I figured as much for casting. Seems like a expensive process. Didn't know if there was a trick to take a round one, put in mold and flash freeze or chemical to apply that would allow oring to hold memory of desired shape
Hardcore Biker
I figured as much for casting. Seems like a expensive process. Didn't know if there was a trick to take a round one, put in mold and flash freeze or chemical to apply that would allow oring to hold memory of desired shape
Hardcore Biker
TZ350, have you thought about timing the injectors to your disc valve below a certain RPM?
Have you confirmed it's just too rich at low rpm?
A reed valve is constantly being open and shut by demand. A disk valve is fixed timing.
Cool thought, strain gage on reed petals linked to ECM letting ECM know engines needs.
Hardcore Biker
Im not disagreeing with him. I just cant change it this year. Maybe next year i can get another cylinder but not right nowOriginally Posted by peewee
Hardcore Biker
I have managed for o-rings to change their shape, but only because they had been misused (heavily overpressed, overheated etc)The cheapest way is to get o-ring wire and o-ring glue from a rubber shop and just glue the ends together after you've generated the desired shape. You can also use the glue to fixate the o-ring inside the groove in e.g. tight bends or so. If the groove is as it should be (height and width), no special shape should be necessary.
Do you have a special application in mind?
Hardcore Biker
I was going to oring my RG500 cylinders. I knew I could just use a round one and use grease/glue to hold in place. Was just one of those what if there's a different way.... head gaskets are annoying.
Hardcore Biker
Here's some 2 stroke FI technology that manages idle/"off the pipe" to full RPM performance.
Vertigo, a Barcelona company, claims that the fuel-injected two-stroke motor in the Combat Camo Works — one of a three-bike professional Combat line (the other two are the Combat Ice Hell and titanium-festooned Combat RR) — puts out 31 horsepower at 9200 rpm. Both of those numbers are unheard of in the trials world.
Thanks to the use of fuel injection, the engine has a wide variety of tuning options. There are four power maps in the computer (a maximum of 24 can be loaded), and I used the softest setting. Sensors tell the ECU the gear position, crankshaft position, and other vitals, which allows the computer to do such novel things as regulate the electric water pump, along with essential adjustments that include different power delivery in different cogs in the six-speed gearbox.
Starting the Vertigo Combat Camo is unique. Unlike the Ossa and Montesa Honda fuel-injected trials bike that use the kickstarter motion to power the fuel pump for starting, Vertigo has a small lithium iron phosphate battery. Push a button and wait for the whir of the pump, then kick within 20 seconds. Unlike the Montesa Honda thumper, which is usually a one-kick affair, the Vertigo sometimes takes a few prods to get the high-compression two-stroke to fire up.
Once fired up, the 300cc motor has a nice sound, thanks to the EFI’s steady delivery of the air/gas/oil mixture. Throttle response is rapid, and with 31 horsepower on tap, it is essential that you ride the Vertigo Combat Camo with a sensitive right hand. I don’t know what 31 horses will do in a section and, unless it’s an insane sand hillclimb, I don’t want to find out!
The sensation of the Vertigo Combat Camo’s motor is unlike anything in trials. Power is extremely strong off-idle — if you stall this bike, you have made a serious error (starting it on the fly in a section will be tricky) — and the powerplant is more than willing to rev. Given that, for most riders — and I’m an Intermediate — you’re rarely going to do more than just crack the throttle.
A fascinating combination of gobs of torque, amazing traction-finding tractability, and a relatively light flywheel, means that you will have to recalibrate your brain from whatever bike you’re used to. Again, slightly opening the throttle will likely get you over any obstacle you will encounter. Revving the Vertigo Combat Camo is neither necessary nor desired.
Modern trials bikes are typically ridden in first gear in most sections. In the case of the Vertigo Combat Camo, second gear will find quite a bit of use. With a bit less mechanical advantage, it smooths out the Vertigo’s ample power and gives you a wide range of possible speeds in a section, without shifting. Plenty of torque is still there off idle, yet you can get good momentum going should you need it on a long uphill.
Gear selection is another useful "Input" for FI mapping and telling the engine how you want it to respond.
Cheers, Daryl.
Moped rider
They have a hose from the crankcase to a pressure sensor.
