Reply With QuoteOriginally Posted by leezor
Bugger, if only I was told this before I bought the Suzuki!!
I tell my wife that the forecast is not looking great and she pulls the pin. Now i just gotta remember to close this window when i get off the computer.
Yeah I agrea. The Vagabond would be a floundering pig with 2 x 70hp..
Depending if the max HP and/or weight changes, it would certainly add some weight to the 2st side off the debate...
Bugger, if only I was told this before I bought the Suzuki!!
I tell my wife that the forecast is not looking great and she pulls the pin. Now i just gotta remember to close this window when i get off the computer.
I suggest that 4 strokes are a pasing fad - suggest the fad will pass within the next 50 yrs - they have greater technolgy prospects in the future
Clee.... Care to expand a bit more re: Future technogly aspects for the 4st...
Remember all fuel injection systems and forced induction systems that work on 4st will also work on 2st, and often with better results..... Also for a 4st to make the same amount off power as a 2st it needs to be near double the size in cubic capasity....
Take Motorbikes for example. In all classes from local MotoX to international GP.. When 4st was introduced into MotoX the 450 4st ran with the 250 2st.. And the 250 4st was ran with the 125 2st...
In GP remember when the switch was made to go 4st... the engine size went from 500cc to a 1000cc, I think some were even 1100cc....... I think now they are down to a 800-900cc pending on cylinder configuration... Still that is 300-400cc more then the 500 2st...
These 4st motorbikes have had great success due to the way they lay the power out, very controlabe. Unlike the 2st which was very aggressive and broke into wheel spin very easerly... But how would the 500GP 2st compare if it was built with the latest DI tech which has a superior power delivery compared to the old carby... We will never know, but I dare say it would run rings around the 4st GP...
Last edited by Jabba_; 09-03-2008 at 07:55 PM.
Jabba_, don't you think they would ahve direct injected the 2 strokes if this was going to be such a good idea? i bety they tried it!
No mate they did not try, it was discussed, but no prototype was made and at the time the tech was not as good as we have it today.....
The pressure was on GP to go 4st, and there was a lot off resistance from the teams. But the laws or rules and homologations were passed because off a political agenda as it was difficult to satisfy all the uneducated politicians around the world and the GP would off lost a lot off circuits......
And with the Millions upon millions off dollars that has been spend on R&D on the GP 4st motor. It will be a cold day in hell before any team would want to dump the 4st to go back to the drawing board with the 2st....
Last edited by Jabba_; 09-03-2008 at 08:23 PM.
Can any of you 2 stroke guru's tell me how a modern 2 stroke can detect a lean burn condition exists???
Garry
Retired Honda Master Tech
I dont quiet follow your question. Are you asking how the 2st CPU detects if the motor is running dangerously lean...
Almost the same as a 4st dectect it.... Exhaust sensor + RPM+ load= optimium AF ratio.... If however the scales of either, Exhaust, RPM, load and AF ratio dont match in an ideal situation, I would presume the CPU would automaticly switch into safe mode to prevent a lean burn situation.......
But if you get a bad batch off fuel, I dare say your screwed...... But with the 4st you not so far away from that either, particulary with the Verardo.... As manufactures are squeazing more an more out of there motors, the tolorance for CPU error and bad fuel get slimmer....
garry what is your main concern here and can you give an example of this problem?
Last edited by disorderly; 09-03-2008 at 08:43 PM.
Jabba, Honda did experiment with a fuel injected NSR500
"The new bike also ran fuel injection that the Aussie (Mick Doohan) refused to use, so Itoh was given the chance of developing the system. At Hockenheim his NSR became the first GP bike to clock 200mph but the PGM-FI never worked better than conventional carbs and was quietly dropped a year later"
not DI, but with the open chequebook HRC had, if they thought it would have worked, they would have done it
So Jabba, an exhaust sensor hey... yes 4 strokes use this exclusively! but what 2 strokes are using this??.. Can you confirm any???
Garry
Retired Honda Master Tech
If you have an injector issue in a 4 stroke you loose power.. if you have an injector issue in a 2 stroke.. you could get a lean burn condition.. what does the modern 2 stoke have to combat this issue?? Ficht struggled in this area. I know BRP has changed the injector but I cant see it being imune to dirt.
Garry
Retired Honda Master Tech
FYI Scott, a lean condition being the fastest way to destroy a 2 stroke!
Garry
Retired Honda Master Tech
being a mechinic (I assume this from the threads I've read) I'm sure you are aware of the possibility for damage from running a 4 stroke lean! The only difference is that a 2 stroke give you a warning by surging when its getting dangerously lean.
Hamish, most modern 4 strokes have several sensors to combat a lean condition ie Knock sensor, O2 Sensor, Core temp sensors and a 4 stroke is most likely to suffer a loss of power due to a lean condition well before the 2 stroke.
Just been doing some research and I can only find info on Exhaust "pressure sensors" on the Etec, these are used to control the exhaust pressure for smooth idle.
Cant find anything on exhaust sensors !
Garry
Retired Honda Master Tech
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