ESE's works engine tuner

[speedpro]

But given how collectable they are now.
Should they be done?

Hell yeah. Ideally you'd rip the motor out, toss the standard frame and then fit the motor into a late model RS125 chassis.

[chrisc]

Ask Pete Sales but they are 5 speed piston port iron cylinder points ignition and quite collectable.
There has been two on Trademe lately that have been raced.
I have a weakness for them and Wolfs but It would be a big ask.
They could be made competitive on a open track with MB5 cylinders but would need two of everything.
The carbs are odd and possibly oversize for the rules which would need to be equivalent to a single 24mm carb Which would be around 17mm I guess.
No doubt it could be done and it would be a hoot. They handle good even in stock trim and they would be beautiful done up as a replica of the 60's GP race bikes. But given how collectable they are now.
Should they be done?

Thanks for that, I just found this:
"Flat parallel twin. Portirtg, piston controlled. Capacity, 124 cc. Bore and stroke, 43 x 43 mm. Compression, (from exhaust port closure) 7.3:1. Power, maximum claimed torque, 9.98 ft/lbs at 700 rpm, bhp, 15.1 at 8500 rpra Carburetters, twin 18 mm Amal MD, breathing through paper air cleaner."

Think the carbs changed over the years, this is meant to be the 1971 year I think.

I personally have no holds against modifying something that may be collectable for the sake of fun

[koba]

It may be better to start with something easier though...

[husaberg]

Thanks for that, I just found this:
"Flat parallel twin. Portirtg, piston controlled. Capacity, 124 cc. Bore and stroke, 43 x 43 mm. Compression, (from exhaust port closure) 7.3:1. Power, maximum claimed torque, 9.98 ft/lbs at 700 rpm, bhp, 15.1 at 8500 rpra Carburetters, twin 18 mm Amal MD, breathing through paper air cleaner."

Think the carbs changed over the years, this is meant to be the 1971 year I think.

I personally have no holds against modifying something that may be collectable for the sake of fun

Great Then I did have to ask.
As long as you paint it up look the ones I have posted.
I have at least one MB5 cylinder and head That I'd donate to the cause.

How many (MB5 cylinder and heads) do You have Speedpro Koba and and Dave?

Ps all the ones I have seen had 18mm Mikunis the Wolf was a debored 125cc to 90cc without the rev counter with smaller (I think) carbs.

PS i hope you have a lot of time machining ability or beer money

Checkout the kickstarter Gear selector mechanism.

[koba]

Bryce would be one to ask.

Avoid Terry 53 and his aliases on trademe, he has a lot of parts but I've had a good look through them and we differ on what constitutes "good condition" by about 100,000 KM and three years in the sea.

[TZ350]

Avoid Terry 53 and his aliases on trademe,

My experience with Terry53 was not so good, I won one of his job lot auctions but didn't get all the parts advertised in the auction photo, he only sent the junk and kept back the good bits. Of course I followed up, and from what I have seen and heard since, he may not be setting out to rip people off, he just seems to have a different idea about what integrity and fair value means.

Steptoe and Son

From what I can see, Terry53 is the Steptoe rag and bone man of Trademe, basically Terrys stock is all other peoples junk and cast offs. And like Steptoe he is one of those people who paints a picture for themselves of gold and commercial possibility in everything they have, whereas other people with better personal hygiene mostly see it for what it is, junk.

Even if you have won an auction or closed a deal with him you may still be disappointed, as his word certainly doesn't seem to be his bond. Being a Steptoe, he will flog your part to someone else if he sniffs a better offer. If your lucky he will find you something else, that's even more decrepit than the original and tell you, you got a bargain.

I am sure if you meet him he would be approachable enough and I am not saying you won't find that essential bit there. But because he appears so out of touch with mechanical reality and has such a totally self focused business manner, it leaves me thinking you have only half a chance of a "value for money" outcome when dealing with him.

He has his opinions, the above are mine.

[NordieBoy]

Avoid Terry 53 and his aliases on trademe, he has a lot of parts but I've had a good look through them and we differ on what constitutes "good condition" by about 100,000 KM and three years in the sea.

Been waiting on a frame and some other bits from him for a while now.

[F5 Dave]

Yeah I went to pick up some MB cases from Terry for Speedpro & ended up buying some bare cases myself, but later to discover when i looked a bit better they had a crack near the gearset (I looked at the front where they usually crack if frame mounted from the front). Unrepairable Junk.

His house is just an explosion of rubbish bike parts.

