ESE's works engine tuner

[wobbly]

If you are getting lower temps at high rpm,then high temp at lower rpm ( throttle opening ) then I would say the main jet is rich
and the overun jetting ( that is the pilot/needle/tube combo is lean ).
You need alot of fuel ( rich ) in the bottom end jetting to stop a lean condition on the overun, when road racing - even more so with an aircooled engine.
It needs to be actually rich ( smoking ) off the bottom when free running - and having a case full of rich mixture as you open the throttle on corner exit is always faster.
The high corner temps would also be an artifact of the over advanced midrange we talked about previously.
I discovered this years ago when initially using a straight line motoplat ignition on an air cooled YZ125 kart - on Methanol back then.
When we changed to a later model retarding unit, it was way hotter mid corner, and lean on corner exit.
It needed way more fuel to keep the CHT/EGT under control at lower rpm with a ton of mid advance.
Many years later we had the same issues with a water cooled engine, running hot CHT on the overun into corners, again it needed a very rich pilot and a big tube
to keep the temps down,and as a result it also ran way harder off the turns as well due to the cooler pipe wall temp.

[TZ350]

My guess is the CHT follows the actual temperature in the cylinder by a few seconds. Obviously the heat generated has to heat the head which heats the probe and this takes time.

I presume that once I tap off coming to a corner that the cylinder heat will go down straight away.

From the graph it looks like the delay is around 7-8 seconds. Does this sound correct?

The highest temp (190 Deg C) is midway round the hairpin at Ruapuna. (See the dot)

Here is another plot.

See how the temperature drops with the 'high' speed down the straight. The max is still behind the corner.

So I suppose a question is, does the bike seize from overheating or over cooling? Would be quite a different story with a water cooled motor.

This is very interesting. I would have thought the cart guys would have looked into this. I hope someone can shed some experienced light on it.

Maybe this is the first time we have any real publicly available aircooled cylinder head data. I would love to know the interpretation and what the data means.

If this is truly the way it is in realty with a good motor then there is nothing much to fear from running a well tuned big hp aircooled motor hard down the straights its just what happens in the corners that matter.

PS, please tell us more about the data logger you are using, I would like to use one too. I have a 4 channel unit but it does not record temperature relative to the position on the track.

If you are getting lower temps at high rpm,then high temp at lower rpm ( throttle opening ) then I would say the main jet is rich and the overun jetting ( that is the pilot/needle/tube combo is lean ).

You need alot of fuel ( rich ) in the bottom end jetting to stop a lean condition on the overun, when road racing - even more so with an aircooled engine.

It needs to be actually rich ( smoking ) off the bottom when free running - and having a case full of rich mixture as you open the throttle on corner exit is always faster.

The high corner temps would also be an artifact of the over advanced midrange we talked about previously.

I discovered this years ago when initially using a straight line motoplat ignition on an air cooled YZ125 kart - on Methanol back then.

When we changed to a later model retarding unit, it was way hotter mid corner, and lean on corner exit.

It needed way more fuel to keep the CHT/EGT under control at lower rpm with a ton of mid advance.

I missed this, Wob must have posted as I was writing mine.

Two strokes like an ignition curve approximating to an inverse of the power curve.
With around 28* in the mid range, that ramps up from an easy kick starting 10* at idle to about 1500,2000 rpm.
Then as the bmep rises and the pipe gets in sync with the port we pull out timing in relation to the dynamic compression created by the wave action, to prevent detonation in the end gasses.
Most engines like around 15* of timing at peak torque, we then drop this away after peak to increase the heat released into the pipe.
We have a finite amount of heat energy to use to heat trapped combustion gas,heat the water, heat the piston/head, or release it into the pipe.
The ignition delay sets the amount dispersed into each element and how much this creates power at the crank is set by the interaction of each component part.

Attachment 249567

In working out a curve to programe into the Ignitec we did various dyno runs with a straight line setting but different base advances. The runs were cut short as we were only looking at the lower part of the curve.

Attachment 249566

Same runs compaired to my previous KX80 fixed ignition 16* BTDC (Red Line).

WTF ….. The Beast screams around the track on full song for a whole lot of laps then quits when taken out for an easy trot around in the two warm up laps for the next race, what is that all about?????

Attachment 261714

Damage is in the exhaust port area, and thats a steel ring thats cleanly snapped in two.

I will dig out the dyno graph and ignition curve.

