ESE's works engine tuner

[peewee]

looking back through my emails they said they use koyo c3 ball bearings typically but wasnt very clear what roller style they use. he just said nj206 so i assumed that to meen normal clearance. and if they needed to be c3 i dont know why they didnt call to say the normal clearance bearings i sent werent the best choice

[TZ350]

Does this mean that the engine RPM stays high after the dyno run when you pull the clutch? I'm having similar issue on my 90cc methanol dragster and I'm wondering does it actually make any power in this situation? Im curious because I just built a DIY slider clutch and I wonder if the bike can be stopped with brakes after the 1/8 mile or does it just keep going? I have not tested if the engine stops with kill switch in this high reving situation...

That's a good point. Clarification please Rob. Ignition on or off when running on after a dyno pull please.

My runaway Mach 3 was sitting on 9000rpm with all the plug leads off and only stopped when it ran out of fuel in the bowls.
Which was a giveaway it had another source of ignition.

My experience with this engine.
RPM stays high after the clutch is pulled in.
Power? hard to tell. But on another bike I ran on methanol it would still pull reasonably hard, nothing like full power. But still made slowing on the brakes challenging. A bit like still being on 1/4 throttle.
Kill switch does nothing. I found I could turn the ignition off and the engine would keep going no problems. The only way to slow the engine was to choke it with a hand over the carb.
Left to its own devices on 100% Methanol. At 9-10,000 rpm with the throttle closed and the clutch in it would run on to 11-12,000 rpm. Shut the throttle at say 8,000 rpm and there would be no issue.
At 9-10,000 rpm it must develop another source of ignition. Because the kill switch was no help at all.

[TZ350]

.

YouTube clip discussing reading Methanol plugs. 4 stroke stuff but still interesting to me:- https://youtu.be/fn6TtIUnIcc?si=THXtk6IXDDUshoGi

The comment about colored plugs mean to much top end lube, suggests to me that with a 2 stroke, a colored plug might not be unusual. It might explain those gunky green ish plugs.
Cadmium heat/mixture burn on the base ring and ignition timing on the earth strap makes sense.

Some more:- https://youtu.be/uNz1na3lqLY?si=jDBnhkA9HTEVDSom and https://youtu.be/rxGP4HDgabw?si=8KV39HspitMtogfw

Ok, so its American drag racing, but practicable guys talking about their methods. They can adjust individual cylinder fueling and ignition timing. 20-25 psi of boost. NGK 9 and 10 plugs. Nickle, No fine wire or platinum electrodes.

[beta]

Beta , just to be on the same page , was the 198* Duration you actually measured done with the CIK dead stop blade ( 0.2mm @ 45* = 0.28mm actual height change ) and
CIK rotary digital encoder.
I use a 0.7mm blade @ 45* as this gives exactly 1mm of height change on a 50mm digital gauge - easy to then calculate the real timing.

Hi,
0.2 blade and digital degree reader yes.

[F5 Dave]

My experience with this engine.
RPM stays high after the clutch is pulled in.
Power? hard to tell. But on another bike I ran on methanol it would still pull reasonably hard, nothing like full power. But still made slowing on the brakes challenging. A bit like still being on 1/4 throttle.
Kill switch does nothing. I found I could turn the ignition off and the engine would keep going no problems. The only way to slow the engine was to choke it with a hand over the carb.
Left to its own devices on 100% Methanol. At 9-10,000 rpm with the throttle closed and the clutch in it would run on to 11-12,000 rpm. Shut the throttle at say 8,000 rpm and there would be no issue.
At 9-10,000 rpm it must develop another source of ignition. Because the kill switch was no help at all.

My last ride on a bucket involved a sticking throttle. Something fell into or apart in a crash damaged whirlpool throttle that I should have replaced but looked OK. I shut the throttle but the carb didn't believe me. It must have been stuck at maybe 1/3 throttle but peak power revs.
They make a surprising amount of power in that condition and can catch you quite unaware, as it did. Uphill sweeper Full Beans knee on deck then slam off throttle, brake and into a hairpin. Except that didn't happen.

My point being, you must fix this to your satisfaction. Running on can be inconvenient, or it can be seriously dangerous. Don't "she'll be right".

[diesel pig]

My last ride on a bucket involved a sticking throttle. Something fell into or apart in a crash damaged whirlpool throttle that I should have replaced but looked OK. I shut the throttle but the carb didn't believe me. It must have been stuck at maybe 1/3 throttle but peak power revs.
They make a surprising amount of power in that condition and can catch you quite unaware, as it did. Uphill sweeper Full Beans knee on deck then slam off throttle, brake and into a hairpin. Except that didn't happen.

My point being, you must fix this to your satisfaction. Running on can be inconvenient, or it can be seriously dangerous. Don't "she'll be right".

I completely agree with that statement. And it can take years to get over some injuries as I can shore you.

