ESE's works engine tuner

[wobbly]

Crowded needle roller small end bearings were discarded years ago, being only suitable for low reving boat and chainsaw use. They start to " skid " against each other and or the bearing surfaces causing heat related failure.
Proper , caged small ends , are the only way to go as we now have no issues at all with reliability in this area.
Modify the piston bosses to suit .

[jbiplane]

Modify the piston bosses to suit .

Thanks. Will think how use 14mm piston pins in 15mm holes or try use bearing with small 1.5mm diameter needles.
Exist 15x18x22mm.

[190mech]

That size is hard to find!
Here is a double roller one for a Stihl chainsaw;
https://www.huztl.net/Aftermarket-St...0-p372598.html

Also INA bearing has one listed,but only 17mm wide;
https://medias.schaeffler.com/medias...K*K15X18X17-TV

[jbiplane]

That size is hard to find!
Also INA bearing has one listed,but only 17mm wide;
https://medias.schaeffler.com/medias...K*K15X18X17-TV

The second variant fit perfectly. Thanks for INA link.

I consider as well use conrods with 20mm upper hole. But 15x20 bearings even more difficult to find.

[Brett S]

The second variant fit perfectly. Thanks for INA link.

I consider as well use conrods with 20mm upper hole. But 15x20 bearings even more difficult to find.

From a pro-x catalogue YZ125 97/99 uses 15x20x18 LE bearing

[speedpro]

Ready to start, at last. Just got to sort through this LINK, so different to what Im used to, way more complicated than the Atom.

One wire at a time, one sensor at a time, one injector, and so on. As you have probably done before. Link's setup documents are pretty good I reckon. Same sort of thing as the Atom I would think, start at the top and work down. I'd be interested to come down and help but, you know. I bought a really good Weller soldering iron and a selection of tips. Small stack of wires and collection of heatshrink. I used some black braid to thread the wires through as I put the loom together on mine. I think it kept it reasonably tidy though it still turned into a birds nest at the main connector

[TZ350]

From a pro-x catalogue YZ125 97/99 uses 15x20x18 LE bearing

Wossner 15x20x17,8 Yamaha YZ125 LE bearing cage. About 8 Euro on Ebay. I use them in my 14,000 rpm NSR110cc beast.

[jbiplane]

Thanks for advice related YZ125 top end bearings! Will definitelly get some.

[Flettner]

One wire at a time, one sensor at a time, one injector, and so on. As you have probably done before. Link's setup documents are pretty good I reckon. Same sort of thing as the Atom I would think, start at the top and work down. I'd be interested to come down and help but, you know. I bought a really good Weller soldering iron and a selection of tips. Small stack of wires and collection of heatshrink. I used some black braid to thread the wires through as I put the loom together on mine. I think it kept it reasonably tidy though it still turned into a birds nest at the main connector

Yes slowly stepping through it. Its all comming back to me now. Usual problems, coolant leak all over the floor, fixed that, forgot to fit an oring. Gearbox full of oil, autolube full of oil, wait, where is the gearbox breather? You know silly little things. Now Im trying to kick it over, with this bastard left hand kick start, bad idea, its bloody awkward.
So sooner or later its going to end up on the engine dyno, so it might be sooner, dyno is getting an electric start fitted. Idea is to take the rear wheel out and make a small carrier, chain to the rear axel then a sub chain to a set of bearings connected to the dyno via a universal drive shaft.
It was going to happen anyway, just its bought forward now.

[ken seeber]

WHY DO 2 STROKES BLOW SMOKE? (or do they just want lung cancer?)

After seeing skywriting planes yesterday during the Australia Day celebrations, it got me thinking. They do it by injecting oil into the hot exhaust = incomplete combustion. I’m sure we have all chucked on an oil soaked rag or bit of paper onto a fire. If it is really soaked we see smoke. Less soaked = less smoke. Years ago at Orbital we ran a generous flow of oil into the intake of a 2 stroke 4 cyl engine carb at high load. No smoke.

Can think of a couple of reasons for smoking, but based on the above, I’ll make the statement that a typical 2 stroke premix fuel (eg 25:1), if completely combusted, does not smoke, and, in the inverse, we get smoke.

Some possible reasons being:

1. One being the short circuiting of some of the charge, escaping out the exhaust and acting exactly like a skywriting plane. One test for this might be to run an engine on straight petrol, not withstanding that the petrol that has short circuited might smoke (a bit). Anyone want to give this a try, in the interests of science of course.
2. Oil, possibly with some of the petrol lighter fractions evaporating off (due to the high engine internal temps), working its way up the bore around the piston skirt and ring and passing into the exhaust passages.
3. An accumulation in the crankcase after draining down after stopping, either escaping into the exhaust directly or around the piston as above. Can be fully or partially eliminated by a draining circuit.
4. Similar to the above, but an accumulation of oil after full or partially closed throttle on an overrun situation passing thru engine.
5. An excess of oil being delivered to the engine, eg a separate pump controlled by a properly programmed ECU. My 300 EXC TPI is an excellent smoker at startup and low loads, either as a result of shit mapping or as per reason #3 above.
6. Others?

Gotta say that I have seen many (but not all) fast race bikes down the main straight and not blowing any smoke at all. Presumably this is because the plugging pulse is so strong that all the mixture that might pass out the cylinder into the exhaust passage is fully returned and fully combusted.

