ESE's works engine tuner

[TZ350]

Wouldnt using a big thick adaptor on a 125 size crankcase lower the crankcase compression especially as you would be putting a 100cc barrel onto it ?

Bucket and Thomas did some measurements........


Crankcase Compression Ratios Revisited

Primary or crankcase compression ratio is determined by dividing the full crankcase volume including transfers with the piston at TDC by the crankcase clearance volume with the piston at BDC.

The Suzuki GP125 has a crankcase compression ratio or primary compression ratio of 1.36:1

From memory the results were std GP125 470cc, just the lower crankcase 280cc and a 10mm spacer plate was another 60cc.

With the spacer plate there is a lot of room above the flywheels that can be filled to reduce crank case volume and contoured for better flow into the transfer ports.

Although, I think a lower ratio (more crankcase volume) could be a good thing in some ways.

[TZ350]

Both Fletchers and Ulrich do heavy wall alloy tube in 6000 series.
This plates just fine according to Grant at the platers down South

Thats interesting, thanks for that.........

[Bert]

Wouldnt using a big thick adaptor on a 125 size crankcase lower the crankcase compression especially as you would be putting a 100cc barrel onto it ?

Yes, not forgetting that you loose a little with the bore size. That that a good thing for high rev'ing strokes isn't it? like yamaha putting in reed block spacers to increase 1 carb to piston face length and 2 case volume. I'm sure speedpro, dave, wobbly and others (where's SS90 when you need him) will have some views on this.


We figure that if the sleeve was much thicker, say 50mm id and 80mm od then the inner radius of the transfer ports can be cut into the sleeve easily and the larger sleeve outside dia gives a much greater surface area for heat transfer at the liner/cylinder interface.

my steal insert is 50 id and 70 od, with some modifications to the transfer port alignment; but no thought went into heat transfer... :weird:

[bucketracer]

Wouldnt using a big thick adaptor on a 125 size crankcase lower the crankcase compression especially as you would be putting a 100cc barrel onto it ?

Yes your right, it would change things alright. Both the GP100 and 125 have the same size crankcase volume at 280cc, so the extra cc of the spacer plate would affect the 100's original overall ratio more than it would the 125's.

But what is the correct ratio?

Speedpro I think it was, said "The crankcase is a good place to store air/fuel and its easier to take a swig from a large mug than from a thimble" SS90 disagreed..........

Me, I think the pipe will have something to do with it all .........

[wobbly]

Case com is a very complex subject but a few rules of thumb apply.
The higher the bmep of an engine then the higher the delivery ratio, thus a larger case can store the higher volume of ingested air at a higher pressure and this is then available to the transfer ducts.
But the quality of the duct and port geometry also affects the case com required.
The smaller the case vol (higher ratio) the greater the pressure rise in the case as the piston drops - this suits compromised transfer ducts with little or no inner wall shape, as it helps force the flow around thru the ducts quicker.
Good duct/port geometry allows the use of a bigger case as they dont need a large pressure ratio across the port to initiate good flow.
Lastly is the effect of the pipe geometry, the diffuser sucks like hell on the Ex port around BDC, pulling flow thru the transfers, and it is important to match the pipe diameter ( and thus the diffuser included angles) to the transfer port/duct geometry.
Suck too hard on crap transfers and they loose directional control - giving greater short circuiting out the Exhaust port.

Thus you have a Catch22 in that you need a small case to speed up the flow, but this limits the available stored mixture, and you want to suck on the transfers as much as possible, but no so much as to loose the control of the flow direction - or to speed up the loop velocity excessively thus reducing the trapping efficiency..

One myth that needs busting here is that the bulk of the flow thru the transfers is initiated by the piston dropping.This happens in lawn mowers, not racing engines.

Pipe diffuser suction when the piston is around BDC forces the bulk of the flow volume, NOT the pressure in the case forcing flow up the ducts.
When the transfers open there is more pressure in the cylinder than in the case.
Thus we get flow reversal at the initial transfer opening point.
This also means that the transfer port that opens first - flows last, as it has the greatest flow reversal affect,down the duct.

In general, high bmep engines that by default will have good port/duct geometry, will like a case com down near 1.3:1, lower performance engines with crap transfer/duct geometry will perform best with the ratio higher, up near 1.4:1.
Thus as you develop an engine, increasing its efficiency with better porting, then this will allow the use of a bigger case, and bigger pipe diameter/vol, to work with that - the two go hand in hand.

[F5 Dave]

. . . (where's SS90 when you need him) ...

I think he went absent when TZs bike started to make 25hp.:msn-wink:

[F5 Dave]

. . .
But the quality of the duct and port geometry also affects the case com required.
The smaller the case vol (higher ratio) the greater the pressure rise in the case as the piston drops - this suits compromised transfer ducts with little or no inner wall shape, as it helps force the flow around thru the ducts quicker.
Good duct/port geometry allows the use of a bigger case as they dont need a large pressure ratio across the port to initiate good flow.
. . .


Ahh, hadn't thought about that. I knew that steeper pipe cones weren't suited to up the side of the liner type transfers like you might find on an RD350, or for that matter most bucket engines.


. . .
Suck too hard on crap transfers and they loose directional control - giving greater short circuiting out the Exhaust port.


I'd assumed over scavenging, but this makes more sense, or is overscavenging by shortccting so way too early to be any use.



. . .
When the transfers open there is more pressure in the cylinder than in the case.
Thus we get flow reversal at the initial transfer opening point.

Which is why esp on bikes with a mismatch of pipe & high transfers you get burning on the reeds. But it happens on TZ250s as well, which had confused me.


. . .
This also means that the transfer port that opens first - flows last, as it has the greatest flow reversal affect,down the duct.

And this is a Graham bell book error it would appear, at least in bikes with expansion chambers. This has been something that I have held the wrong (Bell) way in my head all this time.

Thanks Wayne, lots of things to think about & a few nagging mysteries cleared up, or at least not so mysterious.

[kel]

When the transfers open there is more pressure in the cylinder than in the case. Thus we get flow reversal at the initial transfer opening point. This also means that the transfer port that opens first - flows last, as it has the greatest flow reversal affect,down the duct..

Another curly one to deal with. It would seem that staggered transfer timing would have real flow advantage rather than just taming a too peaky motor.
I figure that with this reversal of flow that the boost port would open first as this would allow the flow from main and aux to potentially reach the rear of the cylinder before being directed up, like wise the aux would open next ensuring the main flows first thus limiting short circuiting out the exhaust??????
Anyone got a spare KE125 cylinder (preferably with aux exhaust ports), mine is heading for the bin!

[wobbly]

Honda first used the staggered transfer setup with the RS125/250 and was developed by Helmut Fath ( my hero) as was Exhaust stinger nozzles,for the factory teams.
With the big T port they opened the main first by around 2*, the secs and boost ports last.
Aprilia later came along with a 3 port Exhaust setup with huge aux Ex ports, they now have the mains lower to allow much bigger aux Exhaust area, with the secondarys and boost opening first.
All have the axial angles set at around 22* - 12* - 55* to clear out as much residuals from within the loop area as possible.
The big hooks on the secondarys also flips the flow over on itself under the boost, to clear this area out as well.
Greater flow reversal occurs when there is insufficient blowdown STA,and the TZ250 sacrificed blowdown for more transfer area, something we now know is a mistake - but with limited transfer port area you take your pick of what to compromise.

[F5 Dave]

Wasn't it Rotax that first used ex sub ports in earnest? Think the 256 has them doesn't it?

I've never really understood what was trying to be acheived with stinger nozzles with either venturi or simple stepped designs, presumable piston crown temp is affected but I don't see past a pressure bleedoff how it affects things.

Another odd thing about the RS port is the ex manifold part of the port step, presumably as a poormans powervalve to disrupt the out of step returning wave but still not affect it as when you want the wave, all I know is if you grind it out you lose midrange with no advantage to peak. Have never tried to emulate it.

[F5 Dave]

. . .The big hooks on the secondarys also flips the flow over on itself under the boost, to clear this area out as well.
. . . .
This is also presumably to colide the streams & kill kinetic energy so the flow out of the gaping exhaust is delayed until the boost clears the contaminated remains, or is this a misunderstanding? (I remember a 90s article by Cameron) so have always tried to emulate this to an extent. Looks right with my water from the tap up the transfers 'flow bench'

But this is at odds a bit if axial angles rather than flat roofs have proceeded further.

[wobbly]

Only Yamaha stuck with the wank flat roof scenario way after the use by date, and got their arses kicked for years in GP.
Till they finally bought a CNC controlled Jante machine from Czech, went square bore/stroke and using the 500 cylinders on the 250 easily won the champs in 2000 with Olivier Jaques.

The secondarys facing each other relatively flat will always collide, but the hooks rotate the flow under the boost as it exits the port ( easy to see with the tap water Jante trick),clearing out a big "dead" area
in front of the rear port.

All modern race engines have a nozzle restriction at the flange face, as big T ports and tripple Exhausts loose alot of velocity going into the header.
Rule of thumb is a 75% of the effective EX area at the flange.
Stepped oval duct into a round flange does work, but I have used a CNC oval to round transition in the spigot for years, as has Honda in A kit, and Aprilia factory engines, this works way better.
Here is a sim showing my new 400cc F3 engine, with and without the spigot nozzle.

The stinger nozzle effectively removes the stinger tube length from the equation - it was developed for Spencers NSR that had one stinger 150 long, the other was 450.
The nozzle is around 2 to 3mm smaller than the tube stinger .

[koba]

my new 400cc F3 engine

Hehehe, I knew it was only a matter of time!

Cool rule change huh!

I can't wait to see some good new gen F3 2-Strokes.

[F5 Dave]

. . .
Rule of thumb is a 75% of the effective EX area at the flange.
Stepped oval duct into a round flange does work, but I have used a CNC oval to round . . .

This is great, maybe not as pertinent to the single port commuter engines we are playing with, but still very interesting. Any chance of an example picture?


. . .
The stinger nozzle effectively removes the stinger tube length from the equation - it was developed for Spencers NSR that had one stinger 150 long, the other was 450.
The nozzle is around 2 to 3mm smaller than the tube stinger .

So assuming I had a 200mm 18mm ID stinger but didn't have the space for it & could replicate it with a 16mm section a couple of cm long & then just run a 209mm section to the pipe to the muffler? A 16mm stinger is 50cc size & would be certain piston crown doom to run on a 100. Is this what you are saying?

I had heard that tapered venturies apparently used on GP bikes?

[wobbly]

Here is an oval to round spigot for Robs GP100 with RGV cylinder.
36mm pipe ID, oval shape at the duct exit is 36 wide by 27 high = effective area of a 31mm round..
This nozzle effect doesnt work on single port engines - I have tried.


Re stinger nozzles - if running a 18mm nozzle on a 100cc then you could connect a 20mm stinger tube to it in basically any length and this would not affect the power at all - in fact using the nozzle with a tapered section out to the bigger tube makes more power.
Aprilia/Derby twins do this as the top pipe has a stinger 60mm long, the bottom one is closer to 220, but the effect works on any 2T.

[TZ350]

The secondarys facing each other relatively flat will always collide, but the hooks rotate the flow under the boost as it exits the port ( easy to see with the tap water Jante trick),clearing out a big "dead" area
in front of the rear port.

This is all good stuff, I would love to see a sketch of the port and proper flow pattern if possible so I know what to look for with the water test.

[wobbly]

All but impossible to show properly the scavenging pattern without one of the CNC controlled Jante screenshots but imagine looking out from inside the duct,the piston is the "floor" in front of you.
The flow attached to the septum wall blows straight past your left ear, and the flow hitting the hooks on your right side, rotates clockwise underneath this left side flow,the bottom attaching to the piston - the upper flow pushing upwards.

[bucketracer]

.......(where's SS90 when you need him) ..........


I think he went absent when TZs bike started to make 25hp.:msn-wink:

He did say some silly things.

And now TeeZee is making 27rwhp out of his old 1978 air cooled GP125 engine.

228841

Looks like Wobbly and Dad are hatching some sort of plan for a new water cooled 100cc engine, saw this picture on the lunch room table today.

[Ned Kelly]

And now TeeZee is making 27rwhp out of his old 1978 air cooled GP125 engine.

I think he had to have a cup of tea and a lie down.

228841

Looks like Wobbly and Dad are hatching some sort of plan for a new water cooled 100cc engine, saw this picture on the lunch room table today.

Well not exactly sure that is what he is planning but he would be looking at my Aprilia 125. It maybe on the drawing board for development.

[kel]

Looks like Wobbly and Dad are hatching some sort of plan for a new water cooled 100cc engine, saw this picture on the lunch room table today.
NO no no, you definitely cant turn an RSA into a bucket. Apart from being against the rules Id have to personally kill you for such sacrilege. Don’t think its possible to own an RSA, certainly an RSW or RSR but RSA? pretty sure they are still lease only. Such a shame 2011 is the last year of these wonderful machines, how long will the FIM be allowed to dictate this four stroke nonsense?

[TZ350]

No not planning anything too radical.

228854228855

Wobbly was just explaining to me the lengths the rotary valve boys are going too, to compete with the reed valvers and how it might be hard to get a big enough inlet port on our GP's with their smallish side rotary valves.

228856

Yum yum stuff........ head inserts and an electric power jet carb with a throttle position sensor.
228857

Real transfer ports ..........

[kel]

Wobbly was just explaining to me the lengths the rotary valve boys are going too, to compete with the reed valvers and how it might be hard to get a big enough inlet port on our GP's with their smallish side rotary valves.

What? The RSA engine is completely dominant, no reed valve comes close. OK so Aiohma won the 250 title on an RS but that was mainly because Simoncelli and Bautista were suffering from meltdowns, tantrums and brain fade, what a fantastic season that was. Point being the 125 with rear cylinder rotary disc out performs reed valves end of story!
I certainly hear what your saying when it comes to the inlet afforded to us on our commuters come race bikes, the disc and subsequent inlet port just isn’t big enough, but we shouldn’t be telling every one this as it will dampen the 2 stroke fear factor. The diesel pigs should be afraid.

[TZ350]

Point being the 125 with rear cylinder rotary disc out performs reed valves end of story!
I certainly hear what your saying when it comes to the inlet afforded to us on our commuters come race bikes, the disc and subsequent inlet port just isn’t big enough....

Yes I think your right about the RSA, but I am limited with the GP vis other commuter reed options.

And your double right, the Diesel’s should be afraid, as there is a 2-stroke renaissance coming.

The Stroker Buckets are becoming F4 Race Bikes.......... :niceone:

[koba]

Yes I think your right about the RSA, but I am limited with the GP vis other commuter reed options.

And your double right, the Diesel’s should be afraid, as there is a 2-stroke renaissance coming.

The Stroker Buckets are becoming F4 Race Bikes.......... :niceone:

True.I'm going to take the reeds out of my bike sometime soon, just to see what it is they do!
When I finally cried "Enough" with powervalve issues on my streetstock and just wired the fuckers at full lift I was thinking "Shit, I should have done this ages ago!".

[Henk]

That may not work. You'll be blowing as much fuel mixture back out the carb as into the combustion chamber. But at a guess this was a fishing expedition.

[Yow Ling]

That may not work. You'll be blowing as much fuel mixture back out the carb as into the combustion chamber. But at a guess this was a fishing expedition.

Might just be a bit hard to start, over 9000 rpm it should be fine

[richban]

And your double right, the Diesel’s should be afraid, as there is a 2-stroke renaissance coming.

Yes you are correct. All this tech talk has got me wondering how to get more grunt out of the 4 banger. Not sure what else we can do to the FXR engine. There is always something else to try. Exhaust and intake need a look the new head will flow 32hp so no big restriction there. Anyone know of a 4 stroke single making 200hp per litre? Wonder what the 250 moto3 bikes will be putting out.

[bucketracer]

And your double right, the Diesel’s should be afraid, as there is a 2-stroke renaissance coming.

My guess the future is going to be...... Buy a Diesel, ride the wheels off it and Win or build a fast 2-Stroke and Hope to Win.......

[Henk]

Or build a fast Diesel and ride the wheels off it?
The reason Diesls are so prevalent at the moment is that they are easy and available.
I love two strokes but realistically don't have the time or talent to build a good one.

[jasonu]

Or build a fast Diesel and ride the wheels off it?
The reason Diesls are so prevalent at the moment is that they are easy and available.


A similar thing happened when RG50's appeared. Now you could buy a bike for not much money, strip off the road stuff, add a pipe and carb and win. The existing bikes, MB's, GT's mostly didn't stand a chance.

