ESE's works engine tuner

[Lightbulb]

were you mixing by volume or weight ? since this is my first time messing with nitro i been doing as much research as i can. from what ive read, if you mix say 20% volume its likely to really be more like 25% by weight. must have something to do with the differences in specific gravity i guess.

tonight i removed the bowl to see what float valve ive got. its 3.3mm main inlet hole with three 1mm secondary inlet holes. combined with the oversized float bowl it was sufficient on methanol. i talked to lectron about it and theyre sending me a different one with 6 secondary inlets just to be on the safe side.

the rest ill just learn as i go. ive got #10 plug installed. the spark curve i have no idea what it looks like so ill adjust it in small increments as needed. kind of sucks when you dont have a dyno to see whats really happening :facepalm:

With fuels for model plane engines, and I guess it is the same with the boats and cars, the fuel is mixed by volume. When the nitro content gets higher than 40% they generally run just synthetic oils only as the castor seem to want to seperate out with 50% nitro or higher. I have heard of people adding some acetone to the fuelt to aid in the fuel staying as a nice mix for longer. When the Nitro is higher than 40 % they also increase the compression ratio. Gets confusing, as with glow plug engines, the compression sets the timing. More advance is a smaller total head volume, more retarded is a higher head volume. So effectively with the higher nitro, they increase the compression to get it to fire earlier or start burning more before TDC. Lohring may be able to shed more light on running higher than 20 to 25% nitro fuels for you.
Neil

[lohring]

We mix by volume as well. The larger engines (15 cc) run fine on 50% nitro, but the smaller the engine, the higher the nitro for good power. 3.5 cc engines often run 66% while I normally run 60% on 7.5 cc engines. I've seen 80% nitro used for record runs. Castor oil won't mix at over around 35% nitromethane so nitrobenzene was used in race engines in my youth. It gave a shoe polish smell to the exhaust. It also causes cancer so is out of favor these days. When the oil percentage is below 18%, I sometimes add a little castor oil (2 oz per gallon) and it mixes fine with the synthetic oil and nitro. A very few people add propylene oxide at the race for record runs, but it isn't common.

As was mentioned, glow engines compression determines the ignition timing. When a combustion chamber volume is set for a particular fuel, changing nitro may actually hinder power. Nitro is an easy way to add torque, but everything needs to be adjusted for the amount. Straight methanol and low nitro classes get power by adding rpm. In one case at a record trial a racer offered us some 80% nitro to run in our boat. it was actually slower than the setup we were running on 60%. We needed to run a bigger prop to take advantage of the increased torque. We also probably needed to play with the pipe length and combustion chamber volume. As with ignition engines, just changing fuel doesn't help by itself.

Lohring Miller

[Frits Overmars]

with glow plug engines, the compression sets the timing. More advance is a higher total head volume, more retarded is a smaller head volume.So it is true that down-under everything works in reverse. Or have you been smoking funny cigarettes Neil?:msn-wink:

[Lightbulb]

So it is true that down-under everything works in reverse. Or have you been smoking funny cigarettes Neil?:msn-wink:

Yeah I got that round the wrong way lol. For some reason I was thinking that closer to tdc the more advance it was. But that's wrong. Closer to TDC is retarded. Ill try and correct and edit my post for future reference.

[lodgernz]

My 50 has a very sharp crackle that no muffler is able to quieten. Everyone comments on it, although the bike still registers an acceptable dB reading on the track.

The engine turns out 11.8HP at the wheel at 13,000RPM and the nozzle has a 14.75mm throat. The tailpipe is 19mm ID.

Is it possible that my de Laval nozzle is forcing the exhaust gases to supersonic speed at the outlet? Any other suggestions?

[Frits Overmars]

My 50 has a very sharp crackle that no muffler is able to quieten. Everyone comments on it, although the bike still registers an acceptable dB reading on the track. The engine turns out 11.8HP at the wheel at 13,000RPM and the nozzle has a 14.75mm throat. The tailpipe is 19mm ID. Is it possible that my de Laval nozzle is forcing the exhaust gases to supersonic speed at the outlet? Any other suggestions?The outflow may become sonic during a small part of each revolution but that should not create what you are describing. A 14,75 mm end cone restriction should be good for over 22 crankshaft-HP, so no problem there. Other noise-contributing factors can be a high exhaust timing, a late ignition timing and a low compression ratio.
And of course an absorbing-type silencer that is not absorbing because its stuffing is either too tightly packed, saturated with oil, or gone with the wind.

[jonny quest]

Is this what you call 'bowling' Jonny?
332547

Exactly, Frits. I guess I don't know a more common term, if there is one?

TZ, I haven't modified one yet. But have researched them. I've heard they don't respond well to mods. I probably would have started with 192-194 ex 128 trans total first just to see if it responded.

Wouldn't hurt at this point to "bowl" out ex now. Does A port closest to ex have a good pronounced angle towards C?

[TZ350]

Does A port closest to ex have a good pronounced angle towards C?

Yes......

I have a Honda RS125 NF4 cylinder to look at and the bowel of the RS and NSR look much the same but the NSR has a discontinuity where the power valve retreats into the cylinder and the RS has a much thinner bridge than the NSR.

[husaberg]

Yes......

I have a Honda RS125 NF4 cylinder to look at and the bowel of the RS and NSR look much the same but the NSR has a discontinuity where the power valve retreats into the cylinder and the RS has a much thinner bridge than the NSR.

The RS PV has a longer pivot to the swinging Gate so it stays closer to the port thoughout its arc.
i have some pics of the ports plus some pics of the kit cylinders, Fits has posted pics of the RS kit pipes as well "READ KTM"

[TZ350]

i have some pics of the ports plus some pics of the kit cylinders, Fits has posted pics of the RS kit pipes as well "READ KTM"

I would love to the pictures if you can find them easily.

[husaberg]

I would love to the pictures if you can find them easily.
bottom of page outlines mods to std rs cylinders
https://www.kiwibiker.co.nz/forums/album.php?albumid=4841&page=3
kit pipa aka derbi ktm
https://www.kiwibiker.co.nz/forums/album.php?albumid=4854&attachmentid=310144
RS port map
http://bonavolta.ch/hobby/en/moto/rs125r.htm
http://bonavolta.ch/hobby/images/moto/rs_1.gif

NSR mc28
http://nsr-world.com/tuning/250-tuning/engine/images/stock_ports_rc_closed.gif
http://nsr-world.com/tuning/250-tuning/engine/images/stock_ports_rc_open.gif
MC18
http://2.bp.blogspot.com/-1Zuhn_qJyDU/T1KWqmxymLI/AAAAAAAABAw/w9Ak_wGsM08/s1600/f2.jpg
http://www.2t-racelab.com/2012/03/mc18-cylinder-port-layout.html

NSR125 drawings
http://thetrxproject.blogspot.co.nz/2013/04/nsr-125-3d-cylinder-finished.html

the kit pics will either be on my hard drive or in the rs125 album
they are rough cast there is also ics of the NRS500 cylinders in the NSR500 album

[TZ350]

Thanks for the pictures Husa, interesting that the RS and NSR cylinders have pretty much the same transfer and exhaust timing.

332551

If the modified NSR cylinder (red line) had more over rev it would probably be useable. I am not sure why it stops so abruptly, the fueling is on the money so the 24mm throttle body restricting it maybe.

The crankcase volume is much bigger than would be usual so may be the inlet timing and the 24mm throttle body are restricting refilling the case volume.

But with the way it "Pops" at the end of a dyno pull I still suspect exhaust blowdown issues.

332552

The rpm range from 6-13k is looking clean and the fueling is pretty good too.

Looking forward to getting the throttling issue sorted.

[wax]

I have a question for our two resident experts

What are the pros and cons of cylinder reed versus case reed.
I always figured the case reed has less restriction in front of it and it doesn't have to travel as far before it get to the combustion chamber

[F5 Dave]

And change direction, not aimed so directly into tublent crank action.
Potentially less change of section.

[wax]

And change direction, not aimed so directly into tublent crank action.

so your saying cylinder reed is better ? doesn't it have to go into the crank case before it goes back up the transfers ?
The case reed does not have to do this

[F5 Dave]

Erm, no the case looks neater to flow. And if done right less section change with large reed.

[wax]

Erm, no the case looks neater to flow. And if done right less section change with large reed.

yeah thats what i was thinking, When you said the turbulent crank i thought you were talking about case reed

[Grumph]

And change direction, not aimed so directly into tublent crank action.
Potentially less change of section.

So is there now anything to choose between what I'll call a barrel reed - with Boyesen's, and a case reed with shields over the rotating crank ?

[F5 Dave]

Um. I was kinda indicating case always. Barrel is more of a compromise but still seem to work ok.

Shields etc Wobbly has covered a little. Well out of my pay grade. Rotation of crank can interfere enough so it's a nasty environment.

[dark art]

One big advantage of case reed engines is the better piston support on the inlet side

[peewee]

One big advantage of case reed engines is the better piston support on the inlet side

and theres a actual C passage. cylinder reed really has no defined C passage. its mostly just a doorway from the reed cavity to the cylinder bore

[jonny quest]

TZ, how are you controling the powervalve? The NSR cylinder only offers PV leakage for blowdown which isn't a good thing. If you can set PV to 50% closed, then fully open... I think that would be a worthwhile test on your mod cylinder.

[lodgernz]

The outflow may become sonic during a small part of each revolution but that should not create what you are describing. A 14,75 mm end cone restriction should be good for over 22 crankshaft-HP, so no problem there. Other noise-contributing factors can be a high exhaust timing, a late ignition timing and a low compression ratio.
And of course an absorbing-type silencer that is not absorbing because its stuffing is either too tightly packed, saturated with oil, or absent.

Thank you Frits. The exhaust opens 84* ATDC so not that. The ignition starts at 30* and drops to 14* by 11,000, so probably not that. I've tried several mufflers, all brand new and the same type that make my 90 very quiet.

Compression IS low at 12.5, so maybe that's it?
I must say that possible cause was a surprise to me. Can you please elaborate a little?

[teriks]

Compression IS low at 12.5, so maybe that's it?
I must say that possible cause was a surprise to me. Can you please elaborate a little?
Not Frits but..

Less compression also means less expansion before ex port opening, resulting in more energy in the exhaust pulse.
Given equal combustion pressures etc..

[Frits Overmars]

You said it, Teriks. And that stronger exhaust pulse is the main reason that I am fond of low compression ratios.
We are using even lower ratios in some successful engines. These do sound healthy, but I can't say they produce much more noise than the competition....

[JanBros]

We are using even lower ratios in some successful engines.....

now I'm curious as what is considered as "low" ? 12:1? 10:1 ?

[Juho_]

14,75 mm end cone restriction should be good for over 22 crankshaft-HP
Is it possible the end cone restriction could be too small and cause the lack of over rev?
When: running on alcohol fuel (E85) and pipe is designed for example 13,000rpm peak hp and the engine now produces the peak hp @ 14,500rpm.

In my case.. it probably is not the problem, or will never be the problem. (last ignition timing change @ 13,000rpm, ducati am6/derbi cdi unit, max. rpm only 15,500 now and peak hp as said above; at 14,500rpm currently on new pipe)
Just interested if 'too small' end cone restriction could cause lack of over rev.:rolleyes:


Erm, no the case looks neater to flow. And if done right less section change with large reed.
@F5 Dave - e.g rotax 453 cylinder (used in sleds, like ski-doo mxz 440) has typical 'rotax -like' boyesen ports. Same thing at 122/123 cylinders (found in aprilia rs/sx/mx 125).
They are aimed straight (to A/B duct divider), instead of to crankcase like most (if not all) japanese 2-stroke cylinders have (like YZ 250).

I've had an opinion, the boyesen ports should be aimed to crankcase, because then the B ducts can be then made better shaped.
But I have no much experience of these cylinder reed engines , and don't really like them much and atleast on my knowledge and skills it is not even close as powerful as case reed engine (or have the potential).

[breezy]

Has anyone found a reasonable priced supplier of blank cylinder sleeves since Akunar ...? only ive just buggerd up my £125.00 bespoke liner which took 5 weeks to be produced and then of course in my excitement 10mins to knacker , even though i spent all day making a jig for holding it on my lathe, marking it up and buying a slot drill to cut the ports with. still never mind aye...practise makes perfect.:weep:

[tdc211]

332543

Well I got to try my new nicely ported NSR cylinder. The workmanship of the last porting effort was a bit disappointing and I was not convinced by the results. Disappointingly my first effort only made 31hp. 31 is that as good as it was going to get or was it being held back by poor workmanship???? I was hoping for more than 31 on the new cylinder.

332545 332544

The good news is that today's tests confirmed that for off pipe slow speed fueling, under piston injection gives much better results and was noticeably better than crankcase injection.




On my second attempt. I was very happy with my workmanship opening the ears up on this new ported cylinder to make it look more like a RS cylinder. But after hours of work on the dyno getting the PV right and ignition and fueling spot on it also did not make more than 31hp, Red line.

Inlet is 240 duration and both cylinders ported and std are 200 Ex duration and 132 Transfer duration.

The Blue line is a standard NSR cylinder with its droopy down exhaust port and the modified one, Red line had the top of the exhaust port leveled off for more blowdown time area. At this point I think the standard cylinder would give better on track results.

332546



I will take your advice about "bowling" out the exhaust port. Also what you say about the short circuiting from the "A"s now that the cylinders have been ported makes sense. Engmod tells me that the transfers have enough transfer time area.

A Honda RS125 makes 40-43 hp. Because both my ported cylinders topped out at 31hp I suspect a common link and think that it might be that the exhaust nozzle I am using is going sonic and choking. I will look here first because that is easiest.

Jonny if you have been working with NSR cylinders I would love to know more about what you have tried and the results.




I have some experience with engines of this size
52 x 48.95 stroke. 117/118/119 tranfers. 82 ex 85 subs.
32mm carb 790 pipe. 1.34 case comp . Case reed
104cc. Or it's called a KTM 105. 34.8 hp. Cyinderis terrible from ktm
Tookabout 4 years on and off trying things. Pipe big help
29.5 carb goes 34.2hp on same numbers. But different cyinder.
So I not sure if it's the carb. Or just maybe my cyinder litte better on that particular one. Balanced sta in sim 40hp worth. With low tranfers.


Sometimes I fix Stroker Engines for guys..Aka more transfer and
110-112 cc and I am where you are at. 31-32hp or so.
20hp at 9000 is common on 30-35hp. 100cc engines.
I still need more r&d time on those. Really the bigger Engines should make more at 9000 with correctly timed pv. Correct pipes (my biggest issue. That and pv seems to be my biggest issue on the strokers

I have posted on here in the past. But I have a Eng Dyno.
It's turned down now in these charts, to match most rear wheel hp dynos. So it's legit.

[RomeuPT]

Hello. It's me again, last time it was because of 2000€ part's to trash in a running in :shutup:, never stopped reading the forum, would worth to start another read all over again :woohoo:

Some questions I would like to have clearer ideas.

At which rpm should a rider change gears in a tuned Honda RS 125, say making peak at 12,7 to 13k rpm, isn't it a lost of time to let the bike overrev to 14k or more in low gears?

Been doing some exhaust's like this (attached pic), no exhaust flange, but the oval to round transition in 3mm sheet plate and 1mm roled sheet, then 0,8mm mild steel going along the header, I question myself if this would not loose power against a well made aluminium spignot due to heating more the end gases....

Is there any dyno somewhere comparing carb sizes in a strong 125? like comparing change from 38 to 41? is it really needed to achieve the holy grail of 50cv on a 54x54,5?

Sorry for my faulty english :)

cheers

[husaberg]

Has anyone found a reasonable priced supplier of blank cylinder sleeves since Akunar ...? only ive just buggerd up my £125.00 bespoke liner which took 5 weeks to be produced and then of course in my excitement 10mins to knacker , even though i spent all day making a jig for holding it on my lathe, marking it up and buying a slot drill to cut the ports with. still never mind aye...practise makes perfect.:weep:

Google John Tice
give me a minute
http://www.smallenginemachineworks.com/2-stroke_cylinder_services
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop
http://www.everything2stroke.com/content/30-2-stroke-Engine-Break-in-and-what-you-need-to-know
if your project is intesrting enough he will do a deal on doing it all

he used to make his own sleves and shows the process of casting them,
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page9
from memory he gets most of them from LA sleeve but he mentioned somewhere elese he calls N.W?
Northwest Sleeve Co.
https://www.manta.com/c/mmsq7lz/northwest-sleeve-inc
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page3

Bert Munro used to old gas pipe that was spun cast.
but i believe he once used a cast iron down pipe from a motel near Bonneville (not sure if that was in the movie or the book)

[wobbly]

Romeau, what you are showing will never work.
The whole idea is to reduce the duct volume, so to have a round duct, that then reduces is backwards thinking.
The best RS125 cylinder I have tested had a 32 by 41mm oval shape at the cylinder duct exit.
This then transitioned from that oval to a 41mm header entry.
38mm is plenty for any RS125 cylinder,as I can get 48.8 Hp ( sprocket ) from a TM with a 30mm carb.
The very best RS125 dyno I have seen was 47 HP - rear wheel, this being a PV factory setup as used by Itoh.
That had a stock 38mm SPJ carb, and that translates to close to 50 Hp sprocket.
The reeds in a RS125 are nowhere near as clever as those we use in the TM kart engine,I suggest you start looking there.

[Flettner]

Has anyone found a reasonable priced supplier of blank cylinder sleeves since Akunar ...? only ive just buggerd up my £125.00 bespoke liner which took 5 weeks to be produced and then of course in my excitement 10mins to knacker , even though i spent all day making a jig for holding it on my lathe, marking it up and buying a slot drill to cut the ports with. still never mind aye...practise makes perfect.:weep:

If its any consolation Breezy I did the exact same thing the other day, making a sleeve for a six cylinder outboard engine, spent all day making it then put a hole in the wrong place!! Outboard engines are shit anyway so who cares, well I did because I had to pay for a new piece of cast iron and remake it, all on my bill. Said some bad words I did.

