ESE's works engine tuner

[Flettner]

Neil i googled armourboard and only came up with it in weatherboard form where do you get yours?


I think "Armourboard" is a laminex group product and is essentially high density customboard.

Yes, I think so. It's been a few years since I bought my pellet load and the place I got it from is gone now.
I still have at least one sheet on the rack. I think originaly I got ten, 8' x 4' sheets. We have made a few patterns!

[jasonu]

Yes, I think so. It's been a few years since I bought my pellet load and the place I got it from is gone now.
I still have at least one sheet on the rack. I think originaly I got ten, 8' x 4' sheets. We have made a few patterns!

Is it like custom wood? That is what we use when wood patterns are required.
www.lancair.com

[husaberg]

I hadn't seen either of them, but these pics look nice and compact compared to the usual scooter units. What kind of power, torque and revs is it supposed to handle?
(BTW, I think you're wrong: the pics are in dutch).

I thought i was the one with all the questions.this is the Yama, i guess it will be over engineered a bit, the honda one will be.

Dry weight / Curb weight

103kg / 108kg

Engine type Air-cooled, 4-stroke, SOHC, 2-valve
Cylinder arrangement Single cylinder
Displacement 113.7cc
Bore x Stroke 50mm x 57.9mm
Compression ratio 8.8:1
Maximum power 6.54kW(8.9 PS)/8,000rpm
Maximum torque 8.63N-m(0.88 kgf-m)/7,000rpm
Starting system Electric and Kick duo
Primary / Secondary reduction ratio 3.133 / 3.583
Clutch type Dry, centrifugal
Transmission type V-belt stepless
Gear ratios 2.369 - 0.820
Tire size(Front / Rear) 70/90-16 / 80/90-16

Model - Honda motorcycle Wave RSX FI AT
Total weight of motorcycle 105 kg

Engine type Gasoline, 4 stroke, 1 Cylinders, Air - Cooled
Displacement 109 cm3
Piston: Diameter x Stroke 50mm x 55,6 mm
Compession Ratio 9,0 : 1
Max out-put 5,74 kW/8.000 rpm
Max Torque 8,24 N.m/5.000 rpm
Transmission Auto
Starter system Electric / pedal

What are the two rubber boots for sprouting from the top of the CVT case for? Cooling air perhaps?
I maintain the best system I've seen uses a chain with hollow boxes at each link set at 90 degrees to the chain travel. Many shim like parts are in these boxes and can slide, sidways. The chain wraps around similar drive wheels like the vairable rubber belts BUT the surfaces of these wheels have grooves, like key ways, running radialy out from the centre. The wheels are set so that if there is a groove on one side there will be a lump on the other exactly opposite. The shims then slide one way or the other depending on what they " see " . This makes for positive drive with NO slipage and can handle large loads at lowish speeds ( final drive perhaps ). System runs in oil.
Bekham plastic extruders used to use this system, small gearbox with high load and minimal heat generated.

yes i posted a pic of a chain CVT a while a go but i doubt i could fab one.
http://www.upsite.co.il/uploaded/ima...842ca42b36.jpg

Neil i googled armourboard and only came up with it in weatherboard form where do you get yours?


I think "Armourboard" is a laminex group product and is essentially high density customboard.

much higher resin component i think

Is it like custom wood? That is what we use when wood patterns are required.
www.lancair.com

much higher resin component i think

[kel]

The heat generated by going leaner over the top of the pipe will mostly be transmitted into the pipe.
Thus maybe the Ex duct in the cylinder will get hotter, but I dont see that being a limiting issue.
What is the ignition curve, as this may be limiting the overev power past 12,000

Rob set the ignition curve on the dyno so should be fairly close to optimum. Unfortunately I don't currently have access to the laptop that the correct ignition curve is stored on. Have made some on the fly changes to the igni during street testing so its no good uploading the curve from the ignition
We'll get the bike on to the dyno in the next couple of weeks, all going well it will rev another 500 or so rpm before falling on its face. Will upload the results.

[TZ350]

.