T125 will not get anywhere quickly. But if you do have one I'm after some chrome seat strip & maybe headlight chrome surround. Maybe some forks.

[husaberg]

Old style 2 stroke tuning 1971 style Two wheels article hand written copy A tuned T125 could be made to see of a good t250 hustler supposedly.

If you were keen to move out of the 1960's port technology. Then maybe you could get something like (the Cylinder) this to work or similar.

[Frits Overmars]

Apologies for not reacting a single time since 11 October. I did try to log on to this forum every day, but each time I got the message
The website cannot display the page HTTP 500. Most likely causes:
* The website is under maintenance.
* The website has a programming error.
I have had the same problem a couple of times in the past, but never as badly as these past two weeks. Any suggestions?

Now that I finally got through (heaven knows why, and heaven knows what will happen the next time I try to log on) I can give a short reaction to some (not all) of the items that went on during my unvoluntary absence.

In 1993 Itoh first rode a Honda NSR500 with water injection into the headers. No injection-water cooling (the small bottom radiator is just a part of the total cooling system as this picture will show), no double-wall constructions, no recirculation, just a simple total-loss system.
It did work to some extent; bottom power improved noticeably. The problem was that once you got the revs up and cut the water injection, the effect of the cooling water on the pipe resonance frequency did not disappear quickly enough. Mike Doohan used it once or twice but never liked it, so it was binned.
Aprilia tried such a system a couple of years before Honda did, in 1987, on Loris Reggiani's works 250 twin. It added 10 HP at 10.000 rpm and it took 0.000 seconds off the laptimes because Reggiani never ran below 11.000 rpm, so the system was scrapped, recovering weight and simplicity.

Somebody asked about the Aprilia's inlet disk diameter. From memory I would say it was 126 mm.

Optimized disk inlets do not generate pulses: you open the disk when the crankcase pressure is equal to the pressure just outside the disk. Opening it any sooner would cause a loss of mixture to the outside world; opening it any later would be a waste of time*area.
You close the disk when the inlet flow has come to a stop. At that moment the pressure at the outside face of the disk will be equal to the pressure in the crankcase, but it will be higher than the atmospheric pressure, so there will be some blow-back, but that does not come out of the crankcase (assuming your closing timing is spot-on); it is just mixture feathering back from the high-density zone outside the disk. For that matter, every conventional inlet system (disk, piston, reed) will show the same blow-back tendency. And it may not be even visible from the outside; maybe the cloud of blow-back moves just a few centimeters and never really exits the inlet tract.
By the way, closing an inlet disk too early (or revving the engine higher than the inlet system's frequency would like to) will generate serious blow-back because then the closing disk interrupts an inward-bound flow which will violently bounce off the disk.
You can observe this very nicely on a dyno: looking into the carburetter you can see the fuel spray exiting the mixing tube and curving towards the crankcase. But rev it high enough and you will see this curving change into a steep front of mixture.

PS: I am sorry to say that time does not permit me to answer private messages. I apologize, but I hope you will understand.

[husaberg]

Apologies for not reacting a single time since 11 October. I did try to log on to this forum every day, but each time I got the message
The website cannot display the page HTTP 500. Most likely causes:
* The website is under maintenance.
* The website has a programming error.
I have had the same problem a couple of times in the past, but never as badly as these past two weeks. Any suggestions?

Now that I finally got through (heaven knows why, and heaven knows what will happen the next time I try to log on) I can give a short reaction to some (not all) of the items that went on during my unvoluntary absence.

In 1993 Itoh first rode a Honda NSR500 with water injection into the headers. No injection-water cooling (the small bottom radiator is just a part of the total cooling system as this picture will show), no double-wall constructions, no recirculation, just a simple total-loss system.
It did work to some extent; bottom power improved noticeably. The problem was that once you got the revs up and cut the water injection, the effect of the cooling water on the pipe resonance frequency did not disappear quickly enough. Mike Doohan used it once or twice but never liked it, so it was binned.
Aprilia tried such a system a couple of years before Honda did, in 1987, on Loris Reggiani's works 250 twin. It added 10 HP at 10.000 rpm and it took 0.000 seconds off the laptimes because Reggiani never ran below 11.000 rpm, so the system was scrapped, recovering weight and simplicity.
Somebody asked about the Aprilia's inlet disk diameter. From memory I would say it was 126 mm.

PS: I am sorry to say that time does not permit me to answer private messages. I apologize, but I hope you will understand.