I could be wrong, but I assume they're looking for the presence of the exhaust suction.
I have a mate with a KTM TPI. Might see if I can get the injector output up on the scope and see what it does when it's misfiring.
Agree with your conclusion regarding the Suter, if you run it lean enough to keep it firing this is what you get. I know when my engine was lean enough, it would break into HCCI and start accelerating, it's very efficient.
Scooter boy
Maybe that's because a 300cc 31 hp single trials engine never really gets "on the pipe".
Gas dynamics in a 125 road race (or 110 bucket) engine would be very different.
Hardcore Biker
TZ's concern is at 1/4 throttle and under the power band.
At that point the exhaust is just a header pipe attached to a box......just like a trials bike.
Vertigo seem to have developed FI and ignition mappings that work extremely well under those conditions.
And, if it can rev to 9200, it will have port timings that are a bit wilder than the usual trial bike.
Cheers, Daryl.
Hardcore Biker
Item 17 is a combined pressure (vacuum?) & temperature intake sensor.
The exploded parts pics don't indicate where it is fitted.
Single point injection, after the throttle body and straight into the reeds.
Way back in the Olden Days, when we used to race with carburettors, we'd tune them to idle well, then lower the slides so they wouldn't/couldn't.
Hardcore Biker
if new barells are expensive you could always lower your existing roof by welding and add extra exh ports while your there. likely you would gain a heap of power and perfect gearbox spacing wouldnt be nearly as important
Forum whore
Yes, very possible or the strength of the suction. You would think change in suction = change in air flow.
That would be very interesting.
Forum whore
Interesting that they are only using a MAP manifold absolute pressure sensor and a inlet air temperature sensor in the inlet. MAP and inlet air temperature, that is the same as my Ecotrons system so there is some hope.
Item 17 is a combined pressure (vacuum?) & temperature intake sensor.
The exploded parts pics don't indicate where it is fitted.
This is where it gets interesting, 300cc cylinder with a single injector spraying into the reed block.
Single point injection, after the throttle body and straight into the reeds.
For myself I have several rules of thumb for 2T EFI. (a lot of this I have learnt from Flettner and Speedpro).
The longer the squirt duration the easier it is to get it right, so use the smallest injectors possible.
A long squirt mimics a carb.
A 360 deg squirt would be ideal especially if it coincides with the engines point of maximum charging efficiency.
Inlet injection maybe Ok for reed valve inlets but it is not so good for rotary valve engines. I have tried this.
There is a sweet spot for timing the finishing of the squirt. Usually somewhere around BDC to TPC.
Cylinders 250cc or greater are easier to get right.
MAP sensors have a settling time 2 - 6ms and they get confused if things get to busy.
Less than 9,000 rpm and you only need 1 injector. Because a small injector up to 9K rpm still has enough time to get the job done.
Above 9,000 rpm and your going to have to quickly start thinking about two stage injection using a small and big injector.
Injectors in the "B" ports are aimed downwards against the air flow.
Or better yet, if its physically possible, from the back aim the injectors horizontally across the bottom of the "B" and "A" ports.
For two stage injection, the single small injector is aimed under the piston for homogeneous mixing.
Alcohol based fuels are much more forgiving of changeable air flow, because they can be run real rich during moments of crappy air flow.
The more industrial the engine and/or application the easier it is to tune properly.
The more the engine depends on symbiotic reinforced wave action for making its power the harder it is to tune below 25% TP.
A EFI Honda RS125 engine would be a challenge to get throttling properly for negotiating corners.
That is good info, tells me something about the minimum fuel required on closed throttle over run.
No8 Wire Extraordinaire
In the not so olden days when we used to race with carburetors we'd tune them then wind up the idle to quite high to take the weight off the front and aid cleaner throttle opening.
Heck TZ just turn it up to 8000 and ride around any inconvenience that might cause.
Don't you look at my accountant.
He's the only one I've got.
Hardcore Biker
Not so insanely interesting or unpredictable but maybe fun to see
No amount of experimentation can ever prove me right; a single experiment can prove me wrong.
There are currently 10 users browsing this thread. (0 members and 10 guests)
Posting Permissions
Reply With Quote
Bookmarks