I have learned from Flettner, that a competition two stroke can be successfully fuel injected and that EFI can work very well on 2T's.



With Flettners guidance and his example of two very successful working bikes using the Link EFI unit, one on E90 and the other on pump gas I have been encouraged to have a go myself using an Ecotrons small engine fuel injection kit for two strokes.

http://www.ecotrons.com/2_Stroke_Sma...e_EFI_kit.html



Blue line is the Fuel Injected YZ250 (pump gas) and Red line is the Kawasaki Big Horn (E90).

The first lessons I had to absorb were that the timing of the Injection end point is critical on a two stroke and should be timed to end at transfer port closing and the fuel should be injected into the transfer ports, either counter stream like the YZ250 or across the port like the Kawasaki but definitely not straight into the inlet or the crankcase itself. To be successful the full fuel charge has to be inducted into the cylinder on each cycle otherwise you get rich/lean cycles and poor running.

As it has turned out … this is the way forward ( port injection ) not inlet injection.

The pulsing of the injectors at below 1/3 ( approx. ) throttle the injectors are on for a very short time.

So within the intake phase only a small part of that flow has fuel the rest is just air.

The crank case is not a 100% pump so some volume is trapped behind each cycle.

The small parcel of fuel MAY NOT be fully transferred to the cylinder each cycle ( mixture strength not constant ) The engine will run and run apparently ( to the ear ) clean but no real power.

Transfer injection allows for the full fuel dump each cycle to be transferred to the cylinder nothing left over to affect the next cycle.

As I understand it: with a carburetor, any time air moves fuel gets mixed with it, so all the inducted air in the crank case has air with fuel more or less evenly mixed throughout it.

With a fuel injection system that has discreet injection pulses and with the injector at the inlet only some of the inducted air will have fuel mixed in with it. Now inside the crank case there are patches of air with no fuel, and some over rich areas.

With inlet injection its random what air/fuel mixture strength gets sucked into the cylinder, you might get a few lean cycles then a heavily over rich one and this is what is happening when the motor is hunting. And if you richen it up so there is no lean cycles then the whole thing goes so rich that the motor will barely run at all.

As we all know, a certain amount of air requires a certain amount of fuel. But with inlet injection the fuel does not get mixed evenly into the air as it passes through the crank case so you have no chance of controlling the exact amount of fuel being inducted into the cylinder with inlet port injection.

But with transfer port injection you have a much better chance of controlling the exact amount of fuel that gets inducted into the cylinder on each cycle.

(direct injection into the cylinder is another very good approach to 2T EFI, but I cant easily get suitable fuel injection parts to try that).

I guess I've been lucky, I put my injectors here to hide them. As it happened this was the right compromise. These two 720 cc injectors flow enough fuel on E90 to be fully fueling at about 180 degrees timing. I fire these injectors at 60 degrees after TDC so there is a time when transfers are not open but fuel is waiting at the transfer catchment ready to go. Because this is the back transfer it seems enough oil is feed down to the bigend. It's done fifty hours now with no bigend or main bearing problems.

YZ250 counter flow injection makes for good air/fuel mixing.

Injectors don't spit, they produce more of a fog. Aiming against the flow is not a bad thing. Or across the catchment of the port.

Took the EFI YZ250 to the Epic Events ride Taupo / Napier road yesterday, in the rain. Performed flawlessly thoughout the whole day. Tuned to give smooth broad power, best for these conditions. It's a lot of fun to ride, this is the first ever "Event" it's been to.

Took the EFI YZ out for another trail ride, 20% fuel savings this time over my standard YZ. It depends on the type of riding, the closer to full throttle the less the savings. This was a tighter track, Tarawera. Last time out it was measured at 14%, Epic events fast and open. Thought it was interesting.

EFI YZ250 at the Acerbis 4 hour two weeks ago. Wayne Blackwood at the controls.

I have seen pics of your efi bike before. How do you find it holds its tune.

We haven't needed to touch the tuning, it just keeps on doing the business, at between 14 - 20% less fuel burn over my standard YZ.

