ESE's works engine tuner

[Grumph]

Even better is Methanol/Toluene with a dash of acetone to dissolve the oil...

[Frits Overmars]

...Acetone is a good fuel and can be run on its own but check how your crank seals cope with it first, soak them in it to see if anything happens to them, Yamaha RD seals with the Teflon lips swell up and create air leaks.

There's more than just the seals to worry about: synthetic main bearing cages do not always take kindly to hydrocarbons. E85 has caused problems and I even seem to remember a two-stroke oil that turned the cage material brittle....

[Perra.S]

If its lean when running Methanol, I am not sure EFI will help.

Back in the day I ran an air cooled Suzuki TR250R on Juice. At 100% Methanol it ran to cold to vaporise all the fuel and consequently ran lean. Increasing the main jet did nothing and in the end there was raw fuel being blown out the exhaust pipes, other riders complained.

The trick was to blend the Methanol with Acetone until the latent heat of evaporation of the fuel blend left enough heat in the engine to evaporate all of the fuel properly.

Acetone has a latent heat of evaporation midway between Methanol and Petrol. Acetone has an Octane rating higher than Methanol and like Methanol, Acetone likes to be run rich.

Acetone is a good fuel and can be run on its own but check how your crank seals cope with it first, soak them in it to see if anything happens to them, Yamaha RD seals with the Teflon lips swell up and create air leaks, Suzuki ones seem OK.

In the end I found a 50/50 mix of Acetone and Methanol (20:1 Castrol R) worked well in the Suzuki but different engines require different ratios and the RD liked 100% Acetone. An air cooled Speedway engine I worked on had TZ750 barrels with big holes cut in the water jackets for cooling air to blow through, it liked a 100% Methanol.

You just have to experiment to find what an engine needs. It’s a balancing act between maximum chilling of the incoming air and enough engine warmth left to vaporise all of the fuel.

You could find that with EFI you can keep firing in ever more Methanol like I did with bigger and bigger main jets but if the engine is running to cold to vaporise it all, you will still be lean.

The main reason why I want to run a EFI is that when you run so much nitromethane you need to deliver huge amounts of fuel to the engine and that is very hard to accomplish with a carb. When running 90% nitro I had to do many mods to the carb and I had to run a fuel pump to feed it, a normal fueltank setup didn't work. Without a fuelpump it emptied the carb in about 40meters of wide open throttle

And of course, I had to run extremely large needle- and main jets (on 90% nitro there was only the needle jet bored to 4.5mm, no main jet) and that resulted in useless atomizing of the fuel so if I'm right a fuel injector that instead deliver a fine mist of fuel would help a lot.


When running on pure methanol there was never any problems with fuel not atomizing correctly (because I still could run normal needle- and main jets), it started when I exceeded ~30% nitro with homemade jets and as you say there was raw fuel blown out the exhaust.

[TZ350]

I can see now why you want to run EFI, your work with the ""chemicals"" is very interesting. I have thought about trying a bit of nitro in the Beast one day on the dyno just for fun. Gigglebutton runs NOS in his 50 on occasions and gets a real boost.

The idea for the Beast, is that Nitro carries slightly more fuel than oxygen and that if an engine was running properly on petrol one could then just dribble some nitro in front of the carb and let it get sucked in or we could run the nitro through a power jet.

Any nitro that's sucked in will only make the existing mixture richer and as long as the compression and ignition are suitable it should run OK, should be fun to try on the dyno sometime.

[FastFred]

Its amazing what TwoTempi can dig out of his junk box.



Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.

[FastFred]

I am sure its off a power restricted Italian old school domestic commuter bike so perfectly legal.

[husaberg]

Its amazing what TwoTempi can dig out of his junk box.



Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.

I am sure its off a power restricted Italian old school domestic commuter bike so perfectly legal.

Ailirpa never heard of them although the dutch crowd do these.http://www.he-ja.nl/2007-RS125-intro.brits.htm
Aprilia top end on a Honda bottom end.