Rob,re the Ignitech curve "issue". I have found that the engine will not make much if any more power, as shown by the dyno load it will pull, but by adding a heap more timing, it will for sure
operate much , much better on part throttle response, on track. Here is a 125 kart engine curve that made 50RWHp,and won 3 back to back 125 National titles easily. This thing would deto like mad on part throttle at 6000 if held there, but on track it would pull out of 1st gear hairpins hard enough to spin the tyres on full throttle from the same rpm, then rev out to 14200. A TPS and a 3D map would achieve a better result, but I didnt have a RS125 Honda carb at the time.

.........

Attachment 261718

To be on the safe side we had richened the mixture up (Blue line)

Attachment 261717

And in case the piston might be to close to the head we tried an extra 0.5mm base gasket (Red Line) but we didn't like that and took it out again.

But it is interesting to see what lifting the barrel only 0.5mm does.

Attachment 261716

There is no evidence the piston was hitting the head, just a lot of derbis crushed into it. I regret we didn't lift the head for a look after the first race, then we would know for sure, but it was going so well I didn't want to disturbe it.

Attachment 261719 Attachment 261720

The original dyno graph and ignition curve.

With a straight line ignition curve the engine made max power around 16 degrees, the advanced portion improved the lower power curve. The ignition curve is 16 degrees at 12,750rpm and retads 10 degrees by 13,500 rpm for max over rev. This curve was carefully developed on the dyno using full throtle runs and took a lot of work and time.

10 degrees retard, on full throttle is that excessive? is it OK to hold it on full throtle in the max retard area at 13-14,000 rpm for longish periods? like holding out to the end of a short straight.

Any way the problems happened at lower rpm and lesser throttle openings when the motor wasn't being driven at race pace.


I am wondering if this could be the problem? and I might need to use a TPS and go the 3D map way, or at least switch between 2 maps depending on rpm and throttle position.

The one and only reason you get a destroyed piston like that is DETONATION.
And looking at the Ignition curve you have posted it is immediately obvious why the thing keeps on blowing up.
NO 2T race engine making any sort of power can take anything like the advance numbers you have except in very fast, short burst, transient testing.
If at any time you had held the engine on part throttle at 10,000 rpm in 6th gear on the dyno, then done a roll on test it would have seized instantly.

I have never seen in 30 years of dyno testing any engine making reasonable Hp that would take 22 degrees of advance at peak torque, 12200 , then 20 * at peak Hp, 12400 in this case.
You have the wrong end of the stick completely with the comment about holding the engine in the overev region.
Its safe as houses up there as its BMEP is low ( little dynamic com ) plus there is not much advance, alot of the heat energy is going into the pipe - not the piston and head .

The real issue is exactly as per the comment of mine you posted re that 125 kart engine - the edvance curve it liked when used at full throttle in the mid range,would deto its tits off when held
for any time at those low rpms, be that on part throttle for a fast corner, or slow acceleration due to corner loading.
In a kart, part throttle is very rarely seen in a corner, as they have tons of grip.In a bike you run part throttle in corners most of the time, especially in the area just under the peak torque point
and having 27* of timing at 11,000 is going to kill the thing every time unless jetted well rich.

Using fuel to cool an over advanced engine looses power big time and it is impossible to set up an ideal ignition curve on a rolling road with no instrumentation at all.
With no deto sensing or being able to track EGT plus CHT you have no idea about what is happening with a particular ignition setup at all.

You used the port timing map off the sim I did as well as the head geometry, that put the overall engine efficiency quite a bit higher, but then ignored the combustion file that had an ignition curve tailored to suit the bmep
plus the overriding fact that it is an air-cooled engine.
If you take the sim as I last ran it then do a Turbulent Model with your ignition curve,the TuMax will be thru the roof,and the program will probably scream DETO WARNING at you in the mis range.

The way to go is pointed to by the fact that the RACE box has two curves that can be used in all sorts of ways - one of which is as per Honda RS125 setup, using a shift rum sensor that has allows alot of advance
in gears 1 thru 3, then uses a retarded map in gears 4 thru 6th when the acceleration rate is alot lower.
But really you first need to get a handle on a single map, that can be used in any gear at any TPS without it destroying itself.

These issues have nothing to do with an inherent problem with the 2T engine as some are joking about - I went to the kart nationals over Easter, with over 300 entries, only one siezure of a 2T all weekend that I heard about,
and that was caused by some idiot running so low on fuel it sucked air.

[adegnes]

TZ, you don't happen to have the gp engines stock crankcase volume recorded somewhere do you? Other measurements are greatly appreciated too!

I'm designing a pipe for my neighbor's bike in engmod.