[Henk]

Remember going to watch at Mt Welly many moons ago, at the height of the RG50 era. F5 bikes outnumbered F4 by two or three to one. Wonder where they all went, given that there are about five regular F5 runners in Auckland now.

[wobbly]

The RSA was developed simply because the KTM 125 reed was faster than the side valved Aprilia/Derby/Garelli.
Its only "dominant" now because no one else is in the sand pit.
Be interesting this year if anyone has taken up Bartols offer to do a bullet reed for the one last year only.
The Aoyama RS250 was a better overall package than the Italian teams had, but it had limited factory support, and no real development for years - thus its top speed was down as a result, but the Italian 250s were still side valved.
Again,it was a shame that the KTM 250 reed wasnt a factory supported effort that year,either.

The GP125 case does have an ultimate restriction in the possible valve/port size, but this only affects the very bottom of the powerband, as radical timings have to be used to keep with the top end available from a soundly sorted reed motor.
Turning the RGV cylinder around and having a rear facing pipe under the seat, holds a certain facination for me though, and maybe Rob will still go with this option.
Whatever case is used, the RGV cylinder porting is identical - to achieve over 30RWHp, its just a matter of making a choice and going with it.

Regarding the 250 - 4 strokes, this flatulant pile of crap sounding shite is what we are in for - oh dear, I for sure wont be getting up early to listen to this.

http://www.motorcycledaily.com/2010/12/who-says-a-250cc-single-has-to-be-slow-honda-nrs-250-video/

[speedpro]

It makes more power but it sounds like a lot of 4T buckets.

[Buckets4Me]

It makes more power but it sounds like a lot of 4T buckets.

so you are trying to say that it makes about twice the power of Richbans bucket ?
and would they be twice? as exciting to watch a bunch of them go around Taupo :weird:


I bet they never get 40+ bikes lined up on the grid :bleh:

[jasonu]

[QUOTE=wobbly;1129958372]
Turning the RGV cylinder around and having a rear facing pipe under the seat, holds a certain facination for me though, and maybe Rob will still go with this option.

We have been considering this for the RG400 cyl KE motor. I have more than enough parts to try it.

[TZ350]

I have been looking at the rear rotary again.........

228904

And wonder if a TF100 case could be fitted with a RG cylinder and an upside down rear rotary valve thats driven by a toothed belt.

As 14,000 rpm is only 233 Hz one also wonders about driving a slide valve back and forth across the inlet using two large elctro magnetic voice coils driven by a 4 pole generator on the crank.

Might be able to have fast opening/closing and a longer fully open period than you could get with a conventional rotary valve.

If it worked it could even lead to variable inlet timing. Then there is phneumatic valve actuation............ lots of possibilities.

[TZ350]

.

Actually when I think about it, one could use the crank generator to charge two capacitors, one for opening the other for closing. And use an Ignitech programmable ignition to trigger them that way the inlet timing and duration could be continuously variable throughout the rev range and throttle position.

This has to be looked into some more………………….. :weird:

[wobbly]

Been there and helped do that, and in this guise the reed was still a little quicker.With the RV attached to the reed box.
May be able to do a bit better now though - but still alot of techo brain damage involved.

[diesel pig]

Turning the RGV cylinder around and having a rear facing pipe under the seat, holds a certain facination for me though, and maybe Rob will still go with this option.


Been there done that, well with a RG barrel anyway. Did it mostly because old school MZ racers had it(and they are fucking cool), making the pipe was way easier and according to tests done by Velocette in the '30,s straight pipes have a small HP advantage over pipes with bends in them.

[F5 Dave]

. . Wonder what the 250 moto3 bikes will be putting out.
Their guts all over the floor with any luck.

[kel]

The RSA was developed simply because the KTM 125 reed was faster than the side valved Aprilia/Derby/Garelli.
Its only "dominant" now because no one else is in the sand pit.

The KTM came good in 2005 but still didnt win the riders title (that Talmasci what a cock) then got its arse kicked in 2006 by the side valved RSW, the RSA was only intrusted to Bautista for the last couple of races and then only 3 riders the following year. The KTM was good but the Italians always came back with something better. There was some young rider who swapped his KTM for a Derbi RSA last year, name was something like Marquez, think he did quite well.
Had some pictures of the RSA inlet and disc but cant find them now, the inlet is enormous and the disc timing looks insane, guessing around 240+ deg?
Can't believe the 2 strokes will be gone from GP's its just not right!

[gatch]

The KTM came good in 2005 but still didnt win the riders title (that Talmasci what a cock) then got its arse kicked in 2006 by the side valved RSW, the RSA was only intrusted to Bautista for the last couple of races and then only 3 riders the following year. The KTM was good but the Italians always came back with something better. There was some young rider who swapped his KTM for a Derbi RSA last year, name was something like Marquez, think he did quite well.
Had some pictures of the RSA inlet and disc but cant find them now, the inlet is enormous and the disc timing looks insane, guessing around 240+ deg?
Can't believe the 2 strokes will be gone from GP's its just not right!

GP is meant to be the highest echelon in motor sport. It makes me sad to see it turn to mega $$$ proddy racing..

We can only hope that 2 strokes are accepted again in the future.

[TZ350]

Can't believe the 2 strokes will be gone from GP's its just not right!

I am begining to see why F5Dave has such a low opinion of Honda.


Had some pictures of the RSA inlet and disc but cant find them now, the inlet is enormous and the disc timing looks insane, guessing around 240+ deg?

I would love to see those pic's if you find them.

[TZ350]

Been there done that, well with a RG barrel anyway. Did it mostly because old school MZ racers had it(and they are fucking cool),

229009

Now thats a good looking GP engine setup ............ :niceone:

[kel]

I would love to see those pic's if you find them.

Found it, check out the valve timing
229016

[TZ350]

Great....... Thanks Kel

[TZ350]

Links and Interesting Quotes from the last 10 pages, other link lists can found on the decade pages starting with Page 80.

A Team ESE bike and enough information to make a copy of this GP125 engine.......

Video clip of Taupo RRS F4/Buckets, first practice on day one. 27-12-2010 Taken from my bike #54

A handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ is based on Blairs and Jennings work.


If someones got enough folding I would soon knock up and guarantee an aircooled with 24mm carb that makes an easy 38crank = 32RWHp,as this only represents a bmep of 11.3 bar or 164psi - so the carb isnt the limiting factor at all,in fact it would help the spread.

An interesting book by Eric Gorr. http://books.google.com/books?id=4MealMAQSeIC&pg=PA93&lpg=PA93&dq=keihin+pwk+tps&source=bl&ots=15w7jKNuhB&sig=Xal7OIeprLKF9U1pOPKP4RlnGB0&hl=en&sa=X&oi=book_result&resnum=6&ct=result

Interesting read about the future of 2-strokes and direct fuel injection ........
http://www.dirt-bike-tips-and-pics.com/future-of-two-strokes.html

http://www.google.co.nz/images?client=firefox-a&rls=org.mozilla:en-GBfficial&channel=s&hl=en&q=Ski+Doo+600+E-tec&um=1&ie=UTF-8&source=univ&ei=WjooTdmZCdCrca7cuZMB&sa=X&oi=image_result_group&ct=title&resnum=1&ved=0CCQQsAQwAA&biw=1024&bih=574

Thanks Bert, you have a lot of interesting pictures on your site, http://www.kiwibiker.co.nz/forums/album.php?albumid=2701

Bert posted this link to a CDI ignition system http://newmanz.co.nz/shop/index.php?main_page=product_info&cPath=66&products_id=205


The complete how too......... of the Jaycar CDI kit

For those interested in F5 and RG50's
R/H Crankcase Oil Seal p/n 09283-28013 $10 (or was 2 years ago)
L/H Crankcase Oil Seal p/n 09283-18004 $5
Gear Change??Oil Seal p/n 09285-12006 $7
Rod kits from later RG/RMX/SMX/TS/GT/RV/MT50 have oiling slots.
ConRod p/n 12161-04710
B/E Brg p/n 09263-16034
L/E Brg p/n 09263-12023
Pin p/n 12211-04711
Washer p/n 09160-16021
Wiseco Piston 826M04100 (std bore) Fits JR50 78-2004 and Kawa KDX50 03-04
The RG50 has only 3 thick clutch plates, 4 thiner TS/TF/GP100 or 125 and a steel will fit for a much better clutch.
Clutch cover gasket p/n 11482-13710 $22
Cly base gasket p/n 11241-04710 $14

If anyone wants to sell any RG50 engine parts or general junk, please PM me..........

Something for those who want to have a go at welding up their own pipes.......
By Glen Morgan THE PRACTICALITIES OF PUTTING A BEND IN A CHAMBER:- http://www.ozebook.com/compendium/morgan/pipes8.htm

"Usually the atomisers on carburettors intended for two-stroke engines are manufactured in two types: The rest can be read here:- http://www.mypage.tsn.cc/rdd/TT/contents/CARB/dellorto/dellorto_3_6.html

For those that wan't to experement with different carbs for their bike........ all sizes of copy cat Keihin flat slides, 24-28-32-34 http://www.alexwarehouse.com/OKO-carburettor-kit-24mm-26mm-28mm-30mm_p331.html
Cheap enough to modify or play with.

[TZ350]

Some Wobbly tech quotes that I thought should be kept together..........


Having a single Ex port will limit power capability - end of story.

And trying to get the big bmep numbers means that the only way is to make the ports higher and wider.

Blowdown is the single most important number in the spec sheet.

The other thing that seems to be overlooked by many is that Hp=T*rpm.

An engine with a 50mm stroke "should" be peaking at 13000,and be running on to 14000.
But when you have to use very high exhaust timing this tends to shut down the power over the top.

Also anything but a square bore/stroke ratio makes it doubly hard to get the port areas needed. With tripple Exhausts and as much transfer width as can be crammed in.
As its a big bore at 56mm the

Ex area is low but this is of lesser importance than the blowdown. Notice the relatively low bmep needed to achieve the power at 13000, with very normal timings of 194/132.



Case com is a very complex subject but a few rules of thumb apply.

The higher the bmep of an engine then the higher the delivery ratio, thus a larger case can store the higher volume of ingested air at a higher pressure and this is then available to the transfer ducts.

But the quality of the duct and port geometry also affects the case com required.

The smaller the case vol (higher ratio) the greater the pressure rise in the case as the piston drops - this suits compromised transfer ducts with little or no inner wall shape, as it helps force the flow around thru the ducts quicker.

Good duct/port geometry allows the use of a bigger case as they dont need a large pressure ratio across the port to initiate good flow.

Lastly is the effect of the pipe geometry, the diffuser sucks like hell on the Ex port around BDC, pulling flow thru the transfers, and it is important to match the pipe diameter ( and thus the diffuser included angles) to the transfer port/duct geometry.

Suck too hard on crap transfers and they loose directional control - giving greater short circuiting out the Exhaust port.

Thus you have a Catch22 in that you need a small case to speed up the flow, but this limits the available stored mixture, and you want to suck on the transfers as much as possible, but no so much as to loose the control of the flow direction - or to speed up the loop velocity excessively thus reducing the trapping efficiency..

One myth that needs busting here is that the bulk of the flow thru the transfers is initiated by the piston dropping.This happens in lawn mowers, not racing engines.

Pipe diffuser suction when the piston is around BDC forces the bulk of the flow volume, NOT the pressure in the case forcing flow up the ducts.

When the transfers open there is more pressure in the cylinder than in the case.
Thus we get flow reversal at the initial transfer opening point.
This also means that the transfer port that opens first - flows last, as it has the greatest flow reversal affect,down the duct.

In general, high bmep engines that by default will have good port/duct geometry, will like a case com down near 1.3:1, lower performance engines with crap transfer/duct geometry will perform best with the ratio higher, up near 1.4:1.

Thus as you develop an engine, increasing its efficiency with better porting, then this will allow the use of a bigger case, and bigger pipe diameter/vol, to work with that - the two go hand in hand.


Both Fletchers and Ulrich do heavy wall alloy tube in 6000 series.
This plates just fine according to Grant at the platers down South


Here is an oval to round spigot for Robs GP100 with RGV cylinder.

36mm pipe ID, oval shape at the duct exit is 36 wide by 27 high = effective area of a 31mm round..
This nozzle effect doesnt work on single port engines - I have tried.

Re stinger nozzles - if running a 18mm nozzle on a 100cc then you could connect a 20mm stinger tube to it in basically any length and this would not affect the power at all - in fact using the nozzle with a tapered section out to the bigger tube makes more power.

Aprilia/Derby twins do this as the top pipe has a stinger 60mm long, the bottom one is closer to 220, but the effect works on any 2T.


Honda first used the staggered transfer setup with the RS125/250 and was developed by Helmut Fath ( my hero) as was Exhaust stinger nozzles,for the factory teams.

With the big T port they opened the main first by around 2*, the secs and boost ports last.

Aprilia later came along with a 3 port Exhaust setup with huge aux Ex ports, they now have the mains lower to allow much bigger aux Exhaust area, with the secondarys and boost opening first.

All have the axial angles set at around 22* - 12* - 55* to clear out as much residuals from within the loop area as possible.

The big hooks on the secondarys also flips the flow over on itself under the boost, to clear this area out as well.

Greater flow reversal occurs when there is insufficient blowdown STA,and the TZ250 sacrificed blowdown for more transfer area, something we now know is a mistake -


Only Yamaha stuck with the wank flat roof scenario way after the use by date, and got their arses kicked for years in GP.

Till they finally bought a CNC controlled Jante machine from Czech, went square bore/stroke and using the 500 cylinders on the 250 easily won the champs in 2000 with Olivier Jaques.

The secondarys facing each other relatively flat will always collide, but the hooks rotate the flow under the boost as it exits the port ( easy to see with the tap water Jante trick),clearing out a big "dead" area
in front of the rear port.

All modern race engines have a nozzle restriction at the flange face, as big T ports and tripple Exhausts loose alot of velocity going into the header.
Rule of thumb is a 75% of the effective EX area at the flange.
Stepped oval duct into a round flange does work, but I have used a CNC oval to round transition in the spigot for years, as has Honda in A kit, and Aprilia factory engines, this works way better.

Here is a sim showing my new 400cc F3 engine, with and without the spigot nozzle.

The stinger nozzle effectively removes the stinger tube length from the equation - it was developed for Spencers NSR that had one stinger 150 long, the other was 450. The nozzle is around 2 to 3mm smaller than the tube stinger .

Tech content gathered together for easy future reference ..................

[ac3_snow]

For those that wan't to experement with different carbs for their bike........ all sizes of copy cat Keihin flat slides, 24-28-32-34 http://www.alexwarehouse.com/OKO-carburettor-kit-24mm-26mm-28mm-30mm_p331.html
Cheap enough to modify or play with.

If someone is thinking of getting some/one of these let me know could be interested in splitting shipping costs.

[wobbly]

I havnt seen that shot of the RSA before - what makes it interesting is if you rotate the view 90* so it looks like a "normal" engine, the port is the opposite shape to what is seen in that application.
Its tall and narrow, maybe this is part of why they work so well, apart from the symetric feeding of the transfer duct entries.

[TZ350]

This is what I see........

229078


The port window is 60deg's and the disk cutout is 230deg's 230+60/2=260 deg's duration

229079

Assuming the disk rotates clock wise the port is fast opening and slow closing.

229081

And so my idea of having a fast opening and slow closing valve wasn't so silly after all.............

[kel]

This is what I see........

The port window is 60deg's and the disk cutout is 230deg's 230+60/2=260 deg's duration

...

Its supposedly a lot tamer than that, photo does tell a lot regarding their inlet strategy. I have the RSA time areas also if anyones interested. Wonder who will get the sack when they find out that photos been released.

[TZ350]

Its supposedly a lot tamer than that.

I guess it depends on how they measure the closing point, actual or mean.

I would be very interested in the time areas, and if you have the actual inlet timings I would be very interested in those too.

229087 229088

Mine opens 145 BTDC and starts closing at 75 degrees ATDC and finishes at 85, it runs ok.

I figure I could go more radical, like starts at 85 finishes 95, and it would be interesting to know if opening earlier than 145 BTDC with a pipe thats sucking heavily at BDC would be a good/workable idea.

[koba]

Its supposedly a lot tamer than that, photo does tell a lot regarding their inlet strategy. I have the RSA time areas also if anyones interested. Wonder who will get the sack when they find out that photos been released.

Could be deliberate too, decoy like.

[TZ350]

.