[RomeuPT]

Romeau, what you are showing will never work.
The whole idea is to reduce the duct volume, so to have a round duct, that then reduces is backwards thinking.
The best RS125 cylinder I have tested had a 32 by 41mm oval shape at the cylinder duct exit.
This then transitioned from that oval to a 41mm header entry.
38mm is plenty for any RS125 cylinder,as I can get 48.8 Hp ( sprocket ) from a TM with a 30mm carb.
The very best RS125 dyno I have seen was 47 HP - rear wheel, this being a PV factory setup as used by Itoh.
That had a stock 38mm SPJ carb, and that translates to close to 50 Hp sprocket.
The reeds in a RS125 are nowhere near as clever as those we use in the TM kart engine,I suggest you start looking there.


I am not sure if you or if I understud. the pipe has in it self a oval to round transition, in this case from this cylinder 40,5x34mm and includes the lenght of the spignot, so theres is no more volume there then with oval to round spignot. The ideia is to have virtually the same dimensions, I was thinking if cooling at the spignot has a role to play and I remember a little some post about that.

About the overrev and gear shift, any ideia?

[JanBros]

idealy, you shift each gear at different rpm's, as the ideal point to shift gears largely depends on the drop in rev's and those drop's change from gear to gear.

basicly you need a dyno to determine the ideal shift rpm's.

[breezy]

Google John Tice
give me a minute
http://www.smallenginemachineworks.com/2-stroke_cylinder_services
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop
http://www.everything2stroke.com/content/30-2-stroke-Engine-Break-in-and-what-you-need-to-know
if your project is intesrting enough he will do a deal on doing it all

he used to make his own sleves and shows the process of casting them,
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page9
from memory he gets most of them from LA sleeve but he mentioned somewhere elese he calls N.W?
Northwest Sleeve Co.
https://www.manta.com/c/mmsq7lz/northwest-sleeve-inc
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page3

Bert Munro used to old gas pipe that was spun cast.
but i believe he once used a cast iron down pipe from a motel near Bonneville (not sure if that was in the movie or the book)

thanks for info Husaberg..

[Frits Overmars]

At which rpm should a rider change gears in a tuned Honda RS 125, say making peak at 12,7 to 13k rpm, isn't it a lost of time to let the bike overrev to 14k or more in low gears?
idealy, you shift each gear at different rpm's, as the ideal point to shift gears largely depends on the drop in revs and those drops change from gear to gear. Basicly you need a dyno to determine the ideal shift rpm's.Romeu, I dropped my crystal ball again, so I will assume that your tuned Honda RS125 has the same power curve as a standard RS125 (many 'tuned' bikes have less than standard). I will also assume that you are talking about an RS125-NX4 because an NF4 and an NX4 have different gearbox ratio options.

Third, I'll assume that you use the standard gearbox option that came with the bike as it was shipped from Japan, as opposed to one of the other 647 combinations, made possible by the 4 options for first gear x 3 options for second, third, fourth and fifth gear each, x 2 options for sixth gear.

Fourth, I have to guess rider weight, initial velocity and acceleration distance. And then we'll see that JanBros is right: you should shift at the intersection points of the rear wheel thrust curves (plus a tad of overrev because of the air resistance-induced velocity-drops during the power-interruption periods of each shift action; are you still with me?)

332588 332589 332587 332590 332591
H125 input values H125 power curve H125 gearbox H125 shift points-01 H125 shift points-02

In the above pictures I assumed an acceleration from 0 km/h over a distance of 800 meters.
In picture #4 you can see a lot of clutch slip, all the way from standstill to 94 km/h where the riding speed in first gear matches the 11200 rpm crankshaft speed of maximum torque. In theory you can accelerate even faster if you slip that clutch each time the engine rpm drops below the rpm of maximum torque.
In practice the clutch might not be too happy about this, and it would put a lot of extra heat in the engine, which in turn would not do the power much good.

Pictures #4 and #5 show that you have to rev the engine the most in first gear in order to minimize the rpm drop from first to second gear, but they also show that you do not need to rev it till maximum rpm. In fact, this engine would not even want to rev to the 14000 rpm that you mention in your question.

And there is a second factor playing a role here: the measured power curve is really only valid for one particular acceleration time. Measuring the same engine on the same dyno with a shorter gearing would give a shorter acceleration time, less temperature build-up in the exhaust pipe, and less willingness to rev.

Well, I hope this answers one of your four questions :p.

[wobbly]

Just to show whats possible with RS125 here are 3 rear wheel dyno runs.
One is a well tuned " customer " bike.
The next is a genuine A Kit engine
The 3rd is Azuma,s PV factory engine

[katinas]

This is from 1936 Michael Kadenacy patent Fig.6

6. A method of controlling two strokecycle internal combustion engines which comprises establishing communication between the cylinder and exhaust system during the flring stroke, providing for the issuance of the burnt gases as a mass, whereby the said mass moves outward and thereafter return from a point which may be within the said system, providing a permanent ree passage for the burnt gases to the limit of outward travel of said gases, preventing the entrance of fresh charging air into the cylinder until the said issuance of the burnt gases is in full progress, admiting fresh charging air into the cylinder when the said issuance of the burnt gases is in full progress and-causes a suction effect to be exerted in the cylinder while the exhaust port is still open, providing for said fresh charge to occupy the cylinder in the interval elapsing between the mass exit of the burnt gases and the interval when the pressure of tire returning gases becomes effective within the cylinder, shutting oi the said communication between the cylinder and the said exhaust system, after the said fresh h charge has occupied the cylinder and before the instant when the pressure of the returning gases becomes efective within the cylinder.

[dutchpower]

Just to show whats possible with RS125 here are 3 rear wheel dyno runs.
One is a well tuned " customer " bike.
The next is a genuine A Kit engine
The 3rd is Azuma,s PV factory engine

Sorry Wobbly.

Azuma had never a PV engine

[wobbly]

So the Azuma dyno run never happened ?

[dutchpower]

So the Azuma dyno run never happened ?

More then 400 runs only by Liégeois Compétition
5 A-kits for one season and you have to give then back to HRC

[RomeuPT]

Romeu, I dropped my crystal ball again, so I will assume that your tuned Honda RS125 has the same power curve as a standard RS125 (many 'tuned' bikes have less than standard). I will also assume that you are talking about an RS125-NX4 because an NF4 and an NX4 have different gearbox ratio options.

Third, I'll assume that you use the standard gearbox option that came with the bike as it was shipped from Japan, as opposed to one of the other 647 combinations, made possible by the 4 options for first gear x 3 options for second, third, fourth and fifth gear each, x 2 options for sixth gear.

Fourth, I have to guess rider weight, initial velocity and acceleration distance. And then we'll see that JanBros is right: you should shift at the intersecion points of the rear wheel torque curves (plus a hint of overrev because of the air resistance-induced velocity drops during the power-interruption periods of each shift action; are you still with me?)

332588 332589 332587 332590 332591
H125 input values H125 power curve H125 gearbox H125 shift points-01 H125 shift points-02

In the above pictures I assumed an acceleration from 0 km/h over a distance of 800 meters.
In picture #4 you can see a lot of clutch slip, all the way from standstill to 94 km/h where the riding speed in first gear matches the 11200 rpm crankshaft speed of maximum torque. In theory you can accelerate even faster if you slip that clutch each time the engine rpm drops below the rpm of maximum torque.
In practice the clutch might not be too happy about this, and it would put a lot of extra heat in the engine, which in turn would not do the power much good.

Pictures #4 and #5 show that you have to rev the engine the most in first gear in order to minimize the rpm drop from first to second gear, but they also show that you do not need to rev it till maximum rpm. In fact, this engine would not even want to rev to the 14000 rpm that you mention in your question.

And there is a second factor playing a role here: the measured power curve is really only valid for one particular acceleration time. Measuring the same engine on the same dyno with a shorter gearing would give a shorter acceleration time, less temperature build-up in the exhaust pipe, and less willingness to rev.

Well, I hope this answers one of your four questions :p.

Great piece of pratical/theorical information, many thanks for your time and willingness. Some things I was guessing and you confirmed and changed!

[RomeuPT]

Ok, more info for this thread.... Sorry if it was explained before, or half way throught

it's easy to take a standard T port cylinder from a MX bike or std RS125 that has like 190/195º exhaust and raise it to 200º by doing a good round chamfer raising the port 1/1,5mm.

The thing is if looking at cylinders from factory that come with 200º we don't see that chamfer, it's mostly straight plain duct on the roof, 1min in paint .....

332618

Doing this helps keeping duct volume low, the return pulse gases can follow this chanfer if big enought, or maybe not.

Would this need a dyno to confirm or is safe to say that will not be has good has a normal 200º port...

Thanks

[Frits Overmars]

it's easy to take a standard T port cylinder from a MX bike or std RS125 that has like 190/195º exhaust and raise it to 200º by doing a good round chamfer raising the port 1/1,5mm. The thing is if looking at cylinders from factory that come with 200º we don't see that chamfer, it's mostly straight plain duct on the roof .....You must have been looking at cylinders from the wrong factory :D.


332618
Doing this helps keeping duct volume low, the return pulse gases can follow this chamfer if big enough, or maybe not.It sure will keep the duct volume small, which is always a good thing. And the radius will help both the outflow and the return flow, but the positive effect on the return flow will be small; keeping the return flow attached over the port edge would require a much bigger radius.


Would this need a dyno to confirm or is safe to say that will not be has good has a normal 200º port...I'd rather say that it is better than a 'normal' 200° port, if only because you can always modify that radiused port into a 'normal' port, but you cannot modify it the other way round.
If you are lucky, the modification effect will be strong enough for a seat-of-the-pants conclusion. But then you still won't know just how big the effect was.
So, if you have access to a dyno, use it.

[wobbly]

The 200* port when used by Honda in A kit form had everything else changed as well.
The flange was different as was the pipe, the ignition curve, the PJ switch point, the cylinder head.
Trying to make a customer engine work with a high port only simply doesnt work.
Look at how different the power curves are.

Re the dyno curves - I got that sheet from Belgium,when I was looking at buying the rolling road software.
The two factory setups had been dynoed in secret, and i was told not to show this to anyone - but that was a very long time ago, and matters not at all now.
As it turned out I decided to go with an engine dyno,using SportsDevices , as kart engines became my main interest,and Jan told me that the Aprilias
were dynoed at the sprocket as well.

[RomeuPT]

The 200* port when used by Honda in A kit form had everything else changed as well.
The flange was different as was the pipe, the ignition curve, the PJ switch point, the cylinder head.
Trying to make a customer engine work with a high port only simply doesnt work.
Look at how different the power curves are.

Re the dyno curves - I got that sheet from Belgium,when I was looking at buying the rolling road software.
The two factory setups had been dynoed in secret, and i was told not to show this to anyone - but that was a very long time ago, and matters not at all now.
As it turned out I decided to go with an engine dyno,using SportsDevices , as kart engines became my main interest,and Jan told me that the Aprilias
were dynoed at the sprocket as well.

I don't really know how much is the gap from say a STD but tuned RS (changing ignition, PJ open point, 800mm exhaust, flange, well worked ports etc) vs A-kit bike.

This is mostly talk, I am not willing to pay for A-kit results just for my Drag NSR to have some fun at fridays and sunday meetings

[peewee]

hey guys just a update. I was able to do alittle testing today with some new things. previously I was having trouble with the crankcase flooding at small throttle openings (ran fine at full throttle) which made it difficult to clear the engine of fuel, so it was launching very rich until the excess fuel was sucked out. since leaning the needle had really no affect on the problem, I then suspected maybe the fuel pump was over powering the needle valve and pushing fuel up the needle bore and into the cylinder. I talked with lectron about this and they thought a different needle valve with smaller main inlet would solve the problem. so I got the new needle valve which is 2.5mm main hole with 6- 1.57mm secondary holes (original valve was 3.3mm main hole and 3-1mm secondaries). this didn't quit makes sense to me since I figured decreasing the main hole diam would increase the fuel pressure through the hole but I don't know. it did seem easier to clear the crankcase but ill do more testing to be sure. if this doesn't work then im thinking maybe go back to the 3.3mm valve and drill 6-1.5mm secondaries instead of 3-1mm.

last night I advanced the static ign timing slightly 3* and installed new #10 plug gapped at .76mm. mixed 1gal methanol at 11% oil for initial testing and be sure the tuning was ok. made another 1/2gal of premix with 3% nitromethane, 16% oil and 81% methanol (all percentages were by volume). anyways I made a couple full throttle runs of about 300' or so with the straight methanol to be sure the tuning was ok . it was running good, engine cleared out pretty easy and ran good at full throttle but I had both powerjets fully open so I wasn't sure if it would supply enough fuel with the nitro.

now it was time to try the other can of fuel :laugh:. I didn't make it very far and the needle was extremely lean . ( I believe adegnes experienced this also in one of his videos when he was using the meth/nitro mix, as he drilled out his needle tube I think). by this point it was getting late so I packed up and went home. I got some video but the wind was so bad it didn't turn out well but next time ill try and get better video. im going to richen the current needle I have and hopefully I wont need a whole new richer needle but maybe so. also im probly going to install a 3rd powerjet and perhaps even a larger capacity float bowl as this will be some insurance incase theres a lack of fuel flow into the bowl. im not for sure yet if ive got sufficient fuel flow for full throttle as I didn't run the engine very long since the needle was so lean. next weekend I plan to spend a lot more time testing and ill report back what happens

even though I only mixed in 3% nitro by volume, I think it may have actually been a even hotter batch. by weight it would have been about 5% and the fuel temp was only 40* F (apparently the specific gravity of nitro is very unstable with temp changes). so im wondering if it was more like 10% in reality, based on some charts I found online. anyways im excited to richen the fuel system and try even higher percentages next time.

[TZ350]

Hi Peewee

Very exciting to see your nitro experiments, I have always wanted to try it myself.

I have not yet, but my plan was to get my bikes basic fueling nicely setup without nitro.

And the plan was to not mix the nitro into the fuel at all. The plan is to drop the nitro into the air stream through a switchable power jet. That way there is no need to richen or play around with the already good basic carburetor jetting.

The theory was that adding nitro by itself through a separate power jet to an already properly jetted engine added oxygen and "a little richness" to the carburetors original basic jetting because nitro caries slightly more fuel than oxygen.

So in theory with the base jetting correct the engine would run a little richer when nitro was being added separately to the air stream.

[adegnes]

Haven't had much time lately.
I have replaced the intake valve and will be back with further experimentation on methanol/nitro soon. As of now I've gone from 15.3 to 17whp, nothing changed except carb settings. The no intake valve thing is put on hold for a while, want to establish a baseline on this fuel and start modifying the cylinder and pipe.

[peewee]

Haven't had much time lately.
I have replaced the intake valve and will be back with further experimentation on methanol/nitro soon. As of now I've gone from 15.3 to 17whp, nothing changed except carb settings. The no intake valve thing is put on hold for a while, want to establish a baseline on this fuel and start modifying the cylinder and pipe.

did you try straight methanol previously ? there was a article where the author claimed that straight methanol required nearly the same afr as a 0-33% load of nitro. im thinking that might be rubbish, atleast to some extent. i say that because my low throttle position went very lean immediatly when i introduced nitro to the methanol. wasnt sure if you had the same experience

[adegnes]

did you try straight methanol previously ? there was a article where the author claimed that straight methanol required nearly the same afr as a 0-33% load of nitro. im thinking that might be rubbish, atleast to some extent. i say that because my low throttle position went very lean immediatly when i introduced nitro to the methanol. wasnt sure if you had the same experience

Haven't tried straight methanol but I share your skepticism about that article. I had read it before my first attempt with 20% nitro, and jet sizes were calculated with the specific gravity of each fuel component taken into account. I richened it some on top of that too. First pull melted the plug in seconds...

[SwePatrick]

Weekend in success and nosedive *lol*

Started her up this saturday with working lubrication for turbo.
First dynopulls showed 0.5-0.55bar of boost with a lot of leak from between cylinder and pipe, and between stinger and pipe.
Had some fueling issues, sorted that out with hanging a fueljug to the ceiling to get more fall for the fuel.
Then needed to richen it up a whole lot on the powerjet, from 1/4 turn to about 3 full turns.
It showed promising results, never recorded anything due to i wasn´t aiming for a powerpull, just to make it rev free throughout whole register.
Even though i had small issues it spinned the tire on dynoroller, which it never has done before.

Then yesterday (sunday) i fixed the exhaustleaks and turned out the powerjet one more full turn.
This time i was curious about what has happened as it was feeling quite nasty/angry ;)
She actually ran so nice i was suprised how easy it was to get it working.

This time i had 0.75bar of boost and this was around the level i am aiming for to get 100rwhp.
I also before the coming pull retarded the igntion about 10degrees.(whole curve)

It was a bit less revhappy due to that, but it builded boost really easy, i could run it at 8000rpm and hit the throttle and boost was almost instant up to 0.5bar, then at ~9000rpm it hit 0.75bar

Now i was ready for a powerpull as it sounded really nice.

So i started at ~6500rpm, it hesitated a bit when running into boost when having full throttle all the time, but i let it pull through.
And then all hell broke loose, totally insane *lol*
I revved it to about 12000rpm
It sounded like perfection, no misfire no nothing.

Hit the brake on roller to make a verifying pull.
Coolant temp was only 53degrees.

On it again,,
The same procedure, but now at roughly 11000rpm it was like a handgrenade through the carb.
I saw the rocketflame, it was about 50cm long *lol*

I instantly hit the brake on dyno, having a thought that it was a lean situation.
After about an hour, (had to do some garden work ;) )
I pulled the sparkplug, and the sight was the nosedive earlier mentioned, aluminiumsand all over the isolator.
F*ck!!
What happened?

