633188.htm

[wobbly]

RS part - No 691-195,branded as RS but is Devcon F - $105

[F5 Dave]

oh yeah, or $94.50 if you buy 12, hoho.

hmm, mix ratio 9:1? Never seen Devcon other than 1:1.


been using Devcon Fasmetal which is equivalent & seems premo for last few years in munty tube form which I got from Blackwoods. Wasn't that much I thought. Hmm, quick google.

http://www.bettymills.com/shop/product/view/Devcon/ORS230-19770.html

[cotswold]

You have a flash logo for your pipe but with the bikes you have already in your stable plus the one I know of in the making I think team ESE needs a logo or decal for their bikes so people know what is dealing to them on the track, I am a useless artist but have this to put forward for ridicule or for development.

[husaberg]

I am a useless artist but have this to put forward for ridicule or for development.

Voting starts now.
Ny bet is one dollar both ways.

I am bettting of course their sponsor prefers them to use their er... own one?

The photo is fuzzy as the bike was going pretty dam fast

[Henk]

I'll go for ridicule, but only out of habit.

[cotswold]

I'll go for ridicule, but only out of habit.

I would feel ignored without it

[cotswold]

Voting starts now.
Ny bet is one dollar both ways.

I am bettting of course their sponsor prefers them to use their er... own one?

The photo is fuzzy as the bike was going pretty dam fast

Oops, very nice Logo but not what I meant, I was thinking more of a tank Logo

[husaberg]

Oops, very nice Logo but not what I meant, I was thinking more of a tank Logo

Ok i see. Well i kind of like the way this first one below would look, laid out on the tank.

I would prefur to run the logo without a fairing mind you.

As with all the best logo designs are simple natural designs are best.

The second one is for the doubting Thomas's out there. Er so here a statement from MR T..................homas

#rd one is my own amateurish design i'd go with the first myself.

[Brian d marge]

Ok i see i kind of like the way this below would look layed out on the tank.

I would prefer to run the logo without a fairing mind you.

As will all the best logo designs are simple natural designs are best.

One thing about 125 cc air cooled and that photo ...I have just shagged both of em

one came back for more

Stephen

[cotswold]

One thing about 125 cc air cooled and that photo ...I have just shagged both of em

one came back for more

Stephen

The other ran off with the pool boy

[wobbly]

Just checked the RS boxes I have here ( I bought 2 as I could not believe the price ).
It is labelled Devcon F Putty and is mixed at 4:1 by volume as has all the putty I have used before.
The 9:1 ratio is by weight.

[dinamik2t]

From what I know , this putty has an older and a newer version (F/10611 & F2/10711 respectively), but I haven't read any specs.
A 0.5 kg can can also be found on ebay usa for $60 + shipping, but I don't know whether it's very old.. It's been there for awhile.

Here it sells around 70 euros or 100- $. On ebay.uk -so classicaly overexpensive...- 100 pounds, meaning 160$. :crazy:

Devcon page: http://www.devcon.com/products/products.cfm?familyID=107

[TZ350]

259059

Bucket has found himself distracted by other interests.

259057

So Darren fearing I might try to weld up the Wobbly Piranna myself offered to help.

259055

After a weld Darren hammered the bead flat and rounded the join into a nice curve.

259056

And yep the sections are still hot.

[TZ350]

Page 450 ....


EngMod2T

For something different Page 400 is going to be the basic info for building a 30+hp Suzuki GP125 taken from the EngMod2T simulation files.

254400 Crank HP. Simulated Dyno Graph from EngMod2T using an early RS125 pipe.

254399 EngMod2T's main screen for developing the model.

254401 Basic engine dimensions.

254402 Exhaust port dimensions.

254403 Transfer port and duct dimensions.

254404 Transfer port cylinder entry design and angles.


EngMod2T

254407 Inlet port and disk timing info.

254408 Early RS125 chamber layout.

254409 24mm pumper carb and inlet tract model.

254410 Combustion data for a flat top piston.

254411 Air cool temp data.

254406 STA's or Specific Time Areas.

[husaberg]

Combustion chamber effects
I was going back reordering some of the attachments i had previously posted. Yes i have finally figured how to do it now.:clap: shame they shut out the editing after about a month.

