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| Jack_Cheese |
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Jack_Cheese
World Chat Champion
Joined: 14 Jul 2005
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 Posted: 15:17 - 19 Feb 2006  Post subject: |
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| NSR-Rulez wrote: | I think that everythings a bit odd here, as to learn on a bike you are restricted to a certain bhp, or power to weight ratio, so all the fazing out of 2t bikes will end up in more people going out and buying bigger bikes. |
I agree, more people may put in for their test quicker to get bigger bikes, but i reckon less people will get into biking. The attraction of sneakily derestricting a 125 will disappear, as the four strokes are built to meet the restriction.
The price of 2-strokes will probably freeze on the used market, too. Wouldn't be suprised if they start to appreciate after a while either.
| chiz wrote: | I read somewhere else that a 2 stroke car was built recently by some EU people. Basically a 4 stroke bottom end with 2 stroke top end and direct injection. Very clean, very powerful for size. |
Probably an old saab, they first used 2t engines in their old cars, but switched to four stroke. I agree with you on the bike warming front, it's an absolute arse pain trying to warm up a 2t 125.
Jack
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| Kickstart |
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Kickstart
The Oracle
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| Jack_Cheese |
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Jack_Cheese
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| Kickstart |
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Kickstart
The Oracle
Joined: 04 Feb 2002
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Posted: 15:35 - 19 Feb 2006  Post subject: |
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Hi
Cars are just as prone to it as well. In winter the oil temperature gauge in the car will often be barely registering anything after a 27 mile journey to work.
Letting it just sit their idling is just fouling the plug up. Personally I just start them up and ride off immediatly. Rarely needs any choke. Just keep below 5000rpm until it is up to temperature.
All the best
Keith
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| Vin |
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Vin
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Joined: 02 Aug 2005
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| Posted: 21:52 - 19 Feb 2006 Post subject: |
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Why do so many people think 2-strokes need to be left at idle to warm them up.
My TZR goes someting like this.
Switch on, marvel at the buzz from the power valve, full choke, two prods on kickstart (no no not our kickstart  the kick start), engine starts, clouds of smoke,blip throttle a few times, clouds more smoke,take off choke, blip throttle another few times, some more smoke, then ride off keeping the revs down for a few miles. (in a cloud of smoke) Usually on the move within a minute.
The 4 strokes I owned..all be it years ago were much more difficult. |
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| 18aprilia |
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18aprilia
I don't get it?
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| Posted: 23:01 - 19 Feb 2006 Post subject: |
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That has got to be the biggest load of bullshit..... I have ever heard! 2strokes being phased out? go make your self a cup of tea boy!
( 2-strokes will never die out theres to many of them hahahahahahahaha!!!!!!!!!!!!!!!!  ) |
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| phantomtek |
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phantomtek
Lil Joe Tek
Joined: 20 May 2005
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| Posted: 23:03 - 19 Feb 2006 Post subject: |
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You back then you muppet?
Phased out means a cease in production, not destroying the existing ones.
They will generally do that to themselves without proper maintainance. |
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| kal9001 |
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kal9001
Trackday Trickster
Joined: 15 Aug 2005
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| Jack_Cheese |
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Jack_Cheese
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| Posted: 10:26 - 20 Feb 2006 Post subject: |
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The thing is, 2-strokes have to leak air/fuel out of the exhaust. It's what the expansion chamber is there for. Many 2-strokes also have an unusual profile in the top of the piston to regulate air/fuel leakage into the exhaust.
The two stroke simply isn't worth wasting money on. A supercharged 4t 125, such as the one in peugeot's jetforce would be far easier to build, probably more economical, and a fair bit more reliable. The technology is here, and it meets emission regs, so why waste money on a 2-stroke that will eventually become impossible to engineer to meet emission regs anyway?
Jack
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| Nath |
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Nath
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| Jack_Cheese |
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Jack_Cheese
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| critical_technique |
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critical_technique
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| Kickstart |
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Kickstart
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| Nath |
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Nath
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| Jack_Cheese |
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Jack_Cheese
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| Posted: 15:42 - 20 Feb 2006 Post subject: |
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| Nath wrote: | | Jack_Cheese wrote: | The expansion chamber forces it back in, as a compression wave strikes the reducing cone and is reflected back to the exhaust port. If you want power from a 2t, the expansion chamber is the easiest, most reliable way to get it. |
You do not need to lecture me about the workings of two stroke engines, as I am perfectly aware of purpose of the backpressure. But we are talking about a hi-tech supercharged engine here. It doesn't need lost mixture to be forced back in as a) There is no mixture escaping, and b) The mixture is already forced in under a very high compression.