332637

The only thing i can think of what heppened after thoughts were running around in my head is that on the compressorhousing there is an recirculating bypassvalve, and i didn´t have it attached to any boost.
So it could creep open and regulate boost pressure without notice.
If doing that the backpressure in turbo skyrockets, and twostrokes DO NOT like those pressurelevels, i promise ;)

Heat builds and melting pistons comes as a letter on the mail.
I came to this conclusion as i never heard any ping or something alarming at all in first pull.

To end story happy anyway, the result was almost fulfulling my goal in first powerpull.

98.56hp at 11600rpm at the wheel =)

So, i need a new piston and a hone of cylinder(i hope it stays there as i haven´t taken engine apart yet.

332638

But, it will take some time before i can follow up on this, my dog needs an operation in right rear knee and,, well budget has gone to zero.
Need to take a break from this for a while.

Regards
Patrick.

[TZ350]

Weekend in success and nosedive *lol*

Now i was ready for a powerpull as it sounded really nice.
The same procedure, but now at roughly 11000rpm it was like a handgrenade through the carb.
I saw the rocketflame, it was about 50cm long *lol*

Nearly a 100hp, great result Patrick....... :niceone:

We too have found it sometimes costs a piston or two to find the right formula.

[TZ350]

332640332639

Below is an extract from DirtBike that talks about the EFI KTM250. Interesting it mentions exactly the same problems with throttle response that I am having and that it mentions a crankcase pressure sensor.

https://dirtbiketest.com/fresh-dirt/two-stroke-fuel-injection-ktms-path-to-tpi/#ote9PlJBGtOBGJI6.97 (https://dirtbiketest.com/fresh-dirt/two-stroke-fuel-injection-ktms-path-to-tpi/#ote9PlJBGtOBGJI6.97)

<ins>Now using accepted and understood parts it all came down to processing the information and getting the mixtures right. Quickly. The window of time for the injector to be open and getting the large amount of fuel a two-stroke needs is the challenge, especially in even smaller displacements we are told. Plus when a two-stroke has a “flame-out” inside the combustion chamber, it can take up to 50 strokes for the engine to recover. This was a big issue in high RPM, low throttle times. For instance when you are going down a hill with the engine revving and then you give it a little gas. Making the throttle response as good as that antiquated carburetor was very difficult. There is not a lot of time for the computer to decide how much fuel and when to shoot it from one stroke to the next since the conditions inside the two-stroke engine can change drastically and very suddenly. Even small things like having the engine’s crankcase pressure sensor and fuel injectors mounted so that vibration was not affecting them were lessons learned in testing. Luckily the new 2017 engine was designed from the beginning to eventually have a non-carbureted fuel system so it would vibrate less and also be able to produce as much electrical power as would be needed.</ins>
<ins>Read more at </ins>https://dirtbiketest.com/fresh-dirt/two-stroke-fuel-injection-ktms-path-to-tpi/#Oo5mp1B4YRrV2OU2.99

332641332642

The crankcase pressure sensor seems to be taken off the back of the cylinder and go up to a sensor in a plenum behind the motor.

Very interesting ..... :shifty:

[peewee]

332640332639

Below is an extract from DirtBike that talks about the EFI KTM250. Interesting it mentions exactly the same problems with throttle response that I am having and that it mentions a crankcase pressure sensor.

https://dirtbiketest.com/fresh-dirt/two-stroke-fuel-injection-ktms-path-to-tpi/#ote9PlJBGtOBGJI6.97 (https://dirtbiketest.com/fresh-dirt/two-stroke-fuel-injection-ktms-path-to-tpi/#ote9PlJBGtOBGJI6.97)

<ins>Now using accepted and understood parts it all came down to processing the information and getting the mixtures right. Quickly. The window of time for the injector to be open and getting the large amount of fuel a two-stroke needs is the challenge, especially in even smaller displacements we are told. Plus when a two-stroke has a “flame-out” inside the combustion chamber, it can take up to 50 strokes for the engine to recover. This was a big issue in high RPM, low throttle times. For instance when you are going down a hill with the engine revving and then you give it a little gas. Making the throttle response as good as that antiquated carburetor was very difficult. There is not a lot of time for the computer to decide how much fuel and when to shoot it from one stroke to the next since the conditions inside the two-stroke engine can change drastically and very suddenly. Even small things like having the engine’s crankcase pressure sensor and fuel injectors mounted so that vibration was not affecting them were lessons learned in testing. Luckily the new 2017 engine was designed from the beginning to eventually have a non-carbureted fuel system so it would vibrate less and also be able to produce as much electrical power as would be needed.</ins>
<ins>Read more at </ins>https://dirtbiketest.com/fresh-dirt/two-stroke-fuel-injection-ktms-path-to-tpi/#Oo5mp1B4YRrV2OU2.99

332641332642

The crankcase pressure sensor seems to be taken off the back of the cylinder and go up to a sensor in a plenum behind the motor.

Very interesting ..... :shifty:

about a year ago I snatched up a '17 carbed model and kind of glad I did , since electrical stuff is something I really know nothing about. how is the oil managed and is there a way to customize the fueling ?

its no surprise they been working in this for a while. seems like there was a article saying they had been working on a counterbalancer since the 90's I think, but never could get it sorted out at the time

[F5 Dave]

They could have copied my 1979 Honda MB50 and no doubt Moses had a counterbalanced 2 stroke when he popped over to the other side of the lake or ocean or puddle.

[ken seeber]

OK you forensics out there, looking for opinions on the rod in the pic. This shows very slight discolourations, almost blueing, at two very small spots on either side at the very bottom of the rod. Why ? is the question. It has tons of side clearance which can be seen between the thrust washer and the crank wheel side. This particular brand of engine is a 54*54 with an 18 mm crankpin, vertical crank reed induction and revs to 15.5/16k. Interestingly this particular brand of engine also has problems with crankpin failures, possibly as a result of crank twisting, thereby causing cyclic loadings on the pin and then fatigue failure. Whether the two are related is unknown.
Anyone else seen rod temp effects like this?

332643

As a total aside, apparently the bucket class in Queensland now allow air cooled engines to go to 125 cc.

[Grumph]

Is there a chain pull on the crank ? Possibly in line with but opposite to the cylinder ?
I'm wondering if it's causing a pinching at TDC due to crank flex.

I'd heard that it was Pauline Hanson holding up changes to the Qld bucket rules....

[Lightbulb]

OK you forensics out there, looking for opinions on the rod in the pic. This shows very slight discolourations, almost blueing, at two very small spots on either side at the very bottom of the rod. Why ? is the question. It has tons of side clearance which can be seen between the thrust washer and the crank wheel side. This particular brand of engine is a 54*54 with an 18 mm crankpin, vertical crank reed induction and revs to 15.5/16k. Interestingly this particular brand of engine also has problems with crankpin failures, possibly as a result of crank twisting, thereby causing cyclic loadings on the pin and then fatigue failure. Whether the two are related is unknown.
Anyone else seen rod temp effects like this?

332643

As a total aside, apparently the bucket class in Queensland now allow air cooled engines to go to 125 cc.

Hey Ken, how sturdy is the crank case. That looks to me like it is flexing to the point where the clearance you do have is still not enough.
I may be wrong as well.
Neil

[wobbly]

The discoloration is localized overheating of the lube film.
So if the pins are failing then you would have to make the guess that they are bending, due to the inertial loads at 15+K rpm.
When they bend the clearance will drop to zero ( or less ) inside the rod at the highest rotational load point,thus trying to crush the needles.
Keep doing this and the cyclic load will eventually break the pin, or lock up the bearing.
Either way 18mm isnt big enough,and or the pin material and its associated heat treatment are suspect.

[Nath88]

The same procedure, but now at roughly 11000rpm it was like a handgrenade through the carb.
I saw the rocketflame, it was about 50cm long *lol*


So the flame was from the carb? Timing too retarded or running too lean?



The only thing i can think of what heppened after thoughts were running around in my head is that on the compressorhousing there is an recirculating bypassvalve, and i didn´t have it attached to any boost.
So it could creep open and regulate boost pressure without notice.
If doing that the backpressure in turbo skyrockets, and twostrokes DO NOT like those pressurelevels, i promise ;)


Do you mean the internal wastegate on the turbine/exhaust side? Without boost pressure hose attached it should stay closed until the exhaust backpressure overpowers the spring. Then the exhaust pressure will drop and the turbo will slow down, and the intake pressure will drop. As you said it should creep open rather than suddenly open, I'm not sure it would cause your backfire problem.



98.56hp at 11600rpm at the wheel =)


An awesome effort, hopefully you'll be able to sort it out soon.

[2T Institute]

OK you forensics out there, looking for opinions on the rod in the pic. This shows very slight discolourations, almost blueing, at two very small spots on either side at the very bottom of the rod. Why ? is the question. It has tons of side clearance which can be seen between the thrust washer and the crank wheel side. This particular brand of engine is a 54*54 with an 18 mm crankpin, vertical crank reed induction and revs to 15.5/16k. Interestingly this particular brand of engine also has problems with crankpin failures, possibly as a result of crank twisting, thereby causing cyclic loadings on the pin and then fatigue failure. Whether the two are related is unknown.
Anyone else seen rod temp effects like this?

332643

As a total aside, apparently the bucket class in Queensland now allow air cooled engines to go to 125 cc.
just keep it under 15,499 rpm , fixed FOC for you Ken :laugh:

[SwePatrick]

So the flame was from the carb? Timing too retarded or running too lean?



Do you mean the internal wastegate on the turbine/exhaust side? Without boost pressure hose attached it should stay closed until the exhaust backpressure overpowers the spring. Then the exhaust pressure will drop and the turbo will slow down, and the intake pressure will drop. As you said it should creep open rather than suddenly open, I'm not sure it would cause your backfire problem.



An awesome effort, hopefully you'll be able to sort it out soon.

1, i think it selfignited in crankcase due to overheating of piston.
2, i have chopped away the internal wastegate, so i´m talking about the BOV, blow off valve that is integrated in compressorhousing.
(where arrow points)
332651
This is a recirculating blowoff valve that helps overcome some turbolag between shifts in a car.
With no referenceboost on the outer side of diagraphm it can creep open from boost in turbo.
And as it is recirculating i can´t see if it does this.
I will some day this week pressuretest it to see if it creeps, if it does i have the answer.

And, when this valve is open the turbo spins freely with no resistance.
This creates backpressure in exhaust turbine.
And to much backpressure is deadly, and it kills fast.
Just as in my case, it left me questioning why it happened, i heard nothing bad from engine at all except that blam through the carb.

Maybe the reedpetals will tell me also.
But engine ran nice on idle before i shut it off after the pull.
So i figure the petals are ok, but i haven´t taken it apart yet.
I´m in middle of porting a couple of foulstrokeheads to ensure the operation of my dog.

And thank´s, it was actually quite easy.
I also had some support from a snowsledguy who has turboed his snowsled.
Also i have a lot of turbo experiance of foulstrokes(Have been designed and built heads for 2 litre engines that has dynoed above 1150hp)

But methanol isn´t the first choice to take when boosting with draw through carb setups.
They are really HARD to get running nice out of boost.
I actually had frost on the compressorhousing after the first pull.

My bad on forgetting connect the bostreference to the BOV. :(

Rgds.

[SwePatrick]

Nearly a 100hp, great result Patrick....... :niceone:

We too have found it sometimes costs a piston or two to find the right formula.

Thanks.. yes,, one has to put some sheep for offering to the gods of speed =)

But i feel that the smart choice is to revert back to NA engine on methanol and try to get max out of that.
I still have some tricks up my sleeve regarding that =)

I want to race it next summer, not change pistons all the time.
It´s like i took a giant leap before beeing done with the last one.

Turbosystem is built, i can whenever i want try it again =)
I want more control so maybe i need to go EFI, or some way of controlling the ignition better (3d map)

[husaberg]

Any one ever seen or used one of these?
NIBBI Programmable CDI Unit + Software

https://www.trademe.co.nz/motors/motorbikes/parts-for-sale/electrics/auction-1421553799.htm

[peewee]

richened the current needle quit alot and third power jet now installed . ill try some nitro again this weekend and see what happens :laugh:. might end up welding on another chamber to the float bowl for more capacity

[SwePatrick]

Well,, it never detonated.
That gives me some comfort in my ego.
As i thought i had control of detonations etc etc.
And as it shows, i still have =)

It was a 'simple' pistonfailure, probably due to pistonspeed.
I´m fully aware of that i am pushing the limits on pistonspeed.
And this failure i can take with 'pride' *lol*

Cylinder and head is still like 'new', no problems there.
I just need to hone cylinder, clean things up.
Put a new piston and new mainbearings in, and ofcourse smallend bearing.
Then it´s ready to go again =)

98.56hp can do this to a cast piston(vertex), maybe a forged one(wiseco) can take the stresslevels a bit better.

332662

[Grumph]

[QUOTE=SwePatrick;1131063950

98.56hp can do this to a cast piston(vertex), maybe a forged one(wiseco) can take the stresslevels a bit better.
[/QUOTE]

So your gout of flame out the carb was the back falling off the piston....Doesn't take 98hp to make that happen.
Perhaps a little less cutting - and a replacement schedule.
Lucky though with so little damage.

[SwePatrick]

It was a little bit of sarcasm and joke involved in that statement ;)

I would say it is quite stressful for a cast piston at up against 14000rpm on 61mm stroke, and i´m like a guineapig.
I couldn´t predict when piston would brake, it had to be tested.
And a forged quality piston would take more abuse is my thought, to prolongue the life.
I never cut anything out of the bottom of the skirt, just drilled boostwindows, very far away from sensitive areas.
Have been doing this to forged pistons earlier in other engines with no problems whatsoever.

So i bet it is my high pistonspeeds added with very high power that killed it.
I also have a long rod/stroke ratio to ensure the piston had some sort of stressless life even due to high revs *lol*

I was around 28.4-28.5ms in pistonspeed.
Everything above 27ms is sorting men from boys pistonwise ;)

[TZ350]

.
%$((&^%$%^## for some reason these pictures from my phone are the right way up on my computer but turned when I up load them, try as I might I can't get them right ...... :angry2:

Some of the spirit of Bucket racing can be found in the clever modifications being done by racers.

332674

This Yamaha R150 was about 136kg originally and is now 84.5kg. Handmade frame, swing arm and lightened wheels and brakes. At 84.5kg this 4T is much lighter than my NSR/GP110 2T.

332675 332676

The latest engine mod on Paul's R150 is the down draft inlet tract. Blue line is the original horizontal inlet, Red line is the down draft inlet, other than fueling, no other changes.

I post about these clever 4T's because they are serious pieces of work and us 2T boys need to keep developing our own bikes if we wan't to keep up.

[Frits Overmars]

This Yamaha R150 was about 136kg originally and is now 84.5kg. Handmade frame, swing arm and lightened wheels and brakes. At 84.5kg this 4T is much lighter than my NSR/GP110 2T... I post about these clever 4T's because they are serious pieces of work and us 2T boys need to keep developing our own bikes if we want to keep up.Losing 51,5 kg is no mean feat. And I get the impression that even more weight could be saved with other wheels. Or do the rules prescribe wheels from a street bike?
I also like the centralized fuel tank, the stepped exhaust header and the high-tension gear pedal (that's an NGK plug cap, isn't it?)
But 22 hp shouldn't worry you too much. A good 50 cc 2-stroke can do that. And a 100 cc 2-stroke should walk all over that R150 power curve.

[ken seeber]

Frits,
It's a H/T brake pedal, so that'll detract from their 22 hp even more. So, the 2 stroke wins again...
Otherwise though, good effort...

[Frits Overmars]

Frits, It's a H/T brake pedal, so that'll detract from their 22 hp even more. So, the 2 stroke wins again...Right you are Ken, it was a brake pedal, not a gear pedal (I blame the tilted picture ;)).
332674

[jonny quest]

How did the rev limiter get changed on that 150 4 stroke?

Any pics of the head mod to downdraft?

[LSENG]

How did the rev limiter get changed on that 150 4 stroke?

Any pics of the head mod to downdraft?

Aracer ecu to change the rev limit, the head was not altered to change to a straight inlet path, only the inlet manifold which was turned up side down and the injector boss transferred to the opposite side. This part is pretty straight forward. It is the modded fuel tank with pump inside and subframe that took a little time

[mr bucketracer]

How did the rev limiter get changed on that 150 4 stroke?

Any pics of the head mod to downdraft?if you look at the graft it was done over speed not rpm , diffient gearing so can't compair them gafts to well

[RomeuPT]

Hi.

Does anybody know if it's possible to put a solanoid power jet on a TMX 38 without paying 120£ just for the kit, any seller?

[breezy]

Any one ever seen or used one of these?
NIBBI Programmable CDI Unit + Software

https://www.trademe.co.nz/motors/motorbikes/parts-for-sale/electrics/auction-1421553799.htm

well.. thats a no from me mate,,,

[peewee]

hey guys. last couple days I been working on increasing float bowl capacity as much as the chassis free space would allow. originally it was 4oz (.118L) and I managed to get it up to 6oz (.177L). so I guess that's a 50% increase. it probly doesn't sound like much but this bike only has to make it about 500' at most. if I run into problems later and it isn't sufficient then I have a few more ideas. might add another secondary fuel inlet with its own float valve but im not concearned until I see how this setup works out.

also I found out these lectron needles can only be richened so far then they will pop out of their bore when the slide is fully opened and prevent the slide from going down which is likely to meen a run away engine or big crash. since mine is on the ragged edge of nearly popping out, if it still isn't rich enough then ill have to get a new richer needle.

[husaberg]

hey guys. last couple days I been working on increasing float bowl capacity as much as the chassis free space would allow. originally it was 4oz (.118L) and I managed to get it up to 6oz (.177L). so I guess that's a 50% increase. it probly doesn't sound like much but this bike only has to make it about 500' at most. if I run into problems later and it isn't sufficient then I have a few more ideas. might add another secondary fuel inlet with its own float valve but im not concearned until I see how this setup works out.

also I found out these lectron needles can only be richened so far then they will pop out of their bore when the slide is fully opened and prevent the slide from going down which is likely to meen a run away engine or big crash. since mine is on the ragged edge of nearly popping out, if it still isn't rich enough then ill have to get a new richer needle.


