ESE's works engine tuner

[Drew]

It did look dirty and it shouldn't be, I was puzzled by that, I will have a better look when I get back to work.

It must be from floating around in the cases, giving some weight to the ignitionless over run of shutting down.

[husaberg]

With this & Frits advice on keeping the tract as short as I could(ish) I have flowed a control reedblock (the differing epoxy makes it look like there is a bad match but I used Kneedit as its easy to form & then Devcon over the top to smooth it out. Then I ground & sanded it back. Needs more but will do for now. Next block will incorporate a fin & test against this one.

But then I measure it & it is 160mm from reed tip to bellmouth (photo makes it hard to see but it is squared up).

I want to peak faster still than 12, probably 13,000, but I'm no where near even 135mm to the Bell mouth. I could perhaps find a shorter manifold rubber, but only by a few mm & mill into the 10mm ally plate. But I'd only find 10mm tops. The manifold is only about 30mm long. Going to the 36mm PWK makes the assembly even longer.

currently an early TZR block (only just fits) with VJ21 32mm Mik.

I sent you a picture of a straight reed manifold from a YAM Phazer snowmobile that was shorter a while back.



BOLT HOLES ON CENTER: WIDTH = 70MM, HEIGHT = 57.5MM

Also if there is enough meat in the RGV carb the spigot recess could be moved inwards like on a TZR250 TMSS28 carb vs STD Mikuni VM
Then the rubber shortened with a scalpel

But i have seen a thread some where that shows how to make a rubber manifold as on the Japanese bikes do.
Can't remember where, ....OK not the one but like this anyway
http://www.precisiontradingsystems.com/inlet_videos.htm

Failing that you could replicate a old Amal or four stroke flange mount cemented direct to the carb with a thin insulting piece.
Much like a MB100 or RD125/200 or Suzuki RG500


There is a Short PWK 36 from the KX125 from around 99 ish but i guess that's what you may already have?


These are 73mm long overall as opposed to 91mm for the std large Keihin PWK.
(Yes have to be modded to suit the angle But Wob has outlined this before)
As a comparison the TA22 Keihin from a NSR250 is about 95mm.
So what are the Mikunis from the VJ21?

[Yow Ling]

With this & Frits advice on keeping the tract as short as I could(ish) I have flowed a control reedblock (the differing epoxy makes it look like there is a bad match but I used Kneedit as its easy to form & then Devcon over the top to smooth it out. Then I ground & sanded it back. Needs more but will do for now. Next block will incorporate a fin & test against this one.

But then I measure it & it is 160mm from reed tip to bellmouth (photo makes it hard to see but it is squared up).

I want to peak faster still than 12, probably 13,000, but I'm no where near even 135mm to the Bell mouth. I could perhaps find a shorter manifold rubber, but only by a few mm & mill into the 10mm ally plate. But I'd only find 10mm tops. The manifold is only about 30mm long. Going to the 36mm PWK makes the assembly even longer.

currently an early TZR block (only just fits) with VJ21 32mm Mik.

V Force reeds may be shorter

[Haufen]

Have tried the remote hose to the Lambda thing and although the probe lasted better it was slow responding.to the extent that it is impossible to log the Lambda
output against rpm/Hp on the printout.
The reading I think was about 2000 rpm behind the engine when accelerating at 300 rpm/sec.
Dynojet has an expensive add on kit that uses a pump to draw the gas thru a tube that goes in the muffler, this has a filter element in it so should make the probe reliable.
But it doesnt work on a 2T - even apart from having something affecting the test by altering the outlet area of the muffler itself..
I have seen one Dynojet session where the customer had to pay for 2 probes in a 4 hour test cycle. NFG.

Re using EGT and CHT.
The only probes that are worth shit come from Exhaust Gas Technologies.They guarantee them for 2 years,and I have had no problems since changing to them.
They sell probes to Nascar/IRL/F1/MotoGP teams with a guarantee - the only guys to do this with exposed tip,high speed temp sensors.
The company sells Digatron gauges on Ebay,and having just started to use one with 2 screens and 5 functions - im sold.
The ones sold by Mychron etc for kart use are crap, seen several brand new setup last two laps.