I came across this one as i was hoping some of the more learned types amongst the thread might pick up on what Cameron mentioned with the combustion and elaborate on it for the less academically gifted.
Wob mentioned at the time that Yamaha had their own ideas relating to squish and comp but didn't elaborate.
esp how the shapes and comp and squish clearance effect engine characteristics like acceleration.

Also what is the modern take (ie Aprilia) I am talking for high lead or low lead to if anyone wishes to expand on the subject.

Keihin carb on late RS125/250
Wob also mentioned the RS125 late model carb (i think he called it the.. sx?pic 2 below i guess is it) can anyone explain how it differs in detail from the earlier Keihins PWK's and the Electric PJ Keihins fitted to MX bikes? It looks like it can possibly deal with greater downdraft as well.

Splitters wings etc
Also i was hoping someone would have had some experience using one of the splitters power wings etc. My understanding is it seems that any obstruction upstream can effect the jetting on a two stroke to .........(bugger can't find my notes (Added below from the source a little latter) Where as an obstruction down stream..... (see attachment below from Robinson)
I have seen a few write up where these wings and similar clean up low speed carbuartion so are they a band aid for incorrect jetting? or just a new shinny bit for the Magpies.

Ceramic bearings
Someone (possibly Bert) regarding ceramic bearings a while back i said i had something to suggest that a lot of MX teams don't use them as they change their bearing too often to justify their use. this was the exert I was talking about.

I found this from one Retailer.

How do you get that Factory-Race bike advantage? One of the secrets is ceramic bearings that are used in nearly every AMA superbike, World Superbike, MotoGP, and Professional Drag Race Motors around the world! Less Weight, less friction and less surface wear equals more horsepower in your motor, simple as that.

Reduced Rotating Mass
The ceramic balls in these hybrid bearings are over 60% lighter than their steel counterparts resulting in faster acceleration and reduced inertial loads.

Low Friction - Less Vibration
The coefficient of friction for the ceramic balls is an average of 3x's lower than steel. When you combine this with the high tolerances for roundness you get a bearing that dramatically lowers vibration levels and produces more horsepower.
Preservation
Due to the unique properties of the ceramic balls these bearings have vastly reduced surface wear when compared to steel balls. The reduction in wear eliminates a large portion of the oil contaminates, thus prolonging lubricant life.
http://www.woodcraft-cfm.com/cgi-bin/commerce.cgi?search=action&category=CBH3
But the price wow that would hurt even with the conversion rate of the current US peso.
Maybe the wheel bearings are Cheaper? What gains could you realistically expect from the engine would it be measurable? or from friction losses from the wheels.
I realise at the competition classes this sort of excess is common while chasing the last nano of performance.ESP when all the other bike are essentially the same as in 125 classes etc.

[wobbly]

The SPJ carb is sort of what is says , a Short version of the old PJ.
But there are a few imprtant detail changes, apart from the obvious power jet solenoid and TPS.
The emulsion tube has a short extension to the main jet that allows fitting different diameters, entering the tube after the main.
This changes the rate of change of the fuel curve and works a little like a bigger or smaller air corrector.
Bigger volume allows more fuel to enter the tubes well,at initial snap open of the slide, helping riders who like to get on it early.
But for gradual, smooth riders, it goes "fluffy" so no free lunch.

Ceramic bearings do exactly as they say - I have always used Micro Blue versions so can only speak about those.
A 50 Hp 125 will make around another 1.5 to 2 Hp with a full set, they last forever and work a treat.
In wheel bearings, a bike or kart will roll easily twice as far in neutral, after a plug chop.
Riders love not having to push back to the pit, and I love plug chops.
One thing I would like to try is to Micro Blue the surface of the sleeves where the seals run.
Seal friction is probably way bigger than the balls rolling friction, so this could be useful too.

Squish configuration is now set in stone, be it race gas or ULP.
As long as you have the tuning aids to overcome the natural effects.
50% SAR, combined with a vertical height that allows the piston to clip in the overev is the baseline.
This gives a VERY close optimum setup, be it domed or flat top piston, combined with a toroid chamber.
The domes like a bathtub ( confirmed by Frits ) and Yamaha factory bikes.
A flat top likes a re - entrant dropped plug shape, confirmed by HRC and me, many times.
Wide, close squish will always give great acceleration, but will restrict overev if you havnt got a digital ignition to pull out timing, and a solenoid powerjet to turn off the fuel past peak torque.
Without the tuning aids you have to juggle com,static timing and squish height, to get back the overev, if its needed for the application.