Pewee have you made the float heavier to account for the different density of the Methanol?

[peewee]

no I don't know anything about that. will the buoyancy not be the same as with petrol ? from what I could tell it seemed to work ok with the methanol so far. I got the floats from a guy that sets them up for methanol so I think maybe theyre different than a standard petrol carb. ill be adding in some nitro and increasing the percentage as much as my fuel system will allow so maybe that will have some different affect on the floats

[peewee]

hey guys i got some questions. the tube that the needle slides in that sticks down to the bottom of the float bowl, does the end of this tube always have to be below fuel level in the bowl ? i wasnt sure if it would mostly just suck air if it was above fuel level. other question is would it be a bad idea to put a powerjet on the front side of the carb slide instead of on the backside ?

[wobbly]

Absolutely for sure the suction tube of the Lectron that the needle slides in, should be right to the bottom of the bowl.
If its above the fuel level in the bowl it will suck air - and kill the engine.
Same applies to the power jet suction tubes, they should be right at the bottom of the bowl, on the engine side if the carb is angled down ( to have the highest fuel level above them ).
If you put a jet on the exit side of the carb it will drown the engine with fuel when you close the slide.

[peewee]

thats what i figured wob. something told me to only make the bowl wider and not deeper

[husaberg]

no I don't know anything about that. will the buoyancy not be the same as with petrol ? from what I could tell it seemed to work ok with the methanol so far. I got the floats from a guy that sets them up for methanol so I think maybe theyre different than a standard petrol carb. ill be adding in some nitro and increasing the percentage as much as my fuel system will allow so maybe that will have some different affect on the floats
The specific gravity for Methanol is different. The float will ride higher due to the increased buoyancy and the bowl will empty faster as a result.
You need a heavier bowl to compensate for the difference . In the old days they used to add lead solder to the brass float.


thats what i figured wob. something told me to only make the bowl wider and not deeper
much like one of these. Boyseen Superbowl
332717
Or this for a hardley
332716

[Tim Ey]

Hey Husa, I only knew the superbowl for Pj/Pwk ( Fb02). Do you know which one fits the Pwm / Pwk Shortbody?

[husaberg]

Hey Husa, I only knew the superbowl for Pj/Pwk ( Fb02). Do you know which one fits the Pwm / Pwk Shortbody?
the one in the pic on top.:msn-wink:
I will have a look at the pic coding and see.
I never knew either till i seen the pic.
Odd i tried looking under 1998-2000 KX and 2016 KTM ansd the only Keihin on Boyseen says it doen't suit?

[41juergen]

A friend of mine has NS400R. Yesterday he opened the water pump cover and I was surprised about Honda's idea of an impeller..
332721

Can this piece work reasonable? I would install something like the RZ style... what do you think?

[speedpro]

Why fix something that isn't broken?

[F5 Dave]

Hand back your Man-card Mike;)

[TZ350]

332721

Can this piece work reasonable?

A lot of cars have that style of impeller, easy to make I guess.

[TZ350]

332723

Red line is throttle, Blue is rpm and Yellow LamWO2 sensor.

Same rpm and load/fuel injection amount at both cursors.

Nothing happens until the engine slows down to about 7k rpm where the pipe starts to work against the engine. Then it fires and Lam goes from lean to near right. Then there is a period of rough running pulling out of the pipes reversion hole. Then takes of at Lam 0.88 as it gets on the pipe.

The puzzle is, why does it fire when the pipe works against the engine and not while the pipe is in tune with the rpm as the motor is slowing down? ... :scratch: same throttle and fueling both sides.

[husaberg]

A friend of mine has NS400R. Yesterday he opened the water pump cover and I was surprised about Honda's idea of an impeller..
332721

Can this piece work reasonable? I would install something like the RZ style... what do you think?

VT250 has a similar impeller
Likely heaps others do as well.
Not sure but it likely is a one piece with the seal not made to be servicable in true Honda style.

[F5 Dave]

You meet the nicest people on a Honda.
Until they get to the parts counter.

[Brett S]

TZ does your ecu change fueling using feedback from the Wideband at all?

Are you saying the first "lean" section after throttle opening is only lean because it didn't fire and therefore could actually be too rich fuel/air to fire?
In the rough running section is the fueling varying much between the little peaks and valley's? Maybe the ecu is chasing its tail in that zone each time it fires?

[speedpro]

332723

Red line is throttle, Blue is rpm and Yellow LamWO2 sensor.

I'd like to see injector pulsewidth in that graph as well

[Nath88]

Same rpm, same throttle position, different airflow. The pipe effect on a misfire is very weak if it exists at all...

332725

My graph doesn't show this well, but above 7k RPM the on-pipe and off-pipe air flow is too different, the on-pipe fuelling (what you've tuned for) will not support combustion off-pipe. Way too rich, true lambda probably around 0.5 or worse. As the engine speed falls below 7k rpm, the on-pipe and off-pipe air flow is not so different, true lambda is approaching the rich limit until it supports combustion. Once combustion begins the small increase of airflow from the pipe effect will bring the lambda above the rich limit, 'clearing' the cylinder. You could install any old MAF sensor to prove this.

I'm still working on the Ion sensing, but I'm getting impatient so I'm going back to measuring the pressure at the PV vent since that worked the best so far (I now have an adjustable bleed to atmosphere so I can adjust it's sensitivity), and using that input to try a table switching approach. Have a fuel table for no-pipe effect, and a fuel table that incorporates pipe effect. Theoretically I could put a box-style muffler on and tune 1 table, then put the expansion chamber on and tune the other. Pressure pulses will determine whether the pipe effect is active and ECU switches between the tables accordingly. Away from the pipe's effective rpm the tables should be more and more the same.

I'm thinking a box-muffler would provide no scavenging effect, and no return wave effect, can someone confirm that?

I'm also designing a 'pressure pulse' sensor. It's basically a piezo electric microphone hooked up to exhaust pressure, it will more accurately and quickly detect the exhaust pulse from the cylinder than the pressure sensor. I figure I can hear when the engine is firing clear as day, why not use a microphone...

[TZ350]

TZ does your ecu change fuelling using feedback from the Wideband at all?

No


I'd like to see injector pulse width in that graph as well


I should be able to do that.


Are you saying the first "lean" section after throttle opening is only lean because it didn't fire and therefore could actually be too rich fuel/air to fire?

Yes I think you are right. It looks lean but it is too rich to fire. But why????


Same rpm, same throttle position, different airflow.

Above 7k RPM the on-pipe and off-pipe air flow is too different, the on-pipe fuelling (what you've tuned for) will not support combustion off-pipe. Way too rich, true lambda probably around 0.5 or worse.

As the engine speed falls below 7k rpm, the on-pipe and off-pipe air flow is not so different, true lambda is approaching the rich limit until it supports combustion.

332726

Once combustion begins the small increase of airflow from the pipe effect will bring the lambda above the rich limit, 'clearing' the cylinder.


Yes Nath I think you and Brett are right, what you say makes sense. Thanks.

[Norman]

A friend of mine has NS400R. Yesterday he opened the water pump cover and I was surprised about Honda's idea of an impeller..
332721

Can this piece work reasonable? I would install something like the RZ style... what do you think?

I do not like that impeller design. I would not be surprised if you can improve flow with 50% or more with a more flow optimized machined/casted version, if you can find something that will fit, or get made. Boyesen makes water pump improvement kits for some engines with an interesting impeller design. But maybe the original will be ok for a standard engine.

[Tim Ey]

I'm thinking a box-muffler would provide no scavenging effect, and no return wave effect, can someone confirm that?


I can not confirm that. A box ( see vespa px 200 standart pipe for example) shows a return wave when it is "full" (helmholz resonance). Also the tube lenght from piston to box might be tuned to support scavenging in a certain rpm range.

[41juergen]

I do not like that impeller design. I would not be surprised if you can improve flow with 50% or more with a more flow optimized machined/casted version, if you can find something that will fit, or get made. Boyesen makes water pump improvement kits for some engines with an interesting impeller design. But maybe the original will be ok for a standard engine.
As the engine shall get more power I think this type of impeller will be ok, along with an adapted pump inlet and a larger rad...
332728

[jasonu]

As the engine shall get more power I think this type of impeller will be ok, along with an adapted pump inlet and a larger rad...
332728

Looks exactly like a Suzuki RG50 impeller.

[Norman]

As the engine shall get more power I think this type of impeller will be ok, along with an adapted pump inlet and a larger rad...
332728

Yes, that looks much better. I am surprised they put that other cheap impeller in, actually.

Another open question; most often you see coolant channels really corroded, is it not allowed in racing to use corrosion inhibitors added to the water?

[wobbly]

The foil type impeller blade is hugely more efficient at moving water.
Two things I have done to improve the flow capability - as the water enters the pump in the middle,replace the center of the impeller with a cone ( threaded internally LH from the back as per original ).
And secondly you can make ( laser cut - easier ) a cover spacer plate,and increase the impeller blade depth the same amount.
Doing this on an old TZ350 pump with a 5mm spacer nearly doubled the flow rate, and keeps my TZ400 engine running under 50*C.

[dtenney]

I am wondering how much the power curve shifts with the blade in the lowest versus the highest position?

[lodgernz]

Another open question; most often you see coolant channels really corroded, is it not allowed in racing to use corrosion inhibitors added to the water?

In MotoGP, the only coolant additive allowed is Glycerol (NOT Glycol) up to 4%.
You can buy Glycerol at the pharmacy.

Just to be clear, Glycol is NOT allowed as it is as slippery as oil if it gets on the track.

I've been using Glycerol for 3 years and it definitely inhibits rust. Apparently it enhances the wetting ability of the water too, so gets better cooling.

[nitro2tfx]

richened the current needle quit alot and third power jet now installed . ill try some nitro again this weekend and see what happens :laugh:. might end up welding on another chamber to the float bowl for more capacity


Just a few words of caution. As you get higher in the nitro % always be prepared for a runaway engine when you are experimenting. Make sure you have a way to instantly loadkill the engine. Even with a dead cold startup and the throttle at the idle position, you can get a runaway under the wrong conditions and shutting the ignition off won't do anything. You need to loadkill it immediately because it will build heat fast and scream to even higher revs real quick.

If the engine is running fine and you hear the revs start to increase a bit, and you haven't touched the throttle, kill it right then and there and look for a problem.

Be careful revving it under no load, again runaway potential.

Don't leave the engine running unattended or wander off to get something, no matter how good it seems to be running.

Nitro runaways are not fun

[peewee]

Just a few words of caution. As you get higher in the nitro % always be prepared for a runaway engine when you are experimenting. Make sure you have a way to instantly loadkill the engine. Even with a dead cold startup and the throttle at the idle position, you can get a runaway under the wrong conditions and shutting the ignition off won't do anything. You need to loadkill it immediately because it will build heat fast and scream to even higher revs real quick.

If the engine is running fine and you hear the revs start to increase a bit, and you haven't touched the throttle, kill it right then and there and look for a problem.

Be careful revving it under no load, again runaway potential.

Don't leave the engine running unattended or wander off to get something, no matter how good it seems to be running.

Nitro runaways are not fun

thanks mate for the advise. ill be running the engine today and report back how it goes. float bowl capacity is increased 50% to 6oz and a 3rd powerjet added. the only problem i may have now is if the needle is rich enough. ive screwed it out to the richest position but it might not be enough and a require a new richer needle but ill find out soon enough. if it runs away ill kill it with rear brakes :cool:

[peewee]

nothing good to report. one of my welds had pin hole so fuel leaked all over and engine wouldnt start either. spark and compression seem good so maybe no fuel was getting to the cylinder or else it was flooded from the needle to rich now:brick:

[Flettner]

Alcohol fuel, time for injection.

[peewee]

naw mate im not putting no more money or time into it . floatbowl is off and ill fix the leak tomorrow. as for why it wouldn't start, im not sure. has always started easily in the past few months but it did give me trouble 2weeks ago also. since its getting colder maybe that has something to do with it. ive heard people have to warm the engine block or fuel sometimes on methanol engines. fuel temp was 50F today when I checked it. ill get it sorted sooner or later. maybe give the intake a squirt of starting fluid next time :laugh:

[Flettner]

That's why they make E85, not E100, a little petrol will assist start and speed the burn up. Even with E85 I still have trouble firing up my 350 sometimes. A little petrol prime is in order when this happens.
https://youtu.be/CnIemdISKrM

[teriks]

naw mate im not putting no more money or time into it . floatbowl is off and ill fix the leak tomorrow. as for why it wouldn't start, im not sure. has always started easily in the past few months but it did give me trouble 2weeks ago also. since its getting colder maybe that has something to do with it. ive heard people have to warm the engine block or fuel sometimes on methanol engines. fuel temp was 50F today when I checked it. ill get it sorted sooner or later. maybe give the intake a squirt of starting fluid next time :laugh:
Starting methanol engines in the cold can for sure be a pain in the...
Get some heat into the engine and try again.
A primer as Flettner suggests is probably the easiest way.

[SwePatrick]

naw mate im not putting no more money or time into it . floatbowl is off and ill fix the leak tomorrow. as for why it wouldn't start, im not sure. has always started easily in the past few months but it did give me trouble 2weeks ago also. since its getting colder maybe that has something to do with it. ive heard people have to warm the engine block or fuel sometimes on methanol engines. fuel temp was 50F today when I checked it. ill get it sorted sooner or later. maybe give the intake a squirt of starting fluid next time :laugh:


Just squirt some petrol into carb before trying to start.
I´m using a 'squirt bottle' as the big guys in dragracing, supersimple!

Always starting on 1st or 2nd kick when cold with that. =)
I have started it down to about 15f with no hassle.

Get a richer needle!
If just adding more and more powerjets i figure the lowspeed system still is very lean?
My jetting on 211cc and ~75.5hp at the crank is in Keihin sizes: 110 pilot, 265 main, homemade powerjet opened about 1/4-1/3 turn.
Starting with 1/4, and when engine is hot i turn it more open to about 1/3.(i figure it starts to free up the containing oxygen, like 'nitro light' effect)
Still when engine is really really hot after a hard dynosession with about 10 pulls in a row it tends to runaway on idle, i might need 120-125 in pilot when hot.
But it is so much harder to get it to warm up properly with bigger than 110.

This with only methanol fuel.
If i were about to run say 20% nitro i would increase pilot a lot, just to make sure engine won´t runaway.

Rgds.

[TZ350]

I'd like to see injector pulsewidth in that graph as well

332767

Pink line is injector pulse width. Blue RPM and Brown is wide band O2 sensor.

WOT, same RPM, same injector pulse width, different Lambda.

I think Nath88 is onto it.


Same rpm, same throttle position, different airflow.

332725

[TZ350]

My first efforts at trying Nath88'ts idea of using the strength of the returning pressure pulse at the exhaust port window to determine if the motor is firing or not did not go so well.

The small bouncing ball one way valve I tried to use stuck open and all I got was the average of pressure and suction pulse. It was not very useful.

332770

Tonight I tried a different style of one way valve. A duck bill, it acts like a reed valve, easy to open and naturally shuts again and does not hang up with gummy oil like the ball valve did.

332768

The pressure bleed was taken from the header, the duck bill is trapped between the grey plastic nuts and the 2.5bar MAP sensor is plugged into the end of the hose.

332769

The black dot is the pressure bleed down hole and the cloth stuffed inside is my attempt at a damper.

332771

Pink line is the MAP sensor, Blue RPM and Red throttle.

This is the first time the engine was responsive to shutting and opening the throttle.

Of course the old fuelling map is ratshit now and will need re mapping but the throttling results with the MAP sensor are very encouraging.

Things are looking up, maybe even possible............. :scooter: EFI whoop whooop.

[Sandokan]

Hi all,

I was thinking that to create a fuelmap for a twostroke , would it be possible to somehow "record" an exhaust harmonic frequency in conjunction with a tps an wideband lambda on a carburated twostroke?

Just a thought but probably worth something for the fi guys

Sander

[Niels Abildgaard]

Put a Piezo thing ring under one of the headstud nuts or between head and sparkplug and a very rude instant cylinder pressure signal can be had.
When piston is halfway down You will know if it fired or not.
And then: Who tried it allready and why does it not work?

[TZ350]

would it be possible to somehow "record" an exhaust harmonic frequency in conjunction with a tps an wideband lambda on a carburated twostroke?

Good idea Sandokan, I didn't record the exhaust but I guess its possible. I did use the wideband lambda and carb to get an idea of what the fuel map should look like.


Put a Piezo thing ring under one of the headstud nuts or between head and sparkplug and a very rude instant cylinder pressure signal can be had.
When piston is halfway down You will know if it fired or not. And then: Who tried it already and why does it not work?

Another good idea, thanks Niels. It could well work, unfortunately my Ecotrons software does not have a suitable input available, it is short on alternative inputs. But it does expect a MAP sensor which is why I am trying to see what can be done with that.

Unlike some other EFI systems the Ecotrons software does not allow for a binary input that switches between two maps. But there is a place for an analog input from the MAP sensor to influence the Ecotrons software to adjust the predicted fueling requirements from the Alpha-N map at any TPS/RPM.

The Ecotrons software adjusts the injector pulse width according to the Alpha-N map and input from the MAP sensor. It is how to make use of that relationship for fuel injecting a two stroke which is the trick I am trying to learn.

[Nath88]

Unlike some other EFI systems the Ecotrons software does not allow for a binary input that switches between two maps. But there is a place for an analog input from the MAP sensor to influence the Ecotrons software to adjust the predicted fueling requirements from the Alpha-N map at any TPS/RPM.


