Comments on: 2004 Maico 500 Long Term Test Report – Part 2

By: 2STROKEREVOLUTION

2STROKEREVOLUTION — Sun, 10 Jan 2010 19:27:00 +0000

I am with Sachsgs250 on this topic. Every bit of knowledge you can have about carb tuning will not replace DI.
With a carb you can tune the bike for high rpm/high power, or less peak power and a wide powerband. DI will give you both.
On top of the power issue DI cleans up emissions and improves fuel economy, all to above 4-Stroke standards.

And Sachsgs250, you have an interesting idea, that expansion chambers won’t be needed with DI. I can understand that because the fuel is injected after the port is closed. BUT what about escaping oxygen? It could still be beneficial to ram the leaked air back in.

By: KX500Pilot

KX500Pilot — Sat, 02 Jan 2010 02:20:34 +0000

What is the weight difference between an aluminum frame and a steel frame? On any bike where it is easy to compare (you choose the bike). I am not in favor of 4-strokes or aluminum frames. Also, I like things that are designed to be worked on. Not thrown away.

By: JohnNicholas

JohnNicholas — Sat, 19 Dec 2009 03:30:57 +0000

An interview with Donnie Emler would be great! I can ask if he’d be willing…

That John guy is the webmaster for this site

Orbital owns the patents for the direct injection two-stroke. The licensing fee is very high (from what I’ve been told). Many of the manufacturers have prototypes of direct injection bikes in the testing stages. Although it is anyone’s guess when or if they will be released to the general public.

As for a small company like Maico doing the amount of R&D needed for something like this, I would look to them any time soon. Although it is very possible with some of the other European manufacturers.

From the rumblings I’ve heard, KTM is the closest to having a production direct injection machine ready. They’ve been testing them for a while now…

By: Sachsgs250

Sachsgs250 — Sat, 19 Dec 2009 01:45:07 +0000

Something I’d like to mention is that variations of the technologies we are discussing are all ready starting to filter down to industry.Evinrude has emissions friendly two strokes that use less fuel then comparable four stroke outboards.Rotax has new generation two stroke sled motors coming on line.Orbital in Australia is developing direct injection “retrofit” kits for the millions of two stroke mopeds in Asia.When two stroke motorcycles will recieve this technology is anyone’s guess.The big five have been so successful at converting everyone to fourstrokes that they will probaly resist these technologies.Maybe Koestler and Maico International can find the resources to do it.It wouldn’t be the first time Maico shook things up.By the way,who is John?

By: Mad Scientist

Mad Scientist — Sat, 19 Dec 2009 00:17:34 +0000

Sachs, I understand the inherent problems with reversion etc. If the pipe is designed correctly (and I am nowhere smart enough to understand all the functions that go on with a 2T pipe) it should also incorporate a reverse pulse to “close” off th exhaust port before the pistion actually gets there. Again, as you mention, this will occur in a very narrow RPM range. Maybe one of us needs to contact Donny Emler at FMF for a clarification on this. Gordon Jennings has a book covering this as well. If you can eliminate the expansion chamber, you make it possible for multiple cylinder 2T’s to make competitive HP, just because room for the expansion chamber is not required!!

John, what do you think about an interview with DE at FMF if he is willing??

By: Sachsgs250

Sachsgs250 — Fri, 18 Dec 2009 23:42:54 +0000

Regarding DI-the problem with two strokes is that to complete the intake,compression,combustion and exhaust cycles in one revolution of the motor the intake charge is used to push the residual exhaust out the exhaust port.The purpose of the expansion chamber is,at the right time,to present a reverse shock wave to prevent too much of the intake charge from flying out the exhaust port as well.The more highly tuned the two stroke the narrower the window to do this,hence pipey 125′s.As well this partial loss of the intake charge greatly increases emissions – which is why certain entities are trying to ban two strokes (and ram four strokes down our throats).Direct injection involves injecting the fuel air charge after the intake port (and reeds) are shut – greatly reducing emissions.This would also negate the need (a friend mentioned this and I agree) for an expansion chamber.I believe I’m signed up but I’ll check my password – something is screwing up.

By: Mad Scientist

Mad Scientist — Fri, 18 Dec 2009 20:34:17 +0000

sachsgs250, Do you have some other sites or info regarding DI? Your comments about DI engines no needing expansion chambers to produce the same or more HP. I have looked at some sites but don’t remember reading that.
BTW, are you signed up to post on the forum? You need a seperate login for that.

M.S.

By: bleake637

bleake637 — Fri, 18 Dec 2009 20:22:12 +0000

I believe you are correct on that and I totally agree, direct injected two strokes are going to destroy four strokes, probably even of double displacement. It’s going to be great to see how the AMA tries to limit two strokes next, no direct injection? 1/4 displacement? go back to dual shocks? hahaha

By: Sachsgs250

Sachsgs250 — Fri, 18 Dec 2009 17:31:45 +0000

I may be wrong about direct injection but let me elaborate:if I’m not mistaken direct injection will eliminate a shnurle looped two strokes need for an expansion chamber to optimize cylinder charging.It will “fill in the gaps” and broaden the torque curve.I’m certain we will see 125s (and 150′s) that will blow past the 250F’s in power output.So much for the AMA’s “two for one” rule.I see the start of this in the new Ossa trials – incredibaly light,powerful,silent and efficient two strokers are just around the corner.

By: 2STROKEREVOLUTION

2STROKEREVOLUTION — Thu, 17 Dec 2009 23:19:12 +0000

Twostrokemotocross,
You know what would be a great story for you to publish? One dedicated to dyno charts. Put on comparison charts with different bikes on the same chart to compare 2-stroke power to 4-stroke power.

For example make a CR500/KX500 vs 380sx vs 450F dyno, a 300xc vs CRF450X vs 525xc dyno, a yz250/250sx vs 250F dyno, a 250xc vs 250xc-f dyno, CR500/KX500 vs XR650 and any others. Those would be great for comparison to prove that 2-strokes not only make much more power but make as much lower end power. Especially cc vs cc.
You could also show weight and hp/lb.

In the meantime here is a video of my new KTM 380SX! It’s my first ride and first video so not great yet.
http://www.youtube.com/watch?v=t21qlxQs0_o