The HONDA RS125 HE-JA A kit cost in the complete outfit € 9700.= exc. VAT

The B Kit is exactly the same as the A Kit, except the electronic. This one is to obtain from BPS or an other branch to rebuild it yourself. One can also use the standard eCU unit. Price € 6588.= exc. VAT.

It is also possible to obtain only the complete cylinder + Exhaust flange and cylinderhead.

The cost of this C Kit is € 3840.= excl. VAT.

Intersting if you added the disk valve crankcases another company makes for the Honda RS125 you could have a Honda engine that is pretty much an aprilia (actually is anything on the crp engine Honda?)

Its amazing what TwoTempi can dig out of his junk box.



Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.

But if someone was to cast their own cylinders..... the peanut gallery would no doubt chirp up and cry foul, not in the spirit etc....... i say f-em

Question for Frits or Jan (i see he pops in occasionally) Jan had mentioned a few times that the Crankcase volume for a reed or case reed would be smaller than the RSA RSW
How much smaller would it be? I realise you don't have your notes but i would be interested in knowing what the Reed Derbi was?

[TZ350]

Its amazing what TwoTempi can dig out of his junk box.

Thanks for posting that, I am particuarly interested in the inside radius of the transfer ports.



The inside curves radius is important, as I understand it the wrong shape will promote flow separation, effectively narrowing the transfer duct.

I will have to look back and check on the angles but I think the transfer port (the smaller one) nearest the exhaust is angled up at 24 deg and what is the main transfer port on this cylinder which is next to the boost port and is angled up at 12 deg.

[TZ350]

Frits talks about that new school cylinders transfer port shape and angles. It worth checking the original post out because Frits posted more pictures and there was quite a bit of discussion about transfer ports at the time.

As we were on the subject of scavenging angles, now would be a good time to write something about the radial angles of the A-transfers.
Surely a duct with a radial angle of over 20° offers a smaller cross-section to the flow than a duct that enters the cylinder perpendicularly?
Yes it does. But there are two good reasons to angle it upward anyway.

First, perpendicular mixture streams coming from the A-ports would collide and slow one another right down. The upward angles provide for less velocity losses and less
pressure losses, so despite their smaller cross-section, upward ports may flow as much, if not more, than perpendicular ports.
(Now you may well ask why the B-ports do not get the same treatment; that is because the central scavenging column, resulting from all incoming scavenging streams together, must not have too much radial velocity, or the loop scavenging will result in a loop-loss into the exhaust).

Second, there is a thing called scavenging balance (I invented the word for my personal use, so this may well be the first time you ever saw it).
If you looked closely at the scavenging picture of the MB-cylinder I posted earlier today, you may have noticed that the 'radial scavenging directional resultant'
had a value of 101,045°.
90° would have meant 'straight up'; more than 90° indicates that the central scavenging column is leaning towards the exhaust side of the cylinder.
But we don't want that; it is bad for the scavenging of the rear part of the cylinder, and it is risky because it may provoke scavenging losses straight into the exhaust.



But how can we prevent a scavenging column from toppling over to the exhaust side like the leaning tower of Pisa? Not by pushing against its basis, but by pushing higher up. Hence the radial angle of the A-ports. The pictures will tell the story. (If only the Pisa architect had known a bit more about two-stroke tuning....)

A link to Yamahas paper on whats important in transfer ports. A bit older school now but its basically the shape of transfer port us Bucketeers find in our old school TZR TF TS GP engines.

The Relationship Between Port Shape and Engine Performance for Two-Stroke Engines



In case you missed it earlier. Here is a little bit of a gold mine:- http://www.2stroke-tuning.nl/media/
Port maps etc, some of its in German.

[TZ350]

But if someone was to cast their own cylinders.....

I am enjoying playing with the aircooled moter but I can see a H2O 100 in my future ....

[koba]

I am enjoying playing with the aircooled moter but I can see a H2O 100 in my future ....