Thanks for the information, I guess with that being said, a Lambda probe is (can be) useful when step testing only.

I looked up Exhaust Gas Technologies on ebay, but found that there are many different probes by that seller there. Are the exposed tip high speed probes all the same and the only difference is the connector and the probe diameter (.25 & .187 in)? My gauge uses K-type thermocouples and no connector, the cables are clamped directly to the gauge. So is this the right probe for me? Or are there any better probes by EGT (faster, more durable, cheaper etc)?

[Frits Overmars]

Thanks for the information, I guess with that being said, a Lambda probe is (can be) useful when step testing only.

A normal car-type Lambda probe lags only about 0.1 sec; that's fine for inertial testing.

[TZ350]

No need to have a peaky engine. Here are Two Very useful Tools. EngMod2T a 2-Stroke simulation package and a handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ which is based on Blairs work.

There are over 3,500 images on this thread. To find the interesting ones use Thread Tools near the top of this page and View Images, then sort them from the Beginning and 70 to a page. Click on the Image to view it and the little N/A sign to go to the Post about it.

BMEP.xls

A handy little tool put together by Bucket for checking the BMEP of different Engines.

You change the values in the yellow squares and the answers appear in the green ones. Its a great tool for compairing different bikes and what development potential they may have left and who's telling porkies.

[wobbly]

That K probe is the good one,is fast and reliable and cheap.

[F5 Dave]

Thanks Husi, but that Yam one doesn't look any shorter, except maybe the plate, but I could take that down, but I'm not going to find 25mm. Rubber is needed to isolate from vibes. Just checking if that really meant 135 to the bellmouth which is tricky.

[husaberg]

Thanks Husi, but that Yam one doesn't look any shorter, except maybe the plate, but I could take that down, but I'm not going to find 25mm. Rubber is needed to isolate from vibes. Just checking if that really meant 135 to the bellmouth which is tricky.

So what is the RGV carb length? is your PWK a shorty?
A long while back i posted a length of inlet rubbers its on a decade page somewhere.http://www.allensperformance.co.uk/p...manifolds.html
but the inlet rubber of the Phazer looks shorter than just your inlet rubber (which acually looks long).

Re the inlet vibes the RG500 and RD200 seem to cope? As Mike said the Vforce seems shorter. I am sure Frits said somewhere if the tract is smaller it can be longer I think? assuming the length Wob posted is to do with the Helmoltz frequency?

Mr Frits..... But I claim that in a normal reed-valved engine you have no real Helmholtz frequency; once the flow direction wants to reverse, it is blocked by the reed. It would be the same as a brake that stops the bouncing mass in your animation once it has reached its highest position.
Only two things can go wrong in a reed-valve engine. With too low a Helmholtz frequency the mixture column in the intake tract has no chance to convert all of its kinetic energy into pressure before the next cycle starts. Or the frequency can be so high that the flow already reverses before the crankcase volume has reached its maximum value (piston in TDC). Between these two extremes there is a broad frequency range that functions well in combination with reed valves......... We need a certain Helmholtz frequency, but there are several ways to achieve it:
via the volume, via the tract length and via the tract diameter.

[TZ350]

Just checking if that really meant 135 to the bellmouth which is tricky.

Yep 130-135 to bellmouth edge. By loosing 15mm (145 down to 130) we gained 1hp on top.

[Frits Overmars]

... I am sure Frits said somewhere if the tract is smaller it can be longer...

And I am sure I didn't. Quite the opposite in fact: if the tract diameter has to be small for some reason (rules), you can diminish its negative effect by making it as short as possible. And because it's a lovely day, here is my solution of making it really short.
I slip a plate (P in the drawing) around the carb. The hole in this plate is about 2 mm larger than the carb's outer diameter. Then I slip a thick O-ring O around the carb. Then I slide this composition into a hole in the disk valve cover D and fasten it with two bolts B.
Plate P compresses O-ring O which centers the carb in the disk valve cover so there is no metallic contact anywhere. With this solution I manage to fit the carb at 2 millimeters from the disk valve. It works with reed valves too.