I was just about to recommend using the map switch :( I tried it out this weekend, its not dialled yet, but it's the best so far, I can roll along at 8500rpm and open and close the throttle as fast or slow as I like and it always responds. I will tune the main map by lambda feedback (it's pretty much done using values from before), and the misfire map by holding the engine at a load point, then holding the kill switch for a second or two, then release and judge the response when it comes back on as rich or lean, it should be instant and clean like a carb.
The map switches when the peak pressure between 85 crank degrees and 125 crank degrees, measured at the PV vent (with an adjustable bleed to atmosphere) reaches 102kpa, atmosphere is 101kpa here.
Means I'm confined to riding at sea level until I sort out a better implementation. Hoping the piezo pulse sensor will be the ticket, since it doesn't care about absolute values, If it works I'll make a bunch of them.

I think the piezo on the cylinder head idea could work, if the signal is not too noisy.

[TZ350]

332794

Smoothed the MAP sensor reading by adding some volume by replacing the MAP sensor hose with a small chamber.

332793

MAP sensor Yellow line. Interesting that the line on the left as the engine is still winding down and zero throttle is higher than the MAP pressure line at WOT and as the RPM starts to rise again.

[peewee]

Just squirt some petrol into carb before trying to start.
I´m using a 'squirt bottle' as the big guys in dragracing, supersimple!

Always starting on 1st or 2nd kick when cold with that. =)
I have started it down to about 15f with no hassle.

Get a richer needle!
If just adding more and more powerjets i figure the lowspeed system still is very lean?
My jetting on 211cc and ~75.5hp at the crank is in Keihin sizes: 110 pilot, 265 main, homemade powerjet opened about 1/4-1/3 turn.
Starting with 1/4, and when engine is hot i turn it more open to about 1/3.(i figure it starts to free up the containing oxygen, like 'nitro light' effect)
Still when engine is really really hot after a hard dynosession with about 10 pulls in a row it tends to runaway on idle, i might need 120-125 in pilot when hot.
But it is so much harder to get it to warm up properly with bigger than 110.

This with only methanol fuel.
If i were about to run say 20% nitro i would increase pilot a lot, just to make sure engine won´t runaway.

Rgds.

what do you guys think of this idea. for starting the engine cold I can drill a hole and tap threads in the carb on the engine side of the slide and install this nipple and attach a small hose so petrol or ether can be squirted in. of course I would put a rubber cap on the nipple before attempting to start the engine. check out photo to see what I meen . other wise I don't know how to get this bugger fired up :facepalm:

squirting petrol or any other starting fluid on the back side of the slide will be time consuming as the seat, body panels and sub frame with airbox would need removed. spraying ether directly to the airfilter may wash away the oil and allow in dirt

[Grumph]

You're not the first to strike this problem. A guy here had a 600 Suzuki GSX racebike - late 80's style with full bodywork. Ran it on methanol and had a lot of problems starting it. Finished up with a plastic tube with a cork in it, up beside the steering head. Tube ran to the airbox, so it was pull the cork, squirt starter fluid (ether) down the tube, replace cork, start bike....A practical solution I thought.

[husaberg]

Wob was it the TZ g pipes you wanted a drawing of ages ago.
332807332808

[Frits Overmars]

A guy here had a 600 Suzuki GSX racebike... Tube ran to the airbox, so it was pull the cork, squirt starter fluid (ether) down the tube, replace cork, start bike...Could have been the original Big Bang bike then. Filling a large volume with air and fuel (LPG in my car) can have surprising effects, like air filter boxes blown to smithereens and a very sporty-looking bulge on the hood:nya:.

[peewee]

You're not the first to strike this problem. A guy here had a 600 Suzuki GSX racebike - late 80's style with full bodywork. Ran it on methanol and had a lot of problems starting it. Finished up with a plastic tube with a cork in it, up beside the steering head. Tube ran to the airbox, so it was pull the cork, squirt starter fluid (ether) down the tube, replace cork, start bike....A practical solution I thought.

great idea and easier than drilling the carb. ill give it a try

[Grumph]

Could have been the original Big Bang bike then. Filling a large volume with air and fuel (LPG in my car) can have surprising effects, like air filter boxes blown to smithereens and a very sporty-looking bulge on the hood:nya:.

While he did manage to blow it up in several surprising ways, that wasn't one of them. Not for lack of trying though...

I know what you mean though - I was very glad at one point that I'd made and fitted a blow-off valve to a roots blown Kawasaki 500 twin when a plenum half full of methanol decided to get excited and go bang. Fastest I've ever got off a bike under my own power.

[wobbly]

Yea, thanks Husa.
I wanted a baseline to do new pipes for customer racebikes.
Job done, the new ones have won the NZ TT several times and IOM classic twice.

[guyhockley]

what do you guys think of this idea. for starting the engine cold I can drill a hole and tap threads in the carb on the engine side of the slide and install this nipple and attach a small hose so petrol or ether can be squirted in. of course I would put a rubber cap on the nipple before attempting to start the engine. check out photo to see what I meen . other wise I don't know how to get this bugger fired up :facepalm:

squirting petrol or any other starting fluid on the back side of the slide will be time consuming as the seat, body panels and sub frame with airbox would need removed. spraying ether directly to the airfilter may wash away the oil and allow in dirt
Different end of the performance spectrum but there used to be a company in England converting outboards to run on paraffin and that's also hard to start. I was told the trick was to have a small auxiliary tank of petrol feeding the pilot jet for starting and tickover. No details of how it was done, though.
Not sure if paraffin is called that in other countries - it's the stuff used in old blowlamps, hurricane lamps, greenhouse heaters etc.

[F5 Dave]

Kerosene. Primary use is cleaning chain lube off motorbikes. Well, in this parish.

[Ocean1]

Kerosene. Primary use is cleaning chain lube off motorbikes. Well, in this parish.

And flying you to other parishes.

[Frits Overmars]

Different end of the performance spectrum but there used to be a company in England converting outboards to run on paraffin and that's also hard to start.... Not sure if paraffin is called that in other countries - it's the stuff used in old blowlamps, hurricane lamps, greenhouse heaters etc.In the Netherlands it's called petroleum. Same uses as stated above, plus some people used it as an illegal (non-taxed) fuel in both petrol and diesel cars.
But in petrol cars the smell gave it away all too easily.

[TZ350]

Same rpm, same throttle position, different airflow.

332725

I understand Nath88's explanation for the change in the LamW02 trace Yellow line. .... :niceone: good one.

332825

Pressure in the exhaust header pipe as measured by a MAP sensor, Yellow line, RPM Blue line, LamWo2 Brown line.

Through a one way valve arrangement the MAP sensor only measures the high positive pressures of the returning pulse in the header and does not see the negative suction pressure.

Interesting that the MAP pressure line on the left as the engine is still winding down and at zero throttle is higher than ambient and the MAP pressure line on the right at WOT which starts at ambient before obviously rising again as the engine gets on the pipe. There is quite a sudden drop in MAP pressure (Yellow line) when the throttle (Red line) goes from fully closed to fully open.

But why does the header pipe positive pressure behave like this? ...... :scratch:.. high and above ambient when there is no throttle and the engine is winding down then goes lower when it's on WOT and starting to pick up again.

[Grumph]

But why does the header pipe positive pressure behave like this? ...... :scratch:.. high and above ambient when there is no throttle and the engine is winding down then goes lower when it's on WOT and starting to pick up again.

Can I suggest that the whole system - from inlet via crankcase to muffler - has one end closed when the throttle is shut and the chamber tailpipe is then doing what it's supposed to and acting as a pressure bleed resistor.
Open the other end to atmosphere - open the throttle - and the system pressure should drop to atm and possibly lower momentarily.

But I've been wrong before...

[Nath88]

But why does the header pipe pressure behave like this? ...... :scratch:.. high when there is no throttle and winding down then low when it's on WOT and starting to pick up again.

I saw something similar with mine.
Since we're measuring the peak, it implies the average pressure in the pipe must be lower than atmospheric by a fair bit?
Has anyone witnessed a vacuum in the pipe at any time?

Once the engine starts making power the exhaust flow creates pressure in the pipe due to the stinger restriction.

A differential pressure sensor with the average pipe pressure as the reference might be the go. Or my new sensor, should be testing the prototype next week.
332827

Can you set the crank angle for sampling the MAP sensor with the ecotrons?

[TZ350]

Can I suggest that the whole system - from inlet via crankcase to muffler - has one end closed when the throttle is shut and the chamber tailpipe is then doing what it's supposed to and acting as a pressure bleed resistor. Open the other end to atmosphere - open the throttle - and the system pressure should drop to atm and possibly lower momentarily.

That is possible I guess, but on overrun with throttle closed and the motor not firing what could be creating the pressure in the pipe?

You would think any residual pressure from a full power run would have bleed away quite quickly but on other graphs it actually looks like it builds up a bit.

Bit of a puzzle


Can you set the crank angle for sampling the MAP sensor with the Ecotrons?

No. But I am very interested in the sensor you are developing.

[Nath88]

That is possible I guess, but on overrun with throttle closed and the motor not firing what could be creating the pressure in the pipe?

You would think any residual pressure from a full power run would have bleed away quite quickly but on other graphs it actually looks like it builds up a bit.

Bit of a puzzle



No. But I am very interested in the sensor you are developing.

That's a shame, timing will be key for this thing.

I thought that it was showing atmospheric pressure off the throttle, going into vacuum as you opened the throttle. What pressure is atmo?
But if its producing positive pressure with a closed throttle I'm out of ideas... Definitely qualifies as a puzzle.

[teriks]

I understand Nath88's explanation for the change in the LamW02 trace Yellow line. .... :niceone: good one.

332825

Pressure in the exhaust header pipe as measured by a MAP sensor, Yellow line, RPM Blue line, LamWo2 Brown line.

Through a one way valve arrangement the MAP sensor only measures the high positive pressures of the returning pulse in the header and does not see the negative suction pressure.
Assuming that the one way valve is working properly, and you still have that bleed between the one way valve and sensor, the lowest pressure you should ever see at the sensor is atmospheric, no matter how low the pressure in the pipe is.


Interesting that the MAP pressure line on the left as the engine is still winding down and at zero throttle is higher than ambient and the MAP pressure line on the right at WOT which starts at ambient before obviously rising again as the engine gets on the pipe. There is quite a sudden drop in MAP pressure (Yellow line) when the throttle (Red line) goes from fully closed to fully open.

But why does the header pipe positive pressure behave like this? ...... :scratch:.. high and above ambient when there is no throttle and the engine is winding down then goes lower when it's on WOT and starting to pick up again.
Well, the pressure should never go below atmospheric as per above, but lets ignore the numbers and focus on the drop in pressure when opening the throttle:
Closed throttle => ~0 airflow thru the header
Open throttle (even without firing) => >0 airflow the the header.
Now, depending on the geometry around your pressure pickup position its not at all unlikely that the pressure drops in that position simply due to flow. -Think venturi..

[41juergen]

The foil type impeller blade is hugely more efficient at moving water.
Two things I have done to improve the flow capability - as the water enters the pump in the middle,replace the center of the impeller with a cone ( threaded internally LH from the back as per original ).
And secondly you can make ( laser cut - easier ) a cover spacer plate,and increase the impeller blade depth the same amount.
Doing this on an old TZ350 pump with a 5mm spacer nearly doubled the flow rate, and keeps my TZ400 engine running under 50*C.

I remember you mentioned that earlier, so I will get a larger / higher impeller hopefully next week. I also made a distance plate the old way, no laser cut (drilling holes, using a chisel to get the large part out and then finalize the shape with the file :msn-wink:)...
332828332829

[Frits Overmars]

... why does the header pipe positive pressure behave like this? ......Pipe pressure varies not only with throttle and rpm, it can also vary locally because of wave superposition.
It might be instructive to experiment with several pressure take-off points along the pipe.
332834

[Lef16]

Hi there,
is there a way for measuring crankcase volume without drilling the piston crown?

[TZ350]

Pipe pressure varies not only with throttle and rpm, it can also vary locally because of wave superposition.

It might be instructive to experiment with several pressure take-off points along the pipe.

332834

Yes I can see how wave superposition can create a localized high pressure spot although I would expect the node to move with frequency as the RPM dropped. I will look for that next time.


Assuming that the one way valve is working properly, and you still have that bleed between the one way valve and sensor, the lowest pressure you should ever see at the sensor is atmospheric, no matter how low the pressure in the pipe is.

Yes, that is how I read it too.


... the drop in pressure when opening the throttle:
Closed throttle => ~0 airflow thru the header
Open throttle (even without firing) => >0 airflow the the header.

Now, depending on the geometry around your pressure pickup position its not at all unlikely that the pressure drops in that position simply due to flow. -Think venturi..

The closed throttle no flow pressure was higher than atmospheric and dropped to atmospheric when the throttle was opened again. Your venturie idea is interesting.

Pressure node and venturie effect could explain it....... :scratch:

332835

[husaberg]

Hi there,
is there a way for measuring crankcase volume without drilling the piston crown?

Put in a very hot heat range plug such as a NGK5 and go for a ride no drill will be required.:innocent:

[peewee]

Could have been the original Big Bang bike then. Filling a large volume with air and fuel (LPG in my car) can have surprising effects, like air filter boxes blown to smithereens and a very sporty-looking bulge on the hood:nya:.

I was thinking about the airbox blown to smithereens and wonder if squirting ether as close as possible to the combustion chamber is the best way. I wasn't about to take the engine apart to make a injection port in the head but right or wrong I decided to put a nipple on the front side of the carb slide. hopefully it doesn't blow my reeds out :lol:. I may try petrol first and see if that works as a good starting aid. if not, then ether it is. I put the hose free end where its easily accessible and can be bent upward when the starting aid is squirted in. the hose end is then pluged with a rubber cork. best of all is no body panel removal needed. ill report back how it works. im hoping to try it out tomorrow since last weekend was a failure

something strange today that had me wondering. I had to use ether to start the lawnmower so I squirted it in the airfilter area. after a few pulls of the starting rope a small backfire explosion happened then it started :laugh:

[peewee]

Hi there,
is there a way for measuring crankcase volume without drilling the piston crown?

what size of piston do you have ? I have a few old spares of various sizes that might be what you can use to drill a hole. you can have it free if its the right size

[Haufen]

Hi there,
is there a way for measuring crankcase volume without drilling the piston crown?

There should be, if you are willing to take the engine apart, then measure crankcase (incl. crank at TDC position) and cylinder (incl piston and crank/rod at TDC position) volume seperately and add both values up at the end.

[Flettner]

700 twin start up, first time with the power valve. No prop and rev limited to 7500.
Ignitech runs the R1 servo nicely, starts opening at 3500 finished at 5500.

https://youtu.be/8IA3Xth6jXc

[Frits Overmars]

700 twin start up, first time with the power valve. No prop and rev limited to 7500.
Ignitech runs the R1 servo nicely, starts opening at 3500 finished at 5500. https://youtu.be/8IA3Xth6jXcAh, the lovely sound of a 180°-firing twin. Takes me back to my RD350-years. I'd really love to see that engine in a bike frame Neil. Reed valves will do fine (KISS, remember?) It will keep the width within limits and we won't be needing the last bit of power for a roadgoing bike. The power your engine is capable of right now, will be quite sufficient.

[RomeuPT]

Just killed a whole week of free afterwork hours doing a new flange and exhaust for the NSR...

Results, not sure, need a dyno :weird:

Oval to round transition, thick flange with some cooling fins, not sure if the best way has I have seen the flanges from honda kits are much thinner and polished.

332841332842332843

Bike is sounding different.

Cheers

[teriks]

I was thinking about the airbox blown to smithereens and wonder if squirting ether as close as possible to the combustion chamber is the best way. I wasn't about to take the engine apart to make a injection port in the head but right or wrong I decided to put a nipple on the front side of the carb slide. hopefully it doesn't blow my reeds out :lol:. I may try petrol first and see if that works as a good starting aid. if not, then ether it is. I put the hose free end where its easily accessible and can be bent upward when the starting aid is squirted in. the hose end is then pluged with a rubber cork. best of all is no body panel removal needed. ill report back how it works. im hoping to try it out tomorrow since last weekend was a failure
Should work just fine, but be sure to have the hose perfectly sealed before starting.. but you knew that of course.

[teriks]

The closed throttle no flow pressure was higher than atmospheric and dropped to atmospheric when the throttle was opened again. Your venturie idea is interesting.

Pressure node and venturie effect could explain it....... :scratch:

I should read more carefully, I was under the impression that you measured below atmospheric pressures..

[marsheng]

It can also i believe shuts off the fuel supply, as the frothy mixture raises the float level.
]

Not sure where I was the other day but I was told never jump into heavily bubbling water, you will drown. After a few thoughts I realized it was true. The float will sink lower.

[teriks]

Just killed a whole week of free afterwork hours doing a new flange and exhaust for the NSR...

Results, not sure, need a dyno :weird:

Oval to round transition, thick flange with some cooling fins, not sure if the best way has I have seen the flanges from honda kits are much thinner and polished.

332842
Bike is sounding different.

Cheers
You need much larger gaps between the fins, that's no more than about 1,5mm, right?
Not that I think it would make a huge difference...

[RomeuPT]

You need much larger gaps between the fins, that's no more than about 1,5mm, right?
Not that I think it would make a huge difference...

They were cut with a angle grinder 2mm disk, so the gaps are much bigger then 2mm. I think you are also right, but since it had room for doing them....

[RomeuPT]

Did a couple more test's, dont really think there is more power, but let the pipe get some carbon on it and maybe do some jetting to see if feels an improvment.