229105

Ok here is a picture that gives me some idea of the carb/inlet size needed

229104

41.5mm

[TZ350]

.

Aprilia RSA 54 HP.

229106

Well I have a little way to go........

[TZ350]

You guessed right: the 24/7-inlet is named after its 'opening hours'. Originally I wanted to keep the idea a secret until it was fully developed. But I suffer from an ever-increasing lack of time and I would love to see my ideas realised, so I have decided to reveal some of them, like I did with the symmetrical scavenging.

The 24/7-inlet idea arose in 1974 when the rotary inlet disk of my racer stuck open and it just kept running, as long as I kept the engine in the power band. It meant that I rould ride back to the pits instead of pushing through the grass alongside the track side (which I had already done often enough...).
This experience proved what I already knew in theory: that the pumping effect of the crankcase only serves to start the engine; as soon as it runs in the power band, the exhaust pipe takes care of all the gas movement.
So how do you build a rotary disk that stops in the open position when the engine revs reach the power band?
I had no idea...
But then why would you need a rotary disk anyway? Because it flows better than a reed valve? That doesn't matter when you only need it to start the engine. And a reed valve is much simpler to open...

Below you see an old prototype with a typical design error: it is too complicated. You do not need two gear-coupled reeds; one reed that swings out of the way would be enough. And it can be operated by the same servomotor that operates the exhaust power valve

229107

There realy are some interesting ideas on the net...........

Some boys try the idea with their scootor http://www.youtube.com/watch?v=utfzYstegE8 not exactly big rpm but it does show that it would run without a reed valve.

[TZ350]

Cant take everything as gosple but some comments on the net get me thinking.......

"But in practice, if you reduce the distances between crankshaft and crankcase walls to less than 1 mm, the viscous friction of the mixture between the surfaces really costs power at high rpm. And if you make the clearances so tight that lubricating oil can no longer reach the big-end and crankshaft bearings, it will also cost engines.

Another negative aspect: any volume with a narrow 'entrance' between the crankshaft and crankcase surfaces acts as an hydraulic damper on the Helmholtz-resonance in the crankcase.
Aprilia has avoided this by making the space between the crank webs as wide as the big-end bearing. As a result the crankcase volume of the 125 cc RSA engine at TDC is about 650 cc, so the exhaust pipe really has some volume to breathe from.

So much for the fairy tale of high crankcase compression."

[TZ350]

.

229108

OK, so some how, I have to get a hole in the side of my GP that looks like this......... :scratch:

[wobbly]

I think that is the real problem with the side rotary valve - the last pic shows the "ultimate" development of the side port, whereas if you look at the RSA it has an almost identical shape,but turned 90*.
This in effect gives a much narrower port width - the narrower the better, as this means that the blade spends less time actually covering it up ( assuming the same open/close timing), but they have got the area back by making the port very high,with a big valve diameter.

[kel]

[QUOTE=TZ350;1129960944]the crankcase volume of the 125 cc RSA engine at TDC is about 650 cc, so the exhaust pipe really has some volume to breathe from.
QUOTE]

RSA primary compression 1,24:1 (650 cc at TDC; 525 cc at BDC). To increase the volume Aprilia lengthened the rods from 115mm on the RSW to 120mm on the RSA, they raised the cylinder accordingly. Sounds a lot like the bucket approach! Wonder if Jan has stollen anymore of our ideas?
I know we have covered the low compression sucky pipe thing before but its amazing how the old 2 stroke ideas have been turned on their heads

[k14]

RSA primary compression 1,24:1 (650 cc at TDC; 525 cc at BDC). To increase the volume Aprilia lengthened the rods from 115mm on the RSW to 120mm on the RSA, they raised the cylinder accordingly. Sounds a lot like the bucket approach! Wonder if Jan has stollen anymore of our ideas?
I know we have covered the low compression sucky pipe thing before but its amazing how the old 2 stroke ideas have been turned on their heads
How do you know this stuff? I was under the impression it was pretty hush hush and the engines aren't even opened during a GP weekend at the track. If anything goes wrong they put a new engine in and they are rebuilt between GP's back at the Aprillia (or derbi) factory??

Any idea how the injection on the KTM worked?

[kel]

How do you know this stuff?
Any idea how the injection on the KTM worked?

Jan Thiel has retired and the two stroke era is over so the designers dont mind shareing info, all kinds of really good info!
KTM injection well thats a strange one even though their GP two stroke program is long gone that still dont talk or release photos (press releases aside). But yes I do know how it works, supplementary injection that feds into the crankcase to richen the mixture, just another approach to a power jet.

[wobbly]

The KTM injection was Bartols way of preventing the engines from siezing on the overev during downchanges.
Pulling 15000 + with no air, and thus fuel, and thus oil, wreaked havoc with some riders, the injector squirted fuel/oil into the case when this was occurring.

[k14]

The KTM injection was Bartols way of preventing the engines from siezing on the overev during downchanges.
Pulling 15000 + with no air, and thus fuel, and thus oil, wreaked havoc with some riders, the injector squirted fuel/oil into the case when this was occurring.
Ok, that makes sense. I read an interview with Bartol about the KTM once and the way he talked about it made it sound like it was the best invention ever. So what changes did Aprilia do from the RSW to RSA to be able to make the jump ahead of KTM quite easily?

[TZ350]

Just a scrape from the net so take it with a pinch of salt ........... interesting though.

The carburation of a disk-valve engine is less sensitive to inlet resonances than that of a reed-valver. And it is far less sensitive to exhaust resonances. I have seen that on the Cagiva 500-4. First it had piston induction, then it got disk valves, and finally reed valves. The disk-valve engine was fairly rideable but its successor was not a pleasant bike, especially in the wet.
On a reed-valve engine the reeds are opened by the suction from the exhaust pipe. When you close the throttle, the energy flow to the exhaust stops, and thus the suction stops.
When you open the throttle again, nothing happens because the exhaust suction is absent; the reeds stay closed and there is nothing in the cylinder to combust. So the rider opens the throttle a bit more, and a bit more, and a bit... and then there is enough mixture in the cylinder to start combustion again. But now the throttle is wide open: Whamm, high-sider!
In a disk-valve engine the disk always opens, combustion or no combustion. So, contrary to popular belief, it is much easier to ride than a reed-valver.
(The Cagiva was cured by inserting 1 mm strips between the reed casing and the reeds, so the reeds did not really close anymore. It cost more than 10 hp, but the laptimes improved...
Because of those 'leaking' reeds setting the carburation was a nightmare. So Cagiva concentrated on injection, and got fairly good results.)

Frits Overmars.

[kel]

I think that is the real problem with the side rotary valve - the last pic shows the "ultimate" development of the side port, whereas if you look at the RSA it has an almost identical shape,but turned 90*.
This in effect gives a much narrower port width - the narrower the better, as this means that the blade spends less time actually covering it up ( assuming the same open/close timing), but they have got the area back by making the port very high,with a big valve diameter.

If Ive got this right the original image I posted is the latest RSA
229367
Heres the earlier incarnation
229366
shows they are always learning/developing

[TZ350]

Ok some more interesting stuff................

You must be able to rely on the ignition, even when the electrode gap has gotten on the big side, when the mixture is so weak, rich or diluted that you can hardly ignite it, or when the compression end pressure is high because of good cylinder filling or a high compression ratio.
All parts of the ignition system are important: the spark plug of course, but also the plug lead (never use carbon core leads), the plug cap (never use resistor caps; if there has to be a resistor in the high tension line, it sould be inside the plug, not in the cap, because caps fail), the coil (with Jamathi, Bultaco and Garelli the fat, blue, oil-filled Bosch coils were used despite the fact that they were almost as heavy as the engine. Replacing them with slim Japanese coils cost several hp...)

Let's take a look at the spark plug. What exactly happens there when the coil sends its high tension voltage? The gas molecules between the electrodes are ionized by the high potential. Starting at one of the electrodes, the ions begin to form a conductive channel through the otherwise non-conductive gas and as soon as this channel reaches the other electrode, a connection is established and a current starts to flow: the spark.
The ionisation needs a certain voltage per mm electrode gap, dependent on temperature and pressure of the gas. The squish turbulence can blow the ions away before they have had a chance to form a channel from one electrode to the other. Then, when the channel is finally completed, it is no longer straight but arched, also longer. Because of the required voltage per mm you then need a higher ignition tension.
Some time ago Honda RS125s would not run with more than 0,4 mm electrode gap, whereas Aprilia used 0,7 mm gap. Then Honda offered a kit with a different (better!) ignition system...

Talking about better ignition systems: our fellow forum member Emotracing offers something nice:
an ignition extension. The normal ignition takes care of the ionisation channel; then as soon as the current starts to flow, the Emot-set sends a big extra current through this channel. It looks like this: http://www.youtube.com/watch?v=7BfQuxyWN90

And if you really want to know all about sparks, look here:
http://www.madsci.org/posts/archives/2000-04/955373778.Ph.r.html

Frits Overmars

[TZ350]

Clearly and unashamably mining the net for interesting ideas................

There is one other possible objection against effective squish. When a gas comes in contact with a solid surface, it tries to cling onto it: it forms a boundary layer. This layer of stationary gas is a fairly good heat insulator. The piston crown enjoys this insulation, as the boundary layer protects it from the combustion heat. In theory the squish flow can blow the boundary layer away, exposing the piston directly to the combustion.
But there is always a far greater danger: detonation. The shock waves in a detonating engine are a thousandfold more effective in shaking the boundary layer loose. So I prefer a good squish that speeds up combustion.

If detonation occurs, it happens in the end phase of combustion, when the pressure in the combustion chamber is high and the temperature of the unburnt mixture in the edges of the chamber is raised by the heat radiation of the burning mixture.
Effective squish flings burning parts of the mixture to the edges of the combustion chamber, igniting all mixture before detonation factors there can reach a dangerous level.

I do believe in these
micro-eddies at the inner edge of the squish band though; it is mr. Coanda making himself noticed.

At Aprilia Jan Thiel performed a series of tests with different radii at this edge. The outcome was crystal-clear: R=0 was best and the bigger the radius, the worse the result. It is all the more surprising that Honda has always stuck to a radius (sometimes as large as 5 mm).

Finally a simple advise for junior tuners: make the squish gap so tight that there is no more room for mixture; if it is not there, it cannot detonate.

Frits Overmars

Squish gap so tight that there is no more room for mixture; if it is not there, it cannot detonate, now where have we seen that before on this thread....... :laugh:



229457

Piston just kisses the copper squish band.

[Buckets4Me]

Squish gap so tight that there is no more room for mixture; if it is not there, it cannot detonate, now where have we seen that before on this thread.......... :D

about the same place you should have seen somthing about not letting water get sprayed up off the back tyre and into the carb :bleh:

[TZ350]

Ok now we have a stepper motor controled power jet........

The 'high compression brickwall' is no longer as hard as it used to be. With leaded fuel the compression ratio was 19,5; nowadays it is about 15. The 'brickwall' arose from the high expansion ratio (which is identical to the compression ratio). The higher this ratio, the more the burnt gases in the cylinder cool down before they enter the exhaust, thus lowering the resonance frequency of the exhaust system.
Riders complained that the engine would not rev, especially not in the lower gears, where the revs rose so quickly that the rising wall temperature of the exhaust pipes could not keep up with them. So you had cold exhaust gas and cold pipes.

The problem was to a large extent solved when the solenoid-controlled on/off-power jets were replaced with stepper motor-controlled jets that could continuously adjust mixture strenght, allowing the engine to rev more freely.

229455

This is it. The stepper motor itself originates from a Fiat Uno where it regulates the idling rpm

Regarding the Aprilia RSW/RSA125 single, Jan Thiel told me that in seven years of testing the racing department had not been able to establish which was best: low or high inertia. I would choose low.....

Frits Overmars

[TZ350]

about the same place you should have seen somthing about not letting water get sprayed up off the back tyre and into the carb :bleh:

Yep, at Taupo in the rain, hydrauliced the piston, jammed the ring and ruined Av's ride .......... :blank:

[speedpro]

squish velocity needs to be taken into account as well as there is an optimum amount of turbulence required in the combustion chamber to control flame propogation rate etc.
Interesting comment about the radius from the squish area into the bowl. The original MB100 chamber has a quite pronounced edge and I've had good results on the dyno by simply making it a curve with about a 3mm radius. As much as possible all other measureable variables stayed the same.

[TZ350]

Someone on this thread was talking about plugs in the piston pin instead of clips, well here is Frits doing exactly that........

Avoiding short-circuiting between transfer and exhaust ports is the most obvious goal of the plugs. But it is not the only one. Do you remember Honda's TRAC system where at low revs a resonator volume was coupled to the exhaust duct to lower the exhaust system's Helmholtz frequency (Suzuki and Kawasaki used similar systems)?
The volume inside a piston pin does more or less the same: during every revolution it is momentarily connected to the auxiliary exhaust ducts and it dampens the system's resonance, even if you don't want it to, i.e. when the engine is running in the power band.

Below left you see the latest version of the original Aprilia piston pin with domed end caps at 136 euro a piece, and at the right my re-usable click-on plugs (that also make the usual steel-wire clips superfluous) at a fraction of the price

229458

[wobbly]

The two pics of the RSA shows where and why the later version was "better".The RV port has been turn 90* and is very high but narrow, thus reducing the time the blade covers the port ( increasing the STA with the same timings).

Frits isnt quite right re Honda and the squish corner radius - the A kit engines had a sharp corner for ages - here is a pic of the chamber CNC shape I did 4 years ago for a RGV100

Re the piston pin plugs, having cutouts above the pin in the skirt is just as bad, as these also can connect the Aux Ex to the transfers.

And re crank inertia, it has to be taken in context - all the top engines run very high inertia ( but low mass),a RS125 is a pig with NO overev if you take off the flywheel and run total loss - that is why the factory and VHM had "high inertia" options.When Frits refers to "low" this still means very high in relation to a "normal" bike crank.

[TZ350]

Thanks Wob..........

[F5 Dave]

Jan Thiel has retired and the two stroke era is over so the designers dont mind shareing info, all kinds of really good info!
KTM injection well thats a strange one even though their GP two stroke program is long gone that still dont talk or release photos (press releases aside). But yes I do know how it works, supplementary injection that feds into the crankcase to richen the mixture, just another approach to a power jet.
Yeah I had heard a number of years ago of some crazy arrangement where people were injecting into the air scoops. It sounded queer & well kind of a fire hazzard & I didn't see why you would do it. But (unless it was total bolocks) maybe they were attempting a similar anti seize measure & hoping to get some atomisation of the fuel/oil in the airstream before it went under the closed slide. I'd forgotten about it till mentioned here.

[gatch]

And re crank inertia, it has to be taken in context - all the top engines run very high inertia ( but low mass),a RS125 is a pig with NO overev if you take off the flywheel and run total loss - that is why the factory and VHM had "high inertia" options.When Frits refers to "low" this still means very high in relation to a "normal" bike crank.

What type of steel do they use for cranks ? And what for the balancing weights ?

[jasonu]

What type of steel do they use for cranks ? And what for the balancing weights ?

1. Crank steel
2. Balance weight steel

Sorry, had a couple and couldn't resist...

[gatch]

1. Crank steel
2. Balance weight steel

Sorry, had a couple and couldn't resist...

It might not look like I'm laughing, but I am, really..

[speedpro]

Interesting flywheels with the constant thickness webs for reduced friction. Nice row of mallory(?) metal slugs for counterbalance.

[wobbly]

The Asian factories use SCM - 415 forgings, but for one off's then EN 36 or 39B case hardened to 58 - 62Rc is the shit.
Mallory Metal slugs are the go for ballancing, but if you want the real deal, then pay 100,000 USD for a licence, and use Depleted Uranium.

[speedpro]

"Depleted" Uranium is for pussies.

[TZ350]

Whether Frits is on the money I don't know, but this is what he has to say about squish.........

Combustion in an ideal homogeneous air/fuel-mixture has a flame speed of maybe 2 meters per second. So how is it possible that combustion in a 125 cc engine, running at 13000 rpm, is completed within 50 degrees of crankshaft revolution?
The answer is turbulence. Burning lumps of mixture are blown across the combustion chamber and then simultaneously start their own fires in every corner. The blowing is taken care of by the squish effect that pinches mixture (red on the drawing below) from between the piston (yellow) and the outer area of the cylinder head (blue).
There are programs that calculate the squish velocity, and they are all bullshit. Why? Because none of these programs take into account that at high rpm the crankshaft bends, the conrod stretches and the piston moves higher by about 1 % of the crankshaft stroke. And it makes a lot of difference for the squish velocity, whether the minimum distance between piston and head is 0,6 mm or 0,06 mm...
The higher the flame speed, the better is is for power and for the thermal load on the engine. So make your squish gap as narrow as possible: 1 % of the stroke. And do not be afraid that the slightly higher compression ratio will cause detonation; effective squish will do just the opposite.