The original tuning was trouble free and within an hour we pretty much had the program that's in it now, ear and seat of the pants.
The reason it's so easy is because of the transfer port injection, each injection is a clean cycle with no residual fuel in the crank case.

Also because of what had been learn't with the Kawasaki F9 injection programe previously. I'm just trying to point out to the doubters, that EFI on a two-stroke is practical.

We both suffered " incidents " ( hit tree roots ) in the race, it took me several miniutes to start my YZ as it lay on it's side ( as did I ) for a while and was flooded, but Wayne's EFI bike started first kick after it had been on it's side for a while, race winning advantage right there!

[TZ350]

First time on a dyno



EFI YZ250 Dyno Run

EFI YZ250 in the Forrest

The EFI YZ is getting used at trail rides, three now, trouble free.

We are experimenting with injection timing changes, interestingly this changes the way the power is delivered.

So far a 14% fuel saving over my carbed YZ 250. Same track, same times, same rider. This must go to show there is less fuel spillage out the exhaust.

EFI Kawasaki Bighorn dyno run and tuning. Air cooled 350cc running on ethanol. Link injection controller. Took a few runs to get it right.

That is awesome, i'm still impressed by the old 350, that thing would had some punch!

I noticed that it *seems* like it really brick walls at the top end of the rev range, is this just the sound of the video making it sound flat or does it not have a lot of over-rev?

It's hitting the rev limiter and the last fueling square is a bit rich I think.



Yes the Kawasaki is a lot of fun to ride, certainly some modern bike riders don't expect to see this old bike accelerate like it does although as soon as it cuts up rough, I'm out.

[TZ350]

Some EFI ideas and tec talk.

Around 50 years ago when EFI wasn't even a dot on the horizon, Irving suggested constant flow injection via the big end. Hilborn injection was pretty much state of the art then with Lucas and Bosch just getting progress on mechanical injecion.It's still a viable scheme - just vary the pump output to suit.

Grumph, yes if you want to inject into the intake constant flow injection would be the way to go ( like a carb ). I made a version of this previous ( not electronic ), sort of worked.

I ended up realising that an electronic variable pump was the way to go ( constant flow ) but in the mean time thought I would have a go at standard ( ish ) EFI in the interim. As it has turned out this is the way forward ( port injection ) not inlet injection.

I have pointed this out earlier that the pulsing of the injectors at below 1/3 ( approx ) throttle the injectors are on for a very short time. So within the intake phase only a small part of that flow has fuel the rest is just air. The crank case is not a 100% pump so some volume is trapped behind each cycle.

The small parcel of fuel MAY NOT be fully transfered to the cylinder each cycle ( mixture strength not constant ) The engine will run and run apparently ( to the ear ) clean but no real power. Transfer injection allows for the full fuel dump each cycle to be transfered to the cylinder nothing left over to affect the next cycle. I worried about the oiling but on inspection it appeared all was oily.

As it happens the F9 is in bits now, a 1973 gearbox bearing let me down. Last trail ride there was some squealing ( from the engine not rider this time ). Sounded like a gearbox bearing, worse on decel and sure enough main input shaft bearing behind the clutch. Engine itself is still in good condition ( and oily ).

I mix at 40 to 1 Micro T with a little castor, injectors and general fuel system seems to be fine with this mixture. Although my fuel burn is approx 1.8 / 1.9 to that of petrol.

DO NOT run dead loss electrical system. Run a suitable aulternator, it doesn't take much voltage loss to affect the injector on time ( it will run lean as voltage drops ). Small high output aulternators are available.

You will spend hours and hours trying to tune something that will never tune. The goal posts are always changing! You NEED constant voltage. I'm sure I've written this before on this forum but I had a regulator that would randomly cut out ( get hot ) and the computer would have to run on battery power for a while until the regulator cooled and decided to work again. The engine was constantly going from lean to rich ( I had it set rich to try and compensate for the lean times ) UN TUNABLE! I ended up running a small digital volt meter for a while after this episode, didn't trust the new regulator!

Just relaying my experiences so others don't fall in the same traps.