Great stuff Frits.
You are a 2 stroke God
But and I hate asking it.
What would this be then?
I can not explain what else it could be, and it is mentioned in the blurb from the Honda press release.
I realise the writer could be mistaken, but all the pictures of the non water injected bikes don't have this bit. Below in pic.
I have serious doubts it contributes much to the NSR500's Engine cooling.

I believe you have confused the lower radiator for the tiny radiator in the fairing nose up by the tacho that both myself and Bucketracer were pointing out.

[quallman1234]

Great stuff Frits.
You are a 2 stroke God But and I hate asking it.
What would this be then? I realise the writer could be mistaken, but all the pictures of the non water injected bikes don't have this bit. Below in pic.
I have serious doubts it contributes much to the NSR500's Engine cooling

Read the caption?

[TZ350]

Two strokes like an ignition curve approximating to an inverse of the power curve.
With around 28* in the mid range, that ramps up from an easy kick starting 10* at idle to about 1500,2000 rpm.
Then as the bmep rises and the pipe gets in sync with the port we pull out timing in relation to the dynamic compression created by the wave action, to prevent detonation in the end gasses.
Most engines like around 15* of timing at peak torque, we then drop this away after peak to increase the heat released into the pipe.

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



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

[TZ350]

Somebody asked about the Aprilia's inlet disk diameter. From memory I would say it was 126 mm.

Optimized disk inlets do not generate pulses: you open the disk when the crankcase pressure is equal to the pressure just outside the disk. Opening it any sooner would cause a loss of mixture to the outside world; opening it any later would be a waste of time*area.
You close the disk when the inlet flow has come to a stop. At that moment the pressure at the outside face of the disk will be equal to the pressure in the crankcase, but it will be higher than the atmospheric pressure, so there will be some blow-back, but that does not come out of the crankcase (assuming your closing timing is spot-on); it is just mixture feathering back from the high-density zone outside the disk. For that matter, every conventional inlet system (disk, piston, reed) will show the same blow-back tendency. And it may not be even visible from the outside; maybe the cloud of blow-back moves just a few centimeters and never really exits the inlet tract.

By the way, closing an inlet disk too early (or revving the engine higher than the inlet system's frequency would like to) will generate serious blow-back because then the closing disk interrupts an inward-bound flow which will violently bounce off the disk.

You can observe this very nicely on a dyno: looking into the carburetter you can see the fuel spray exiting the mixing tube and curving towards the crankcase. But rev it high enough and you will see this curving change into a steep front of mixture.

Closing the valve to early ...... Now, could this be what is happening in the video clip of my GP125 on the dyno? As its coming up on the pipe you can see fuel being sucked in and then blow back appears at at the top end like Fritz described happens when the valve is closed to early.

Fritz is this enough blow back to suggest I should try closing the inlet little later.

[Frits Overmars]

....What would this be then? I can not explain what else it could be, and it is mentioned in the blurb from the Honda press release. I realise the writer could be mistaken, but all the pictures of the non water injected bikes don't have this bit. Below in pic. I have serious doubts it contributes much to the NSR500's Engine cooling. I believe you have confused the lower radiator for the tiny radiator in the fairing nose up by the tacho that both myself and Bucketracer were pointing out.

You are right, Husaberg. When you mentioned a small radiator, I did confuse the lower radiator with this tiny one. I cannot explain either what else it could be (I hardly expect Honda experimented with a water-cooled motor control unit) but then I can't see any sense in cooling that pipe injection water either; its container was built into the gas tank where the water will never pick up any heat.
And I know for a fact that the pipe injection system was total-loss. Honda (and Aprilia six years before them) already had a problem with the cooling effect not wearing off quickly enough once you got into the power band; the problem would have been far worse with double-walled light-alloy headers.

Closing the valve to early ...... Now, could this be what is happening in the video clip of my GP125 on the dyno? As its coming up on the pipe you can see fuel being sucked in and then blow back appears at at the top end like Fritz described happens when the valve is closed to early.
Fritz is this enough blow back to suggest I should try closing the inlet little later.

You can notice some blow-back at low revs + full throttle (only normal); it disappears at medium revs and comes back at high revs. So yes, this might be an indication of an early-closing disk.
You can try closing it 5° later but I would look at the inlet tract length first. If you can shorten that, you may solve the high-rev blow-back without the need for a late-closing disk. That would make setting the carburation a lot easier and it would also lower the inertia of the mixture column in the inlet tract, which in turn would make it easier to get this column up to speed; especially important when you have to use a small-bore carburetter.
O, and one more thing, TZ350. Fritz is German. I am a Dutchie and I spell my first name with an s .