229526

In days of old the ideal combustion chamber was considered to be a sphere with the spark plug in the center, so that the flame path was as short as possible in all directions. And because that was impractial, the next best thing was a semi-sphere. But that is ancient history; we need turbulence!
Toroidal cylinder heads are shaped so that the inital turbulence, created by the scavenging streams of fresh mixture and still present in the cylinder after the transfer ports have closed, is enhanced as the squish effect moves the mixture towards the spark plug. And after that, the toroidal turbulence takes burning lumps of mixtures from the plug area towards all corners of the combustion chamber.

Frits Overmars

229525

And this is the head Wobbly is designing for my new project, it looks the bizzz, I can't wait to get started .............

[TZ350]

Mallory Metal slugs are the go for ballancing

Where can I get Mallory Metal slugs? is it possible?.........

[TZ350]

.

Check this out for a decent sized exhaust port.

The cylinder is off a ( 360kmh??) racing model aeroplane.

229532

The amazing exhaust port eyebrows are possible as the piston dosen't have a piston ring.

[gatch]

The Asian factories use SCM - 415 forgings, but for one off's then EN 36 or 39B case hardened to 58 - 62Rc is the shit.
Mallory Metal slugs are the go for ballancing, but if you want the real deal, then pay 100,000 USD for a licence, and use Depleted Uranium.

Right so some 4140/4340 would be the go should I do a short stroke crank.

Wikipedia link on mallory metal.

http://en.wikipedia.org/wiki/Mallory_metal

[RMS eng]

Whether Frits is on the money I don't know, but this is what he has to say about squish.........

Combustion in an ideal homogeneous air/fuel-mixture has a flame speed of maybe 2 meters per second. So how is it possible that combustion in a 125 cc engine, running at 13000 rpm, is completed within 50 degrees of crankshaft revolution?
The answer is turbulence. Burning lumps of mixture are blown across the combustion chamber and then simultaneously start their own fires in every corner. The blowing is taken care of by the squish effect that pinches mixture (red on the drawing below) from between the piston (yellow) and the outer area of the cylinder head (blue).
There are programs that calculate the squish velocity, and they are all bullshit. Why? Because none of these programs take into account that at high rpm the crankshaft bends, the conrod stretches and the piston moves higher by about 1 % of the crankshaft stroke. And it makes a lot of difference for the squish velocity, whether the minimum distance between piston and head is 0,6 mm or 0,06 mm...
The higher the flame speed, the better is is for power and for the thermal load on the engine. So make your squish gap as narrow as possible: 1 % of the stroke. And do not be afraid that the slightly higher compression ratio will cause detonation; effective squish will do just the opposite.

229526

In days of old the ideal combustion chamber was considered to be a sphere with the spark plug in the center, so that the flame path was as short as possible in all directions. And because that was impractial, the next best thing was a semi-sphere. But that is ancient history; we need turbulence!
Toroidal cylinder heads are shaped so that the inital turbulence, created by the scavenging streams of fresh mixture and still present in the cylinder after the transfer ports have closed, is enhanced as the squish effect moves the mixture towards the spark plug. And after that, the toroidal turbulence takes burning lumps of mixtures from the plug area towards all corners of the combustion chamber.

Frits Overmars

229525

And this is the head Wobbly is designing for my new project, it looks the bizzz, I can't wait to get started .............

looks like a 2001 RS125 head

[k14]

looks like a 2001 RS125 head
Was just going to say the same thing. I was told that it was only good when running unleaded. But the results I had seemed to say it went pretty good running av gas too.

[Buckets4Me]

looks like a 2001 RS125 head

looks like a casting for a valve cut in half to me ?

[wobbly]

Crank wheels need a ductile core, so all the surfaces that wont be ground need to be painted with a copper based coating to prevent the hardening gas from thru hardening the whole part.
EN39B is the best material and is readily available.Heat treatments ltd can do all the processes including stress relief after rough machining the shape - talk to Adam there if you are going to do a crank.

I have some Mallory slugs in stock.

A true Toroid shape was developed to control deto with unleaded fuel, the processes involved work just as well with better octain fuels.

The zero corner rad was a "secret" for years that I tried for the first time when working with Bartol on his Yamaha and my BSL cylinder layout - well before Thiel and Aprilia got onto it.
But its funny how people make "assumptions" that are usually revealed later as "errors".
A CFD analysis of the Toroid head shows that the mixture ejected from the squish, actually adheres to the vertical wall, around the sharp corner, and rotates anticlockwise - opposite to what Frits shows.
This is why it works even better with a flat top piston.
Who cares though - it works.

I dunno where Frits is getting his info from but the Dellorto with the "Fiat Uno" stepper motor was soon replaced by the stock Keihin solenoid as shown in the pic above.
This was better than the original solenoid in that it can be "pulsed" or PWM controlled by the ECU to vary the fuel flow as needed when the Deto sensor ( on the head - from a Subaru) said bad shit was happening.

[speedpro]

My crankpin was made by heat treatments. machined, heat treated, and ground. Hasn't let go yet but still early days. 20mm ends with a 22mm centre, offset .75mm. Very helpful guys.

[F5 Dave]

So how do they get on with caged bearing offset pins? Yours would be ok as the offset could go another .25 & still slide the bearing straight on, but what about larger offsets? My 500 crank has a 7mm offset & I imagine same size centres & ends. Never really had to think about that before. Non caged rollers would be an option, but bags not load them.

[kel]

I dunno where Frits is getting his info from but the Dellorto with the "Fiat Uno" stepper motor was soon replaced by the stock Keihin solenoid .

Yeah he corrected this in his next post stating the Keihin solenoid replaced the stepper motor and is the same unit as used on the RS125.

[gatch]

Crank wheels need a ductile core, so all the surfaces that wont be ground need to be painted with a copper based coating to prevent the hardening gas from thru hardening the whole part.
EN39B is the best material and is readily available.Heat treatments ltd can do all the processes including stress relief after rough machining the shape - talk to Adam there if you are going to do a crank.

I have some Mallory slugs in stock.



If I do, it'll be a 3 piece..

I should be able to harden/grind everything at work, I think..

Last time I used the tool post grinder I made a guard for it as it didn't have one, the next guy who used it threw the guard out "coz it's for poofts and amateurs", then the cup wheel he had on exploded.. :niceone:

[TZ350]

.

My new carb, not exactly the one Wobbly suggested ... but something to look at and learn how it is supposed to be used.

229592

Throttle position sensor and electric power jet.......... how are these used?

[kel]

My new carb,

KX125? I love ebay

[kel]

Come to think of it didnt Kawasaki dump this carb after only a couple of years and go to the no frilles Mikuni TMX

[TZ350]

KX125? I love ebay

Me too .


...... didnt Kawasaki dump this carb after only a couple of years .....

............... what :( ............ no, your just trying to upsetme ...... :msn-wink:

[TZ350]

My early efforts at a retarding ignition......


Well that was fun, an afternoon on the dyno with Gavin from Henderson motorcycles dialing in the RM retarding ignition. The idea was to have the ignition over advanced in the lower revs to pickup some extra torque and then retard back for max power as the revs went up.

229625

What Frits has to say about how retarding ignitions work.

"" In a 125 cc race engine the spark-plug sparks at about 14° BTDC @ 13000 rpm. Then combustion starts really slow: after the spark another 10° go by before you can detect the first signs of combustion. Then combustion continues for a little over 40° (this is at full throttle; with less cylinder filling, combustion is a lot slower).

Is it useful to slow down combustion on some operating phases? Yes and no. I will try to explain this in a little physics lesson.
No matter which way the piston is moving, as long as there is combustion, the pressure in the cylinder keeps rising. Only after combustion is finished the expansion of the burnt gas can begin.
Slow combustion means that the piston is already well on its way down before expansion can begin; it means less expansion for the burnt gas in the cylinder before the exhaust ports open.
Less expansion means less cooling down of the gas in the cylinder: it is still hotter when it enters the expansion chamber. In hotter gas the speed of sound is higher and that means a higher resonance frequency for the cylinder-pipe system, so it works better at high rpms.

But how do you slow the combustion speed down? Less squish? Mixture too rich? You do not want to do that...
Fortunately there is a simpler solution. We do not slow combustion down; we just start it later: we retard the ignition timing. As far as the exhaust gas temperature in the expansion chamber is concerned, the effect is the same: the engine runs better at high revs.
That is the reason for programmable ignition systems.
Below the power band the ignition advance can be more than 30° so that there is a whole lot of expansion; the burnt gas contains hardly any energy when it enters the exhaust pipe, so the exhaust pulses that arrive at the wrong moments at low rpm, are weak and will not disturb the scavenging too much.
At the rpm of maximum torque the ignition advance is about 14° (careful, a litte too much advance here and you get detonation), and at maximum revs the advance can be 10° or less (Honda even went to 3° after TDC"

A programmable ignition is the way to go.........


I got the job of setting up NedKellys IgniTech programmable Ignition.

With the initial advance setup more or less where you want it, you are ready to rock and roll on the dyno optimizing the ignition curve.

The IgniTech software is very clever as changes to the ignition curve can be made on the fly and the Ignition itself re-programed while the engine is still running............

There are more pictures and a vido on the original post.

Some Pictures from Buckets post on setting up a programmable ignition from scratch.

[TZ350]

Frits's ideas on radiusing the edge of the barrel where the transfers are.

""noticed that the inner radius of your transfer ducts ends in a sharp edge at the cylinder bore.
Most cylinders are like that. But not the Aprilia RSA...
Below I have tried to show this, using a picture of my FOS cylinder (which has radii identical to the RSA).
There is some good horsepower in that modification"" Frits.

229642

[TZ350]

.

I am out serching for a piston and rod kit for my new project.

Here is TKR's home site, http://www.tkrj.co.jp/product/index.html

There is a 13mb PDF download catalog with dimensions.

[TZ350]

229681

Can't wait to see what Wob is cooking up.

229680

Desperatly keen to get started on my Wobbly engine.

229679

Who said money and a smile can't buy you an Aprilia RSA

[TZ350]

229682

How many hp is that on a 28mm carb? I make it around ....... 50!!!!!

[TZ350]

Buddfab Motorcycle Streamliner –Worlds Fastest Small Displacement Motorcycle

50cc, 100cc, and 125cc World Records (pending FIM ratification)

This is how they ran:
50cc Blown Fuel 144.891mph
100cc Gas Normally Aspirated 155.110mph
125cc Fuel Normally Aspirated 186.649mph (over 300kph)

Eric’s cockpit video of the 125cc 187mph down run:
http://www.youtube.com/watch?v=Vz_r_3yqqR4

John’s cockpit video from last year of a 50cc 141mph return run:
http://www.youtube.com/watch?v=mYINrhTNiyM

2009 BUB Report:
http://www.geocities.com/buddfab/buddfab3

Scraped from the net........ interesting speeds from 50's and 125's and shows what aerodynamics can do for you.

[speedpro]

229682

How many hp is that on a 28mm carb? I make it around ....... 50!!!!!

I was chatting to JC yesterday and it sounds like the carb restriction for aircooled 125s is close to being a thing of the past. I mentioned to him that it generally wasn't considered to be a handicap now but I didn't get the impression he was going to stop the change. He sees the restriction to air-cooling as being the limiting factor which I think TZ would agree with.

He had some interesting thoughts on the "fast" FXR150s and cited figures from other quick 4 strokes.

[speedpro]

229682

How many hp is that on a 28mm carb? I make it around ....... 50!!!!!

I was chatting to JC yesterday and it sounds like the carb restriction for aircooled 125s is close to being a thing of the past. I mentioned to him that it generally wasn't considered to be a handicap now but I didn't get the impression he was going to stop the change. He sees the restriction to air-cooling as being the limiting factor which I think TZ would agree with.

He had some interesting thoughts on the "fast" FXR150s and cited figures from other quick 4 strokes.

[TZ350]

I was chatting to JC yesterday and it sounds like the carb restriction for aircooled 125s is close to being a thing of the past. I mentioned to him that it generally wasn't considered to be a handicap now but I didn't get the impression he was going to stop the change.

I think it was Wobbly and others too, have pointed out that fast kart engines make over 30hp with 24mm carbs.


He sees the restriction to air-cooling as being the limiting factor which I think TZ would agree with.

Traditionaly aircooled F4 125's 2Ss have always lagged behind the 100cc water cooleds and I havent been able to do any better either, its a water cooled 100 for us next year.

[ajturbo]

Remember going to watch at Mt Welly many moons ago, at the height of the RG50 era. F5 bikes outnumbered F4 by two or three to one. Wonder where they all went, given that there are about five regular F5 runners in Auckland now.


still got mine......:bleh:

[ajturbo]

I was chatting to JC yesterday and it sounds like the carb restriction for aircooled 125s is close to being a thing of the past. I mentioned to him that it generally wasn't considered to be a handicap now but I didn't get the impression he was going to stop the change. He sees the restriction to air-cooling as being the limiting factor which I think TZ would agree with.



FUCK YEAH..!!!

GT125's rule.... (if i could ride it that is..lol)

[wobbly]

Get it right guys - the 125 KZ2 kart engines make 44RWHp = around 50 crank at 13000 with a 30mm restricted carb,pump gas and a straight line ignition.

The issue with the aircooled I believe is the basic technology available, if it was allowed to use aftermarket cylinder castings with super sex ports/ducts, that equal those in say a RGV250 for example, then its easy to build a rocket.
The bmep is lower in the 125 size cylinder, making the same power as a 100, so the 24mm carb would not be such an issue.
But if the carb restriction was lifted, then a serious relook would be needed.

[jasonu]

I was chatting to JC yesterday and it sounds like the carb restriction for aircooled 125s is close to being a thing of the past. I mentioned to him that it generally wasn't considered to be a handicap now but I didn't get the impression he was going to stop the change. He sees the restriction to air-cooling as being the limiting factor which I think TZ would agree with.

He had some interesting thoughts on the "fast" FXR150s and cited figures from other quick 4 strokes.

How is it up to JC to stop or not stop this or any rule change? I thought there was a process that involved putting in a remit to your club and then the club decides wether or not to take it to the MNZ or ACU agm.
Please correct me if I am wrong.

[CM2005]

How is it up to JC to stop or not stop this or any rule change? I thought there was a process that involved putting in a remit to your club and then the club decides wether or not to take it to the MNZ or ACU agm.
Please correct me if I am wrong.

All he has to do is submit it through the AMCC then, i'm sure no-one will complain if the playing feild is levelled slightly.

[jasonu]

All he has to do is submit it through the AMCC then, i'm sure no-one will complain if the playing feild is levelled slightly.

What do you mean by levelled slightly? TZ350's GP makes 27hp with a 24mm carb. There is only a handful of H2O 100's that make more. That sounds 'level' to me.
Just because other 125'ers have not had the same success with their bikes doesn't automatically mean the rules should be changed to make it easier.
Also, if the presant carb restriction is, as others are saying, not the limiting factor for the 125 aircooled bikes, then why bother changing the rule at all. Quote from Wobbly 'But if the carb restriction was lifted, then a serious relook would be needed'... Yeah no shit!
TZ350's bike 27hp with 24mm carb, obviously more hp with no carb restriction.

[ajturbo]

What do you mean by levelled slightly? TZ350's GP makes 27hp with a 24mm carb. There is only a handful of H2O 100's that make more. That sounds 'level' to me.
Just because other 125'ers have not had the same success with their bikes doesn't automatically mean the rules should be changed to make it easier.

there is always ONE who needs more power than anyone else..... unfortunately I also fall into that category :doh:

[Kickaha]

there is always ONE who needs more power than anyone else..... unfortunately I also fall into that category :doh:

That's because you're a fat cunt, lay off the pies and you wont need as much HP

[CM2005]

there is always ONE who needs more power than anyone else..... unfortunately I also fall into that category :doh:

me too, i need power to make up for my riding inadequacies.

[TZ350]

How is it up to JC to stop or not stop this or any rule change? ....... Please correct me if I am wrong.

I don't think your wrong, but things may have changed a little. After MNZ has received a proposed rule change from where ever, competitor or club, they talk with people recognised as knowledgable in the area, if it sounds sensible then MNZ list it on their web site for input and comment after that things could change or be left as they were depending on feedback.