[dinamik2t]

50% SAR, combined with a vertical height that allows the piston to clip in the overev is the baseline.

Wob -and Frits-, you have our gratidute for sharing and explaining heaps of different stuff!
Troubling you a little more, could you use a different expression for that one? It must be a metaphor, but being in english, I didn't catch it. :( Would you mean 'to almost touch'?
Furthermore, an air-cooled engine can handle the same amount of msv with a water-cooled one? So far, my readings about MSV said that it shouldn't be higher than what the fuel octane can handle, otherwise extra-needless(?) heat would be created.

[F5 Dave]

he means, I believe. to touch or appear to touch its that close. On my 50 I have had it so close that it will totally clean surface of piston & head squish (0.5mm on the RG) but if I reuse the base gaskets (2 of) too many times you can actually hear it tinkle a bit on overrev. That is probably a bit too close so I change the gaskets, or rather don't reuse them more than twice.

[2T Institute]

One thing I would like to try is to Micro Blue the surface of the sleeves where the seals run.
Seal friction is probably way bigger than the balls rolling friction, so this could be useful too.



Hey Wob, looks like finaly found that one thing you haven't heard about.

http://sharkshifter.com/zc/index.php?main_page=product_info&cPath=88_122&products_id=810

Most seal manufacturers can make them, seal friction is very high these make a massive difference

[bucketracer]

Troubling you a little more, could you use a different expression for that one? It must be a metaphor, but being in english, I didn't catch it. :( Would you mean 'to almost touch'?

259303259302

This is what it looks like, pictures of TeeZees piston and head, he can shim the barrell so the piston just touches, kisses, clips or skims the head on over run.

The carbin on the squish area of the pistion is polished, more so on the back where it rocks over TDC, the little pock marks are made by ingested dirt being trapped between the piston squish band and head and leaving little craters.

When TeeZee is setting it up he allows about 0.5mm for rod stretch on overrun at max rpm and he talks about static and dynamic squish clearance.

[husaberg]

http://www.ebay.com/itm/1999-KX125-CARBURETOR-KX-125-CARB-FUEL-/180833412211

This is what it looks like, pictures of TeeZees piston and head, he can shim the barrell so the piston just touches, kisses, or skims the head on over run.

Kisses metaphor probably isn't helping either Bucket? :lol:

Kisses,Touches. skims ,head on over. TZ said you were a little distracted.

259059Bucket has found himself distracted by other interests.

The SPJ carb is sort of what is says , a Short version of the old PJ.......
Ceramic bearings do exactly as they say - .......
Squish configuration is now set in stone, be it race gas or ULP.A........

Thanks Wob

So you would use them in preference to phenolic bearings
do you have a pic of the extension tube in the carb also do they allow more downdraft i believe some KTM and the KX125 99ish reputably ran the shorty version as well but with differing PJ outlet and possibly(likely) other changes no doubt.?
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=259326&stc=1&thumb=1&d=1330933467

So that just leaves the Powerwing Splitter anyone?


Re seals
I am pretty sure i posted the Greeves solution to the seals a while back Std Honda Parts too.(only used on Works bikes and factory supported racer mind you.)
I can't remember what they were worth in HP.... something along the lines of 1.5-2 HP out of 30 i think. Lasted forever as well though.
This was pre admittedly telflon days though.

http://www.lortim.demon.co.uk/vsih/cranksha.htmWhen the Greeves Silverstone was first introduced it was recommended that the crank seals were changed after every meeting, as the wear rate was so high on the racing engine. The modern solution is to use Teflon coated oil seals. Before the times of Teflon coatings, Brian Woolley came up with an answer that not only worked but increased the time between servicing. His method entailed the use of Honda C50 piston rings to form labyrinth seals in place of the rubber seals. The rings were held in position by a steel sleeve which was a press fit into the crankcase, running in a slotted alloy carrier that rotated with the crank, the rings stopping any gas flow much in the same way that they do on the piston. As the seals on the standard 9E cases are smaller than the Greeves cases this modification may be a difficult one to embody without resorting to machining the seal housings, but for someone with machining know how it may be a feasible project. On the drive side the labyrinth seal can be located between the two bearings, the slotted carrier doubling as the bearing spacer. The original rubber seal can be left in position, and the outer bearing fed with lubricant from an external reservoir, or fed from the primary chaincase. The same technique can be employed on the timing side, if the 11E double bearing set up is used.