Irving's idea was injection via the big end - ie, fuel under pressure fed into the crank and exiting via the big end slots, cooling the bearing as it passed - and incidentally being well vaporised in the process.

Interesting comments re electrical supply - and all true in my experience too.
Some years back I was asked advice on small alternators by a local engineering firm doing a small 4 stroke aero engine. They had space and weight probs and thought a bike alternator could help. Sadly I couldn't point to one small enough for them.

The internet and advances in rare earth magnets have made available just what they needed. One of the biggest probs Rob Selby had on the Britten motor was packaging the alternator securely. He was never really happy with it.

Would it be sound to use an 02 sensor? Injecting at the back port and timing right you will spill air out the exhaust, not fuel air, so your sensor will say to the computer more fuel required when it will not be required.

Avgas will kill any O2-sensor; pump fuel mixed with two-stroke oil will in theory do the same, but if you take care to heat the sensor to working temperature before starting the engine, and provided the sensor is not too close to the cylinder so it won't be hit by washed-through mixture, the sensor will last a long time.

I can hardly imagine that with the right injection timing you can avoid fuel entering the exhaust, certainly not over the entire rev range.
In order to make real power, the pipe needs to receive and subsequently push back about 40% of the cylinder capacity and I do not think you can separate air and fuel to such a degree that no fuel will enter the pipe.

But in order to keep the sensor clean it will have to be fitted well away from the cylinder anyway.
At the end of the day it all depends on how the injection system is instructed to handle the various sensor signals.

No, I am talking about low speed, bottom third throttle.

I'm only guessing but I don't think an 02 sensor in a twostroke is a very useful tool.

With the LINK, we run the MAP off the exhaust ( load ). This runs a separate overlay graph that influences the fueling with load. Also this same pipe is connected to the fuel regulator.

I've always thought running a mechanical variable fuel pressure regulator was not a good idea. Unless you are also monitoring fuel pressure you have introduced a variable.

All good if you have confidence that the regulator reliably and consistently varies the fuel pressure against the manifold, or in this case exhaust, pressure. Just relying on the mechanical regulator to do the same thing all the time seemed hopeful.

That's how almost all cars run their regulators, connected to the inlet manifold, turbo engines also.

I thought it was to maintain a constant pressure at the nozzle, add 10 lbs boost in the manifold so add 10 lbs to the fuel rail , your system seems to be for a different purpose, that could have been covered by a simple map/ exhaust pressure sensor and mapping accordingly. Why add mechanical complexity when you can use even more complicated electronics to do it.

yes, you are right, this system is to maintain constant pressure differential at the injector. This effectively changes the mixture if you like, with out this the computer has to work a little harder on the calculations.

This is a simple system to help maintain relativity, has worked like this for forty years now with high performance turbo engines relying on this simple piece of tech. It works as accurate and as fast as it needs to, in the real world. It would not work well connected to the twostroke intake, unless you used a sampling type of system. Only reads at a certain point of the intake process but that would be difficult to set up.

I can only speak from my experience with the Kawasaki, it worked for me ( connected to the mid section of the chamber )

most efis run around 40 psi (in cars) I would assume that is what he would run

Yes between 42 and 45 psi, depending on the chamber pressure.

Timing is critical. Injecting into the inlet port is no good on a twostroke, that is where everyone else EFIing twostrokes goes wrong! It Doesn't work.
I had no problems up to 9000 RPM ( getting injectors energised and get fuel moving, on ethanol too )

The twostroke has a lot less crap to turn over, I think you will find Rotax DI twostroke snow engines have been shown to be better in every way than the fourstrokes they compete with, including emissions and fuel economy, that's still just a loop scavenge engine.
Also indirect injection ( rear transfer port ) has been shown to burn approx 20% less fuel than a standard twostroke under the same riding conditions, same top end power. Dyno tested. EFI Twostroke's are looking pretty good

Why is it always assumed the " twostroke" has to be a loop scavenge type engine. Sure it's what we have ended up with by default ( when supercharging was banned ), It's sort of the best of what was around at the time. Move on, loop scavenge has problems that have only partly been solved by electronics ( EFI ). The exhaust port needs to move to the other end of the cylinder from the inlets.

