2T. Not dead yet by a long chalk.

[TooFastTim]

Posted this over at Trials central where the topic is trials bikes revving their nuts off. http://www.motorcycle.com/manufacturer/honda/quick-take-honda-exp2-15170.html.

"Honda has tamed pre-ignition; on the EXP-2 this auto-ignition is computer controlled to enhance performance and most importantly virtually eliminate pollution. Usually thought of as a bastion of four-stroke technology, Honda's new two-stroke design promises less pollution, better fuel economy and most important, no loss in power.

Pre-ignition will destroy a normal two stroke. It is caused when the temperature and pressure in a cylinder builds to a critical point and the air/fuel mixture ignites prematurely in a violent explosion rather than in a controlled burn.

The premature explosions are ignited either by red-hot engine parts or highly ionized reactive molecules left from the last exhaust cycle. Using premature combustion to more thoroughly burn the mixture is not a new idea -- diesels don't have spark plugs either. But it's the first time that auto-ignition has been successfully applied to a gasoline two-stroke. Above idle, and below 40 percent throttle, the spark plug is not used. The exhaust power valve automatically regulates combustion pressure, guaranteeing that pre-ignition will start and end at the correct time. Once the critical pressure is reached, the reactive molecules act like millions of tiny spark plugs, firing the mixture much more evenly than any single plug could."

[chrisdespo]

funny thing compression ignition. not trying to hijack your thread but you have reminded me of a thing tha a friend of mine once told me to do , he was an old bloke very smart, he was an auto elec and used to work on magnetos in the air force. whe i was doing some port work and hot ups on the then new TM 125 k i think he assked why we only ran 1 spark plug. we tried with two plugs with a two wire coil off i cant remember or if we used 2 one lead coils it seemed to make for a better burn as the bike ran a lot cleaner he did explain the reason but it was a while ago.

[Marc.com]

Posted this over at Trials central where the topic is trials bikes revving their nuts off. http://www.motorcycle.com/manufacturer/honda/quick-take-honda-exp2-15170.html.

"Honda has tamed pre-ignition; on the EXP-2 this auto-ignition is computer controlled to enhance performance and most importantly virtually eliminate pollution. Once the critical pressure is reached, the reactive molecules act like millions of tiny spark plugs, firing the mixture much more evenly than any single plug could."

Is Honda reviving one of its 20 year old ideas .... I seem to remember previous attempts to harness free radicals.

[TooFastTim]

Is Honda reviving one of its 20 year old ideas .... I seem to remember previous attempts to harness free radicals.

Oh this is quite old. Honda entered the EXP-2 in the Dakar (with Jean Brucy riding) in the early '90's.

[tony27]

Don't think Honda will ever revive the EXP-2 concept as that would involve them going against their 4strokes only philosophy.
Am I correct in saying they built that bike before getting the capacity rules changed in bike racing to favour 4 strokes?

[huskibul]

    Maybe they will realized the error of there ways and do a backflip ! (which by the way 2t's do better) with a little help from the GFC and average dirtbike riders the world over starting to wakeup to the BS theyd been fed !

[TooFastTim]

Am I correct in saying they built that bike before getting the capacity rules changed in bike racing to favour 4 strokes?

yes

[Lozza]

funny thing compression ignition. not trying to hijack your thread but you have reminded me of a thing tha a friend of mine once told me to do , he was an old bloke very smart, he was an auto elec and used to work on magnetos in the air force. whe i was doing some port work and hot ups on the then new TM 125 k i think he assked why we only ran 1 spark plug. we tried with two plugs with a two wire coil off i cant remember or if we used 2 one lead coils it seemed to make for a better burn as the bike ran a lot cleaner he did explain the reason but it was a while ago.

That would have been from the shit cylinder head design. running 2 plugs will have the voltage to each plug.

The CRM 250 AR uses controlled detonation but it is just on constant throttle trailing  or WOT it is not used.

[montynut]

running 2 plugs will have the voltage to each plug.

Lozza I think you mean half the energy to each spark plug measured in joules not the voltage. If you used a double wound secondary coil or two single plug coils then the energy would stay the same along with the voltage but the primary current would go up. The voltage is related the the collapsing magnetic field not the number of spark plugs where as the energy produced would be shared between the number of plugs. Well that would be my take on the operation of any coil. Assuming a positively good negative earth that is

[Oldbiker]

TFT..why would they be revving their nuts off? I have ridden trials for over 26 years and only ever revved it to get up some huge steps, it's not constant. MAybe the A+ and Experts do rev the engines to clear it before some obstacles.
Interesting..

[Captain Bilko]

If you used a double wound secondary coil or two single plug coils then the energy would stay the same along with the voltage but the primary current would go up. The voltage is related the the collapsing magnetic field not the number of spark plugs where as the energy produced would be shared between the number of plugs.

Greg stuck a fork in a power point when he was a wee boy. Marvel Comics could've dedicated an entire Superhero life about him.

Electronut

[tony27]

TFT..why would they be revving their nuts off? I have ridden trials for over 26 years and only ever revved it to get up some huge steps, it's not constant. MAybe the A+ and Experts do rev the engines to clear it before some obstacles.
Interesting..

The thread was about bikes that have come down on the throttle side & jammed open, normally the killswitch then has no effect

[Marc.com]

I think the internal combustion engine is pretty much finished as far as trials is concerned. It is an all electric future and trials is perfectly suited to it.

[TooFastTim]

I think the internal combustion engine is pretty much finished as far as trials is concerned. It is an all electric future and trials is perfectly suited to it.

Not quite there yet Marc. There was an argument over at TC where somebody compared a 2T motor with a battery powered equivalent. I forget the details but 'leccy motors have approx 1/10th the energy of 2T motors (so it would KW/h vs joules). Weight is also a factor.

A few guys have dropped electrical motors into trials bikes and the results have been encouraging.