Yes, two strokes are traditionally used for their simplicity, but the only reason why we don't have complex ultra high performance two strokes is because of trends and comformity. The same reason why we still use poppet valves and telescopic fork suspension. |
Sorry, didn't mean to be patronising, but surely the whole thing behind this is cost.
The thing i'm trying to get at most is why bother? Take the cbr125. It succeeded the nsr, which according to most was a far superior bike in every way. But the cbr125 was probably easier to develop, sold for less, and sold a hell of a lot quicker, meaning honda got lots more money.
Manufacturers will eventually have to face that developing a 2-stroke to meet emissions regulation will be less economical than trying to make a 4-stroke as powerful as the 2-stroke.
The 2-stroke will eventually be phased out.
Jack
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| Kickstart |
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Kickstart
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| Posted: 15:57 - 20 Feb 2006 Post subject: |
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| Jack_Cheese wrote: | Sorry, didn't mean to be patronising, but surely the whole thing behind this is cost. |
Very true, and a 2 stroke engine is a hell of a lot cheaper to make than a 4 stroke. Use direct fuel injection and you add to the cost (but then the 4 strokes need fuel injection as well), but you still have a basic engine with 3 moving parts against far more in a 4 stroke. Results in a 2 stroke engine being cheaper, smaller and lighter.
| Jack_Cheese wrote: | The thing i'm trying to get at most is why bother? Take the cbr125. It succeeded the nsr, which according to most was a far superior bike in every way. But the cbr125 was probably easier to develop, sold for less, and sold a hell of a lot quicker, meaning honda got lots more money. |
CBR is a special case as it is targeted at a market where the max power is restricted (almost all the 2 strokes in the class were developed when most European countries allowed learners to ride full power 125s). It would be easy to produce a 2 stroke with the same low level of engineering at an even lower cost. The CBR is designed to the same cheaper standard as things like the original TZR125 (a bike that was 1/3 cheaper than the original AF1).
| Jack_Cheese wrote: | Manufacturers will eventually have to face that developing a 2-stroke to meet emissions regulation will be less economical than trying to make a 4-stroke as powerful as the 2-stroke. |
Something that is not possible. Simply put the chances of getting 25~30hp from a 125 4 stroke for road use is nil in the short term. Aprilia already have their Ditech system in use on their scooters. This could easily go onto the RS125 but would result in a loss of power (doesn't work at high revs yet apparently). However it would still be easily more powerful and cleaner than the CBR.
All the best
Keith
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| Jack_Cheese |
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Jack_Cheese
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| Posted: 16:09 - 20 Feb 2006 Post subject: |
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Surely peugeot can't be that far off 25hp with the jetforce compressor. I've heard of gilera 180 motors pumping out 27bhp at the rear wheel, and that's naturally aspirated. A supercharged 125 can't be so far off.
Jack
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| Kickstart |
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Kickstart
The Oracle
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| Posted: 16:23 - 20 Feb 2006 Post subject: |
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Hi
Think the Jetforce is a claimed 19hp, so a long way short of a full power 125 2 stroke (and bolting an expensive supercharger onto the side of an already more expensive to make engine will increase prices even more). The supercharged version of the Jetforce is also almost 60% more expensive than the normal version.
The Gilera 180 engine might be 27hp (no idea, take your word for it), but with almost a 50% capacity advantage it should manage a comparable figure (scaled down to 125cc that is about 19hp).
Need to also be careful about quoting claimed figures and where they are claimed (crank, back wheel, rider imagination) and real back wheel figures from a dyno (and then watch out for people claiming dodgy inflated figures).
All the best
Keith
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| fuzz |
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fuzz
World Chat Champion
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Posted: 23:46 - 20 Feb 2006  Post subject: |
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| bish777 wrote: | Look at diesel 2 strokes in lorries and trains, they run a low pressure supercharger to blow mixture into a conventional two stroke inlet port, then the exhaust escapes from poppet valves in the top. |
https://static.howstuffworks.com/gif/diesel-two-stroke.gif
Makes sense now with the aid of a diagram 
This is the spec of a 2 stroke diesel engine used on trains:
* Cylinder diameter - 9-1/16 inches
* Piston stroke - 10 inches
* Displacement per cylinder - 654 cubic inches
* Number of cylinders - 16 or 20
* Compression ratio - 14.5:1
* Exhaust valves per cylinder - 4
* Engine weight -
o 16 cylinders: 34,526 pounds / 15,661 kg
o 20 cylinders: 40,144 pounds / 18,209 kg (The oil pan alone weighs over a ton!)
* Idle speed - 315 rotations per minute (rpm)
* Full speed - 900 rpm
* Power - 4300 bhp
 Stick that in your Punto!
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| jok |
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jok
Scooby Slapper
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Old Thread Alert!
The last post was made 18 years, 67 days ago. Instead of replying here, would creating a new thread be more useful? |
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