[TZ350]

TZ, you don't happen to have the gp engines stock crankcase volume recorded somewhere do you?

Bucket did some measurements, I think the number less transfers is 470cc but best follow the link and check.

Crankcase Compression Ratios Revisited

He also posted on page 500 a lot of info or links to info on the Team ESE GP125 engines. From memory we got good results with the Ex at 80atdc 72% bore width, Trans 114atdc and In 145/85 to get any power we found that the rear transfers had to be opened up. Anyway take a look at what Bucket posted on page 500.

[adegnes]

Bucket did some measurements, I think the number less transfers is 470cc but best follow the link and check.



He also posted on page 500 a lot of info or links to info on the Team ESE GP125 engines.

Thank you great sir!
Man I suck at searching...

[marsheng]

PS, please tell us more about the data logger you are using, I would like to use one too. I have a 4 channel unit but it does not record temperature relative to the position on the track.

It is a GPX Pro 4. This is one of the best instruments I have ever bought. As an Electronic Engineer I have designed, built, bought many instruments over the past 50 years. This one it up there with the best.

Switch it on, go ride and it picks up the track and then feeds you info. By the second lap, it starts giving me faster of slower LED flashes each time it crosses the finish line and all I do is switch it on. If the start finish line is not correct, you just edit it on the screen.

You can program the unit for different bikes so I use it for the SR500 and Maico.

http://www.xtracing.com/en/gpxpro/index.php

http://www.racesupplies.co.nz/produc...o-4-and-pro-8/

[marsheng]

More info.

http://www.racesupplies.co.nz/assets...gs-GPX-Pro.pdf

[TZ350]

Great thanks for that.

I added some of Wobs ignition curve comments to my previous post.

[adegnes]

Any ideas for balance factor on a 45ish deegre upside down engine supposed to have peak power at about 15krpm? 50%?
It's vibrating badly and spewing fuel out the carb vent and overflow, event hough the carb is rubber mounted.

[marsheng]

Any ideas for balance factor on a 45ish deegre upside down engine supposed to have peak power at about 15krpm? 50%?
It's vibrating badly and spewing fuel out the carb vent and overflow, event hough the carb is rubber mounted.

I've been playing with balance factors and have had little success.

What I have found is that sometimes adding a head brace reduced the vibrations, other time, removing the front engine mount !! Both made quite a big improvement.

I do know that the Aermacchi 350 which had a horizontal mount had a 20% BF

My guess is some where in between. Say around 35-40%.

It also depends on the frame design as well, not just the motor.

Cheers Wallace

[wobbly]

Yes, the further forward the cylinder is tilted from vertical the balance factor should be reduced.
Engines that are around 30* tilted drop to 35 to 40 %, so my guess for a 45* tilt would be 30 to 35%.
What you are trying to achieve is the minimum vertical shake component that is felt the worst by your hands
on the bars - horizontal shake is no where near as annoying to the riders parts that contact the chassis.

[adegnes]

Thanks guys!

[F5 Dave]

Well I'd dismissed the Sutter project as a bit of folly, interesting toy for the wealthy perhaps. But in a fit of work time blues I bought a PB and an unhealthy lunch to take my mind off. Not usually a tomb of decent technical writing since JR departed this mortal coil. But the fuel injection points were interesting and next progression is direct injection and then traction control.
The chassis evolutionary path that also took place at the time the 500s phased out was interesting too.

What has this got to do with buckets? Well nothing really but it made for a decent lunch read. I'll cough my way through the rest of the mag but it will probably be a skim read at best.

[husaberg]

I've been playing with balance factors and have had little success.

What I have found is that sometimes adding a head brace reduced the vibrations, other time, removing the front engine mount !! Both made quite a big improvement.

I do know that the Aermacchi 350 which had a horizontal mount had a 20% BF

My guess is some where in between. Say around 35-40%.

It also depends on the frame design as well, not just the motor.

Cheers Wallace

I have found the same thing with Head steadies, also the frame material as well as the design makes a difference, For instance CR500's vibrations are felt much more with the Alloy frame than they do in the original steel chassis. whether its is stiffness or resonance or design (or both) I am not sure. But a lot of old British twins had different balance factors depending on the frame they were mounted in.
Also some older bikes also have oversize engine mounts that make maters worse.

[adegnes]

Are there any supplementary "tricks" for minimizing carb vibration and fuel frothing?
Are horizontal shakes better than vertical for the carb too?

Hmm... The vibrations may have gotten worse after I restricted the sideways movement in the engine mounts to eliminate flying belts.