You can play with the O-ring size and the rate of compression to vary the flexibility of the carb mounting. You can also fit a second, smaller O-ring at the bevelled end of the carb, next to the disk valve, to keep the carb from sagging when applying a light rate of compression on the large O-ring.
The ideal would be an O-ring with a sleeve. Maybe you can produce something like that with 'liquid rubber'.

[husaberg]

I am sure Frits said somewhere if the tract is smaller it can be longer I think? assuming the length Wob posted is to do with the Helmoltz frequency?

OK maybe not so sure but i did have a Question mark

And I am sure I didn't. Quite the opposite in fact: if the tract diameter has to be small for some reason (rules), you can diminish its negative effect by making it as short as possible.

Can you expand on the text i misquoted Frits?

"Frits Overmars"
But I claim that in a normal reed-valved engine you have no real Helmholtz frequency; once the flow direction wants to reverse, it is blocked by the reed. It would be the same as a brake that stops the bouncing mass in your animation once it has reached its highest position.
Only two things can go wrong in a reed-valve engine.
With too low a Helmholtz frequency the mixture column in the intake tract has no chance to convert all of its kinetic energy into pressure before the next cycle starts. Or the frequency can be so high that the flow already reverses before the crankcase volume has reached its maximum value (piston in TDC). Between these two extremes there is a broad frequency range that functions well in combination with reed valves.........
We need a certain Helmholtz frequency, but there are several ways to achieve it:
via the volume, via the tract length and via the tract diameter.

PS your carb looks a lot like a Suzuki one in profile rather than design

[Frits Overmars]

Can you expand on the text i misquoted Frits?

I could, if I had the time. But I haven't.
What I can do, is pester you with an article that I wrote for a German two-stroke forum. It's in German (they like that in Germany)...

[Frits Overmars]

Here's some more Helmholtz-encouragement:

Regarding induction systems: build a short induction tract and visit a test bench.
You can forget about calculations. The formulas you find in various books are all based on the Helmholtz resonator. It made me write a simple story, called:
Helmholtz blues
"A Helmholtz resonator consists of a volume connected to a duct". That is what Wikipedia tries to tell you.
But that is a Helmholtz resonator in its simplest form; one that you won't find anywhere in an engine.
What you do find in an engine is an intake tract with a variable cross-sectional area. This tract is from time to time connected to a variable volume (the crankcase) through a very variable window (the intake port / reed valve / rotary inlet).
The crankcase is connected to a number of transfer ducts with variable cross-sectional areas, which are from time to time connected to a very variable volume (the cylinder) through a number of very variable windows (the transfer ports).
The cylinder is from time to time, through a very variable window (the exhaust port), connected to an exhaust pipe with a very variable cross-sectional area who at the same time doubles as a volume. This pipe volume is constantly connected to a big volume (the outside world) through a tailpipe with a constant cross-sectional area and constant entry and exit windows (thank God, finally someting that's not variable).
We call this a compound Helmholtz resonator .
The various papers also tell us how to calculate the resonator's frequency:
" frequency = speed of sound / (2*pi)* Sqr ( cross-sectional area of the neck / ( volume of the resonator * effective neck length ) ) ".
O yes, the speed of sound... It is dependent on temperature, which is not really constant in the intake tract and the crankcase, rather variable in the transfer ducts and very variable in the cylinder and the exhaust pipe.
Now the above frequency formula is not exact; it is an approximation that is usable as long as the volume of 'the' tract is very small compared to the resonator's volume.
So when engines are concerned, that formula goes very far out the window.
Who said gas dynamics is simple dull?
PS:
It's a similar story with acoustics. That is a sub-branch of gas dynamics, simplified with a lot of assumptions that are acceptable as long as the sound pressure does not exceed a certain limit. The wave pressures in a two-stoke exhaust exceed that limit by a factor of thousand. Bye bye, acoustics...

[Frits Overmars]

Why does all text on this page self-center? I tried overriding it with advanced editing and clicking 'align left', but to no avail. It is beginning to annoy me....