I guess MNZ have been talking to JC about a suggested rule change and he could back it or poo poo it depending on how he sees it. JC probably won't be the only one they have talked with.

Anyway something like that..................

MNZ's compition rule change policy:- http://www.mnz.co.nz/download/Competition_Rule_Change_Policy.pdf

[TZ350]

me too, i need power to make up for my riding inadequacies.

Double ditto, me too ........

[richban]

He had some interesting thoughts on the "fast" FXR150s and cited figures from other quick 4 strokes.

And what was so interesting. Did he mention its really hard to get much more than 160hp per liter of on a air cooled 4 stroke single. The only rule change should be for the 4 strokes. Bigger bigger bigger.

[Buckets4Me]

And what was so interesting. Did he mention its really hard to get much more than 160hp per liter of on a air cooled 4 stroke single. The only rule change should be for the 4 strokes. Bigger bigger bigger.

they had the last rule change our turn now:bleh:

[jasonu]

they had the last rule change our turn now:bleh:

Yes, 4 stroke 145cc changed to 150cc which is why buckets is as popular as it has ever been.

[Buckets4Me]

Yes, 4 stroke 145cc changed to 150cc which is why buckets is as popular as it has ever been.


i'll take a 5mm change 24mm to 29mm carb :bleh:

if it wasent for the fxr150's it would be a lot easier for the 2 strokes to get threw the traffic to the frount :blank:

[Buckets4Me]

And what was so interesting. Did he mention its really hard to get much more than 160hp per liter of on a air cooled 4 stroke single. The only rule change should be for the 4 strokes. Bigger bigger bigger.


yep easy if you swap it for a cbr150 :weird:

JC having been involved with racing cbr150's in aussie has mentioned that the fxr dosent stand a chance against a developed cbr

[richban]

yep easy if you swap it for a cbr150 :weird:

JC having been involved with racing cbr150's in aussie has mentioned that the fxr dosent stand a chance against a developed cbr

Not seen a fast one yet. Bike that is.

[Kickaha]

JC having been involved with racing cbr150's in aussie has mentioned that the fxr dosent stand a chance against a developed cbr

A couple of those CBRs have been racing down here, they not really much flasher than a FXR

[koba]

yep easy if you swap it for a cbr150 :weird:

JC having been involved with racing cbr150's in aussie has mentioned that the fxr dosent stand a chance against a developed cbr

Has JC seen Rich and Andrew on their FXRs?

[Ned Kelly]

Has JC seen Rich and Andrew on their FXRs?

JC was in the pit crew working on you Daniels bike at TAUPO. He was watching the buckets and i am sure he knows who they are.

[wobbly]

I think you guys need to be aware of the "expert" factor.
We are dealing with fukin buckets afterall, and if Kev had a chance to develop the "best" 150 - 4T to the highest level he could ,he would be easily be able to better anyone on the planet with that engine.
Unfortunately for him there is another expert or two around that can easily kick his arse right off this planet with a properly developed 2T - 100, that are inherently superior , due to the fact we only need 2 strokes to get off, big time.
We have to applaud TZ350s results, in the 2 stroke arena, just as we have to applaud the 4 stroke - 150 riders results, but at the end of the day, when real experts get involved it comes down to Physics, and sorry guys but an aircooled 125 with the port and pipe technology from an RSA, would simply destroy anything you could possibly dream off - all it takes is knowledge and cash.
This is a close run thing - the H2O - 100 would have to be wound tighter to achieve the same bmep level as the 125 aircooled, but would be capable of maintaining that power level , for longer - and easyer.
Sorry, but even with Kev doing the buisness, the 4T is fucked when the 2T is even 1/2 done well.
I for one woudnt put money on who would win if the riders and chassis were on the money, with equally deep benches.
You pays your moneys - and takes your chances.

[koba]

JC was in the pit crew working on you Daniels bike at TAUPO. He was watching the buckets and i am sure he knows who they are.

True.

I liked the MB100 with his JCR stickers on it, Dave Manuel was it?


I think you guys need to be aware of the "expert" factor.
We are dealing with fukin buckets afterall, and if Kev had a chance to develop the "best" 150 - 4T to the highest level he could ,he would be easily be able to better anyone on the planet with that engine.
Unfortunately for him there is another expert or two around that can easily kick his arse right off this planet with a properly developed 2T - 100, that are inherently superior , due to the fact we only need 2 strokes to get off, big time.
We have to applaud TZ350s results, in the 2 stroke arena, just as we have to applaud the 4 stroke - 150 riders results, but at the end of the day, when real experts get involved it comes down to Physics, and sorry guys but an aircooled 125 with the port and pipe technology from an RSA, would simply destroy anything you could possibly dream off - all it takes is knowledge and cash.
This is a close run thing - the H2O - 100 would have to be wound tighter to achieve the same bmep level as the 125 aircooled, but would be capable of maintaining that power level , for longer - and easyer.
Sorry, but even with Kev doing the buisness, the 4T is fucked when the 2T is even 1/2 done well.
I for one woudnt put money on who would win if the riders and chassis were on the money, with equally deep benches.
You pays your moneys - and takes your chances.

So true. Although I'm not even an expert enough to know what approach would be the best if pushed to the limit.

I know you think 4 strokes are poojabber motors but I know I would definatley be able to lap long and short tracks faster on a well developed 4 stroke.

I suspect only exceptional riders (there are quite a few in buckets) would be able to make the most of any extra power given by the superior (2T) type of motor.

[koba]

I suspect only exceptional riders (there are quite a few in buckets) would be able to make the most of any extra power given by the superior (2T) type of motor.

I know quoting oneself is a bit ego but, was just re-reading that and thinking perhaps I went off a bit premature.

Just started thinking about weight and how fucken awesome my MB based bike is to ride... Maybe I'm talking shit after a few beers...

[gatch]

I know quoting oneself is a bit ego but, was just re-reading that and thinking perhaps I went off a bit premature.

Just started thinking about weight and how fucken awesome my MB based bike is to ride... Maybe I'm talking shit after a few beers...

I'll get you Nabbs, on my poojabber powered, massive street tired spada.

Ohhhhh if it's the last thing I do.

[speedpro]

Personally I was a bit disappointed to hear the carb restriction was being lifted. Not because I'm afraid of being beaten, I'm used to that, but because I don't like seeing rule changes that aren't needed.
As for how fast Richban's bucket is, and what size, you only have to watch the videos he posted and see Fish dealing to him and Andrew on his Longchin to realise it isn't all about horsepower.
I've started on my new cylinder. Not totally sure where it will end but I'm aiming to break 30, and I still won't win.:crybaby:

[koba]

I'll get you Nabbs, on my poojabber powered, massive street tired spada.

Ohhhhh if it's the last thing I do.

I have a bit of a conundrum.

I want to leave my bike as it is to school you on it but as the carb is severely limiting its power at the moment Dave has put the hard word on me to upgrade it.
If I beat you with the big carb it would be as hollow as a teenage girls head. I think I may have to risk the wrath of Dave threats to do horrible things should he ever see that standard carb again...

[koba]

Personally I was a bit disappointed to hear the carb restriction was being lifted. Not because I'm afraid of being beaten, I'm used to that, but because I don't like seeing rule changes that aren't needed.
As for how fast Richban's bucket is, and what size, you only have to watch the videos he posted and see Fish dealing to him and Andrew on his Longchin to realise it isn't all about horsepower.
I've started on my new cylinder. Not totally sure where it will end but I'm aiming to break 30, and I still won't win.:crybaby:

Are they going to? Looking at it? aye?!

I agree, well intentioned but un-necessary rule changes ruin race classes.

Edit: Nothing on MNZ website under proposed rule changes bit.

[gatch]

I have a bit of a conundrum.

I want to leave my bike as it is to school you on it but as the carb is severely limiting its power at the moment Dave has put the hard word on me to upgrade it.
If I beat you with the big carb it would be as hollow as a teenage girls head. I think I may have to risk the wrath of Dave threats to do horrible things should he ever see that standard carb again...

By the time I get all (claimed) 16 horse powers reined in front of my buggy you will be wishing you listened to mr Dave.. He'll beat you good.

So will I nyaahahah

[TZ350]

.
Thinking out side of the box here.

Now the GP125 is limited by the size of the inlet port possible with the side mounted rotary valve.

And reed valves work best at a particular rpm depending on their phsical characteristics.

Then would it be possible to have a reed on the other side of the engine for two carbs, a rotary valve and reed valve.

And have the throtle connected to one carb and the IgniTech ignition controle the other carb, opening it for WOT conditions like it does the power valve for rpm and thereby get a much increased port area at WOT and broad spread with the smaller throtle controled carb at lesser rpm.

Then there is the posibility of adding another rotary valve to the other side of the engine.

This is buckets and we are allowed to think about these things.

[RMS eng]

.
Thinking out side of the box here.

Now the GP125 is limited by the size of the inlet port possible with the side mounted rotary valve.

And reed valves work best at a particular rpm depending on their phsical characteristics.

Then would it be possible to have a reed on the other side of the engine for two carbs, a rotary valve and reed valve.

And have the throtle connected to one carb and the IgniTech ignition controle the other carb, opening it for WOT conditions like it does the power valve for rpm and thereby get a much increased port area at WOT and broad spread with the smaller throtle controled carb at lesser rpm.

Then there is the posibility of adding another rotary valve to the other side of the engine.

This is buckets and we are allowed to think about these things.
look up, Puch 250 MX o the net.had two carbs .disc and piston port,20 years ago Jason and i made this bridge port RG50 cylinder,just to see how hard it would be,waste of time now just get a Derbi GPR 50 cylinder some have bridge ports STD as did the old honda NSR80.2 photos of 1978 50cc gp bike 28mm carb 21hp.229751229752229753

[jasonu]

Are they going to? Looking at it? aye?!

I agree, well intentioned but un-necessary rule changes ruin race classes.

Edit: Nothing on MNZ website under proposed rule changes bit.

That is what I thought. Spill the beans Mike, I suspect you have some actual inside info about this carb thing and the 4 strokes as well.

If, as TZ said a rule chance proposal was put forward to MNZ ant they are talking to folks like JC, where or who did the original proposal come from?

I totally stand by my previous statement 'if the 24mm carb restriction is NOT the power limiting factor for the 125's (bullshit) then why the move to change the rule?' Things seem farily balanced at the mo 2t h2o 2t 125ac and 4t 150 all have
+'s and -'s depending on the track, rider, chassis.

If rule changes are made everytime someone shows up with a 'better' bike or someone claims they can't get enough power from their engine, it won't be good for buckets. If, and it will, this change makes the 125 aircoolers significantly better than they are now (remember TZ350 is currently makeing 27hp), what next allow 125 H2O motors, MX85 motors, 150 2T aircoolers, 175 4T??? Won't be 'Buckets" as we know it anymore.

IMO the biggest thing that limits MOST of the 125 aircoolers is putting high HP engines like Tzees 125 into uncompetitive chassis that don't do the motor justice. Not to point the finger but a prize example of this is TZ350's bike (sorry mate). He has most likely the best 125 aircooled motor but is running it in the heavy and uncompetitive GP chassis. If that bike was 20kg lighter and more (rs125) racey...

[jasonu]

.
Thinking out side of the box here.

Now the GP125 is limited by the size of the inlet port possible with the side mounted rotary valve.

And reed valves work best at a particular rpm depending on their phsical characteristics.

Then would it be possible to have a reed on the other side of the engine for two carbs, a rotary valve and reed valve.

And have the throtle connected to one carb and the IgniTech ignition controle the other carb, opening it for WOT conditions like it does the power valve for rpm and thereby get a much increased port area at WOT and broad spread with the smaller throtle controled carb at lesser rpm.

Then there is the posibility of adding another rotary valve to the other side of the engine.

This is buckets and we are allowed to think about these things.

As long as you meet the equilivent to 24mm carb rule. However, if that rule is changed...

[Buckets4Me]

IMO the biggest thing that limits MOST of the 125 aircoolers is the crap chassis guys are using. Not to point the finger but a prize example of this is TZ350's bike (sorry mate). He has most likely the best 125 aircooled motor and is running it in the heavy (and shitty, sorry again) GP chassis. If that bike was 20kg lighter and more (rs125) racey...



so the fzr250 delta box chassie and spoked wheels at 80kg is to heavy ???:sleep:

229754 chambers bike but much the same

[jasonu]

so the fzr250 delta box chassie and spoked wheels at 80kg is to heavy ???:sleep:

229754 chambers bike but much the same

I did use the word 'MOST' in my statement and have since reworded it.

[bucketracer]

Personally I was a bit disappointed to hear the carb restriction was being lifted...........but because I don't like seeing rule changes that aren't needed.

It might be, that because TeeZee is so good at getting air flow through his carbs, not only the sleeved one but his special one that's 24mm at the original slide position that they are leveling the playing field for other 125 builders by allowing them an easy way to keep up with TeeZee's efforts.

Or you could of course just ban any carb modified/made by TeeZee and forbid him to exercise any cleverness .........

[jasonu]

It might be, that because TeeZee is so good at getting air flow through his carbs, not only the sleeved one but his special one that's 24mm at the original slide position that they are leveling the playing field for other 125 builders by allowing them an easy way to keep up with TeeZee's efforts.
Or you could of course just ban any carb modified/made by TeeZee and forbid him to exercise any cleverness .........

But that is the whole point. TZ has proved good power can be made under the presant rules so therefore so can other tuners. The rule doesn't need to be changed.


Only modifications made by anyone that are outside of the rules should be banned/protested. TZ has been clever enough to make his mods work within the rules.

[Henk]

I liked the MB100 with his JCR stickers on it, Dave Manuel was it?


Yep

I'm curious to see what the result of the rumoured rule changes is. Things seem to work ok at the moment. The carb change to 125 air cooled bikes probaly won't make a huge difference to the way things stand at the moment, at the front you need a fast bike and a fast rider, there is nothing I can see that will change this unless something comes about that makes the majority of bikes obsolete overnight (such as MX motors).
The reason Diesels are so popular right now is that they are easily available and cheap to put together, I'm sure that if there was either a 125AC or 100LC that was out there in numbers on the second hand market, at about 10 years old the grids would be packed with them instead of FXRs.

[TZ350]

.

If there is one thing I have learnt, its that, the right sort of HP helps but by itself it does not win races no matter how much you have .....

[richban]

. If there is one thing I have learnt, its that, the right sort of HP helps but by itself it does not win races no matter how much you have .....

True that.

To Mikes point you can easily see both Andrew and I have the legs on fish so how can he win so much. Skill!.

To what Wobbly said. The first time I raced the GP Kev was there and he asked me what the 2 stroke rules were. I told him and he said then why aren't they pasting you .... He new straight away there was an advantage in the rules for a well developed or half developed 2 stoke as wobbly an expert has confirmed. The fastest lightest "bikes" with the most HP are 2 strokes end of story. And as wobbly has mentioned if you sent the best base engine you could find to Kev with and open cheque book and did the same to wobbly. Wobbly would win with the current rules.

[kel]

True that.

And as wobbly has mentioned if you sent the best base engine you could find to Kev with and open cheque book and did the same to wobbly.

Ah now thats bucket racing - wheres the cheque book?

[jasonu]

I hope the MNZ read this piece of TZees (excellent, best one on KB by far) thread BEFORE makeing any decisions re. the carb rule.

[koba]

I hope Mike isn't sitting there giggling at a successful windup

[speedpro]

I've checked the MNZ website for contact details for the Road Race Commissioners and called them. I only got through to one and he was aware of the proposed change and was happy to listen to my view of the change. I encourage others to put their view forward as well. The commissioners and others are due to discuss the proposal and then make a decision. Generally it doesn't sound like they will be getting advice from people such as Wobbly but rely on people calling in.

So do it!

[Buckets4Me]

But that is the whole point. TZ has proved good power can be made under the presant rules so therefore so can other tuners. The rule doesn't need to be changed.


Only modifications made by anyone that are outside of the rules should be banned/protested. TZ has been clever enough to make his mods work within the rules.


I think that the rule change was started some time ago :blank:
before TZ350 got any sort of power out of his bike

[koba]

I've checked the MNZ website for contact details for the Road Race Commissioners and called them. I only got through to one and he was aware of the proposed change and was happy to listen to my view of the change. I encourage others to put their view forward as well. The commissioners and others are due to discuss the proposal and then make a decision. Generally it doesn't sound like they will be getting advice from people such as Wobbly but rely on people calling in.

