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View Full Version : Duc back to trying the twin pulse



merv
16th June 2004, 11:54
Read it here http://www.superbikeplanet.com/2004/Jun/040615a.htm

They rejected the big bang twin pulse engine last year and went very well, now they must have refined it to try it again.

riffer
16th June 2004, 12:03
While they are at it, can they refine their suspension so Troy Bayliss stops falling off.

He's going to hurt himself one day, that boy... :sly:

vifferman
16th June 2004, 12:10
Isn't this basically the same road that Honda went down with the RC45?

merv
16th June 2004, 13:07
Isn't this basically the same road that Honda went down with the RC45?

Honda always try all kinds of things. VFR's like mine have a 180 deg crank, the stock RC30s and I think RC45s had 360 deg cranks. Back around 1994-1995 I spoke to Aaron Slight at Sawyers and asked him about big bang RC45s because big bang was all the rage on the V4 2-strokes at the time. He said they had been testing them - I guess they have some funny angle crank to get the cylinders all firing close together and/or change the cams and ignition timing. Info from Aaron seemed to be it hadn't worked for them at that time.

They changed heaps on the RC45 before they retired it and certainly John Kocinski easily won the WSB championship on one if no one else could. What form the engine took then I don't know but there were rumours of all sorts of radical shit to make them fly. They had awesome top end anyway were the rumours - Slight had said he had more horsepower than the 500s at the time. I heard they had servo controlled intake stacks that would vary the length of the intake to the throttle body and stuff like that to alter the torque characteristics. The real issue with the RC45 seemed to be handling and while they had more power than anything else few could get them around corners. Kocinski I know was horrified he couldn't alter the steering head - bloody production based formula. It seemed that Honda just blew it with the frame of the RC45 compared to the RC30 and they never seemed to overcome that problem. Don't know why they didn't homolgate a new frame. They did try single and double sided swingarms.

Racing is a tricky business getting it all to gel and Duc have certainly come up against it this year compared to last.

Initially I think Duc wanted the twin pulse four to sound like the L-twin as that was their trademark. Now they seem to be having another go in desperation because the pack, especially Yamaha have made great strides on them performance wise.

When Mick Doohan was carrying on with big bang etc on the NSR it was because he was already the champ and he did things to stay ahead. Many would say a lot of it was psychological, especially when he went back to what he then called the screamer engine when others were really just getting to grips with big bang.

vifferman
16th June 2004, 13:16
Didja know you can change your VFR to 360 degree just by reversing the cams? A guy on the US VFR list did it - called it "the Twin Twingle".
I never felt any need to do it on my VFR - I liked it how it was.
I miss my VFR.... :crybaby:

merv
16th June 2004, 13:32
Didja know you can change your VFR to 360 degree just by reversing the cams? A guy on the US VFR list did it - called it "the Twin Twingle".
I never felt any need to do it on my VFR - I liked it how it was.
I miss my VFR.... :crybaby:

Guess you'd have to do something about the ignition too or did he just swap plug leads around or something? It still wouldn't have a 360 crank though.

Like you I like the feel of mine now - power at any revs and not too vibey and easy on fuel. Basically the 180 crank suits road bike use.

pete376403
16th June 2004, 13:50
Many would say a lot of it was psychological, especially when he went back to what he then called the screamer engine when others were really just getting to grips with big bang.
Could it also be that tyre technology had advanced sufficiently in the interim to allow the use of the "screamer". My understanding of the rationale behind the big bang was to allow the tyre a chance to grip in between power pulses, which never happened with the conventional engine. that and the fact that Doohan was God of the 500s, and could do things no mortal could attempt and live. Good article about HRC engines here:http://www.amasuperbike.com/NSR500.htm

quote: "HRC built several different motors in their search for that user-friendly power delivery. Finally, they settled on the Big Bang, that fired all four cylinders within 70 degrees, giving the rear tire time to regain traction between each salvo."