I see one in mine too

[husaberg]

I am enjoying playing with the aircooled moter but I can see a H2O 100 in my future ....

I think and i could be well wrong that the Transfers or at least the b ports are smaller in the RSW vs the RSA the septum on some of the pictures i have seen are more rounded on the RSA too i think, but i could have that backwards?
will add pics and quote later. Can't find the bit i wanted but can frits confirm anything i always assumed the cylinder drawings from the Frits Files were RSW?

The duct entry area of the Aprilia cylinder's B-ports is slightly smaller than their port exit area. This stems from the old obligation to develop cylinders that had to fit the existing crankcases of the Aprilia RSW engine, of which there are hundreds around. the RSA engine did not have this limitation, but simply enlarging the B-duct entries disturbed the scavenging, so the ducts were left as they were (and remember: while the B-ports' exit areas are only open part of the time, the entry areas are open all the time).
The transfer timing is 130° for the A-ports (they are really close to the auxiliary exhaust ports) and 132° for the B-ports and the C-port.

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 onthe 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 2004nothing much was changed but we improved with different power jet and ignition mapping. It seemed nearly impossible to improve the transfer ductsany more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

There is hardly an optimal ratio of duct area to port window. I generally try to obtain a value of 1,5 but when you look at the B-transfers of an Aprilia (A is the set nearest the exhaust; then come the B-ports, then the C-port opposite the exhaust) you will see that the entry at the cylinder base is almost a rectangle, with a width of 19mm and a 'length' (in riding direction) of 16 mm; that gives 304 mm².
The B-window in the cylinder wall has a width of 25 mm, a height of 13,2 mm and an upward angle of 10°; the effective port area is 325 mm²; it's bigger than the entry area 8).

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

You want the aux ports as big as possible to have more blowdown.
You want the most blowdown with a limited exhaust timing in order not to lose power at low revs.But there are limits.
You have to keep away from the transfer ports to prevent fresh charge going into the aux. ports.
That is why their bottom is inclined.The same happens if you make the aux. ports too wide.You loose fresh charge.This also cools the exhaust gases, so you loose revs.Symmetry is also important.We tried a piston with a closed pistonpin hole on one side.
With this piston power was very bad!Worse than with a 'normal' piston!
Closed piston pins did not improve power at all revs.Only at some points in the power curve.Mostly at high revs.
At some points in the power curve you loose something, but not much.

With aux. ports you can use a lower exhaust port, so that you have more power at low revs.

What really counts is blowdown.
But discharging of the burned gases may not be complete until BDC.
In this case you get 'short circuiting' of the fresh charge from the transfer ports into the exhaust.
By using auxiliar exhaust ports you can improve blowdown quite a lot.
So that you might be able to raise the exhaust's 'floor'.This helps improve blowdown flow, as seen on a flowbench.In 2007 we started to raise the underside of the exhaust port.The first results were very promising!But at the end of 2007 I retired, so I could not finish what I started.The idea was to raise the exhaust underside as much as possible until power dropped.
And then, with a smaller exhaust port underside it might have been possible to widen the A-ports more
without losing the fresh charge into the exhaust.The ideal situation would, of course, be that all the burned gases are discharged from the cylinder beforethe transfer ports start opening.So it is difficult to have too much blowdown.But in trying to achieve enough blowdown you can arrive at a too high exhaust port.Which first causes power loss at low revs, and if exaggerated still more also a loss of max. power.Because of shortening the power stroke.

[TZ350]

If you say had a 158cc single 4 stroke with a really nice plain bearing bottom end. Custom light forged piston. Redesigned port layout. An ingitech allowing 14000 to 15000 rpm. Flowed head that can pump 32hp worth of air. Massive titanium valve's and huge cams and a close ratio 6 speed in a good frame and a total bike weight of 82kg. That should go ok don't you think.

Thats what I want. Might be a bit loud.