So do it!

That's shit as that the website says nothing!

[koba]

Hell, I stand to benefit from such a rule change yet I still don't want it!

[speedpro]

Hell, I stand to benefit from such a rule change yet I still don't want it!

Call then. To make it simpler here are the two to phone. I spoke to Neil.

Road Race Commission Chairman Peter Ramage 09 443 3111 a/h
Road Race Commission Neil Smith 03 5786208 a/h

[speedpro]

Hell, I stand to benefit from such a rule change yet I still don't want it!

In the end you don't stand to benefit which is the point that needs to be made. the 24mm carb restriction is not the limiting factor in the end. With little or no mods, or poorly done mods, then a bigger carb "may" give you more power, but at the end of the day if everything is done right then the carb is not going to be what stops you making more power. On top of that the engines the rule applies to all have suspect cranks, sub-standard gearboxes, and poor design cylinders. All are fixable before you need to start worrying about the carb, which isn't a problem.

[jasonu]

I hope Mike isn't sitting there giggling at a successful windup

Na, it's on the internet so it must be true...

[richban]

Na, it's on the internet so it must be true...

Heard the one about air cooled 4 strokes going to a 190cc capacity limit to have a change against the 30hp 2 strokes. Got until the 25th Of Feb for submissions to MNZ.

[speedpro]

Geez, that'll be a bitch. Will you sleeve yours down or destroke it?

[jasonu]

Heard the one about air cooled 4 strokes going to a 190cc capacity limit to have a change against the 30hp 2 strokes. Got until the 25th Of Feb for submissions to MNZ.

As far as I know, no 2 stroke has cracked 30hp (YET!!!)

[richban]

Geez, that'll be a bitch. Will you sleeve yours down or destroke it?

Nearly spat my coffee all over my keyboard. Nice one. I was thinking of just taking it up to a 250.

[koba]

In the end you don't stand to benefit which is the point that needs to be made. the 24mm carb restriction is not the limiting factor in the end. With little or no mods, or poorly done mods, then a bigger carb "may" give you more power, but at the end of the day if everything is done right then the carb is not going to be what stops you making more power. On top of that the engines the rule applies to all have suspect cranks, sub-standard gearboxes, and poor design cylinders. All are fixable before you need to start worrying about the carb, which isn't a problem.

Would the water cooling still be more of an advantage than 25cc on a Kart track type motor?? i.e. broad power, shorter periods on full welly...

[koba]

Call then. To make it simpler here are the two to phone. I spoke to Neil.

Road Race Commission Chairman Peter Ramage 09 443 3111 a/h
Road Race Commission Neil Smith 03 5786208 a/h

Don't have a phone (really!) but I E-mailed MNZ this morn.

(I know it doesn't make sense that I'm on the internet but its wireless doesn't need a landline)

[wobbly]

Its as was said by Mike a few posts back - the aircooleds are more hindered by crap geabox ratios, crap cylinder geometry etc etc.
If it was possible to get a port/duct layout like an RGV cylinder ( even thats not a very good example) into an aircooled, the 25% increase in cubes would make it a very potent machine.
And as I said, if its possible to get 44RWHp from the kart engines using a 30mm carb,crap fuel and an analogue straight line ignition, then using a 24mm carb and trick shit ignition, is going to get 30+ RWHp easy, with good ports.

[TZ350]

IMO the biggest thing that limits MOST of the 125 aircoolers is putting high HP engines like Tzees 125 into uncompetitive chassis that don't do the motor justice. Not to point the finger but a prize example of this is TZ350's bike (sorry mate). He has most likely the best 125 aircooled motor but is running it in the heavy and uncompetitive GP chassis. If that bike was 20kg lighter and more (rs125) racey...

Your right about the original 96kg GP chassis, they had pretty much come to the end of the road, handling wise and a RS chassis would be the Bees Knees if I could fold up enough to fit onto one. Currently there are two RS chassis in Team ESE, Buckets4mes and NedKellys.

My FZR (3LN rolling chassis) weighs much the same as the old GP but handles much better and is comfortable to ride. Chambers FZR with the wire wheels, lighter rear calliper and other refinements is down to 83kg with a dash of fuel and with a lighter rider like Av or Chambers it sure looks the part.

Chambers FZR lightened rolling chassis is not quite as light as an RS but it's light years ahead of the GP's in weight and handling and more comfortable for me to ride than the RS's.

NedKelly will probably get my old 27hp engine or something else for the new season, and Buckets will get an upgrade too so it will be interesting to see how the old GP engines with a bit of hp go in RS chassis.

And I hear Av has got herself an RS chassis and GP engine to build a superduper Bucket with, and if/when that hits the track it should get interesting .............

[Yow Ling]

Your right about the original 96kg GP chassis, they had pretty much come to the end of the road, handling wise and a RS chassis would be the Bees Knees if I could fold up enough to fit onto one. Currently there are two RS chassis in Team ESE, Buckets4mes and NedKellys.

My FZR (3LN rolling chassis) weighs much the same as the old GP but handles much better and is comfortable to ride. Chambers FZR with the wire wheels, lighter rear calliper and other refinements is down to 83kg with a dash of fuel and with a lighter rider like Av or Chambers it sure looks the part.

Chambers FZR lightened chassis is not quite as light as an RS but it's light years ahead of the GP's in weight and handling and more comfortable for me to ride than the RS's.

NedKelly will probably get my old 27hp engine or something else for the new season, and Buckets will get an upgrade too so it will be interesting to see how the old GP engines with a bit of hp go in their RS chassis.

And I hear Av has got herself an RS chassis and GP engine to build a superduper Bucket with, and if/when that hits the track it should get interesting .............

RS frames they stacked 10 high in peoples sheds
Honda made 1000 of them in the first year, only any good for buckets now !

[Buckets4Me]

RS frames they stacked 10 high in peoples sheds
Honda made 1000 of them in the first year, only any good for buckets now !


well if you find some spare can you let me know as I would like another rolling frame
thanks

I have 2 boys coming of age and they would like to have a bike each to ride

[jasonu]

RS frames they stacked 10 high in peoples sheds
Honda made 1000 of them in the first year, only any good for buckets now !

That was a few years ago now. I ( and probably so do you) know a guy who bought 2 1/2 RS rolling chassis for $700 in the late 90's. Now you pay that much for just a pair of RS wheels if you can find them.

[TZ350]

.
Wobbly has sent me drawings for the RGV H2O 100 in Reed and Rotary Valve configurations.

I am planning on using what I have about the place, so it’s a TF100 bottom end for the case reed motor and a GP100 for the rotary valver.

But I am tempted to ask Wobbly to put some details together for a 125 aircooled rotary valve version based on the old GP125 instead as the GP’s have been such good friends and I rather like them.

[kel]

.
Wobbly has sent me drawings for the RGV H2O 100 so it’s a TF100 bottom end for the case reed motor.


Hasnt Green already tried the TF RGV conversion?

Regarding the 125 - We have a family friend who is a CNC engineer/operator, he's going to machine a block of ally to form the ideal transfer ducts (based on the RSA of course) then we'll glue them into the side of the cylinder. Of course it will be a 130cc not 125 giving me an extra 30% capacity to blow past your little 100, plus I've already bought the 32mm carb to take advantage of the latest rule change.
27hp :sleep:

Oh yeah, does anyone have a spare KE125 barrel?

[Yow Ling]

Oh yeah, does anyone have a spare KE125 barrel?

Just get your CNC guy to start with a bigger block of Aluminium !

[speedpro]

Screw the barrel, you want the whole motor - sweeet gearbox and the rest can be fixed.

[RMS eng]

.
Wobbly has sent me drawings for the RGV H2O 100 in Reed and Rotary Valve configurations.

I am planning on using what I have about the place, so it’s a TF100 bottom end for the case reed motor and a GP100 for the rotary valver.

But I am tempted to ask Wobbly to put some details together for a 125 aircooled rotary valve version based on the old GP125 instead as the GP’s have been such good friends and I rather like them.

why not just make a head and weld a water jacket on a GP100 cylinder,or use a RG400 cylinder,you may end up with the same problems ND has with his RGV100 on the fast tracks,you would need a sleeve around 5-6mm thick to stop the bridge getting to hot.the RGV150 cylinders have a hole in the alloy part of the bridge for water to pass through for better cooling

[kel]

Screw the barrel, you want the whole motor - sweeet gearbox and the rest can be fixed.

I dont know what you heard about my gear box, malicious lies Id say.
But seriously I do need another barrel, must be a few left over from all those RG conversions?

[TZ350]

.

The things that turn up at work.

230169

Afterburner, a 16 foot long drag bike ....... :eek:

230168

680+ rwhp, and we are busting our arses looking for 30 ......... :facepalm:

[TZ350]

why not just make a head and weld a water jacket on a GP100 cylinder,or use a RG400 cylinder

The GP and RG400 cylinders with their single exhaust port don't allow enough blowdown time area to make decent power. But I could sleeve an aircooled GP125 cylinder and add a T or tripple exhaust port, but thats not so easy to do with a RG400 cylinder as there is not much meat around the exhaust port area on one of those.


you may end up with the same problems ND has with his RGV100 on the fast tracks,

I am not sure what the cause of ND's problems was, or what the sleeve he used was made of, or if he fitted an iron sleeve within the original steel sleeve and had a bad thermal path. I just don't know much about how he went about things but I have heard he made a new sleeve and has pretty much got on top of the long track reliability issues now.

230183 230184 230185

My plan is to use a large diameter, thick walled, plated alloy sleeve and bore the cylinder out as much as possible to maximize the heat transfer area between sleeve and alloy cylinder jacket. And of course it will be put together with CPU heat transfer paste.


you would need a sleeve around 5-6mm thick to stop the bridge getting to hot, the RGV150 cylinders have a hole in the alloy part of the bridge for water to pass through for better cooling

I like your idea of using an RG150 cylinder as that would allow a thick sleeve like you suggest and possible a water gallery through the sleeves exhaust bridge too.

Wobbly has been planning everything for me around sleeved down RGV250 cylinders, but I like the idea of a larger sweeping bend up to the transfer port.

230180 http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Yamaha in their SAE paper said that the number one thing that affected power delivery was the angle of the port entering the cylinder and number two was the radius of the transfer duct, then the upswept angle of the port roof.

I will get Wobblys opinion on the shape and suitability of the RG150's port ducts which look a little different to the RGV's.

[koba]

Some Links I've been reading that may be useful regarding handling etc..

http://www.motorcycle.com/how-to/chassis-alignment-basics-3444.html

http://www.fatbaq.com/mainpage.phtml?topic=sag


Current Model 125 Specs Straight from the maker:

http://world.honda.com/HRC/products/machine/rs125r/spec/

[koba]

Another on aerodynamics:
http://www.sportrider.com/tech/146_0106_aero/index.html

[wobbly]

The 1st RGV conversion I did 4 years ago odd was a 150 based cylinder with a steel liner.
That made over 28 RWHp at only 11500 even with the std reed in place.
But its so long ago I cant remember what the actual duct differences are with the 125 cylinder.
Need to have them side by side to see - but with the bigger bore the PV positioning will be different, not an issue as this setup needs to be remade for the 50 bore anyways.

[jasonu]

I dont know what you heard about my gear box, malicious lies Id say.
But seriously I do need another barrel, must be a few left over from all those RG conversions?

http://cgi.ebay.com/ebaymotors/Kawasaki-11005-139-21-Cylinder-KD125-KS125-KE125-NOS-/380307795321?pt=Motorcycles_Parts_Accessories&hash=item588c1c6d79

Kel mate only $250US When you buy it, have it send it to me and I will forward it to you for a 'small' charge...

[TZ350]

Ok it might be a Honda 50 and 4-Stroke but you still have to be impressed with 320 BHP/l

Scraped from the net............ 1966 50cc twin 4 Valves a cylinder GP Racer.

230255

But Honda was always about the engines, and they reached their pinnacle in the 1960's with the RC116
Bore = 35.5 mm
Stroke = 24.14 mm
16.5 BHP @ 21,500 RPM...Redline at 22,500 RPM
And that is 320 BHP/Liter

230256

Yes...that's a dry clutch
Yes...those are flat-slide semi-downdraft carbs (And, yes, they are Keihins. Just 40 years older than the FCR model they sell today)

230253

And yes...it is mostly magnesium (except, obviously, the cylinder head)
And just because the cylinders were little didn't mean Honda was going to go all cheap-ass and crude.

230254

It is still a four valve per cylinder design...they just happen to be very small valves (13mm In / 11.5 mm Ex...3.5 mm stems)

............

[TZ350]

This was before the Aprilia, Jan is wearing the yellow T shirt.

Interview with Jan Thiels about his work with Rumi ............

Translated version:- http://translate.google.co.nz/translate?hl=en&sl=fr&u=http://nrmoteur.skyrock.com/166.html&ei=Lm1ETdvvK8ieceu9qZIO&sa=X&oi=translate&ct=result&resnum=1&ved=0CBwQ7gEwAA&prev=/search%3Fq%3Dhttp://nrmoteur.skyrock.com/166.html%26hl%3Den%26client%3Dfirefox-a%26hs%3Ds8b%26sa%3DG%26rls%3Dorg.mozilla:en-GB:official%26channel%3Ds%26biw%3D1024%26bih%3D574 %26prmd%3Divns
(http://translate.google.co.nz/translate?hl=en&sl=fr&u=http://nrmoteur.skyrock.com/166.html&ei=Lm1ETdvvK8ieceu9qZIO&sa=X&oi=translate&ct=result&resnum=1&ved=0CBwQ7gEwAA&prev=/search%3Fq%3Dhttp://nrmoteur.skyrock.com/166.html%26hl%3Den%26client%3Dfirefox-a%26hs%3Ds8b%26sa%3DG%26rls%3Dorg.mozilla:en-GB:official%26channel%3Ds%26biw%3D1024%26bih%3D574 %26prmd%3Divns)

[TZ350]

.

So you can have multi cylinder rotary valves.

230298

A decent piece of CNC work.

230297

Note the water jacket around the crank cases.

230299

Making your own carb is possible.

230300

Looks like the carb has been made to match a rotary valve port.

I have one or two ideas for my own special 24mm class legal carb.

[TZ350]

.

Check the size of the rotary valve ports

230305

My GP will have an inlet port that looks like this soon ....... :lol:

And I have an idea how I could make a variable port where the closing point can be changed, much like a blade power valve.

[RMS eng]

.

So you can have multi cylinder ratary valves.

230298

A decent piece of CNC work.

230297

Note the water jacket around the crank cases.

230299

Making your own carb is possible.

230300

Looks like the carb has been made to match a rotary valve port.

I have one or two ideas for my own special 24mm class legal carb.

shape looks the same as the D bore carb i got from FW in the UK for my 1991 RS125 in 1996,with other parts made 43HP,carb made 1 HP from 8500-13000 over STD carb

[RMS eng]

If Ive got this right the original image I posted is the latest RSA
229367
Heres the earlier incarnation
229366
shows they are always learning/developing

looks like maybe the wops did Jap and made a copy of an old yamaha ?,this is a photo of Ron Lechiens 1983 works OW125 and it has a disc valve motor and the disc is on the back of the motor.driven from a shaft running from the crank.see next to water pump,bike was said to be fastest that year.

[kel]

1983 works OW125 and it has a disc valve motor and the disc is on the back of the motor.

The early YZR500's OW54 to OW70's ran the rear rotary discs, I had no idea Yamaha ran them on the factory YZM's, always thought reeds were the prefered intake on all motocrossers from around 1980 on.

Question for Wobble - What was the thinking behind the dished pistons Kawasaki run on the KX125's? I cant see any clear advantage what with the reduced squish band and its effect on cooling, end gases etc

[Kickaha]

.
And I have an idea how I could make a variable port where the closing point can be changed, much like a blade power valve.

A friend of mine has one of those PVP engines down here, very tasty bit of kit and there was a FPE or BRC over here a few years ago racing, they're pretty much a newer improved Rotax clone, but anything would be an improvement over a Rotax

[TZ350]

Page 230

There are over 1,200 images on this thread, to find the interesting ones use “Thread Tools”, then “View Thread Images” near the top of this page. Using the sort options at the bottom you can view the images 70 at a time from the beginning. And it’s a quick way to find some of the interesting posts too.

Links and Interesting Quotes from the last 10 pages, other link lists can found on the decade pages starting with Page 80.