[peewee]

Should work just fine, but be sure to have the hose perfectly sealed before starting.. but you knew that of course.


yes its perfectly sealed with a rubber plug on the ID and a rubber cap on the OD. while it wasn't cold yesterday (fuel temp of 60F/15.5C) I did squirt some petrol in the primer tube to see if it would work and it does. within three kicks it started so I think it will work fine when colder also. some more good news from yesterday is, the third jet is barley one turn open with the 5% nitro. since it has a max of six turns, I think ive got enough fuel enrichment for up to 20% nitro or maybe even higher. unless that article was correct in saying that up to 33% will use the same AFR as straight methanol. in which case I wont need to add anymore fuel :wings:

my plan next time is to try 10% and work up to atleast 20%, provided theres no mechanical or fuel delivery problems. yesterday I tested full throttle operation to 650' and it did fine. the bad news is, I richened the current needle as much as it can go and its just barely rich enough. after two consecutive 650' runs, closing the throttle causes the idle to runaway just alittle. so as the nitro pecent and oxygen content is increases, I think for sure ill need the next size richer needle. so this week ill try to get another needle

heres a question for anyone. ive been reading with nitro you can advance the spark lead even further than with straight methanol but I also read just the opposite. anybody know the truth to this ? right now ive got only 3* static advance and the reason is because im afraid of it back firing and trying to start the engine backwards which often time can break the kcick start gears in the crankcase. yesterday it back fired and tried to push the kick lever in reverse. so im thinking I should leave it alone or be very cautious if I advance it any further as I don't want broken crankcase or gear cogs

[TZ350]

I was just about to recommend using the map switch :( I tried it out this weekend, its not dialled yet, but it's the best so far, I can roll along at 8500rpm and open and close the throttle as fast or slow as I like and it always responds. I will tune the main map by lambda feedback (it's pretty much done using values from before), and the misfire map by holding the engine at a load point, then holding the kill switch for a second or two, then release and judge the response when it comes back on as rich or lean, it should be instant and clean like a carb.
The map switches when the peak pressure between 85 crank degrees and 125 crank degrees, measured at the PV vent (with an adjustable bleed to atmosphere) reaches 102kpa, atmosphere is 101kpa here.
Means I'm confined to riding at sea level until I sort out a better implementation. Hoping the piezo pulse sensor will be the ticket, since it doesn't care about absolute values, If it works I'll make a bunch of them.

332861

Just realised/remembered that the ecotrons EFI system does have a switch for switching between two maps. I had been using it for so long as an input for the wide band O2 sensor that I had forgotten about it.

But after I have got the on the pipe map sorted it looks like I may be able to use one of your switches to then develop an off pipe or miss fire map.

The performance switch just switches in another table of values that are used to divide the values in the main map. Ie if you have a load value of 120 in the Alpha-N map and switch in the performance map that has a Lambda value of 0.85 then the Alpha-N map gets divided by 0.85, 120/0.85 = 142 ie the result is a richer mixture for exceleration.

I guess there is no reason why the performance switch can't be used to lean the Alpha-N map off when the engine has misfired or is off the pipe.

[husaberg]

Not sure where I was the other day but I was told never jump into heavily bubbling water, you will drown. After a few thoughts I realized it was true. The float will sink lower.

which makes it the opposite?
I think what happens in the bowl rather than a river or waterfall where you have undertow is the bubbles raises the effective level. Much like a boiling pot overflowing.
I was confused i couldn't recall the post, but i see it was ten months ago lol

[Flettner]

Pipe pressure varies not only with throttle and rpm, it can also vary locally because of wave superposition.
It might be instructive to experiment with several pressure take-off points along the pipe.
332834

Is there any data from this test we might be able to read about?

[Frits Overmars]

I was told never jump into heavily bubbling water, you will drown. After a few thoughts I realized it was true. The float will sink lower.
I think what happens in the bowl rather than a river or waterfall where you have undertow is the bubbles raises the effective level. Much like a boiling pot overflowing.

When I see heavily bubbling water, it's usually time to put the eggs in. And no, I would not advise jumping into it. Maybe you won't drown, but you won't like it either.

Now let's take a closer look at bubbling fluid. It has a lower density, hence less buoyancy, and you'll go in deeper. But then you'll drown or suffocate in the froth,
not in the fluid.

Will a float sink lower because of the bubbles? No. The level of the froth will be higher than the level of non-frothing liquid would have been. But the float will keep its original height with regard to the top and bottom of the float chamber. If the float sinks, more fuel will enter the float chamber, increasing the float's buoyancy until it is sufficient to carry the float to its original height and close the float valve. And the main jet entrance is usually situated low enough to always be immersed in liquid,
so it won't be bothered by the froth either.

So how come a vibrating carburetter can be drowning the engine?
The froth is not the culprit. It may rise so high that it exits the float chamber air vents (indeed, just like a boiling pot overflowing). But the fuel pressure at the main jet entrance depends not only on the head of fuel above it, but also on the density of that fuel. The bubbles themselves and their level would not effect this pressure.

There's a cause for the bubbles: vibration. Frothing is just a side effect; the real problem is the float valve bouncing on its seat: it just doesn't close the way it should any more. And this raises not only the froth level but also the level of the non-frothing part of the fuel, hence the fuel pressure at the main jet entrance.

[Frits Overmars]

Is there any data from this test we might be able to read about?Queens University of Belfast holds those data, but approaching Gordon Blair has become rather difficult lately...
I'm sure there is a paper containing this test but I don't know the relevant SAE number, Neil.
332876

[Vannik]

queens university of belfast holds those data, but approaching gordon blair has become rather difficult lately...
I'm sure there is a paper containing this test but i don't know the relevant sae number, neil.


sae 2004-01-3561

[Frits Overmars]

You're priceless Neels :niceone:.

[WilDun]

Good one Frits, I'll file that away! :niceone:

BTW, I originlly lived 56 miles from Belfast, but seldom went there even before all the strife (I don't really like cities even though I live in a suburb of Auckland now).
Queens University was always right up there and Gordon Blair was right there for motorcycles and engines in general, helping them into the computer age.

You probably know, but others may not know that he died around 2010. (this may be the reason why approaching him has become rather difficult!).:msn-wink:

[Flettner]

sae 2004-01-3561

Thank you, I'd like to think i had my own data soon but it would be good to read what I might find beforehand.

[Nath88]

332861
I guess there is no reason why the performance switch can't be used to lean the Alpha-N map off when the engine has misfired or is off the pipe.

If it's another TPSxRPM table with multipliers it should work great. I'm doing the same thing right now but in a spreadsheet, then dropping the numbers into the tuning software. The multiplier is the pipe effect on airflow so it's a more sensible value to use anyway. You'll need to extrapolate the tuned 'firing' map you have into the skip-fire/misfire regions as best you can. Making the switched input to feed into the ECU will be the hard part, but I want to do that for my setup as well to free up the MAP input, and make the sensor unit a plug and play product for any ECU.

Had a play with the piezo disc for the exhaust pulse sensor, looks promising, very sensitive, minimal noise, nice.

https://www.youtube.com/watch?v=C5yOTfo2FKw

[TZ350]

If it's another TPSxRPM table with multipliers it should work great. I'm doing the same thing right now but in a spreadsheet, then dropping the numbers into the tuning software. The multiplier is the pipe effect on airflow so it's a more sensible value to use anyway.

Had a play with the piezo disc for the exhaust pulse sensor, looks promising, very sensitive, minimal noise, nice.

Yes that piezo looks promising as the basis for a switch. I will definitely be a customer for one.

332883

This is the Ecotrons EFI softwares Basic 16x12 Alpha-N map.

332884

When the "Performance" switch is activated the corresponding cells in this 16x12 map are used to divide their related values in the original Alpha-N map to give an alternative fueling value.

This seriously looks like it could be used in the way you have described previously of leaning the fuel off when there is less air flow when there is no pipe action drawing air through the motor.

[husaberg]

When I see heavily bubbling water, it's usually time to put the eggs in. And no, I would not advise jumping into it. Maybe you won't drown, but you won't like it either.

Now let's take a closer look at bubbling fluid. It has a lower density, hence less buoyancy, and you'll go in deeper. But then you'll drown or suffocate in the foam,
not in the fluid.

Will a float sink lower because of the bubbles? No. The level of the foam will be higher than the level of non-foaming liquid would have been. But the float will keep its original height with regard to the top and bottom of the float chamber. If the float sinks, more fuel will enter the float chamber, increasing the float's buoyancy until it is sufficient to carry the float to its original height and close the float valve. And the main jet entrance is usually situated low enough to always be immersed in liquid,
so it won't be bothered by the foam either.

So how come a vibrating carburetter can be drowning the engine?
The foam is not the culprit. It may rise so high that it exits the float chamber air vents (indeed, just like a boiling pot overflowing). But the fuel pressure at the main jet entrance depends not only on the head of fuel above it, but also on the density of that fuel. The bubbles themselves and their level would not effect this pressure.

There's a cause for the bubbles: vibration. Foaming is just a side effect; the real problem is the float valve bouncing on its seat: it just doesn't close the way it should any more. And this raises not only the foam level but also the level of the non-foaming part of the fuel, hence the fuel pressure at the main jet entrance.
Right you are Frits
This was my complete original post (complete with pics) :)
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1632?p=1131021127#post1131021127
It came about as we were talking about adding weight to dampen the resonate frequancy of the carb (something i had read Jennings had done) or changing the rubber stiffness to achieve a similar affect.

Cameron also mentioned that the first KR3 was near impossible to carburate on account of it severe vibration.

The fuel frothing (i think) does two things first it gives an inconsistant mixture that can be actually be alternating between rich and lean depending on the RPM.
It can also i believe shuts off the fuel supply, as the frothy mixture raises the float level.
The liquid fuel can also be diverted directed away from the mainjet. being replaced by a bubbly air/fuel mix
Some mikunis and Keihins have jet sheilds that might help. Aftermarket FCR bowls have deeper wells and different designs to overcome frothing on whoops and similar conditions.
These below are stock CRF230.
327510327511327513

This is the mikuni part
327514327515327516

[SwePatrick]

heres a question for anyone. ive been reading with nitro you can advance the spark lead even further than with straight methanol but I also read just the opposite. anybody know the truth to this ? right now ive got only 3* static advance and the reason is because im afraid of it back firing and trying to start the engine backwards which often time can break the kcick start gears in the crankcase. yesterday it back fired and tried to push the kick lever in reverse. so im thinking I should leave it alone or be very cautious if I advance it any further as I don't want broken crankcase or gear cogs

No, don´t advance spark from optimal degree of 100% methanol use.
You are adding more air with nitro, this speeds up the burnprocess, it´s like turbocharging, decrease ignition.
What you should look into is piston to cylinder clearance, you also need to increase the ring gap from methanol setup, also due to increased heat, you don´t want to warp the ring.
Nitro engines need more clearance to be sure the piston does not smear on cylinderwalls, if so happens the piston is toast really quickly, also the nicasil will often be scraped off the cylinder.
This is because if piston smears you will get insane blowby because of the really high cylinderpressure.
This heats up the piston insanely fast.

I run with 18.5-1 in compression on 100% methanol, and my ignition is set to around 14-15 degree at ~3000rpm and peaks at ~5500 with 27-28degree, then almost linear retard to 12 degree at 11000rpm
This gives me ~460-480 celsius exhaust temp in header where it is around 580 degree on petrol.
One need to recalculate the pipe if running this low temps.
But nitro raises the temp again.

Be careful!

Rgds

Edit:
A methanol engine produces max power around 85-90 degree engine heat.
A 20% nitro engine produces max power around 110-120degree celsius.

Keep this in mind, do not be afraid to run the engine hot, but do not overheat it!
Like balancing on a thin line. but it awards you =)

[Frits Overmars]

sae 2004-01-3561
Thank you, I'd like to think i had my own data soon but it would be good to read what I might find beforehand.I tried to download that paper for you Neil, but somehow it refused to go past the introduction page. Maybe you'll have more success.
332890

[Lef16]

what size of piston do you have ? I have a few old spares of various sizes that might be what you can use to drill a hole. you can have it free if its the right size
Thank you pee,but it isn't necessary,I just had this question in general,so when I want to measure an engines crankcase cr I wont have to destroy a piston.
Now,for the past few days I'm messing around with crankshaft balancing.I cant really get what excactly does a-say-80%balance factor instead of 50% and what balance factor is good for my engine.
Cheers

[wobbly]

General rule for a 2T race engine with a near vertical cylinder is 58% is the best compromise.
As you tip the cylinder forward the factor reduces to when its horizontal,35% is the go.
Al the changing factor does is move the peak shaking force from a horizontal bias at 58% to the vertical plane as the % is reduced.
Vertical shake is perceived as much more annoying to the riders hands/feet/crotch,than a horizontal shake.

[Tim Ey]

General rule for a 2T race engine with a near vertical cylinder is 58% is the best compromise.
As you tip the cylinder forward the factor reduces to when its horizontal,35% is the go.
Al the changing factor does is move the peak shaking force from a horizontal bias at 58% to the vertical plane as the % is reduced.
Vertical shake is perceived as much more annoying to the riders hands/feet/crotch,than a horizontal shake.

Hi Wob and everyone.
Is there some math in the background? Or it this sheer experience?
Hence I have seen a few motocross engines with 70-80%, I changed my latest crank to be in that ballpark.

Talking balancing factors: To which percentages would you change a 90° Twin (Aprilia RS 250)?
I have asked this question some time ago and I think Frits answered, that it should have the same percentage as a single cylinder with a balancing shaft.
In theory this means both cranks want to have 100% to eliminate the first order frequency.
But as I have just witnessed an engine with balancing shaft and ~50% running smooth as a electro motor, I doubt the 100%.
Would be happy to hear your opinion on that

Thanks!
Tim

[Frits Overmars]

sae 2004-01-3561Here is the complete paper, thanks to Vannik.332896

[Frits Overmars]

To which percentages would you change a 90° Twin (Aprilia RS 250)? I have asked this question some time ago and I think Frits answered, that it should have the same percentage as a single cylinder with a balancing shaft.
In theory this means both cranks want to have 100% to eliminate the first order frequency. But as I have just witnessed an engine with balancing shaft and ~50% running smooth as a electro motor, I doubt the 100%.There may be more than one misunderstanding here, Tim. First of all: an Aprilia RS 250 can be either a street bike with a 90° Suzuki V-twin engine, which for balancing purposes should be regarded as two single cylinder engines, or it can be an Aprilia racing engine with two contra-rotating crankshafts.

A single cylinder engine with a balance shaft should theoretically have a 50% balance factor in the crankshaft (in practice it's usually a bit more in order to compensate for the effects of the finite con rod length). The other 50% is then provided by the balance shaft.

The Aprilia racing engine is quite a different animal. Usually it's called a V-twin, but I'd rather call it a W-twin because of its two separate, contra-rotating crankshafts, one above the other.
In a contra-rotating tandem twin such as the Rotax 256, with parallel cylinders, one behind the other, each crankshaft doubles as a balance shaft for the other crankshaft. So each crankshaft has a 50% balance factor to compensate the reciprocating mass of its own piston + con rod, and it has a 50% balance factor in order to fulfil its function as a balance shaft. In sum, each crankshaft of a contra-rotating tandem twin has a 100% balance factor.

The Aprilia racing engine is a twin and it's contra-rotating, but it's not a tandem. Its cylinders encase a 90° angle, and that has an effect on the angular location of the balance masses, as shown in the picture below left. Below right you can see the angular offset in practice, in the crank webs of an Aprilia RSW 250.
I'll leave it to you to work out the balance factor of this strange beast. A bit of intellectual exercise won't hurt :D.
332898 332913

[Tim Ey]

First of all: an Aprilia RS 250 can be either a street bike with a 90° Suzuki V-twin engine, which for balancing purposes should be regarded as two single cylinder engines, or it can be an Aprilia racing engine with two contra-rotating crankshafts.


Oh, i wish to own a "real" Aprilia RS250 - Standing in my shed are actually the suzuki leftovers with aprilias balsamic dressing...
Therefore I politely decline your suggested interlectual excercise about the "real" thing.



A single cylinder engine with a balance shaft should theoretically have a 50% balance factor in the crankshaft (in practice it's usually a bit more in order to compensate for the effects of the finite con rod length). The other 50% is then provided by the balance shaft.


Does this mean the procentual factor of an engine with balancing shaft is not depending on whether the engine is horizontal or vertical?
Or asking about my japanese italian twin - would it need to be 50% left / 50% right or 58% left / 58 % right (the right cylinder is facing down. Does it make him equal to a cylinder that got the same angle upwards? Adegnes, what is your experience with the Billet IAME Engine?)

Thanks!
Tim

[SwePatrick]

General rule for a 2T race engine with a near vertical cylinder is 58% is the best compromise.


I need to make it crystal clear for myself :)

58% with or without balanceshaft with 'vertical' cylinder?

Rgds

[Frits Overmars]

Does this mean the procentual factor of an engine with balancing shaft is not depending on whether the engine is horizontal or vertical?That's right. A balance shaft neutralizes all primary unbalance forces, so it won't really matter anymore if the cylinder is horizontal, vertical or somewhere in-between.


asking about my japanese italian twin - would it need to be 50% left / 50% right or 58% left / 58 % right (the right cylinder is facing down. Does it make him equal to a cylinder that got the same angle upwards?If your Suzaprilia has a balance shaft: see above. If it hasn't: see Wobbly's post.
One more detail: if you engine does not have a balance shaft, the balance masses in the crank webs will not only partly balance the reciprocating masses; they will also set up a rocking couple.
Therefore it could pay to concentrate the balance masses on the inner crank webs, so they are closer together and will cause a smaller rocking couple.

[Lbracing]

Hello everyone ,

My name is Luc from LBracing , I have read the whole thread twice over the last two years and I must say the amount of information is mindblowing . I would also like to thank EVERYONE who contributed to making this happen .

We are based in Canada and build chaisaw engines for speed cutting ranging from 50cc to 140cc and have been for close to ten years now . We manufacture our own pistons , heads , cylinders and carburetors all from billet .

The only limitations are :
cc class
Production based ( mostly look like a production chainsaw except from the pipe )

Wich means we can run any fuel ( usually methanol with 20 up to 30% nitro ) .