Twostrokes are far from fully developed. If you want a clean, fuel efficient engine, the twostroke would be the obvious choice. Uniflow type scavenge twostoke engines have already shown the way forward. This interestingly can be done without EFI / DFI. Fill the cylinder from one end and exhaust from the other end, clean combustion each cycle with ( if done properly ) no exhaust recirculation. This type of scavenge will produce BMEP's similar to fourstrokes, truly twice the power per cc. At the moment it's not, even including free supercharging from the resonant pipe. The problem is they run out of port time / area / pressure, at higher rpm like a normal twostroke. There are systems "out there" that can produce uniflow scavenge AND increase port time / area ( still using simple light / cheap crankcase pumping ). These have not yet been fully explored.
Using poppet valves in the head is not the answer, perhaps for a low speed diesel, but not for a high speed twostroke.

APART from electronics, as these can be used on both 2 and 4 stroke, what has the fourstroke bought us development wise that's that much different than say the 1960's? Still four valve ( poppets ), still twin over head cam, still require many revs to make power ( BMEP is still much the same, just at a higher RPM ). Parts are lighter, a little less internal friction ( special coatings ). Not much excitement there!

Twostroke development was just getting started but the rules soon took care of that!
I think perhaps the " manufactures" didn't like the idea of modifying your twostroke with just a die grinder and a few clues. Fourstroke's are far more profitable to hot up with all that stuff, cams, valves, springs, pistons, etc, etc. The more you spend, the shorter the fuse.

The only fourstroke I have in my shed is sitting there waiting for it's 50hr piston change and I just can't get excited about it! I'd rather ride my "dirty old twostroke", way more fun.

The Big Horns variable rotary valve cover.

Nothing wrong with an o ring head seal on air cooled two stroke.

The physical layout of the system is very important too.

You must send the fuel back to the tank, separately.

You must have a large flow pipe to the pump from the tank also a large flow pre filter and an high pressure after filter.

Much fuel is traveling around the circuit. You do not want cavitation, you do not want any blockage or you engine will expire, quickly.

Those little chinese pumps do not like any contamination / cavitation.

Your engine relies heavily on this pump maintaining constant flow / pressure.

The YZ250's Drum Valve inlet.

TZ 350, Have you got one TPS feeding the two computers?

Yes ....

[TZ350]

My EFI stuff from Ecotrons http://www.ecotrons.com/2_Stroke_Sma...e_EFI_kit.html turned up today, only 4 days delivery time and it was Easter, how good is that!

Great Excitement.



The Beast, with its EFI heart beating feebly lives, although its still on life support.

I am learning as I go and have found that in setting up an EFI there are a number of things to consider.

1) Start Conditions range of Temperature and engine RPM where start conditions stop.
2) Starting cold or warm starting at cranking speed
3) Transition from cranking speed to low running warm up speed.
4) Warm Up at higher speeds like, while blipping the throttle.
5) VE Map Volumetric Efficiency also called Speed Density or Load map, the axis are RPM/MAP
6) Alpha N map, the axis are TPS/RPM
7) A way of switching between or Blending the VE and Alpha-N maps

The EcoTrons EFI has some basic fuel factor settings and curves associated with getting the engine started and warmed up.

Global Factor, ranges from 0 to 4 , < 1 it leans things off, > 1 it richens things up.
Start Factor only applies at cranking speed and its value reduces to 1 at 1000 rpm
After Start Factor lasts 60 sec and is the transition from Starting to Warming Up
Warm Up Factor lasts up to 360 sec, shorter if the engine warms up quickly.

These Fuel Factors are multiplied together by the CPU to dynamically get the Fueling value required.

Start Fuel = Start Factor * Global Factor
After Start Fuel = After Start Factor * Warm Up Factor * Global Factor
Warm Up Fuel = Warm Up Factor * Global Factor

After the motor has warmed up the Fueling is governed by the Global Factor and Load (VE/MAP) or Alpha-N (TPS/RPM) map.