Re proposed change in rules to "Open Carb for All Air Cooled F4 2 & F5 4 Strokes".
I've checked the MNZ website for contact details for the Road Race Commissioners and called them. I only got through to one and he was aware of the proposed change and was happy to listen to my view of the change.

I encourage others to put their view forward as well. The commissioners and others are due to discuss the proposal and then make a decision. Generally it doesn't sound like they will be getting advice from people such as Wobbly but rely on people calling in.

Call them...... and to make it simpler here are the two to phone. I spoke to Neil.

Road Race Commission Chairman Peter Ramage 09 443 3111 a/h
Road Race Commission Neil Smith 03 5786208 a/h

A handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ is based on Blairs and Jennings work.

An interesting book by Eric Gorr……. http://books.google.com/books?id=4MealMAQSeIC&pg=PA93&lpg=PA93&dq=keihin+pwk+tps&source=bl&ots=15w7jKNuhB&sig=Xal7OIeprLKF9U1pOPKP4RlnGB0&hl=en&sa=X&oi=book_result&resnum=6&ct=result#v=onepage&q&f=false

Interesting read about the future of 2-strokes and direct fuel injection ........
http://www.dirt-bike-tips-and-pics.com/future-of-two-strokes.html

And Pictures……. http://www.google.co.nz/images?client=firefox-a&rls=org.mozilla:en-GBfficial&channel=s&hl=en&q=Ski+Doo+600+E-tec&um=1&ie=UTF-8&source=univ&ei=WjooTdmZCdCrca7cuZMB&sa=X&oi=image_result_group&ct=title&resnum=1&ved=0CCQQsAQwAA&biw=1024&bih=574

For those that want to experement with different carbs for their bike........ all sizes of copy cat Keihin flat slides, 24-28-32-34. Cheap enough to modify or play with. http://www.alexwarehouse.com/OKO-carburettor-kit-24mm-26mm-28mm-30mm_p331.html (http://www.alexwarehouse.com/OKO-carburettor-kit-24mm-26mm-28mm-30mm_p331.html)

The normal ignition takes care of the ionisation channel; then as soon as the current starts to flow, the Emot-set sends a big extra current through this channel. It looks like this: http://www.youtube.com/watch?v=7BfQuxyWN90

And if you really want to know all about sparks, look here: http://www.madsci.org/posts/archives/2000-04/955373778.Ph.r.html


The Asian factories use SCM - 415 forgings, but for one off's then EN 36 or 39B case hardened to 58 - 62Rc is the shit. Mallory Metal slugs are the go for ballancing….


Right so some 4140/4340 would be the go should I do a short stroke crank. Wikipedia link on mallory metal. http://en.wikipedia.org/wiki/Mallory_metal


Crank wheels need a ductile core, so all the surfaces that wont be ground need to be painted with a copper based coating to prevent the hardening gas from thru hardening the whole part.

EN39B is the best material and is readily available.Heat treatments ltd can do all the processes including stress relief after rough machining the shape - talk to Adam there if you are going to do a crank.

A true Toroid shape was developed to control deto with unleaded fuel, the processes involved work just as well with better octain fuels.

The zero corner rad was a "secret" for years that I tried for the first time when working with Bartol on his Yamaha and my BSL cylinder layout - well before Thiel and Aprilia got onto it.

But its funny how people make "assumptions" that are usually revealed later as "errors". A CFD analysis of the Toroid head shows that the mixture ejected from the squish, actually adheres to the vertical wall, around the sharp corner, and rotates anticlockwise - opposite to what Frits shows. This is why it works even better with a flat top piston.
Who cares though - it works.

the Dellorto with the "Fiat Uno" stepper motor was soon replaced by the stock Keihin solenoid as shown in the pic above.
This was better than the original solenoid in that it can be "pulsed" or PWM controlled by the ECU to vary the fuel flow as needed when the Deto sensor ( on the head - from a Subaru) said bad shit was happening.


My crankpin was made by heat treatments. machined, heat treated, and ground. Hasn't let go yet but still early days. 20mm ends with a 22mm centre, offset .75mm. Very helpful guys.

Setting up an IgniTech Ignition . There are more pictures and a vido on the original post.


......setting up NedKellys IgniTech programmable Ignition.......

Here is TKR's home site, http://www.tkrj.co.jp/product/index.html
There is a 13mb PDF download catalog with dimensions.

Eric’s cockpit video of the 125cc 187mph down run:
http://www.youtube.com/watch?v=Vz_r_3yqqR4

John’s cockpit video from last year of a 50cc 141mph return run:
http://www.youtube.com/watch?v=mYINrhTNiyM


If it was possible to get a port/duct layout like an RGV cylinder ( even thats not a very good example) into an aircooled, the 25% increase in cubes would make it a very potent machine.

Yamahas SAE paper on transfer ports http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf


Some Links I've been reading that may be useful regarding handling etc..
http://www.motorcycle.com/how-to/chassis-alignment-basics-3444.html
http://www.fatbaq.com/mainpage.phtml?topic=sag
Current Model 125 Specs Straight from the maker:
http://world.honda.com/HRC/products/machine/rs125r/spec/
Another on aerodynamics:
http://www.sportrider.com/tech/146_0106_aero/index.html

Interview with Jan Thiels about his work with Rumi ............
Translated version:- http://translate.google.co.nz/translate?hl=en&sl=fr&u=http://nrmoteur.skyrock.com/166.html&ei=Lm1ETdvvK8ieceu9qZIO&sa=X&oi=translate&ct=result&resnum=1&ved=0CBwQ7gEwAA&prev=/search%3Fq%3Dhttp://nrmoteur.skyrock.com/166.html%26hl%3Den%26client%3Dfirefox-a%26hs%3Ds8b%26sa%3DG%26rls%3Dorg.mozilla:en-GB:official%26channel%3Ds%26biw%3D1024%26bih%3D574 %26prmd%3Divns

[F5 Dave]

A friend of mine has one of those PVP engines down here, very tasty bit of kit and there was a FPE or BRC over here a few years ago racing, they're pretty much a newer improved Rotax clone, but anything would be an improvement over a Rotax
Yeah, that's what I was thinking, how they'd moved on, but a mate has a 256 Rotax from 1980 & it had the measure on the equivalent TZs of the time.

We had it on the dyno some years back & with smaller Mikunis rather than the Mag Delortos & pipes made for NZ goattrack tracks of the time it still made 60hp with a big fat curve & something silly like 10,000 rpm 'cause you can't rev them with the tiny bigends.

Had some idea about buying it & fitting some aprilia rods & going post classic &/or bears, but the one off ally frame it's in is an 83, so its only good for bears & we don't have much up here. + it wasn't easy to pushstart by yourself (sometimes), though some rollers would cure that.

[TZ350]

A friend of mine has one of those PVP engines down here, very tasty bit of kit ........

Thanks for the pointer, did a search on PVP supercarts and found http://www.pvpkart.com/

230469

Yummy looking inlet ports.........:yes:

230468

Inlet Opens 136 BTDC Closes 83 ATDC. calculated from their mm BTDC figures.

230471

From what I can make out, Inlet Opens 148 BTDC Closes 86.5 ATDC with soft close.

230475

Sintered Clutch Plate, just what I need for those ripping starts.

[TZ350]

230476230479230478230477230480

More yummy bits.............

[TZ350]

Recently I got myself (Ebay) a 38mm carb with Throttle PS and Electric PJ from a motor crosser.

Wobbly told me that on those the PJ nozzel is to low and starts to flow to soon for a road racer and the MX ones are hard to tune.

230481

I couldn't afford to buy a good second hand TZ or RS unit. So I figure that moving the discharge nozzel.

230483

And adding an adjustable jet from a large model aero engine could be worth a try.

230482

On the dyno I have seen how a leaner mixture rev's on further and how richining it up for best power the over rev drops off.

I think that as the rpm goes up the mixture strength on an ordanery carb at max rpm goes over rich.

And at the moment I think the idea is that the PV is shutoff after peak power to get back to the correct mixture and by retarding the ignition at the same time extend the over rev, but I am sure there is more to it.

I would love to know more about how this type of carb should be used and/or setup.

[wobbly]

The FPE superkart engine that won the NZ road title at Manfield a few weeks ago makes 92 RWHp on the Dynojet 168 I use.
Still not quite as good as the RS250 setup we did that won at Laguna Superkart Worlds a couple of years ago.

The powerjet carb is controlled by the Ignitech with a combination of throttle position and rpm in a "truth table".
In general the solenoid is activated with 12V ( no fuel flowing) below 4000 rpm and 75% throttle on the TPS.
Above 75% and around 12400 rpm it is activated again to lean off the fuel curve over the top of the pipe.
Looks like you will be able to reverse the fuel exit, blocking off the hole on the throttle bore side, and take off fuel from the outside bung, thru a needle jet and into the top of the venturi next to the slide.

[TZ350]

Wobbly had a look at my RG150 cylinder and this is what he had to say:-

""I have the RG150 sitting here side by side with the RGV. No contest - dump ( sell )the 150 as its in good nik..

The RGV has much smaller duct entries and thus will simply need some filling of the case walls to get a good entry shape.

The RG150 would have way too big taper down to the port area of the 50mm bore, in comparison the RGV will have alot better area ratios and is technically a better basis for sleeving down the small amount needed to get 50mm.

The 150 has a water way in the bridge, that is a good idea in itself, but makes the bridge a huge flow reducer thru the duct down to the exit flange, luckily the bolt pattern is the same. ""

So RGV cylinder it is, the reed valve TF100 cases are away now being bored for the RGV cylinder spigot.

230712

I already have a set of GP rotary valve cases half finished that Bucket has been working on for me.

230713

Also I have started converting a set to a bigger rotary valve for a better inlet port shape/area.

[TZ350]

It sure looks like there are some very interesting 2-Stroke projects being worked on out there. I love seeing pictures of other peoples projects posted on the ESE thread.

Not sure who sent me this, but I remember they said it was ok to post the pictures.

TeeZee check the following link:
http://www.pro-x.com/downloads/Technical.pdf

And check Connecting rod dimensions, there you will find all details.

Best Regards,
Hans van Hulten
International Sales
PMI Europe BV
www.pmi-europe.nl (http://www.pmi-europe.nl)
Pesetaweg 32 - 2153 PJ - Nieuw Vennep - The Netherlands
Tel: +31 (0)252 687713 (ext. 5101)
Fax: +31 (0)252 689252
hvanhulten@pmi-europe.nl

The link came with some photos of their own 125 conversion to water cooled 100cc F4 project.

A sleeved RG125, they made their own sleeve and tell me that the RGV barrel is much the same as the RG125 one but they are both narrower across the transfers than the RG150 one, so some case filling is required if your going to fit a RGV250 cylinder onto a RG150 crankcase.

Their RG125/RGV100 engine looks a much neater solution than fitting an RGV250 cylinder to a GP or TF bottom end like I am doing and their RG engine fits very well into the RS chassis, anyway its a good looking job and they are streets ahead of me.

Another fast bucket heading to track near you and Taupo hopefully.

[kel]

Question for Wobble - What was the thinking behind the dished pistons Kawasaki run on the KX125's? I cant see any clear advantage what with the reduced squish band and its effect on cooling, end gases etc

Anyone?
Kawasaki ran these in the KX's from 88 to 90 (maybe other years as well?) while they ran standard dome pistons in the KR1's of the same era, why, what was the advantage of the dished piston with is narrow squish band?
230766

[F5 Dave]

Not sure by any stretch but I would venture that they thought having a nice hemisphere for a combustion chamber made a pretty picture of burning gas. Whether that turned out to be the best way to heat the air above the piston to increase the pressure, for that is all you are trying to accomplish - if you didn't have the inconvenience of having to burn gas to do it, (& do it many times in quick succession) is mute. Flow over the piston from the transfers can't have improved.

Nice idea to try, wrong side of the compromise. 'Course I could be wrong, but Kawa-too-much-saki gaffed on the KR1 pistons as well, at least in terms of ring pegs.

[wobbly]

Well funilly enough that Kawasaki piston gave rise to the idea of a toroid shape.
I think they were trying to get the plug closer to the centre of the combustion area, but of course it shagged the squish action as well as the transfer flow regime.
The toroid shape does everything right and there is no reason to use anything else.

[F5 Dave]

I wonder at what point there are diminishing returns for the Toroidal shape? In the 50s - & I mean the cc class, not the decade, I'm not that old, we use tiny chambers & tight small squish areas. Seemingly you can do no wrong with such a small chamber and a traditional shape, the conclusion is that you end up with a shallow dome quite close to the piston. The spark lead is short to every point of the chamber.

However pushing the idea a friend built a very shallow rectangular chamber, (with a normal narrow squish), so much so that the bike didn't start as the piston closed the sparkplug gap:facepalm:. A quick linish of the top of the (admittedly fairly domed RG50 piston) fixed that. On testing in such a shallow area he found that he could get very measurable better results by trimming back the plug earth strap, ultimately using a side entry racing plug. The strap of a normal EGV was shielding the burn it appeared.

[kel]

TeeZee check the following link:
http://www.pro-x.com/downloads/Technical.pdf
And check Connecting rod dimensions, there you will find all details.

Now thats a great catalogue/reference. :niceone:
Be careful using the TKRJ catalogue some of the dimensions are incorrect, that said their staff are really helpful and a quick to sort out any problems

[speedpro]

On testing in such a shallow area he found that he could get very measurable better results by trimming back the plug earth strap, ultimately using a side entry racing plug. The strap of a normal EGV was shielding the burn it appeared.

I've tested "J" gap plugs in a bike on the dyno and recorded noticeable power increases. Same for tapered earth electrode plugs. Even better ignition systems were worth horsepower which was a surprise. Having said that they use "MONSTER" ignition systems in blown drag race cars way beyond what's required just to light the mixture and that's supposedly because it's worth horsepower.

[bucketracer]

they use "MONSTER" ignition systems in blown drag race cars way beyond what's required just to light the mixture and that's supposedly because it's worth horsepower.

Posted before but still interesting. http://www.madsci.org/posts/archives/2000-04/955373778.Ph.r.html

The normal ignition takes care of the ionisation channel; then as soon as the current starts to flow, the Emot-set sends a big extra current through this channel. It looks like this: http://www.youtube.com/watch?v=7BfQuxyWN90

[TZ350]

Before I start on my Wobbly engine I wanted finish the Ex side port mods on my old air cooled engine and run it up on the dyno.

First step is to prep a new piston, I have been using a dished piston but Wob tells me they are not that great so future ones will be flat top.

230863

The oiler holes for the exhaust bridge need plugging.

230864

Normaly I would weld them but was persuaded to try glueing them with some super duper stuff thats as tough as shark shit.

And hey, this is Buckets, we are allowed to try new ideas.

So the were prept up with a dremmil.

230866

And the finished result.

230865

Then new holes were drilled for oiling the bridge between the exhaust and transfers.

230862

The Ex/Trans bridge

[F5 Dave]

I've tested "J" gap plugs in a bike on the dyno and recorded noticeable power increases. Same for tapered earth electrode plugs. . .
I think you have to test to be sure. The same racing plug pulled out of his bike & tried in mine 5 min later in back to back comparrision with my B9EGV gave not an ounce of difference. In my old fairly low spec H100 & found the garden variety B9HS was as good as anything else. Oddly that was with a marginal MB ignition that used to limit spark plug life to about 4 meetings, the CR ignition stopped that carry on, but I'm not sure it improved power (too long ago).

[F5 Dave]

Belzona? Never heard of it, presumably higher temp spec than Devcon? I struggle to see that holding on, but would be glad to be proven wrong. That was one compromise on my old 125 that I didn't get around to plugging while I was thinking how best to do so. Bad place to lose gas through, but such tiny holes & without super high CC compression I don't know how critical.

Sub port very close to the transfer tops.

[speedpro]

I understand you can get it from Morgan Engineering and they swear by it.

[wobbly]

Here is a test I did ages ago when I was pissed at having to pay $140 for shorty RS125 plugs - and more for the cap..
The test shows 4 different 10.5 plugs in a 3 time Nationals winning 125 kart engine,and each curve is a 3 run average.
Red is B105EGV .
Lime is Denso TAE01-32 ( later Honda replacement for the NGK shorty)
Brown is NGK R6252K - 10.5 ( kawasaki 125 special)
Orange is NGK R6120A - 10.5 Shorty Iridium as sold by Honda.
The trick plug is worth a couple of Hp , this can be bought now as a normal length plug with the Iridium center and Platinum Earth as NGK R7376 for about 1/2 the price, and uses a normal plug cap.