Grumph or one of our Euro contributers will have a pic or diagram of them i am guessing but the explanation is pretty simple, the fitting into a modern engine less so.looks like this only less rings
http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Labyrinth-seal.png/200px-Labyrinth-seal.png

Teflon ones from 2tinsitutes site he found includehttp://sharkshifter.com/zc/images/medium/man-03.jpg
HS_30
Seal crank clutch side R/H Honda 125 Carbon Teflon
Honda CR 125 right hand crank seal Carbon / Teflon 30x45x7mm low drag best seals available
$10.00

HS_22
Seal crank clutch side R/H Honda CR80 / 85 Carbon Teflon
Honda cr 80/85 right hand crank seal Carbon / Teflon 22x40x7 mm low drag best seals available
$10.00

HS-20
Seal Crank Ignition side L/H CR 125 & 80/85 Carbon Teflon
Seal Crank Ignition side L/H CR 125 & 80/85 Carbon Teflon 20x32x7mm best seals low drag available not legal in spec stock moto
$10.00

HS-17
Seal output shaft CR 80 & 85 Honda Teflon Carbon
Honda CR 80 / 85 counter shaft seal 17x28x6mm Teflon carbon best seal available low drag
$10.00

HS-26
Seal output shaft 99 CR 125 Honda Teflon Carbon
Honda CR 125 counter shaft seal 90 to 06 motors 26x37x6mm Teflon carbon best seal available low drag not spec stock legal
$12.00

You can't argue with the price i guess.Cheaper than std Honda

But doesn't seem useful for a MB100 or even a Nsr125 such as Vanessa.bugger


RS125 oil seal and crankcase seals sizes attached below
forgive any errors it bloody late Wob.
Source they have all sorts of parts manuals and service manuals etc.
http://www.rscycles.com/pdf_partsbooks.htm
I do not part centre code 166 is CR80 the air cooled of around 1980 which shares parts with the MB5 and MB100 series.

[wobbly]

The carbs of the MX bikes with the Powerjet and TPS all have the air guides in the bellmouth in front of the slide.
This kills a heap of flow compared to an SPJ, but does give good response down low ( worth a couple of Hp on a RS125 in the top end for example ).
The flow thing isnt really an issue for a bucket motor as they are only made in 36 and 38mm - so plenty big enough to get the flow back with area.
The SPJ will handle more downdraft due to the Powerjet fuel pickup point in the bowl.
The MX ones have an issue with this as the suction point is right at the back of the bowl and would not be under water if tipped up too far.
I posted a pic of the fix a while ago.

Are the teflon seals for the RS125 kit, available in a range of sizes ie where do they come from.

You dont want the piston hitting during normal running,just short of a hit is whats needed at the peak rpm you would normally see on track - often when idiot riders bash the shift pedal on the overun into corners,
with no dynamic com pressure at work.

Saw an amazing ride in the weekend.
A 70+ guy now holds the lap record for post classic pre 82 Junior at Pukekohe,on a C model TZ350.
Im sure the toroids made a difference,but even with Dual Carbon pads you have to know how to go down inside 4 bikes at a time into the hairpin.
Poetry in motion on a bike - makes all the hard work seem easy.

[teriks]

While on the topic of seals, I'm thinking the SKF speedi-sleeve might be useful in bucket racing.
Anyone tried these yet?

http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=4_5_3



SKF SPEEDI-SLEEVE

This thin-walled sleeve [0,28 mm (0.011 in.)], developed by SKF, is simply pushed in position over the worn area, providing a counterface surface that is optimized for radial shaft seals.
There is no shaft disassembly or machining involved and costly downtime is minimized. Since the same sized seal as the original can be used, there is no need to search for other seals, or keep a stock of different sizes.
No special equipment is required since the installation tool is supplied with the sleeve. A mallet and a pair of pliers are all that is needed for the installation.