Fuel = Global Factor * Load (VE/MAP)map.
or
Fuel = Global Factor * Alpha-N (TPS/RPM)map.

The Global Factor is just a quick and dirty way of leaning or enriching things up. When all the maps are OK the Global Factor should have been able to be set at 1.

I have been able to get the Beast to start and run roughly during warm up but after a few minutes when it gets to running temperature it splutters to a stop.



This suggests to me that the first (load) map is set too rich as indicated by the dotted line on the right of my graph, and/or something else is going on.

Pretty sure with Ecotrons on a 2-stroke they only use the TPS and not the MAP sensor to determine fuel at any point, + revs of course.

Ok ... you might be right.

With the VE map, MAP manifold absolute pressure vis RPM, after a week or two on the dyno I now think I have been barking up the wrong tree.

Its not obvious from reading the manual but I have come to suspect your right, on a 2-Stroke Ecotrons only uses the Alpha-N load based map.

I will check this with Matt.

I checked with Matt, and now we know for sure that Ecotrons EFI software for 2T's comes with only the TPS Based Load map functioning and the Volumetric Efficiency map disabled even though we can still see it and make changes to it.

support@ecotrons.com
Re: Does a 2T ignore the VE map?

For the 2 stroke engine, it use A/N MAP in default and disable the P/N MAP.
Because usually the 2 stroke engine intake pressure change is very small, phase judgment is not very accurate.
You can log some data and send to us, if the intake pressure change is bigger, we can help you switch to P/N MAP.
Thx
Ecotrons Tech Support 001

So now we know for sure, although you can see and adjust the MAP/RPM VE map, apparently for two strokes Ecotrons EFI systems are provided with only the TPS/RPM Alpha-N map switched on, Ecotrons will unlock the VE volumetric efficiency map for you if you really want to work with that one too.

Performance Fuel Systems has great technical articles about fuel injectors. http://performancefuelsystems.com/tech.htm

It would seem that connecting the fuel regulator to the manifold is all about maintaining consistent fuel pressure at the injectors metering orifice for consistent delivery volume. Flettner points out that we can attach it to the expansion chamber to enrichen the fuel under load.



An injector does not instantaneously snap open, it take a finite amount of time to reach full flow. 2ms (2 thousandths of a second) is the rule of thumb, below that, the flow is mostly non-linear and erratic.

Thankfully its better on the closing side as the fuel injection pressure helps with closing the injector’s needle valve so closing is much more rapid than opening.

A little math ..... 8,000 rpm / 60 = 133 rps x 360 deg = 48,000 deg sec / 1000 = 48 deg/ms

So at 8k rpm the crank turns 48 degrees in one mille second or 96 degrees in the time it takes to open the injector properly (ie 2ms).

2ms @ 8k rpm = 96 deg of crank rotation
2ms @ 10k rpm = 120 deg of crank rotation
2ms @ 12k rpm = 144 deg of crank rotation
2ms @ 14k rpm = 168 deg of crank rotation

If the transfers open 115 deg ATDC then they are only open for 130 deg total.

So if at 12k rpm it takes 144 degrees (2ms) to get the injector fully open and another 72 degrees (1ms) to deliver sufficient fuel then the injectors pulse width is 3ms and it is energized for 216 degrees which is way more time, than the transfer port is actually open.

Thankfully most of the early fuel will be a cloud hanging around in the transfer duct waiting to be blown into the cylinder when the transfer port opens, much like the cloud of fuel waiting behind the inlet valve in an EFI four-stroke.

With my two injector system the EFI CPU will swap to the larger injector when the pulse width on the smaller one gets out to 324 or so degrees (for 90% duty cycle).



Green line is the transfer port duration, red line is the pulse width of the injector, in this drawing it takes 2ms to ramp up and another 1ms to deliver the full fuel load. So the injector is energized for 3ms or 216 degrees or for longer than the total transfer duration at 12,000 rpm. The right hand side shows the partial fuel cloud forming in the transfer duct as the injector opens and before the transfer port opens. Thankfully the injector turns off faster than it opens.