[RDjase]

Here is a test I did ages ago when I was pissed at having to pay $140 for shorty RS125 plugs.
The test shows 4 different 10.5 plugs in a 3 time Nationals winning 125 kart engine.
Red is B10EGV and each curve is a 3 run average.
Lime is Denso TAE01-32 ( later Honda replacement for the NGK shorty)
Brown is NGK R6252K - 10.5 ( kawasaki 125 special)
Orange is NGK R6120A - 10.5 Shorty Iridium.
The trick plug is worth a couple of Hp , this can be bought now as a normal length plug with the Iridium center and Platinum Earth as NGK R7376 for about 1/2 the price.

Hi Wayne,

Hows Steve and the Shop after the Storm? Hope all is well and you had no or minor damage

Lucky you are this side of the Tasman

Cheers
jase

[kel]

Before I start on my Wobbly engine I wanted finish the Ex side port mods on my old air cooled engine and run it up on the dyno.

About time, could this be the first 30hp bucket?

[gamma500]

Wobbly, what do you think about hydroformed expansion chambers?

[wobbly]

Spoke to Steve in Cairns last night - his email is still dead, and so are most of the trees in his front yard.
They were lucky the eye hit about 80 miles South and they only had 180Km/Hr winds.

I spent months learning how to do real nice blown pipes when I worked for JL in England and we were contracted by ZipKart to do some special pipes for the British Superkart GP at Silverstone.No matter what I did I couldnt get the same power as the hand made cone pipes.
The problem is that no matter how you do it, the changes in area are "smeared" together, especially around the mid section.
Finally we decided to make the curved header part only as a blown section, as this is very time consuming when welding alot of sections together.
This combination actually made 1.5 Hp per pipe more ( only the front pipe is curved on a Superkart).
If you look at Honda factory bikes the pipes are pressed in 2 halves and have very sharp "corners" where the angles change.
And the last GP pipes I had anything to do with - the 250 KTM, were made this way.

[RMS eng]

Spoke to Steve in Cairns last night - his email is still dead, and so are most of the trees in his front yard.
They were lucky the eye hit about 80 miles South and they only had 180Km/Hr winds.

I spent months learning how to do real nice blown pipes when I worked for JL in England and we were contracted by ZipKart to do some special pipes for the British Superkart GP at Silverstone.No matter what I did I couldnt get the same power as the hand made cone pipes.
The problem is that no matter how you do it, the changes in area are "smeared" together, especially around the mid section.
Finally we decided to make the curved header part only as a blown section, as this is very time consuming when welding alot of sections together.
This combination actually made 1.5 Hp per pipe more ( only the front pipe is curved on a Superkart).
If you look at Honda factory bikes the pipes are pressed in 2 halves and have very sharp "corners" where the angles change.
And the last GP pipes I had anything to do with - the 250 KTM, were made this way.
some times you have to go back to go forward ,have photos of 1990s NSR 500 GP bike they have blown pipes to the rear cones which look hand made.

[TZ350]

About time, could this be the first 30hp bucket?

It would be great if it is, but I suspect that if one already has 27hp it will be easer to lose a few than add two or three more.......but fingers crossed.

More chance of the new Wobbly motor cracking 30.

[TZ350]

Sub port very close to the transfer tops.

I am not sure what a good separation here looks like, but these do look a bit close.


Belzona? Never heard of it, presumably higher temp spec than Devcon? I struggle to see that holding on, but would be glad to be proven wrong. That was one compromise on my old 125 that I didn't get around to plugging while I was thinking how best to do so. Bad place to lose gas through, but such tiny holes & without super high CC compression I don't know how critical.

I am not sure how much difference plugging the holes will make and using glue, not to sure about that either.

I was sceptical about Devcon in the transfers at first and that worked, but hey who knows, and this is Buckets so we are allowed to experiment, fingers crossed.


I understand you can get it from Morgan Engineering and they swear by it.

Yep, thats the place .............. now we are about to find out if its any good in pistons.

[TZ350]

I have been told about carbon fiber pistons with ceramic tops being used in factoryTZ's and without any other changes they picked up another 1,000 rpm of reliability, could be a myth, but its an interesting idea.

Something I scraped from the net:-

"Internal-combustion engines would be constructed with cylinders and ringless pistons made of lightweight carbon/carbon composite materials, according to a proposal. This proposal is a logical extension of previous research that showed that engines that contain carbon/carbon pistons with conventional metal piston rings running in conventional metal cylinders perform better than do engines with conventional aluminum-alloy pistons. The observed performance improvement (measured as increased piston life during high-performance operation) can be attributed mainly to the low thermal expansion of the carbon-carbon composite. Carbon-carbon pistons can continue to operate under thermal loads that cause aluminum pistons to seize or sustain scuffing damage due to excessive thermal growth and thermal distortion." http://www.techbriefs.com/component/content/article/2258

Makes you think......... :scratch:no piston rings = the possibility of much wider exhaust ports for better blow down time area.

[TZ350]

Carbon fiber cylinder barrel, and fiber conductivity better than copper, this gets better all the time:-

"this configuration could likely be chosen to maintain the close-tolerance piston/cylinder clearance because it would exploit two features of carbon fibers that are very attractive in this application: high lengthwise thermal conductivity (for some fibers, greater than that of copper) and nearly zero lengthwise thermal expansion. This configuration would minimize thermal expansion of the cylinder bore while maximizing the outward conduction of heat through the cylinder barrel" http://www.techbriefs.com/component/content/article/2258?start=1

[kel]

It would be great if it is, but I suspect that if one already has 27hp it will be easer to lose a few than add two or three more.......but fingers crossed.

Come on give yourself some credit here, you made 27hp through considered study and implementation, 30hp is certainly on the cards with the reworked cylinder.

[TZ350]

30hp is certainly on the cards with the reworked cylinder.

Hopefully know by the end of the week.

[koba]

That carbon stuff all looks pretty damn cool.

I'd read about the Britten team experimenting with carbon fibre conrods and other stuff.

[wobbly]

No one has managed to get "ringless" pistons to work in a normal sized bore on petrol, but a company I work for has a patent on a trapped piston ring that allows a T port with no bridge.
See
http://www.wipo.int/pctdb/en/wo.jsp?WO=2005121608

[speedpro]

Sort of like an inside out Dykes ring. Fitting it will be the trick. Winding it in through a slot leading to the ring groove and then pegging it to stop it rotating it's way out could be a possibility. Making the slot would be a mission for the machinist but I can't see a piston that's screwed together staying together at revs. Interesting idea though, if I've got it right.

[TZ350]

.

Trapped Ring, thats a clever idea.........

231235

Instead of a screwed together piston, there may be other ways of retaining the ring, like using another ring with an OD smaller than the ring land and that clips above the inverted dykes ring.

231241

With the retaining ring bottoming on the ring land and not free to move it would not add anything to the mass of the captivated compression ring and compression pressure would still be able to get past the retaining ring to seal the compression ring.

[speedpro]

The screwon piston crown could be useful. Squish could be adjusted by adding shims and screwing it together. Or if you had problems with detonation you just screw in another crown.

[kel]

I've been reading some more from Jan Thiel and Frits Overmars musing on the development of the Aprilia RSA, thought Id share this one from Jan Thiel on expansion chamber development -

"We once had an exhaust design software on loan from a very well known company, the results were useless! It was mostly cut and try"

Seems even the very best subscripe to the cut and try method.

[gatch]

The screwon piston crown could be useful. Squish could be adjusted by adding shims and screwing it together. Or if you had problems with detonation you just screw in another crown.

Using this method you could just about fabricate your own pistons from scratch.

Bore some heavy ally tube. Drill a hole larger than the gudgeon right through. TIG in some bosses. Turn the outside, the ring groove and thread the bore for the screw on crown. Finish the hole for the gudgeon. Mill in whatever skirt shape you like.

Turn an external thread to suit. Then using either the finished piston or a fixture, turn the top of the piston crown. To get the deck height perfect you could either machine some off the crown or piston, or shim to suit.

Might even work with a little experimentation..

[kel]

Quote Originally Posted by F5 Dave - Sub port very close to the transfer tops.



I am not sure what a good separation here looks like, but these do look a bit close.

Should be OK, here's a picture of the RSW125 ports for comparison.

231339

[wobbly]

The software Thiel tried was from Ricardo, and yes its useless at close comparisons of pipe geometry.
In an SAE paper that they did on how fabulous the sofware was they showed the sim bmep curves for 4 different pipes on a TZ250 cylinder.
A pair of pipes were identical except for the header length.The sim showed no difference, the dyno showed a 2Hp change.
I Emailed them about the statement that the sim could predict small changes but failed to see a "huge" 2Hp difference in the results they published.
Anyway it all got nasty in the end when I suggested they spend more time on perfecting the code and less time spouting how good it was in SAE papers when clearly it didnt work.
The code I now use has proven to be very accurate, as its updated almost weekly,but as with all high end stuff like this it depends upon having alot of emperical background knowledge to begin with.
For example, twin angle headers that show up a result in the sim very easily, show exactly the same trends on the dyno, but the thing that does take time to suss is the length of each section and can only be seen by watching the pressure traces in real time on the screen to see what each engine config really "likes".
Kev and I used to spend hours doing this with the old Dynamation 4T when he first got it - and we learned a huge amount from even that old code simulator, and were able to for example design a much better cam/pipe combo for the Britten.

[richban]

Found one of the charts from the new engine. The exhaust gas analyzer was giving a different reading on almost every run I think it was on its way out. Anyway crank is being fixed this week so can't wait to get this thing up and running again. I think it has lots more potential. It really wants to rev to the moon just not sure how much it could take and last.


231361231362

[wobbly]

Dont be a big girls blouse - the FXR with 48.8 stroke should be at 13000 all day, its well under 4500 ft/min and the pressure fed big ends are way less prone to cage skidding causing failure..
Christ the 450 singles are reliable to 12500, after that it gets horrible real fast.

[richban]

Dont be a big girls blouse - the FXR with 48.8 stroke should be at 13000 all day, its well under 4500 ft/min and the pressure fed big ends are way less prone to cage skidding causing failure..
Christ the 450 singles are reliable to 12500, after that it gets horrible real fast.

OK 13 sounds good. Now if you could just join forces with Kev again and design an exhaust cam head package to see off some of them 2 strokes you have been building.

[wobbly]

Get Kev to fill in the inputs needed for my header design program I gave him a while ago, easy to make a screamer if the FXR hardware is able to be "fixed" properly.

[richban]

Get Kev to fill in the inputs needed for my header design program I gave him a while ago, easy to make a screamer if the FXR hardware is able to be "fixed" properly.

Sweet will do.

[kel]

231390
Get Kev to fill in the inputs needed for my header design program I gave him a while ago, easy to make a screamer if the FXR hardware is able to be "fixed" properly.

There's something wrong with your attachment, I can't enter any data into the fields

[richban]

Apart from looking cool and probably costing a lot I would like to see if these things work. The bit on the bell not the carb. I might try making one.

[TZ350]

.

231402

Faw...rk ...........a 25hp 4-stroker with a long liner power spread, now what am I going to do????? :facepalm:

[Henk]

.

231402

Faw...rk ...........a 25hp 4-stroker with a long liner power spread, now what am I going to do????? :facepalm:

Buy an FXR?

[kel]

Apart from looking cool and probably costing a lot I would like to see if these things work. The bit on the bell not the carb. I might try making one.

Thats so hot, hate to think what it costs.
I have a couple to try this weekend admitable not yoshi quality but nice 25 and 50mm bells/stacks what ever you want to call them. Also have some to sell if anyones interested.

231405

[richban]

Thats so hot, hate to think what it costs.
I have a couple to try this weekend admitable not yoshi quality but nice 25 and 50mm bells/stacks what ever you want to call them. Also have some to sell if anyones interested.

231405

I did some testing with some that look the same last year at manfield. I was surprised how noticeable the lenght change was. Ended up sticking with the short one. Was easy on the big open straights on full noise.

[wobbly]

You have to print the attachment and fill it in, scan and send to me.

[TZ350]

Apart from looking cool and probably costing a lot I would like to see if these things work. The bit on the bell not the carb. I might try making one.

231453

I am not sure how this is supposed to work, a venturi ejector maybe. But if there is a tuned length aspect to it then one could have two or more different lengths that swing into place and a controller like the IgnTech could position the different lengths in front of the bellmouth according to the rpm.

[koba]

231453

I am not sure how this is supposed to work, but if there is a tuned length aspect to it then one could have two or more different lengths that swing into place and a controller like the IgnTech could position the different lengths in front of the bellmouth according to the rpm.

Or maybe in the case of the pic the different behavior of the air at different revs takes care of the transition.

I know that doesn't really make sense but its the best way I can put what I'm thinking.

[kel]

Some more RSA125 development info from Jan Thiel

"No pressure transducers were ever used in our engine development.
And time/aerea was never calculated.
The port timings remained practically the same during 15 years!
What we did was trying different angles and radiuses, mainly on
the transfer ducts. I think we tried 40 different types of transfer ducts
that did not chanche the time/aerea. It was all about in which direction
the charge entered the cilinder and how the tranfer streams influenced upon
each other! Also about 200 different exhaust pipes were tried. After 2004
nothing much was changed but we improved with different power jet and
ignition mapping. It seemed nearly impossible to improve the transfer ducts
any more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

Didnt calculate time area? Im guessing that means the time area requirement hasnt changed any in the last 15+ years.
So there you go its all about the transfer ducts, now where have I heard that before?
Check out the attached photos, I guess the idea of thinning the transfer duct bridge has gone out the window, and the exhaust duct hows that for a crazy shape


231454
231455
231456

[koba]

Some more RSA125 development info from Jan Thiel

"No pressure transducers were ever used in our engine development.
And time/aerea was never calculated.
The port timings remained practically the same during 15 years!
What we did was trying different angles and radiuses, mainly on
the transfer ducts. I think we tried 40 different types of transfer ducts
that did not chanche the time/aerea. It was all about in which direction
the charge entered the cilinder and how the tranfer streams influenced upon
each other! Also about 200 different exhaust pipes were tried. After 2004
nothing much was changed but we improved with different power jet and
ignition mapping. It seemed nearly impossible to improve the transfer ducts
any more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

Didnt calculate time area? Im guessing that means the time area requirement hasnt changed any in the last 15+ years.
So there you go its all about the transfer ducts, now where have I heard that before?
Check out the attached photos, I guess the idea of thinning the transfer duct bridge has gone out the window, and the exhaust duct hows that for a crazy shape


231454
231455
231456

Very Interesting Pics!

[TZ350]

Ok this is where I am at now........

231462


Ran the tripple Ex port up. Blue Line. Red line is my old single Ex port.

231461

Clutch slip at about 12.5 and timing and carburation all wrong.

I am looking forward to seeing what it looks like when everything is setup and dialed in properly.

[F5 Dave]

Its making that 4 stroke look pretty shabby. Nice work.

[F5 Dave]

Quote Originally Posted by F5 Dave - Sub port very close to the transfer tops.




Should be OK, here's a picture of the RSW125 ports for comparison.

231339
I'm not one with a propensity for swearing; but look at those cunting mother ball slapping fukn ex sub ports.

Jiminy Cricket they are big.

I suppose when you don't care about what happens at 10,000, short ccting isn't an issue.

[wobbly]

Yes, dead right the STA numbers havnt changed at all since the theoretical work was published out of Queens in Belfast by Blair etal.

But Thiels comments about the ports is a bit misleading really.
Aprilia completely changed the whole layout from previous 3 port geometry.
Instead of the main port being right at the 72% limit, they reduced this to 68% and dropped the main transfers below the rest.This enabled the large secondary Ex ports to be added, plus gave room to pull all the transfers around and create more area with less timing.
What this lead the way with,is being shown all the time now in the sims I run, that the Ex STA means jack shit,Blow STA is everything.
The powervalve cranks up the power at 10,000, but despite what Frits says about reeds not working well at low rpm/WOT operation, the KTM and Honda factory engines still nailed the Aprilia/Derby with off corner acceleration.

[bucketracer]

Faw...rk ... 231402 ... a 25hp 4-stroker with a long liner power spread, now what am I going to do????? :facepalm:


Buy an FXR?

Well, yes, good idea, by hand feeding it bits of FXR, the taste for blood could make the Monster GP go harder ...... :laugh:

[bucketracer]

Dad's got me and Thomas dialling in his bike on the dyno.

231627

Blue = new side port cylinder, Red = Old cylinder

Starting to clean the power curve up nicely but the clutch slip has come back......