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I think if your tube is properly attached to the main jet or needle jet,the tube would feed "calm fuel" to the main jet..Question is whether a bouncing float and needle changing the float level at revs will still have an impact on the mixture into the engine..
It is quite some time ago since i posted anything new about my ugly 212cc(211.6) Kawasaki dragracer.
First shakedown went really ok, no superresult to write home about, but i saw a lot of potencial.
However, this fall i built my own rollerdyno, instead of my old enginedyno.
And last week, the week after new years eve it was time to test the rig.
I have chosen not to touch the bike since the shakedown as i was curious about how good my buttdyno was *lol*
My plans was to acheive about 60hp to the wheel.
And first dynopull ended up spot on funny enough.
60,1xhp at 10400rpm.(uncorrected)
But i have tuned the pipe to 11800rpm, something was wrong.
I quickly figured that it was my odd stingerlocation, on the middle of the belly.
the program i use to calculate pipes also said i should use a 26mm stinger, i had 28.9mm(took a pipe i had lying in garage when building)
Well, i moved the stinger to the rear of end baffle, made a pull.
I lost 8hp but now the peak power was at 11600rpm.
Still too big stinger( i save this mod to last)
I knew my inlettract wasnīt nice so i epoxied and grinded it to make a smooth stuffer down in the reedcase.
I also jetted up from 152 to 158, didnīt touch anything else.
62.16hp uncorrected, (64.71hp corrected), now at 11731rpm, and almost 40Nm even thou i had small misfires in this pull.
I feel that i have only scratched the surface on this machine, or otherwise it was pure luck to reach this level this easy.
And iīm lacking torque down low, but i figure it is due to very big piston to cylinderclearance, actually thereīs a lack of nicasilplating in cylinder above exhaust(about 5mm) and down at the inlet.
I measured the bore, itīs acually 66.49, and it should be 66.40
I was very aware of this, but i planned just to test engineconfig to see if was worth develop further.
I have ordered new piston and new sleeve, will also change the crank as this isnīt balanced at all.
(i was short of time when building the bike)
Will overhaul engine about a month or so.
After overhaul i will do some dynoruns to see if i pick up som torque.
And after that i will jump over to methanol fuel instead.
Your build looks very good!
How about some good pics of your dyno and some info. What software are you using? What type of rpm pickup do you have? How did you come up with the roller you use?
Methanol requires about 230% of gasoline flow and that goes for everything from the tank breather to the fuel cock, the filter, the float valve and main and needle jets.
I agree with your aesthetics judgement; if this bike wins prizes, it won't be for 'best of show'. But do you really need rear suspension and a rear wheel that looks like it weighs a ton? Making the combination 10% lighter may be much easier than finding 10% more power.
Out of curiosity, what would be a typical range of BSFC figures for a racing two-stroke on petrol? 0.6ish?
The datalogger i use is from Performancetrends and is called Datamite.
The roller i use is a heavy steeltube that i have prepped in a lathe and mill.
Measurements is 300mm diam and 870mm long.
Itīs filled with concrete also to kill eventual vibrations on the shaft that goes through whole roller.
I downloaded them at work and uploaded the pics to an another space, so i can post some now.
Turning the roller:
In my small mill:
Milling grooves to help traction, will need less strapping down:
Measuring throw, i Managed to keep it under 0.05mm
Bolted together for inital testing, the space between the beams to the left in picture is to allow me to add a flywheel if running big hp configs, will let me have 10s pulls with about 450hp dragracing motorcycles:
Started to hook up the electrics, i have an volkswagen starter to start the roller to help firing up engines, it is also a brakedisc there to be able to reduce speed on roller quickly:
Doing some measuring to setup the inertia, very easy in Datamite:
I have left to dress it up with some sheetmetal and painting it.
But i was so eager to test it first, so it will be done this spring.
I will also add some protection around roller and flywheel(when itīs mounted)
To this date i have spun the roller at 2600rpm and no vibrations.
I have problems with pvl ignition to get interferencefree pickup.
So these runs i have used the function in datamite to calculate enginerev from roller rev.
When using ignitech i have no problems.