[Pursang]

Solved a problem with a 500 Maico that started running way too fast at idle. Scary during an enduro.
Bike had been fitted with new throttle, cable and rebuilt carby (40mm Bing).
Cable end ferrule was slightly smaller diameter than the adjuster screw recess.
Someone (or thing) had tweaked/tugged the cable and it was no longer seating inside the nut but up on the outer edge, lifting the slide, say 6mm. Rubber boot held it there.
It made an appropriate sounding clunk noise when shut quickly and because of the long soft spring the variation in free play was barely detectable.
Solution: Ferrule was bushed with teflon tape and secured with tie wire hooked under the adjuster lock nut.

[aljaxon]

to get a wider power band using FOS exhaust can i just reduce the belly diameter?



im new here, for the last week ive read the last 500 pages on this thread and dont feel qualified to ask my questions but here i am. i want to make yet another pipe. or 3 to see what works best.
ive made a dozen or more pipes using blair, 2t calc and FOS and had a bit of advice from frits on the pitlane forum. ive used janbros excell sheet to get my porting something like.

a new project 74cc kitted moped has only 4 gears - spaced out too far so i need a wider powerband.
porting 180 122, revs to 10500 in third but drops to 7500 when i change up into top.

i dont have engmod2t and being a only humble bricklayer some of it may be above my head.
i am incorporating wobblys duct recomendations 90% for a single ex port. i might try lower as well cos my headers first 2 sections form the "duct" because my cyl tract is only 29mm. ive welded the cylinder up a bit to get a better shape. it was diverging. its now converging slightly and its oval.
ex port effective diameter is 25.1mm blowdown area is 244 so effective diameter 17.6mm
the kits have poor port and tunnel layouts

i have a few other questions about pipe design, would i get a better pipe if i worked out the actual temps in the pipe and applied them to each separate wave ? obviously a wave is like a car doing 70mph. just cos it hits a cooler bit of pipe ie a 30mph zone it isnt going to slow down immediately.

using an average temp could be wrong. or is the temp difference too insignificant to have an effect on wave speed and cone function? to my laymans eye the suction wave travels at a faster speed than the stuffing wave which travels through cooler sections of the pipe.

i do appreciate questions have been asked a thousand times before and it like how long is a piece of string. i dont have engmod so i can run a sim. so its basically guesswork.
i have access to a pals dyno and so can make 3 or 4 pipes and compare them.
i have static ignition set at 16 degrees. its aircooled big fins runs cool reed valve (with stuffer) 21mm carb. i can post up a portmap but all i want is some general advice about wider powerband.

i hope to get a reply even if its dont give up your day job or leave it to the experts lol. but either way its been very interesting reading this thread and ive learned more in the last week reading this than in 12 years of tinkering in my shed.

[jbiplane]

Our new IGBT ignition

[Flettner]

Wobbly, how high can I make the exhaust dam and get away with it?
More than say 5mm? On a 48 stroke.

[aljaxon]

i tried a reply yesterday with questions, it said it was awaiting admin approval. but its not appeared? so ill try again now.


i want to make a pipe using FOS. ive done a few. if i want a wider powerband due to having wide spaced gears do i simply reduce the belly diameter? i need a 500rpm wider powerband.
blairs recomendations were for iirc 2.125 - 3.25. frits says 3.5 but his belly is shorter which lowers the cones angles back a bit. its a single ex port with 4 real transfers and 3 boost transfers from the reed valved inlet duct.
ive used a wobbly duct 90% on a pipe i recently made for this project and due to cylinder tract being 29mm bore 47mm so duct = 94mm. the 65mm shortfall in duct length ive made as my first 2 sections of the header giving the 90% constriction and then back to 100% of effective ex port. so im thinking instead of 3.5 x exd i go to just under 3? and keep header same so start of diffuser is same diameter to give a shallow angle to the reduced belly? i leave the belly length as it is 8% of tuned length?


also when designing a pipe im thinking that the suction wave travels slightly faster than the stuffing wave due to it passing through hotter parts of the pipe. so should i take the time to work this out? i could take readings of a similar pipes temps and act accordingly. i apreciate all this will do is adjust header and belly lengths a tiny bit.

i also appreciate waves when reaching a cooler section wont slow down to that speed instantly just like a car slowing down entering a 30 limit. cept the wave it will be speeding.
most software or calcs just assume an average speed of sound in an average pipe temp. which in the real world doesnt happen?

i havent got engmod2t just a calculator and pencil. i have nicely balanced ports using janbros excel to get my areas angles sta's and blowdown amongst other things.

[wobbly]

Here is just a few ramblings in reply to pipe geometry.

The cooled part of the duct is ideally around 1.5 x bore so 47 bore = 70.5 duct length - as this contains the outer limit of overscavenged mixture available to be shoved back into
the closing port by the return wave.
So fins on an aircooled extension , or water access is helpful to stopping deto induced by over an heated returned mixture volume.