Flettner makes the point that its important, in fact the whole key to successfully fuel injecting a two stroke, to have the injection period timed to end at the transfer port closing.

So the first lessons I had to absorb were that the timing of the Injection end point is critical on a two stroke and should be timed to end at transfer port closing and the fuel should be injected into the transfer ports, either counter stream like the YZ250 or across the port like the Kawasaki but definitely not straight into the inlet or the crankcase itself. To be successful the full fuel charge has to be inducted into the cylinder on each cycle (just like a 4T) otherwise you get rich/lean cycles and poor running.

The next step is to figure out how to get the injection end point timing right.

Flettner suggested to me a way of making a trigger mechanism for a timing light that will show where the injection points are.

Its basically a 12V solenoid coil with 14 Ohms DC resistance or there abouts. Fitted with a mild steel core and a CDI trigger coil attached so its pole piece is held firmly against the mild steel core of the solenoid coil. Then the solenoid coil is plugged into the injector socket. Connect the CDI trigger to something like an Ignitec set on zero advance and ignition coil and spark plug and by using a timing light and by reversing the solenoid coil connections back and forth you can see the injection end point and starting point.

Clever idea I reckon.

[wobbly]

But what im saying is that if the ignition curve isnt correct for making power above 12,000 then turning off fuel up there could kill the engine in a flash.
I dont get what you are saying Kel, the "changed" curve in the box now, is what you are running, so thats what I want to see???
Hard to help with no info to go on.

[Flettner]

[QUOTE=husaberg;1130638332]moved on to bb's from the beads...... more masculine

Yes the beads, I found a shop that sells beads and that sort of stuff. So go in, dressed in my overalls with a vernier to measure and after a time find the right size plastic beads. Over to the counter to pay for the things, the lady asks what are you going to do with these beads, O pattern making I say. With that she raises an eyebrow and looks a bit sideways at me, I think, thats odd?
So half way home I'm driving and suddenly the thought comes to me, She ( the lady behind the counter ) thought I ment DRESS pattern making! I can't go back to that shop again so I find B B gun pellets are just as good and no one looks sideways at you when you purchace them.

[2T Institute]

EFI YZ250 at the Acerbis 4 hour two weeks ago. Wayne Blackwood at the controls.

Should have been barred from the meeting with texta numbers, if your going to do that it should have been electrical tape or proper brought ones

[RAW]

Wobbly, this increased heat within the exhaust, would it lead to increased heat upon the piston skirt and if to great result in the burning away of the skirt about and below the ring groove / no burning away of the piston above the ring

Power jet issue and or timing issue ?

I've got another piston burnt away now, HELP

[speedpro]

Every time I've had pistons fizzled away around the ring on the exhaust port side it's been an ignition timing issue.

[wobbly]

I have heard of late model TZ250s have an issue with piston burning due to excessive retard ( like after TDC ) when in the overev - as well as having the powerjet switch off , but its usually
too much advance at some point lower down in the rev range that tears up the ring lands.
If its too much timing at peak, you will hole the piston.


Here is the link to the Frepin TZ400 startup and first dyno session

https://www.youtube.com/watch?v=p8ZJCPXAIyA

[husaberg]

Looks cool wasn't expecting the astralikes and kinda thought it was going Yellow....
Wax my half baked thoughts are that scooter with its CVT would be living its entire life in the Two stroke death zone. the PJ and ignition functions were not designed for a life there, were they a method of extending the over rev for a few short moments.
edit i realized the Scooter is WAX not RAW whoops
oh Wob wasn't the rs honda's firing them after tdc too

chucked this here as it gets more traffic.
Anyone seen this crazy Hp for the carb size........... optimistic dyno?
http://www.kiwibiker.co.nz/forums/sh...ght=mb100+h100

http://www.bikechatforums.com/viewtopic.php?t=279145

http://www.bikechatforums.com/viewto...er=asc&start=0

engine looks like it was tuned in Germany.
Cylinder Head is like our H100 less fining than fish fillet and open road.
No exp with plated bores but i have never ran in a 2 stroke without taking of the high spots during the bedding in process.