We always run the stock ignition coil ( sem AM50 , AM33 (flat line ignition)) but I have been looking to upgrade to something more powerful and reliable . I have been looking at universal PVL and selettra ignitions but I am totally lost as I don't know anything about them . Maybe some of you guys can help me ? ( wobbly , kart ignition ? )

Here are factors to consider :
-Acceleration speed is important for categories where we must start the chainsaw from the ground and then do the usual 3 cuts .
-Low and mid power is unimportant , only peak power is .
-Peak power is ranging from 14000 to 16000 depending on the engine size .
-Ignition must have a low rpm cut in point ( 500 rpm )
-We run R7376 plug in all our engines .
-Compression ratio is usually around 19:1 .
-It usually takes under 3 second to complete the cutting so heating the engine is very unlikely to happen .
-Ignition advance is currently 25-27* .

Thank you for your time !

[jonny quest]

That's a lot of compression for the fuel you're running

[SwePatrick]

Maybe very little or no squishband?
thereby the high compression and high ignitionvalues?

[Lbracing]

Our engines are VERY oversquare ( 1.4 ratio ) by stroking and making the piston smaller I get them under the 1.15 .

Being oversquare from what I have found makes the engine less prone to detonation , that combined to VERY short run time (2-3 second ) and the low temperature our engines operate at is what allows us to run such high level of nitro , comp and ignition .

Squish band usually ends up around 55% of bore . Heads are toroidal with flat top pistons . When my post count goes up I will gladly share some pic ;)

[wobbly]

Hey a new Luc on here - welcome.
The PVL ignition is " better " than the equivalent Selettra, I have done direct back to back dyno tests.
I have posted on here before about the PVL setup, but the basics are as follows.
The stator coil winding spec does two things.
The higher the number of wire " turns " sets the amount the ignition will retard, they are usually set up so that the timing lines align at 10,000 rpm.
The kart ignition has the least number of turns ( measures 50 ohms ) and delivers most high rpm " power " to the plug, but less voltage at low rpm, and has no retard.
I would suggest a stator with around 2000 turns, these are around 200 ohms ,do have some retard and give more voltage at the plug when starting.
The 5000 wind coils ( the maximum ) were designed for Banshee quads, that hardly have any rpm at kickover, but they suffer from high speed misfire if used with high com
or lots of power.

[Lef16]

I need to make it crystal clear for myself :)

58% with or without balanceshaft with 'vertical' cylinder?

Rgds
+1 here,
also,I think YZ 125 & 250 are running without a balance shaft,am I right?
Does anyone know balance factor's used there?
Cheers

[Lbracing]

Thank you Wobbly for the input ! Much appreciated !

Has anyone heard or even better tested WPC ? Is the so called ''magic'' around it working ? I am mostly interested in it for piston skirts .

[RomeuPT]

Good info about countershaft's! :niceone:

Does anybody know if a stator/alternator from the road 2stroke bikes causes some drag to the engine if there is no load/demand for power?

cheers

[TZ350]

Good info about countershaft's! :niceone:

Does anybody know if a stator/alternator from the road 2stroke bikes causes some drag to the engine if there is no load/demand for power?

cheers

If it absorbs energy from the motor it would heat up like a brake does, energy absorbed has to go some where.

[peewee]

Hello everyone ,

My name is Luc from LBracing , I have read the whole thread twice over the last two years and I must say the amount of information is mindblowing . I would also like to thank EVERYONE who contributed to making this happen .

We are based in Canada and build chaisaw engines for speed cutting ranging from 50cc to 140cc and have been for close to ten years now . We manufacture our own pistons , heads , cylinders and carburetors all from billet .

The only limitations are :
cc class
Production based ( mostly look like a production chainsaw except from the pipe )

Wich means we can run any fuel ( usually methanol with 20 up to 30% nitro ) .

We always run the stock ignition coil ( sem AM50 , AM33 (flat line ignition)) but I have been looking to upgrade to something more powerful and reliable . I have been looking at universal PVL and selettra ignitions but I am totally lost as I don't know anything about them . Maybe some of you guys can help me ? ( wobbly , kart ignition ? )

Here are factors to consider :
-Acceleration speed is important for categories where we must start the chainsaw from the ground and then do the usual 3 cuts .
-Low and mid power is unimportant , only peak power is .
-Peak power is ranging from 14000 to 16000 depending on the engine size .
-Ignition must have a low rpm cut in point ( 500 rpm )
-We run R7376 plug in all our engines .
-Compression ratio is usually around 19:1 .
-It usually takes under 3 second to complete the cutting so heating the engine is very unlikely to happen .
-Ignition advance is currently 25-27* .

Thank you for your time !

good to see you here luc. the more 2t experts there is here the better. do the rules only allow 30% nitro or mechanically thats all your engine will tolerate or theres some other reason ? ive just started using nitro in my engine and could use all the help i can get.

what i found out rather quickly is the low throttle position needs richened quit alot , even with small nitro pecentages. i richened the lectron needle as far as it could go , 2.5 turns more than i had been using with straight methanol and it still wasnt barely enough as it had a small run away at idle but ive got a richer needle that will be here in a few days so i hope it can provide enough fuel for about a 20% mix.

recently ive been using only #10 heat range plug and it seems to be doing fine, so ill probly just continue with those unless theres a good reason to use something else

one question i have is about the afr range that nitro is happy with. with methanol it seems to do fine and make good power even when pig rich. leaning it out made no difference in power that i could tell and just caused the water temp to rise rather quickly. does the nitro methanol mix also work fine when excessively rich or it responds better if its leaned a bit ? unfortunatly i dont have a dyno or any other fancy machines so i can only test by seat of the pants and listen for any strange engine noises

my comp ratio is 16:1 (527cc single cyl engine) because originally i planned on only using straight methanol. but in my research about nitro it seems lowering the comp ratio as the percentage increases is the way to go. except in special situations like your largely over sqaure engine i suppose. so im not sure if the 16:1 will some day cause me any trouble or not.

[Lbracing]

good to see you here luc. the more 2t experts there is here the better. do the rules only allow 30% nitro or mechanically thats all your engine will tolerate or theres some other reason ? ive just started using nitro in my engine and could use all the help i can get.

what i found out rather quickly is the low throttle position needs richened quit alot , even with small nitro pecentages. i richened the lectron needle as far as it could go , 2.5 turns more than i had been using with straight methanol and it still wasnt barely enough as it had a small run away at idle but ive got a richer needle that will be here in a few days so i hope it can provide enough fuel for about a 20% mix.

recently ive been using only #10 heat range plug and it seems to be doing fine, so ill probly just continue with those unless theres a good reason to use something else

one question i have is about the afr range that nitro is happy with. with methanol it seems to do fine and make good power even when pig rich. leaning it out made no difference in power that i could tell and just caused the water temp to rise rather quickly. does the nitro methanol mix also work fine when excessively rich or it responds better if its leaned a bit ? unfortunatly i dont have a dyno or any other fancy machines so i can only test by seat of the pants and listen for any strange engine noises

my comp ratio is 16:1 (527cc single cyl engine) because originally i planned on only using straight methanol. but in my research about nitro it seems lowering the comp ratio as the percentage increases is the way to go. except in special situations like your largely over sqaure engine i suppose. so im not sure if the 16:1 will some day cause me any trouble or not.

There is no rule regarding fuel , more than 30% just doesn't add anything from our testing . We see an increase , mostly in rpm , going from 20 to 30% nitro thought .

We run R7376-10 plug in everything and its been working great !

Nitro carrying a healthy dose of oxygen , makes the mix as much if not more rich tolerant . Setting the engine very rich also take care of a lot of temperature and atmospheric pressure fluctuation .

Regarding compression ratio , your application being far from my scope of expertise , I wont advise anything . The idea behind reducing the comp ratio is mostly because of the low octane rating of nitro . As stated earlier in this thread , at high rpm the octane needed lowers trendemously wich is probably another reason why we can get away with such high nitro percentage and comp .

[koenich]

+1 here,
also,I think YZ 125 & 250 are running without a balance shaft,am I right?
Does anyone know balance factor's used there?
Cheers
jep no balance shaft, the new KTM 250SX is the only 2-stroke engine which has one. I don't know the balance factors but from my understanding the "soft" tires and whole chassis sort of distribute the vibrations differently and they don't end up on the handlebar/pegs/seat that much. The MX engines which are used for road racing usually vibrate like sh*t where as in the MX chassis it's totally different...

[speedpro]

MB100s have balance shafts, just sayin'.

MX engines in road race applications are revved harder for longer I suppose and I expect nobody bothers to rebalance them for the application. Pretty stupid considering how easy it is in a single. No maths required, you know which way to go, make a change and test.

[peewee]

There is no rule regarding fuel , more than 30% just doesn't add anything from our testing . We see an increase , mostly in rpm , going from 20 to 30% nitro thought .

We run R7376-10 plug in everything and its been working great !

Nitro carrying a healthy dose of oxygen , makes the mix as much if not more rich tolerant . Setting the engine very rich also take care of a lot of temperature and atmospheric pressure fluctuation .

Regarding compression ratio , your application being far from my scope of expertise , I wont advise anything . The idea behind reducing the comp ratio is mostly because of the low octane rating of nitro . As stated earlier in this thread , at high rpm the octane needed lowers trendemously wich is probably another reason why we can get away with such high nitro percentage and comp .

thanks for the insight. i would be interested in seeing how your carb and fuel system is setup when your able to post photo

whats your thoughts on oil content ? i started using 16% (75% caster 25% synthetic) mostly because i read it should help slow internal wear. since im not racing professionaly i would rather have the piston and bearings last a bit longer

[SwePatrick]

If it absorbs energy from the motor it would heat up like a break does, energy absorbed has to go some where.

No ;)
It can´t absorb more energy than it´s own weight can produce.
It never absorbs energy from the engine, just from it self.
And as there are no friction the heatlosses are very very very very very small, (if there even are any?)
As a rotating weight has the only friction coming from surrounding air or fluid, you have to go faster than a spaceshuttle coming through the atmosphere to build some melting heat ;)
Why faster?
Because it has so small frictionarea compared to the spaceshuttle :)

[RomeuPT]

If it absorbs energy from the motor it would heat up like a break does, energy absorbed has to go some where.

you are right, should I test the bike running the cdi only with the battery to see if the stator cover gets hot? Or I can be asured alternators don't do any drag without power demand?

[RomeuPT]

jep no balance shaft, the new KTM 250SX is the only 2-stroke engine which has one. I don't know the balance factors but from my understanding the "soft" tires and whole chassis sort of distribute the vibrations differently and they don't end up on the handlebar/pegs/seat that much. The MX engines which are used for road racing usually vibrate like sh*t where as in the MX chassis it's totally different...

I have the SX from 2002, and vibration is insane, is probably the biggest issue of the bike. Can barely take a sit and relax :D. But still great bike.

[Lbracing]

thanks for the insight. i would be interested in seeing how your carb and fuel system is setup when your able to post photo

whats your thoughts on oil content ? i started using 16% (75% caster 25% synthetic) mostly because i read it should help slow internal wear. since im not racing professionaly i would rather have the piston and bearings last a bit longer

We run pumper carbs because of all the angles we put the saws at and for spacing reasons . I doubt seeing them will be of any help to tune your lectron / float type carburetor .

When running methanol , especially with some nitro mixed in , a LOT more fuel goes thru the engine already improving lubrification trendemously so 16% is excessive for anything but model engines . We run Klotz Original Techniplate mixed with a ratio of 6% .

[RomeuPT]

No ;)
It can´t absorb more energy than it´s own weight can produce.
It never absorbs energy from the engine, just from it self.
And as there are no friction the heatlosses are very very very very very small, (if there even are any?)
As a rotating weight has the only friction coming from surrounding air or fluid, you have to go faster than a spaceshuttle coming through the atmosphere to build some melting heat ;)
Why faster?
Because it has so small frictionarea compared to the spaceshuttle :)

Thanks!
Then I should replace all lamp's to led lights all over the bike and use a battery smaller has needed so there is minimal drag/load on the alternator!?

[nitro2tfx]

There is no rule regarding fuel , more than 30% just doesn't add anything from our testing . We see an increase , mostly in rpm , going from 20 to 30% nitro thought .

Something is very much not right if you are not getting more power with higher nitro %. Going to higher nitro % does NOT generate diminishing returns it generates greatly increasing returns.

It is best to think of nitro like this : instead of thinking you have methanol with an additive (30% nitro), think of it as you have nitro with a massive % of low powered diluent, that being methanol, (you have nitro tamed with 70 % methanol).

On a 4 stroke NA engine you can expect about 5-6 times as much power on 100% nitro as on 100% methanol under the right conditions. You could do even better than that on a 2 stroke if you ignored the fact that the cylinder pressure had to blow down before the transfers opened LOL, but of course that is something that can't be ignored. As you reduce the diluent (methanol), blowdown becomes an issue, when blowdown becomes an issue so does power, and when blowdown becomes a big issue "crankcase venting" may occur. I think you can see where I'm going with this.

[Frits Overmars]

On a 4 stroke NA engine you can expect about 5-6 times as much power on 100% nitro as on 100% methanol.Maxim in the office of a dragracing friend:
332905

[SwePatrick]

Thanks!
Then I should replace all lamp's to led lights all over the bike and use a battery smaller has needed so there is minimal drag/load on the alternator!?

I was never talking about the magnetic drag. ;)

[Lbracing]

Something is very much not right if you are not getting more power with higher nitro %. Going to higher nitro % does NOT generate diminishing returns it generates greatly increasing returns.


4 stroke thinking doesn't direcly apply to 2 strokes ... again .

Nitro have a very slow burn rate , remember the flames going out of the headers of dragsters ? its mostly nitro still burning .

Maybe the shorter power stroke of 2 stroke engines is why more nitro doesn't seem to make more power ?

[peewee]

Something is very much not right if you are not getting more power with higher nitro %. Going to higher nitro % does NOT generate diminishing returns it generates greatly increasing returns.

It is best to think of nitro like this : instead of thinking you have methanol with an additive (30% nitro), think of it as you have nitro with a massive % of low powered diluent, that being methanol, (you have nitro tamed with 70 % methanol).

On a 4 stroke NA engine you can expect about 5-6 times as much power on 100% nitro as on 100% methanol under the right conditions. You could do even better than that on a 2 stroke if you ignored the fact that the cylinder pressure had to blow down before the transfers opened LOL, but of course that is something that can't be ignored. As you reduce the diluent (methanol), blowdown becomes an issue, when blowdown becomes an issue so does power, and when blowdown becomes a big issue "crankcase venting" may occur. I think you can see where I'm going with this.

interesting. if i were to gain no power from say 10% to 20% nitro, the likely suspect may be insufficient blowdown ? and if the blowdown is insufficient but the nitro percentage is increased,, theres likely to be an explosion or case venting as you call it ? :laugh:. ill keep this in mind

[speedpro]

Thanks!
Then I should replace all lamp's to led lights all over the bike and use a battery smaller has needed so there is minimal drag/load on the alternator!?

If you are using the alternator output for "anything" and have the regulator/rectifier connected, assuming it is a permanant magnet type, it will produce the same output power at the same rpm. Whether it goes to the regulator or the load it doesn't matter. Permanant magnet alternators therefore create the same load on an engine whether you use the output or not. The windings do get hot, hot enought to sometimes get scorched and regulators get hot as well which is why on big road bikes for instance they will be finned. Smaller alternators may produce 10A at the output of the reg/rec at 14V so we are only talking about 140W absorbed from the engine, minus any drag from rotating parts.

[TZ350]

.
.
.
Another unfulfilling and downright frustrating experience with Ecotrons support Dept.... :brick:.

I had really wanted the Ecotrons system to be good value for everyone, but their support system lets them down badly.

[wobbly]

Did it occur to you TeeZee that just possibly, you know more about the system now, than they do.

[RomeuPT]

If you are using the alternator output for "anything" and have the regulator/rectifier connected, assuming it is a permanant magnet type, it will produce the same output power at the same rpm. Whether it goes to the regulator or the load it doesn't matter. Permanant magnet alternators therefore create the same load on an engine whether you use the output or not. The windings do get hot, hot enought to sometimes get scorched and regulators get hot as well which is why on big road bikes for instance they will be finned. Smaller alternators may produce 10A at the output of the reg/rec at 14V so we are only talking about 140W absorbed from the engine, minus any drag from rotating parts.

I am asking this because I have seen tuners taking the windings out and just keep the one that feed the cdi/spark plug working and they keep ignition and the wheight of the flywheel.

I dont really know if it's worty because they make it a secrecy... I always thought alternators only consume power when on load. I would like to be more sure. It would be interesting to reduce some friction to tune DT125, NSR, Aprilia RS, banshee etc

[TZ350]

Another unfulfilling and downright frustrating experience with Ecotrons support Dept.... :brick:.

Did it occur to you TeeZee that just possibly, you know more about the system now, than they do.

With small capacity high performance 2T EFI that maybe true ... :laugh: ... and sure, I can't expect them to be expert at everything.

But what I asked for was a simple change to a basic cal file to turn on the LamO2 sensor.

Its easy enough, other EFI software packages come with tick box's for that sort of thing. With Ecotrons you have to enlist their assistance and it is often a slow difficult process dealing with their help dept.

[speedpro]

... I always thought alternators only consume power when on load.

For a permanant magnet alternator it will always generate power if the magnet is moving past the windings. The way they are regulated is by loading them. Basically the reg/rec short circuits the output to ground until the desired voltage is attained at the output. The more the external load draws the less the reg/rec has to short to ground. If enough load is drawn by pumps and ignition etc then the reg/rec won't have to regulate at all.

[Grumph]

For a permanant magnet alternator it will always generate power if the magnet is moving past the windings. The way they are regulated is by loading them. Basically the reg/rec short circuits the output to ground until the desired voltage is attained at the output. The more the external load draws the less the reg/rec has to short to ground. If enough load is drawn by pumps and ignition etc then the reg/rec won't have to regulate at all.

So the dickhead we found when checking 250 production bikes back in the day who was running with a flat battery, possibly wasn't losing much...It certainly showed a healthy charge rate when tested.

He was a dickhead and got disqualified anyway as it had no air filter element. Much complaining - "it was like that when I bought it" - dickhead.