It'd be nice to be able to stop it. Thoughts?

Jeez Ken, nice post and you’ve got me thinking.

On the basis of your points #2 & 3, I am going to try a drain circuit as in the sketch Essentially it is a gutter across the full width if the bottom of the exhaust port. To assist feeding into the gutter , the liner has been ground away to encourage any oil (or oil/fuel mix) to run into the gutter. From the bottom of the gutter, a small drilling will act as a drain. Perhaps a small valve in the drilling to be able to cut off any drain flow. The net positive exhaust system pressure should act as the propulsion force.




What if it works and there is actually a flow? Well I reckon it’d be logical to just return it into the intake of the carb/throttle body. Keep the stuff active and not creeping into the hot exhaust the inevitable incomplete combustion = smoke.

Have no idea, even if it actually works, of what would happen in a horizontal cylinder with an exh. port on top.

So have put a gutter in the base of the exhaust of this Yamaha KT100J cylinder Used a Dremel #199 slot cutter, it’s around 3 mm deep * 2 mm wide. Bit shitty, as hard to get to. Still have to put in the actual drain hole, it will need some careful setting up to meet the gutter.



Oh shit, I forgot to put in the transfers….shouldn’t haven’t listened to Fletto…

Further to this, I might also put in a crankcase drain. When we did the Orbital 3 cyl X engine, we did this, and manifolded the drained flow to enter the inlet above the reed valves of the “trailing” cylinder to enhance the pressure differential of the draining function.

Hopefully should have it running in a few weeks…..more to come…..

[F5 Dave]

Jeez Ken, nice post and you’ve got me thinking.

On the basis of your points #2 & 3, I am going to try a drain circuit as in the sketch Essentially it is a gutter across the full width if the bottom of the exhaust port. To assist feeding into the gutter , the liner has been ground away to encourage any oil (or oil/fuel mix) to run into the gutter. From the bottom of the gutter, a small drilling will act as a drain. Perhaps a small valve in the drilling to be able to cut off any drain flow. The net positive exhaust system pressure should act as the propulsion force.




What if it works and there is actually a flow? Well I reckon it’d be logical to just return it into the intake of the carb/throttle body. Keep the stuff active and not creeping into the hot exhaust the inevitable incomplete combustion = smoke.

Have no idea, even if it actually works, of what would happen in a horizontal cylinder with an exh. port on top.

So have put a gutter in the base of the exhaust of this Yamaha KT100J cylinder Used a Dremel #199 slot cutter, it’s around 3 mm deep * 2 mm wide. Bit shitty, as hard to get to. Still have to put in the actual drain hole, it will need some careful setting up to meet the gutter.



Oh shit, I forgot to put in the transfers….shouldn’t haven’t listened to Fletto…

Further to this, I might also put in a crankcase drain. When we did the Orbital 3 cyl X engine, we did this, and manifolded the drained flow to enter the inlet above the reed valves of the “trailing” cylinder to enhance the pressure differential of the draining function.

Hopefully should have it running in a few weeks…..more to come…..

Jezsus. I'd generally thought you were the cleverest person on here, but I have no idea what you are on about.

. . . Actually that doesn't change the original tenent.

[Vannik]

Further to this, I might also put in a crankcase drain. When we did the Orbital 3 cyl X engine, we did this, and manifolded the drained flow to enter the inlet above the reed valves of the “trailing” cylinder to enhance the pressure differential of the draining function.

You do know Suzuki used to do this on their triples in the early 70's?

[WilDun]

Sorry guys,
I'll stick my neck out (and no doubt get my head chopped off!)
Lets get out of the nasty habit of filling a large bulky exhaust chamber with fresh charge - in fact, why not get rid of the bloody chamber! - that's where all the smoke and oily shit comes from - we have to face facts that that is why the two stroke became unpopular in the first place and hasn't got a hope in hell of getting back again without acknowledgement of that fact - it needs a complete redesign.

Why can't we stop using the exhaust as a supercharger when we can do any supercharging from the inlet side? - I acknowledge that this thread is mainly based on improving "normal" two strokes of course - that is fine and a great obsession to have and a lot of fun, but these machines are fast disappearing and soon we will have no "normal" two stroke motorcycles to improve the performance of!

I don't normally contribute here but there have been plenty of weird and wonderful ideas coming from this thread and I'm sure there are plenty of enterprising guys contributing here who could come up with ideas to bring out the huge potential of this engine and so be able to discard all the offending things in the current models which quite frankly have almost made it a dead duck and which we have continually been making excuses for (is it now too late?)!

[Frits Overmars]

Idea is to take the rear wheel out and make a small carrier, chain to the rear axel then a sub chain to a set of bearings connected to the dyno via a universal drive shaft.

Let's KISS that idea:

Why can't we stop using the exhaust as a supercharger when we can do any supercharging from the inlet side?

We can only effectively supercharge a cylinder via the last opening that closes before compression begins. In a four-stroke that is the inlet port, in a conventional two-stroke it is the exhaust port.

[WilDun]

We can only effectively supercharge a cylinder via the last opening that closes before compression begins. In a four-stroke that is the inlet port, in a conventional two-stroke it is the exhaust port.

Yes, you are correct and I do see what you mean, but I never think "conventional two stroke" - I think "next generation two stroke". I believe that it's got to change drastically in order to make a comeback, or even survive! - my knowledge of the finer details is limited of course, but even a dummy like me can see that!