Normally i use the 'purple lead' to wrap it around plugwire, but PVL is so noisy.
With Ignitech i can use the datamiteīs input directly from tachometer output in Ignitech, this is a really nice signal.
The grooves in the roller makes really really good traction, i can actually see on tire that it doesnīt slip at all.
I kept the flange in the end of roller as i can easily add more weigth if wanted.
Yes, a couple of friends of mine is competing in professional dragracing with cars, up against 3000hp.
And a couple of other guys running methanol in their dragracing 2t snowmobiles.
I have their support and experiances in racing with methanol as a 'databank' to get answers from =)
About weight of rear wheel etc, yes itīs quite heavy.
I used a lighter setup in the 'shakedown' but it became crooked in only 7 runs.
So i donīt want to make my drivers life to exciting by building a setup that canīt take the power iīm aiming for in the future.
All in all the whole bike weights as is now 86kg, and the driver 70kg.
The power to weight ratio is 2.4kg per hp at this point if calculating rearwheel power.
It would be equal as if mine mercedes had 773hp to the wheel.
That should be good for about low 10īs at the quarter mile.
But we only run 150m in my class, so my topspeed is geared to about 150km/h
And for the looks,, well, i built it in 5 weeks
And the blue R6 seat is just a test on picture.
I got a complete R6 kit iīll dress it upp with this winter.
But it will most certanly be painted satinblack and Ninja green.
i use Datamite as well , good program , hope filling with concrete works out ok for you
i'm over buckets
I have a steel support inside tube also.
Itīs located in the middle of the roller, to support the shaft inside.
But before i filled it with concrete the shaft still made a 'ring' when tapping on the ends.
Now when filled with concrete the shaft is 'dead', no resonance whatsoever.
I also used concrete that actually increases in volume when hardening.
This concrete has almost the same density as aluminium so it was easy to setup datamite.
I was just wondering how some of the big wigs on this forum feel about airflow meters for 2 stroke development? Just wondering if the likes of Fritz, Wobbly, Juan and anyone else have used airflow meters and/or feel they are useful. The reason I ask is cause I have not really seen them mentioned on here before, unless they have been and I just lost conversation in the thousands of pages of text.
Airflow meters can be a help to understand what has happened in the engine after a modification. For example if the engine breathes 10% more air, but power is only up 5% and lambda and ignition timing is as before, then it could be that the modification also increased scavenging losses.
If you want to use one, you have to connect it to the inlet of a BIG plenum to avoid air passing though the meter multiple times. Without knowing your engine, I'd say the size of an oil drum should be okay as a start. We used it barely and only to calibrate the simulation as we had a fuel balance and exhaust gas analysis available at that time. This way, we could reverse-calculate the air flow through the engine which made the big plenum obsolete.
On an otherwise "naked" dyno, measuring equipment wise, it can be a "nice to have" once you are searching for an answer to a specific engine behaviour. But I would not say it is a must have, especially if you have a tool like EngMod available, too.
I would reckon that if a racing 2 stroke "on tune" got better than 300 gm/kWhr (0.5 lbs/hphr) then itd be doing well. Your 0.6 might be closer to the mark.
Its probably not a matter of charge loss, but a lot more fuel to maintain temperatures.
Agree though, itd be great to see a full load vs speed plot of BSFC, as would the same for air flow. Both for a race engine, but also for a less tuned engine.
Looking at https://en.wikipedia.org/wiki/Brake_...el_consumption and knowing this is a few years old, and the way that every new high tech engine which comes out is 30% better than the previous engine, wed (or theyd) have to be close to the 200 gm/kwhr
Thanks SwePatrick for the good pics and info on your dyno. Looks like it will turn out very nice. Did you weight the roller after you filled it with concrete and did it figure out for the right numbers with the concrete inside? If I may ask what numbers did you come up with and how large of an bike/engine can you use with just the roller. I also have the performancetrends datamite setup. But I have mine on a water brake dyno now but want to change to a inertia dyno soon. Nice feature about being able to use roller rpm right in the program. What setup did you get from performancetrends for measuring rpms. Because they have different ones available. Nice work.