Features
The new generation SKF SPEEDI-SLEEVE uses a proprietary stainless steel material and manufacturing process, resulting in an optimized seal counterface surface that minimizes wear on both sleeve and sealing lip. The proprietary material provides increased strength and excellent ductil ity properties of the sleeve. Imperceptible lubricant pockets enable the lubricant to reside on the sleeve and thereby prevent dry running of the sealing lip that otherwise can create excessive wear. The contact surface is wear resistant and machined to minimize directionality (0° ±0,05) with a finish of Ra 0,25 to 0,5 µm (10 to 20 µin.). This is, in fact, a better counterface surface than can often be achieved on a shaft.

SKF SPEEDI-SLEEVE has a removable flange to simplify installation (fig). The flange can most often be left intact, but in applications where the flange will interfere with other system components, it should be removed so as not to cause friction heat and wear debris. The flange should also be removed in applications where it may reduce the supply of lubricant to the seal. This would reduce the cooling effect of the lubricant, resulting in elevated underlip temperatures and premature ageing of the seal material.

If the flange is to be removed, it should be cut from the outside diameter into the radius in one location prior to installation. The flange can then be twisted and raised up after installation and grasped with a pair of long-nosed pliers and twisted into a coil.

Size range
The standard size range covers sleeves for shaft diameters from 11,99 to 203,33 mm (0.472 to 8 in.). Depending on production quantities, non-standard sizes can be manufactured. Each sleeve is designed to fit a specific shaft diameter range, usually above and below the nominal shaft diameter. This permits some flexibility to accommodate variations in the actual shaft diameter.

Also available in a coated version, gold indicates TiN.


SKF SPEEDI-SLEEVE Gold (fig) is an enhanced version of standard SKF SPEEDI-SLEEVE, offering improved resistance to abrasive wear. Designed for applications where extended sealing system life is needed, SKF SPEEDI-SLEEVE Gold bridges the performance gap between the standard sleeve and expensive custom shaft treatments. A thin, metallic coating applied to the base stainless steel imparts a gold colour and significantly increases durability. SKF SPEEDI-SLEEVE Gold is particularly effective in environments where there are abrasive contaminants, especially when combined with a seal manufactured from the SKF fluoro rubber material, SKF Duralife.

The installation procedure is identical to that of standard SKF SPEEDI-SLEEVE and the original seal size can still be used.

Test results
SKF SPEEDI-SLEEVE Gold has been thoroughly tested to establish its level of abrasion resistance in severely contaminated environments using both coarse and fine sand (diagram). The tests were carried out at temperatures up to 110 °C (225 °F) and at shaft speeds up to 8,6 m/s (1 700 ft/min). Under these conditions, seals on SKF SPEEDI-SLEEVE Gold ran for an average of 2 500 hours.

Size range and availability
SKF SPEEDI-SLEEVE Gold is available in the same sizes as standard SKF SPEEDI-SLEEVE.

259350

[F5 Dave]

. . .
The SPJ will handle more downdraft due to the Powerjet fuel pickup point in the bowl.
The MX ones have an issue with this as the suction point is right at the back of the bowl and would not be under water if tipped up too far.
. . .
But will the excessive lean cause the pilot cct to flood?

[F5 Dave]

While on the topic of seals, I'm thinking the SKF speedi-sleeve might be useful in bucket racing.
Anyone tried these yet?

Also available in a coated version, gold indicates TiN.
Sounds interesting although low friction isn't being heavily pushed as an advantage. One may consider on small shaft sizes you would have considerably more spring pressure as the thin sleeve is a larger percentage of the dia than on a bigger shaft.

If the sizes were available you could machine your shaft & press fit the sleeve on. . . .Actually having said that I have a crank that has a goove in it currently. Mind you the thread end is a bit mullered so I was going to use another crank next build anyway.

[wobbly]

You cant run as much down angle as a Lectron or FCR type ( RGV250 carbs are good ) but the SPJ will run with alot more than most carbs without flooding via the idle circuit.
They cost a bloody fortune though.

[teriks]

Sounds interesting although low friction isn't being heavily pushed as an advantage. One may consider on small shaft sizes you would have considerably more spring pressure as the thin sleeve is a larger percentage of the dia than on a bigger shaft.

If the sizes were available you could machine your shaft & press fit the sleeve on. . . .Actually having said that I have a crank that has a goove in it currently. Mind you the thread end is a bit mullered so I was going to use another crank next build anyway.
Salvaging grooved shafts was indeed my main thought, any increase in seal life and/or reduced friction could be a side benefit.