ESE's works engine tuner

[TZ350]

2-stroke tuning is a hobby for me and I am constantly awed by a self proclaimed professional’s ability to surprise me with the depth of his knowledge.

I assure you Turbo charged 2 strokes have been around since the 50's..... Just because you cannot find one on google does not mean they did not exist.

I don’t think so but change my mind with a picture……., get your friends to help you, in all of Europe there must be at least one picture you could find.

This is what you posted regarding your Plenum Dyno runs TeeZee It makes no sense what so ever.

I posted the data so you could use the BMEP method to make an informed judgment about the std vis plenum dyno runs.

You wiffle on about BMEP, but it reads to me like smoke and mirrors.

BMEP is the universal yard stick for piston powered internal combustion engines, a quick Google will turn up heaps of information on BMEP, the way to use it and the science behind it.

A target BMEP is usually the first place to start when planing an engine development (hot up) program…… check out TSR, MOTA, Bimotion and other 2-stroke development software systems.

Also exhaust gas temp or target BMEP is one of the first questions that any chamber development program asks.

Amongst other things average exhaust gas temp can be determined from BMEP.

What is this about the air passing 3 times passed the main jet?

And

I honestly have never heard about that.….do all Two strokes do this?

This is new to me.

Try the last page of the carburettor section of Jennings book.

“ Air passes the nozzle moving into the intake tract, then reverses direction as a result of the pulse
generated when the intake port chops shut, and passes the spray nozzle a third time as the
next intake period begins. This may sound slightly improbable - but there is absolute
evidence it is happening in the fog of fuel one sees dancing in front of the two-stroke
engine's carburetor.”

Under normal conditions, fuel does not pass through 3 times……….

At certain RPM some spit back is thrown out so far it does not get sucked in again and the fuel wets the area around the carburettor, I would call this the Blarrrs and is not what I am talking about.

But I have seen the carb fog phenomenon on the dyno and expect you have too.

So when the engine is up on the pipe and making real power, what is that dancing reversion cloud of fuel in the carbs bell mouth if its not fuel mixture passing the jet three times. Jennings

.

[SS90]

Yes, but it seems only on Disc valve, at high RPM.

Giving the backfiring at the carb you mentioned.

I used to think that disc valves had a ceiling rpm limit of say, 12 or 13 thousand, the that was it (due to the phenominon you describe), and it certainly seemed true with different experiments I tried.

I then learned of a Minerelli engine from (I think) 1973 or 74 - It was an 80cc disc valve, GP engine (tuned by a company from Vienna who's name illudes me just now) water cooled head, thermosyphon set up) that revved to 20,000 and produced a claimed 27ps, when their piston ported engine could only manage 21 or 22ps revving to 17,000.

That kind of blew me away, and I stillmhave never managed to get a disc valve revving ghat hard, and I know of a tuner who has never got to rev over 13,000, from a disc valve- and he really knows his shit.

I am baffled by the symptom you have, where either with or with-out the plenum, the engine spits back out of the carb at high rpm, as you would expect that if it was inlet timing issue, you would expect one inlet set up to remedy the fault, unless, like I say, the symptom is the Same, but for different reasons.

Do you know where in the rev range this phenomenon occurs, I mean is it 10,000 rpm or more?

[TZ350]

.
What you have written in your last post sounds like Wiffle to me...............

We were talking about why the plenum carb needed a much larger jet than the conventional carb does, and I believe that's because in the conventional setup the mixture passes the main jet at least three times and in the plenum setup, only once, when they are both running at there best..

A reasoned argument about what the fuel fog in the bell mouth or lack of it, at full power means, is the topic at the moment.

Yes, but it seems only on Disc valve, at high RPM.

The last page of the carburetor section of Jennings book was not specifically talking about rotary valve engines.

“ Air passes the nozzle moving into the intake tract, then reverses direction as a result of the pulse
generated when the intake port chops shut, reverses

(and travels back out to the bell mouth passing the nozzle for the second time, reverses again at the open bell mouth end) (added by myself for clarity)

and passes the spray nozzle a third time as the next intake period begins.

This may sound slightly improbable - but there is absolute
evidence it is happening in the fog of fuel one sees dancing in front of the two-stroke
engine's carburetor.” Jennings.


If there is not three passes of the mixture mass past the main jet then how do you think that the pressurized mass of mixture that every tuner tries to get pressing up against the inlet valve just in time to burst into the crankcase as soon as the valve opens gets there? whether its piston-reed-or-rotary-valve, its all the same.