[wobbly]

The permanent magnets in the flywheel simply pass their field thru the coil - this magnetic field passing thru the wire creates voltage.
It makes no difference if that created voltage is used or not.
The on/off " resistance " you feel when turning the rotor ( especially with Neo magnets ) is the fields passing over the steel stator elements,and that is a constant.
Many tuners thought they were being clever dumping the magnetic rotor in favour of total loss, only to find the thing then simply would not rev out.
Honda and VHM had to make heavy cranks, that in effect simply recreated the original rotational inertia of the stock crank - and this brought back the overev power.

[sb07]

The permanent magnets in the flywheel simply pass their field thru the coil - this magnetic field passing thru the wire creates voltage.
It makes no difference if that created voltage is used or not.
The on/off " resistance " you feel when turning the rotor ( especially with Neo magnets ) is the fields passing over the steel stator elements,and that is a constant.
Many tuners thought they were being clever dumping the magnetic rotor in favour of total loss, only to find the thing then simply would not rev out.
Honda and VHM had to make heavy cranks, that in effect simply recreated the original rotational inertia of the stock crank - and this brought back the overev power.

Hy Wobbly, i'm Stefano
I dont able send you a private message...:doh:
i understand you work in the world of the kart ... the next week you are in Lonato circuit?

[Haufen]

Many tuners thought they were being clever dumping the magnetic rotor in favour of total loss, only to find the thing then simply would not rev out.
Honda and VHM had to make heavy cranks, that in effect simply recreated the original rotational inertia of the stock crank - and this brought back the overev power.

Are you talking about a dynamic or steady state situation?

[wobbly]

A race engine is never in " steady state " on a track, except on part throttle,traction limited mid corner.

The next kart race for me is SuperNationals in Vegas, mid November,after which I go back to the TM factory in Pesaro.

[Haufen]

A race engine is never in " steady state " on a track, except on part throttle,traction limited mid corner.

I totally agree. And hence I have always used the acceleration type dyno with race engines. What I found was, that you can have too much inertia which reduces power everywhere in the powerband. I have never experienced that too little inertia kills overrev, so far.

an engine with 'back to okay' inertia by the use of a heavy crank as described by you above, would it behave as follows?

on a steady state test it would fall flat on it's face, no or very little overrev at all (same as with too little inertia on the roller type)
on an acceleration type dyno, overrev capability would be depending on the inertia of the dyno
thus almost steady state like behaviour at very high dyno inertias and dyno pull durations
ideal overrev capabilities if the time for the dyno pull matches the inertia of the engine
and lower power everywhere if the time for the pull is too small

all assuming that EGT and pipe wall temperatures can keep up with the dyno pull.

Good luck at the SuperNationals in Vegas!

[wobbly]

The dyno inertia has a big effect on the run time accelerating thru the pull.
If its too low, then no matter what you do the pipe wall temp,and egt will never stabilize at the correct level - reducing overev power,simply due to lack of heat soak..
The crank in the RS125 Honda was quite low in inertia, and removing the flywheel tipped it too far in favor of low inertia and faster acceleration capability.
The Aprilia by comparison has a huge amount of added Mallory around the outside of the wheels, making it a high inertia assembly by default.
Adding more would tip that too far the other way and slow down the acceleration capability.
I have used an old KZ9 crank with alot of mass removed with alloy plugs, and re-balanced it with Mallory, and that made better top end power than the
latest so called high mass KZ10C factory crank.

[TZ350]

I received a reply from Ecotrons lastnight. The advanced calibration file needs some changes to be able to monitor and record results from the wide band oxygen sensor. Hopefully I will get to try it out this afternoon.

I used to think that it was easier for the local 2T Kawasaki 350 and Yam 250 that are successfully running EFI because they did not rev much past 9,000 and so only needed one logical injector and that the bigger capacity helped mask fueling miss steps.

I started to have doubts about that when I saw that some small 2T drone aero engines 25cc or less were successfully running the Ecotrons EFI system. But these engines basically run at a constant speed.

The issue for me is drivability, i.e. throttling off for a corner and then on again exiting. After Nath88 pointed out that you can have two different air flows through the engine due to pipe action/non action for the same Throttle/Rpm position on the Alpha-N EFI fueling map. And remembering Frits's explanation of how the wave action in a pipe collapses when throttling off and how it takes some time to re establish after throttling on again.

I now think that one of the big differences is how aggressive the pipe is. On a small capacity high performance race engine the pipe action in drawing air through the engine would be much more variable than the pipe action on a larger capacity MX or Trail bike engine setup more for power range and usability than outright power hit.

So in getting 2T EFI to work, it turns out the pipe makes a huge difference, who would have thought ...... :rolleyes:

[Flettner]

I received a reply from Ecotrons lastnight. The advanced calibration file needs some changes to be able to monitor and record results from the wide band oxygen sensor. Hopefully I will get to try it out this afternoon.

I used to think that it was easier for the local 2T Kawasaki 350 and Yam 250 that are successfully running EFI because they did not rev much past 9,000 and so only needed one logical injector and that the bigger capacity helped mask fueling miss steps.

I started to have doubts about that when I saw that some small 2T drone aero engines 25cc or less were successfully running the Ecotrons EFI system. But these engines basically run at a constant speed.

The issue for me is drivability, i.e. throttling off for a corner and then on again exiting. After Nath88 pointed out that you can have two different air flows through the engine due to pipe action/non action for the same Throttle/Rpm position on the Alpha-N EFI fueling map. And remembering Frits's explanation of how the wave action in a pipe collapses when throttling off and how it takes some time to re establish after throttling on again.

I now think that one of the big differences is how aggressive the pipe is. On a small capacity high performance race engine the pipe action in drawing air through the engine would be much more variable than the pipe action on a larger capacity MX or Trail bike engine setup more for power range and usability than outright power hit.

So in getting 2T EFI to work, it turns out the pipe makes a huge difference, who would have thought ...... :rolleyes:



Who??? Crank angle enabled exhaust pressure sensing perhaps. The exhaust chamber, and the piston / cylinder / crankcase are two separate engines, not exclusively working together.

[TZ350]

Crank angle enabled exhaust pressure sensing perhaps.

Definitely.


The exhaust chamber, and the piston / cylinder / crankcase are two separate engines, not exclusively working together.

Yes, nothing simple about the simple two stroke.

[diesel62]

Can I ask where you have the O2 sensor mounted? In stinger?

Sent from my SM-P555 using Tapatalk

[TZ350]

Can I ask where you have the O2 sensor mounted? In stinger?

The wide band O2 sensor is mounted in the convergent cone near the start of the stinger.

[RomeuPT]

The permanent magnets in the flywheel simply pass their field thru the coil - this magnetic field passing thru the wire creates voltage.
It makes no difference if that created voltage is used or not.
The on/off " resistance " you feel when turning the rotor ( especially with Neo magnets ) is the fields passing over the steel stator elements,and that is a constant.
Many tuners thought they were being clever dumping the magnetic rotor in favour of total loss, only to find the thing then simply would not rev out.
Honda and VHM had to make heavy cranks, that in effect simply recreated the original rotational inertia of the stock crank - and this brought back the overev power.

Thank you.

Ok, Then is worth to cut some if not needed.

Do you have any ideia of ignitech and other cdi's power consuption?

Cheers

[Frits Overmars]

Crank angle enabled exhaust pressure sensing perhaps.Very definitely. If you monitor the exhaust return pulse, you can see whether it arrives at the exhaust port too soon, too late or just in time, and then you can adjust the ignition timing accordingly. No need for rpm-throttle-advance tables anymore; not even a need for exhaust gas temperature measurement anymore.

[dutchpower]

What Frits if you have new exh. and make other cdi curve's all not respons better then OEM part ( cdi )

[jamathi]

The dyno inertia has a big effect on the run time accelerating thru the pull.
If its too low, then no matter what you do the pipe wall temp,and egt will never stabilize at the correct level - reducing overev power,simply due to lack of heat soak..
The crank in the RS125 Honda was quite low in inertia, and removing the flywheel tipped it too far in favor of low inertia and faster acceleration capability.
The Aprilia by comparison has a huge amount of added Mallory around the outside of the wheels, making it a high inertia assembly by default.
Adding more would tip that too far the other way and slow down the acceleration capability.
I have used an old KZ9 crank with alot of mass removed with alloy plugs, and re-balanced it with Mallory, and that made better top end power than the
latest so called high mass KZ10C factory crank.

At Aprilia we did not have an inertia dyno, as I would have liked.
Crank inertia tests were done on-track.
Exchanging dyno information with 'track-people' was forbidden....
You know by whom I think!
But we still won....
I still think we could have done a lot better than we did!

[lohring]

Can I ask where you have the O2 sensor mounted? In stinger?

Sent from my SM-P555 using Tapatalk

Below are some pictures of a stinger slide on O2 sensor for small engines.

Lohring Miller

332927 332928 332926

[jasonu]

At Aprilia we did not have an inertia dyno, as I would have liked.
!

You seamed to do OK without one...

[diesel62]

What is the red material. Nylon seal?

Sent from my SM-G900F using Tapatalk

[RomeuPT]

Hi.

This is the Gearbox from NSR/CRM 125:

from 1st to 6th

11/34
15/30
17/25
19/23
(23)/24
(24)/22

This gear box is ok for a road bike, but 5th to 6th is a huge jump of 13.74%, for a top end engine, that is far too much, and the engine gets out of the real power band.
Other better gear boxes are about 9%.
So I took a backup engine gearbox to see what can be done, and the 23 tooth sproket from tht 5th can fit in the 24 of the 6th gear the tooths are only 1mm wider, this would put me right at 9% jump.

But of course they have different diameters (around 2,5mm) and the tooths are a bit further apart. Can this cause any trouble or bigger loss of power?

Cheers

[RomeuPT]

At Aprilia we did not have an inertia dyno, as I would have liked.
Crank inertia tests were done on-track.
Exchanging dyno information with 'track-people' was forbidden....
You know by whom I think!
But we still won....
I still think we could have done a lot better than we did!

It's wonderfull how it still achieved so much.
It looks like the Aprilia team had considerable restricitions and disagreement between yourselfs and the "boss".
Always had a thought that this dellorto used in the Aprilia would be better then keihin and read at pit lane that it wasn't exacly that way.

Was any component from the Aprilia made in Japan or other place besides Europe?

What would had happen in your opinion if the 125 2t was still at GP, do you think it would have achieved 60cv by now after more 6 years of R&D?

[TZ350]

Below are some pictures of a stinger slide on O2 sensor for small engines.

Lohring Miller

332927 332928 332926

Hi Lohring, that is a very interesting setup.

332935

Here is a picture of where I placed my O2 sensor, the position at the back of the convergent cone was suggested to me by Wobbly, seems to work well. The blue hose is an experimental pressure take off for the EFI system.

[diesel62]

Very definitely. If you monitor the exhaust return pulse, you can see whether it arrives at the exhaust port too soon, too late or just in time, and then you can adjust the ignition timing accordingly. No need for rpm-throttle-advance tables anymore; not even a need for exhaust gas temperature measurement anymore.Hi I'm just trying to process why the EGT would not be required any more. I understand that the temp is changed by timing. But fuel will still change the EGT and as I'm writing this I'm thinking O2 sensor is fitted so fueling is known!

Sent from my SM-G900F using Tapatalk

[wobbly]

In my opinion getting to 60Hp would have been done long ago.
Here is the potential of simply changing the Ex duct exit and spigot geometry,from Neels code.
The pipe geometry of the last designs were not so good, and Jan had to do the big radius on the timing edge just to get the top end power back.
Using a better pipe would have not needed this change to the duct Cd, and again my opinion ( this is a 2T after all ) would be that alot better combination
of timing/Cd and pipe could be found

[2T Institute]

Just by a Ryger and get 60hp

[wobbly]

Man arent we dumb,of course, who needs a whole lot of hard work to get 60 from the Aprilia.
Ryger has already done it, and some, with dyno printouts to prove us doubting wankers completely wrong.

[RomeuPT]

Man arent we dumb,of course, who needs a whole lot of hard work to get 60 from the Aprilia.
Ryger has already done it, and some, with dyno printouts to prove us doubting wankers completely wrong.

Wasnt that a scam?

what is this?
332937

[wobbly]

Not a "real " dyno printout - another Luc wet dream.

Romeau you cannot swap the gears as you are saying.
All gears are designed as pairs to maintain the correct shaft center and diametrical pitch ratio.
Take the 23/24 gears from 5th and reverse them ie 24/23 in 6th gear position.

[RomeuPT]

Not a "real " dyno printout - another Luc wet dream.

Romeau you cannot swap the gears as you are saying.
All gears are designed as pairs to maintain the correct shaft center and diametrical pitch ratio.
Take the 23/24 gears from 5th and reverse them ie 24/23 in 6th gear position.

That was what I thought first, but that won't fit at all, the 22 of 6th gear has the shift fork guide, and there is no 23 sproket equal in the gearbox. that way only If I order a personalized gear.

[jamathi]

Man arent we dumb,of course, who needs a whole lot of hard work to get 60 from the Aprilia.
Ryger has already done it, and some, with dyno printouts to prove us doubting wankers completely wrong.

After having been 2.5 sec a lap slower than a Tm on a 35 sec a lap track they are finally silent.
Their power was estimated at about 33HP
Not something to be proud of.....

[jamathi]

It's wonderfull how it still achieved so much.
It looks like the Aprilia team had considerable restricitions and disagreement between yourselfs and the "boss".
Always had a thought that this dellorto used in the Aprilia would be better then keihin and read at pit lane that it wasn't exacly that way.

Was any component from the Aprilia made in Japan or other place besides Europe?

What would had happen in your opinion if the 125 2t was still at GP, do you think it would have achieved 60cv by now after more 6 years of R&D?

Piston rings and big-end cages came from Japan, also the spark plugs.
I think we would have achieved 60HP by now.

[katinas]

Jan, when you rise EX window bottom on Aprilia cylinder, do you change angle of A transfers side wall near exhaust?

[jamathi]

Jan, when you rise EX window bottom on Aprilia cylinder, do you change angle of A transfers side wall near exhaust?

No, I couldn't, they were already as much rearward inclined as possible.

[adegnes]

Been trying to find info on CVT efficiency, here's the best paper I've found so far.
https://www.google.no/url?sa=t&source=web&rct=j&url=http://forums.bajasae.net/forum/uploads/465/experimental_investigation_of_efficiency_of_pulley-drive_cvt.pdf&ved=0ahUKEwjJ8aqgv_PWAhWoF5oKHSywC7s4ChAWCCswAg&usg=AOvVaw2Q5fpqMyG3eMIDFLS5CN4S

With estimated 20% total transmission loss I have to lower efficiency in my engmod simulations to 0.79 for them to match real life dyno results. It doesn't seem right.

332939

Blue/green = dyno run
Red/black = simulated
Yellow/pink = simulation ported engine but same pipe

Either transmission loss is higher than 20%, or my engine is very inefficient...

Had a minor blowup...


https://youtu.be/-VVLD06KveI


https://youtu.be/dA9pwHiO6iU

[SwePatrick]

After a dynopull.
How hot were the pulleys for the belt?

Really hot = a lot of loss
Almost no heat at all = your engine isn´t producing power.

Well, that is a really harsch statement, but it can guide you to what´s correct in your research =)

[adegnes]

After a dynopull.
How hot were the pulleys for the belt?

Really hot = a lot of loss
Almost no heat at all = your engine isn´t producing power.

Well, that is a really harsch statement, but it can guide you to what´s correct in your research =)

They're hot, really hot. One pull and you can't touch them.
On the 17.4whp pull there even was smoke coming from the belt around peak power...

So, on the plus side I am probably making good power, on the minus side the CVT is probably very inefficient.

[SwePatrick]

Well,, you have the answer ;)

This summer i dynoed a small 50cc to 19.22hp, and we never started from standstill.
We rolled up into about 200rpm on the roller, then gave it hell ;)

After a run there wasn´t almost any heat buildup at all.
In the future, try remember that, start from rolling. :)

This is much more less aggressive to the belt and gives more precise numbers from pull to pull.

Rgds.

[RomeuPT]

good video from VHM

https://www.youtube.com/watch?v=4KRwOObWCtA

[Frits Overmars]

If you monitor the exhaust return pulse, you can see whether it arrives at the exhaust port too soon, too late or just in time, and then you can adjust the ignition timing accordingly.
No need for rpm-throttle-advance tables anymore; not even a need for exhaust gas temperature measurement anymore.
What Frits if you have new exh. and make other cdi curve's all not respons better then OEM part ( cdi )
With my system there would not be any CDI-curves anymore. Instead of looking up the prescribed amount of ignition advance for a certain rpm and thottle position,
the CDI would constantly monitor the exhaust pulses and adjust the ignition timing accordingly. It would also automatically adjust to a different exhaust pipe.


Always had thought that this dellorto used in the Aprilia would be better then keihin and read at pit lane that it wasn't exacly that way. Was any component from the Aprilia made in Japan or other place besides Europe?Spark plugs, piston rings and big end cages, as Jan wrote. And, funniest of all, Keihin powerjet valves on the very special (incredibly expensive) Dellorto carbs :p.


What would had happen in your opinion if the 125 2t was still at GP, do you think it would have achieved 60cv by now after more 6 years of R&D?6 years? As from 2008, Aprilia had to make do without Jan Thiel. That's 9 years. And I think it would have been realistic to expect an improvement of 1 hp per year.
And what do you think would happen if a 2007-version of the Aprilia RSA125 was fitted with 2017-tires and turned loose on the Moto3-class? They might as well hand over the victory bowl to its rider before the start.

[lohring]

What is the red material. Nylon seal?

Sent from my SM-G900F using Tapatalk

It's a silicon seal material that can be changed by unscrewing the end. That way it will fit several stinger sizes. An o-ring containing end plate might be an alternative.

Lohring Miller

[RSC]

I've been looking into the MVX250 electrical system and noticed it has TCI instead of CDI ignition,as well as a field coil alternator instead of a permanent magnet one.Both seem kind of an unusual option,do they have any inherent advantages?