ESE's works engine tuner

[Brett S]

Speak to Bob from Australian Gokart Spares, he has it in stock and is great to deal with:

https://www.agskartparts.com.au/prod...-oil-caster-2t

[_____]

Hi folks,

speaking of karts - does anyone by chance have a Rotax 122 / 123 or karting engine in Engmod? I would like to play a bit with it.

Regards
Chris

[TZ350]

.
You could see clear rust tracks with pitting outlines of the rollers along the pins and in the bearing races. With engines that had been running Methanol then pulled apart after sitting for a while.

To avoid this the post race trick was to run an oil rich petrol mix to purge the motor. Fiddly and took a bit of time.

After dyno runs I am trying a quick and dirty purging trick with CRC.

With the motor running. I turn the gas tap off and squirt CRC anti-rust lube into the carb until the methanol is purged from the carb and motor.

With carefully timed squirts the engine will keep running on CRC alone no problem.




Methanol being the noxious thing that it is I use a respirator when working in the dyno room.




Still quite a bit of tuning required as the bike runs rough until about 8,000 rpm and really starts to smooth out at 9,500 but even though Engmod says that it should be mechanically good for 11,500 I am a little nervous about going there.

[wobbly]

I have a Rotax FR125 kart engine sim I modified to run in a junior dragster car.
But it had a Tillotson pumper that was designed as a replacement for the class but was never homologated , my pipe , Ignitech ignition controlling the PV as well , sleeved down Ex duct exit, VF4 ,
way high com and lifted Ex timing.
It won a bunch of titles and then had a DD2 cylinder fitted.
Its on an old hard drive somewhere , I will look if you are interested , maybe I have all the stock files as well - PM me with email.

[TZ350]

.


The Beast is sucking gearbox oil. Common fault with rotary valve engines. Difficult to seal the RV cover. The big surprise is finding gearbox oil in the carburetor bowl.

Gearbox oil is all through the engine. Ignition is doing pretty well firing a spark through all the mud on the end of the plug.

[F5 Dave]

Probably self medicating to ward off corrosion when it sniffed methanol

[philou]

I read dragonfly75 theories on the exhaust

many of his thoughts strike me as bizarre and false


"But because it lessens the diffusers suction wave peak, which is essential when the reed valve is too restrictive for the engine size at its top RPM, then I don't recommend a flared header for that situation. What is "too restrictive"? These are typical: 1) a tame street bike that has been modified for racing (which now emphasizes power at high RPM), 2) a racing bike that has been modified for much higher RPM without enlarging the reed vave, 3) an engine that has been bored out for a significanty larger size. Any of these situations need the best diffuser wave possible from an increasing angled diffuser and a straight header."

"The diffuser angles should also be in relation to crankcase compression ratio because a high ratio (1.5:1 or more) has more need of a strong vacuum wave from the diffuser to counter the crankcase suction as the piston rises after BDC. Otherwise some exhaust gas gets sucked back down into the crankcase"

[Condyn]

“He who must not be named” is a psychopath who is notorious for spreading misinformation.

[lodgernz]

What is the general consensus, if any, as to the best location of a piston oil hole to lubricate the exhaust septum of a twin-port engine, a Honda?

I've done it before, guessing at about 5mm down from the ring, but I'd like to be a bit more confident for this new engine build.

[wobbly]

The A kit race piston I have here has one 15mm from the timing edge and one at 30mm

[husaberg]

i thought the bartol KTM had some holes but i cant find them but i did see this when i was looking
I remember another GP engine had a divot there to pool oil also but i cant remember what one.


i first assumed this isn't the injector hole.....?
although now i see it goes all the way through rather than just a divot i am not so sure.... i think it might be




anyway here is the works NSR500

[wobbly]

The deluded ,obsessional ideology with using radical diffuser angles to ameliorate deficiencies in any engines performance envelope is ignoring one major factor that in general
applies to all the examples given , where it is supposed to be beneficial.
The " tame street bike " , a " race bike that has been modified " , but has a too small reed cage , and an " overbored " engine that retains the stock cage.
All these examples will , in general , have crap transfer duct geometry , and the biggest mistake that escapes most pundits , is that as soon as you apply heavy diffuser efficiency to crap duct geometry
you instantly incur the wrath of the " overscavenging effect ".

This , as detailed a ways back , simply means the diffuser action over powers the directional coherency of the transfer streams scavenging ability , and huge short circuiting occurs.
Thus any power increase gained from depression efficiency around BDC is completely obliterated by a huge amount of fresh purged A/F mixture that is pulled well down into the header , lost forever for use in making power.

And the ideology ignores the factor that has only become obvious since accurate code pressure traces have been commonplace.
That is that any depression in the case , sufficient that it could pull exhaust gas down the transfers , or open the reeds for that matter , does not achieve sufficient amplitude until near TPC
and has nothing to do with the rising piston.
So that eliminates the CCR from that equation , and who the fuck has seen an example of a CCR in the range of 1.5 in over 40 years


And as for making the diffuser steeper , by simply reducing the header angle , as was mooted previously for the 85cc example of using a 1.8* included angle header to achieve a superior scavenging effect , is completely erroneous
in my mind and sim tests.
I tried several examples where the header was a simple 3.2* and several more where it used a 50/50% split of a 3.2/5.2 combination and all lost power.
As for the proposed header length of over 34% , I didnt even try that , as I went there 20 years ago , and it was then , and is still shit now for modern engines with what we would agree were reasonably
well designed transfer efficiency , and STA numbers that match well.

What I cant quantify with these tests , is that all the people seriously modifying 85cc MX engines , all spend a heap of effort correcting the inner transfer radi , roof angles and duct entry area ratios.
So just maybe a huge deficiency in this area , can be offset by weird arse pipe geometry , that has no relevance in any other engine combination.
And as for a parallel header , yea right - the only examples of that were in very early Proff Blair code outputs , and they were quickly dropped in favor of what we now regard as SOTA , ie 3 - 5* included.

[lodgernz]

The A kit race piston I have here has one 15mm from the timing edge and one at 30mm

Thanks Wobbly. I'll scale that down a bit for my short-stroke 100.

[ken seeber]

Instant castrations, no gov't health subsidies required.
1732+ rpm and they'll both fall off.

https://www.visordown.com/news/gener...aR1p81fWLU4pxU

[lohring]

I have built and tested a variety of pipes for our piston port race engines. They have piston ports and four crude, open transfers. Exhaust timing is usually raised to 180 to 190 degree duration with 126 degree (stock) transfer duration. The rear transfer is widened over the intake port. The piston skirt is cut to give at least 160 degree duration. The most effective pipes have a straight or two step diffuser with a low (1.2) horn coefficient and a small diameter.

The one exception is a pipe I developed a long time ago on the stock engines. Here the exhaust has about 165 degree duration with the same transfer duration and 144 degree intake duration. The rear transfer is narrow. Here there is a lot more restriction to flow and a larger diameter pipe with a 1.4 horn coefficient helps power. The various lines for the large pipe represent different band widths with the moveable baffle cone. The smaller pipe is still best at higher rpm, but that's not where the stock engine develops peak power.

Lohring Miller