Whats the path the mixture has traveled in the inlet tract when every thing is working at its best?...............I have written the clue above...........

I couldn't quickly find any 2-stroke examples so these 4-stroke ones will have to do, its the same objective, large pressure pulse at the inlet valve just as it cracks open.

http://video.google.com/videoplay?do...73019926133763

http://video.google.com/videoplay?do...&q=V10+Engine#

The reversion or fuel fog can be clearly seen at the bell mouth when the motor is on full song.

I believe this is the same for normaly asperated 2-strokes of any inlet type except for a carb on a large plenum.

If I am mistaken, then maybe someone could show me a good video clip of a reversion-less stroker on the dyno at full power.

I am open to any kind of persuasion except endless Wiffil...........

[speedpro]

My motors, piston port and full crankcase reed, have had a fog of fuel/air standing off the carb entrance on the dyno when the motors were off the pipe. As soon as the motors started climbing on the pipe the fog went away completely. I've had flames dancing round the carb off pipe as well but that was from something else.

[TZ350]

Thanks for that, gives me something to think about.

Our rotary valve engines have as far as I remember had a fog all the time, I did not take much notice of the piston port-read valve RG50's carb when they were on the dyno, I will specifically take note next time.

Will try and video it next time too.

One other thing that interested me was that when we ran a power jet carb. As the revs built up we could see the fuel sucked up the tube to the jet then as the engine started to really get on the pipe the fuel in the power jet tube would start pulsing back and forward. Then at Max rpm the fuel ran back down the tub into the float chamber. Curious.

As we get the bike on the dyno and track, I will be sure to get some video footage of these things to post.

[gatch]

Sort of related but not really..

My buddy had a starlet rally car that had 2 side draft webers equipped. During tarmack events he would have the bonnet off for cooling. A few times it shot some pretty big flames out of one of the webers.

Cool to see from the side of the track, not so cool when inside the car..

[Buckets4Me]

Yes, but it seems only on Disc valve, at high RPM.

Giving the backfiring at the carb you mentioned.

I used to think that disc valves had a ceiling rpm limit of say, 12 or 13 thousand, the that was it (due to the phenominon you describe), and it certainly seemed true with different experiments I tried.

I then learned of a Minerelli engine from (I think) 1973 or 74 - It was an 80cc disc valve, GP engine (tuned by a company from Vienna who's name illudes me just now) water cooled head, thermosyphon set up) that revved to 20,000 and produced a claimed 27ps, when their piston ported engine could only manage 21 or 22ps revving to 17,000.

That kind of blew me away, and I stillmhave never managed to get a disc valve revving ghat hard, and I know of a tuner who has never got to rev over 13,000, from a disc valve- and he really knows his shit.

how about a Suzuki engine that would rev to 20,000 rpm and came out in the late 60's and was ROTARY VALVE ?

Suzuki RP 68
Engine type: Water-cooled 50 cc triple cylinder 2-stroke.
19 hp/ 20,000 rpm (380 bhp per liter), 170 kph.

Suzuki RS 67 U / RS 68
July 1967 - February 1968
Dry weight: 95 kg (209 lbs)
Wheelbase: 1,240 mm
Engine type: Water-cooled 125 cc 90° V-4 2-stroke.
Bore x Stroke: 35.5 x 31.5 mm
Compression ratio: 8.4
Carburetor: VM24
42 hp / 16,500 rpm (350 bhp per liter), 145 mph.

Attachment 217981 1967 Suzuki 125

Attachment 217982 1967 Suzuki 50


http://www.ozebook.com/compendium/suzi/rs67.htm Attachment 217983

Suzuki RS67

First raced Japanese Grand Prix 1967 (last race of the season in October). 90 degree V4, 4 X 24mm carbs, 4 geared cranks, 12 gears, liquid cooled, positive oil lubrication, disc valve induction. Peak power 42 BHP at 16,500 revs (by Feb of 68 power improved to 43.8BHP), top speed 137 mph, dry sump gearbox with forced lubication from a trochoidal pump. Extensive use of titanium and alloy (frame made from alloy) 95kg weight. Engine produces 340 bhp/litre! Banned after FIM changed the rules and limited 125s to 2 cylinders.


Suzuki did it back in the 60's

[F5 Dave]

My motors, piston port and full crankcase reed, have had a fog of fuel/air standing off the carb entrance on the dyno when the motors were off the pipe. As soon as the motors started climbing on the pipe the fog went away completely. I've had flames dancing round the carb off pipe as well but that was from something else.