The slip joint out to 2x bore is the steep expansion back to 100% of effective chordal Ex area, and is not technically part of the duct.
In a full noise design the steeper the transition , the better the peak and overev power , but it quickly becomes diminishing returns.

The first general pipe geometry to establish is the piston to header end @ 28 to 32% of TL , longer for broader power delivery , and piston to diffuser end @ 64 to 68% , again
longer for broader power.

The mid section in my opinion isnt an input , its the result given by the chosen diffuser % and the tailcone included angle - again the longer the tailcone the broader the power delivery.
Going from a 28* to a 22* rear cone will hugely affect the power delivery , and those dimensions are absolutely proven empirical data , the mid section length does affect volume , but it
is a secondary function to the other two variables.

If you are not using a simulator but then worrying about the temp induced speed of those waves at varying length positions , is simply way over thinking the issue.
Real world experience gives you the simple diffuser length % data, not a wave speed analysis.

And what is an Ex dam Neil , if you mean the port floor being above BDC to reduce the duct area , then there is only one source of actual dyno tested information.
Jan ( and myself by extension ) have tested 3mm above in a 54.4 stroke , and this works well as long as the Blowdown geometry is optimized for the bmep.
No one to my knowledge has tested above this level and achieved an actual verified result , its part of a list I have had for years - but sure , going higher then grinding it down and testing in increments
is easy to say , but I shit my pants doing any testing of ground Exhaust ports in a chrome bore sitting at 72%.

[aljaxon]

thanks for that wobbly. ive sussed the duct and already made a pipe with a finned header section. i am guilty of calling the steep diverging 0.5 x bore length part of the "wobbly duct".

i was told by a pipe manufacturers "friend" some top secret percentages 12 years ago and realised they were only 1 or 2 percent different to blairs. and the FOS is the similar,

the longer header for wider power confuses me because it then creates a sharper angle on the diffuser which i thought sharper angles - more narrow powerband?
and does my diffuser angle want to be half that of the baffle/rear cone?

without angles i dont know what my diameter will be at mid point.


its because i cant run a sim that i wanted to try and narrow the sums down as much as i can. and once its built there wont be much altering/ testing going on.

today i worked out my diffusers tuned length wants to be 435mm i assume that is the midpoint of the cone? i will compare that to the percentages rule of thumb

i an learning lots. i only learnt today that from 90 degrees ATDC to BDC with my con rod length and stroke isnt 50% of the time of half a revolution but 44%. ive never known this. i then looked at piston speeds at every degree from tpc to epc and averaged them out to see if i could get the stuffing wave returning halfway through the blowdown degrees on the compression stroke, overdesigning?

if im designing and cutting my sections to within 0.5mm then who knows it might be worth considering every variable.
either way i have a big dustbin


im not convinced that pipes designed for modern multi port engines are applicable to my old single port machines with poorly designed transfer tunnels and ducts. but thinking about it a pulse is a pulse. maybe my pipe wont be reaching the same temps and with the motor being aircooled, small finned, running lower compression and general lower state of tune the pipe might need tailoring to this?

[F5 Dave]

I was going to say what is the engine? If you look into, say an RD350 , the transfers hug the vertical. But your port description confused me so maybe something real odd with rv and boosts added?

[wobbly]

One big misconception needs binning immediately - low power , air cooled ,low compression , crap transfers etc etc has nothing to do with the bulk pipe temp , or more specifically
for tuning , the EGT in the header.
You only need to look at the old KT100 Yamaha used in karts forever , they were seeing near 700*C EGT on 91 pump gas as the idea was to utilize as much of the fuels energy to heat the pipe
and make it rev to 16,000 - not heat the fins and loose power from thermal runaway.

Yes header length is a bit counter intuitive , but the vast majority of engines will like close to 32% , and only super tuned , on the edge things will like 29% as this starts the depression at the port face as soon
as possible . In a sim you see the peak depression value moving rightward past BDC as the revs rise , so starting the negative pressure ratio quickly helps maintain this high amplitude value
closer to BDC at peak power rpm.

There is no relationship to diffuser and rear cone angles to give any guidance in what to use - an 18* rear cone will naturally be combined with a small diameter mid , that also then dictates shallow diffuser angles.
A 28* tailcone can only be used with fat mids that also naturally require steep diffusers , and in a few odd cases where a steep rear is wanted to lift peak but kill overev potential.

The mean reflection point of a single rear cone is 1/2 its length if it was extended to a point , but how the hell do you calculate that for a diffuser or tailcone with 3 steepening angles.

What is important is that crap transfer angles and ducts are very easy to overscavenge ie short circuiting is the enemy - best example from many years ago was trying to drag more power out of
a TZ750 , a pipe only a little over 100mm Dia would loose power no matter how clever Erv Kanemoto was at designing the things.
Just as well as nothing bigger would fit anyway.