I am starting to think the 4T boys might pull this off ..... I know of another project like this not far from us.

Why a plain bearing bottom end?

A plain Brg can carry more load and rpm, notice rpm .....

Rich's posts are carrying a big hint about where things are already at and are going to with some of the FXR's that are on the front row of the grid ......

Sounds cool. I know the KTM 250 dirt engine revs to 13000 all day with a normal bearing setup. Mr honda has gone plain bearing for the moto3 engine. Not sure what the others have done. There is plenty of power in the current engine setup its just up out of reach at the moment. Its all about chasing the weakest link.

Not sure at what rpm things get a little stupid on a single OHC 4 banger. 14500 sound like a good number.

And there is the key to what TeeZee is saying
150cc 4T at 14500 needs over 200psi bmep to go mid 30s crank power.
Full house intake and exhaust tuning, mega cams, tons of TDC overlap, and you think the 2T powerband is too narrow at 30Hp,try riding that FXR.
Sure Kev could make it happen, but I think the reliability cost and rider ability needed is out of reach to most.

There are close ratio kits available in Thailand for their version of the FXR150 commuter bike to convert them from commuters to the "sport bike feel" whatever that means.

BMEP is the guide, so, yes getting more difficult but it looks like its not impossible to pump things up a bit more than the current 24rwhp. Lighter, good handling bikes, well the 4T boys already have those, it will be interesting to see how things develop on the 4T front.

And from the man who is best placed to know .......

21hp in a RS still gets blown away on big track and only just hangs onto Gavs FXR on the short tracks, 25hp is needed to live with any sorted 4T ! Nathaniel was on The faster of the 2 bikes at Taupo and that has 25hp and it's a shame he could not hold on to it for a few more laps ..

[husaberg]

I am starting to think the 4T boys might pull this off ..... I know of another project like this not far from us.

There are close ratio kits available in Thailand for their version of the FXR150 commuter bike to convert them from commuters to the "sport bike feel" whatever that means.

BMEP is the guide, so, yes getting more difficult but it looks like its not impossible to pump things up a bit more than the current 24rwhp. Lighter, good handling bikes, well the 4T boys already have those, it will be interesting to see how things develop on the 4T front.

If you say had a 158cc single 4 stroke with a really nice plain bearing bottom end. Custom light forged piston. Redesigned port layout. An ingitech allowing 14000 to 15000 rpm. Flowed head that can pump 32hp worth of air. Massive titanium valve's and huge cams and a close ratio 6 speed in a good frame and a total bike weight of 82kg. That should go ok don't you think.

sounds like a nice wee small budget like build doesn't it.
custom forged piston ???????????$500
TI Valves ???????$200
Custom porting and head flowing(assuming its not ya Bro)????? $300-500
Full house cam (assuming its not ya Bro) ???$250
Close ratio box ????????$300+
Plain bearing bottom end and oil pump mods 300+????????
Special valve springs and retainers ????????200+
I am glad Dorna went the 4 stroke way as they are far cheaper aye.............
From memory the NR500 valve collets were 2000 pounds back in the early 80's but they did have 64 of them.

[richban]

sounds like a nice wee small budget like build doesn't it.
custom forged piston ???????????$500
TI Valves ???????$200
Custom porting and head flowing(assuming its not ya Bro)????? $300-500
Full house cam (assuming its not ya Bro) ???$250
Close ratio box ????????$300+
Plain bearing bottom end and oil pump mods 300+????????
Special valve springs and retainers ????????200+
I am glad Dorna went the 4 stroke way as they are far cheaper aye.............
From memory the NR500 valve collets were 2000 pounds back in the early 80's but they did have 64 of them.

Change of plan. Develop the current bike to make more power and get it to handle better. Exhaust ignition and intake are all untested really. Then ride it like I stole it.

I will be building another engine in the next couple of mouths. refreshing old faithful to the spec I have now. Maybe look at the gearbox then. Not much time to play at the moment.