Yeah +1 on that.

Flames? too high transfers perhaps? Some bikes scorch reeds.

[bucketracer]

Turbocharged European small 2-stroke bike, maybe early 60's or late 50's???.

http://www.youtube.com/watch?v=diCp4F7FU0k ...........

[TZ350]

Thomas and Bucket have got the generator system working OK now, using two coils with 420 turns of 0.6mm enameled wire on each and wired in parallel. The system was made with a new $15 pit bike rectifier/12v-regulator from Trademe and two rolls of 0.6 wire from JayCar at $11 each.

A voltage measurement is more accurate when there is a dummy load on the generator that represents what the running load will be and that's what the light is for. Without the light the generator wouldn't have anything to work against and the voltage would measure (be) too high.

The trick is to use a light bulb that draws the same amount of current as the running load will, in our case that is 2.5A at 12V for an electric water pump and the ignition system.

Pic-1 DC voltage from the rectifier/regulator shown on the left meter and AC from the ignition generator on the right.

Pic-2 Ignition stator with two experimental coils, (not the final ones used though).

Pic-3 Ignition stator, a new coil with 430 turns of 0.6 enameled wire and a $15 pit bike 12V rectifier/regulator from Trademe. The color code is:- Red to battery, Green to earth, Violet and Yellow AC from the generator.

[ac3_snow]

So have you gone back to runing the magneto purely to power an electric water pump?
I'm assuming the benefit of a total loss ignition is to have less rotating mass on the crank therefore the engine revs free'er? but it seems like a fair bit of hassle for what I imagine would be a rather marginal gain?

[TZ350]

Yes your right, destroying a good ignition, someone needs a whipping for that. I know, a lot of people take advantage of the reduced mass to get their bikes to be a little zipper.

But we have found a little extra flywheel weight is useful at a tight track like Mt Wellington, the extra flywheel inertia helps with keeping up the bikes momentum.

The new IgniTech CDI runs directly off the battery and all we needed from the original magneto was the trigger and flywheel mass. So if we can get the old high voltage coil(s) to keep the battery charged, it should be a plus, fingers crossed.

[TZ350]

Got to Christchurch Friday, after some difficulty finding our way around the closed off streets, it was great to catch up with Yow Ling and Bren_CHCH for a chat over coffee.

It was very interesting to hear about Bren's RG400/Kawasaki100 conversion and the thinking and inspiration behind it, it should be a very competitive bike. I was most impressed by Yow Lings printing machinery and the accuracy that goes into printing work.

I was asked the hard question "does the plenum actually work" and yes, in its present configuration it does but only makes 20rwhp. The BMEP numbers suggests it has the potential to be much better.

To make more power it needs the inlet duration lengthening by closing the inlet later than the 35 degrees ATDC that it does at present, 60 would be more normal, even more is possible and I believe it could be done, without causing any unusual problems.

Yow Ling made some very sensible and interesting suggestions about how the plenum idea could be improved, I am thinking about how I could incorporate them.

All in all it was a great afternoon.

[jasonu]

...It was very interesting to hear about Bren's RG400/Kawasaki100 conversion...

Is that a Kawa 100 or 125 bottom end maybe???

[gatch]

Got to Christchurch Friday, after some difficulty finding our way around the closed off streets, it was great to catch up with Yow Ling and Bren_CHCH for a chat over coffee.

It was very interesting to hear about Bren's RG400/Kawasaki100 conversion and the thinking and inspiration behind it, it should be a very competitive bike. I was most impressed by Yow Lings printing machinery and the accuracy that goes into printing work.

I was asked the hard question "does the plenum actually work" and yes, in its present configuration it does but only makes 20rwhp. The BMEP numbers suggests it has the potential to be much better.

To make more power it needs the inlet duration lengthening by closing the inlet later than the 35 degrees ATDC that it does at present, 60 would be more normal, even more is possible and I believe it could be done, without causing any unusual problems.

Yow Ling made some very sensible and interesting suggestions about how the plenum idea could be improved, I am thinking about how I could incorporate them.

All in all it was a great afternoon.

Do you think it necessary to have the plenum between the carb and the crank case ? Wouldn't a "pressurized" airbox be of benefit, without the risk of 1,5 liters of petrol vapor blowing your leg off..

Not being a naysayer mind you.. Just trying to work through the nuts and bolts of it.