Shifting at peak torque?

[Ratman]

If you were to do a hypothetical dyno drag against a pro stock Harley, at what RPM would you likely shift at? I wouldn’t know I have never or would ever do such a thing.

But if you were to do such a thing, how would you start off the line. Dump the clutch at say 4 grand? Or would take it a little easy off the line and then giver all she got when things start happening. No one would want to hurt the bike if they were doing it. Every one would like to ride home after..

 

[ionbeam]

How you leave the line varies from person to person and makes a big difference in clutch heat and clutch life. I'm somewhat hard on the clutch – and I don't know exactly what RPM I leave the light because I do it by feel and put all my attention on the light. If you are looking at the tach you will blow your reaction times. I do run up the RPMs to around 4-5k RPM and feed as much clutch as quickly as I can. I balance wheel spin vs wheelie as much as possible. I usually slightly carry the front wheel giving me the best weight transfer to the rear wheel. When Feejer's suspension is set up and tire pressure is set correctly you should hook up good enough that wheel spin won't be an issue because it will lift the front wheel first. I typically have no worse than a 1.7x 60 foot times and can sometimes get into 1.6x 60 foot times depending on track condition. Traction compound rocks! New England Dragway treats the stuff like gold and rarely uses it where as Lebanon Valley Dragway (near Albany, NY) slathers the stuff on. Both my car and my FJR always have significantly better times at LVD.

Time slips show that the best RPM to shift at is between 8.5k and not more than 9k. On a cold night I may run close to 9k RPM and on a hot night I may shift closer to 8.5k. I have a real problem with the 1-2 shift because I can't get my foot on the shifter fast enough after a good launch so 1-2 shift RPMs are usually a bit too high. I have ticked the rev limiter a couple of times being late on the 1-2 shift. Being fat, old (and ugly) is catching up with me on the 1-2 shift.

[Edited to add: Guess I'm a candidate for an AE, eh?]

What's with the pro stock Harley? That puppy is a dedicated racing machine and can run 7.00 quarters. NHRA rules allow it to have more weight and gives it other consessions to make it competitive with the Ricers. In bracket racing they would spot your FJR ~4.1 seconds at the lights.

 

[Ratman]

Thanks for the info. This would be a Dyno drag, every thing is straped in place. Am to fat and feel to old to do anything like what your doing.

This would be a gentlemen’s drag just to see what happens, there's no nitrous being used on his part.

 

[Randy]

Is it a rolling start or dead start? Are you spinning a drum just like a regular dyno run? I can't see how they could make that emulate a real-world start. I personally wouldn't beat the **** out of my bike to do a dyno drag against a purpose-built straightliner.

Our local track has a banked turn-around at the end of the 1/8 mile. The straight liners tiptoe around the turn. Scares the **** out of them when you stuff it inside of them on the gas.

 

[ionbeam]

If this is a true Pro Stock HD, you will need ~250 normally aspirated HP from unadulterated gasoline to be competitive.

 

[Ratman]

What? ~250 What!

This is a Dyno drag, they strap two bikes down and for $20.00 you get three runs. I am NOT going to beat on my bike. I have way to much fun riding a normal pace with normal people. This is just for fun at an A.B.A.T.E. rally.

When the HD riders get together at the tavern it would give them some thing to talk about. We have fun with it then go for a ride. I can carry all the part that fall off there bikes and still catch up with little or effort.

 

[ionbeam]

What? ~250 What!

Err, that would be horsepower. "...~250 normally aspirated HP ...."

 

[vmaxed]

How you leave the line varies from person to person and makes a big difference in clutch heat and clutch life. I'm somewhat hard on the clutch – and I don't know exactly what RPM I leave the light because I do it by feel and put all my attention on the light. If you are looking at the tach you will blow your reaction times. I do run up the RPMs to around 4-5k RPM and feed as much clutch as quickly as I can. I balance wheel spin vs wheelie as much as possible. I usually slightly carry the front wheel giving me the best weight transfer to the rear wheel. When Feejer's suspension is set up and tire pressure is set correctly you should hook up good enough that wheel spin won't be an issue because it will lift the front wheel first. I typically have no worse than a 1.7x 60 foot times and can sometimes get into 1.6x 60 foot times depending on track condition. Traction compound rocks! New England Dragway treats the stuff like gold and rarely uses it where as Lebanon Valley Dragway (near Albany, NY) slathers the stuff on. Both my car and my FJR always have significantly better times at LVD.
Time slips show that the best RPM to shift at is between 8.5k and not more than 9k. On a cold night I may run close to 9k RPM and on a hot night I may shift closer to 8.5k. I have a real problem with the 1-2 shift because I can't get my foot on the shifter fast enough after a good launch so 1-2 shift RPMs are usually a bit too high. I have ticked the rev limiter a couple of times being late on the 1-2 shift. Being fat, old (and ugly) is catching up with me on the 1-2 shift.

[Edited to add: Guess I'm a candidate for an AE, eh?]

What's with the pro stock Harley? That puppy is a dedicated racing machine and can run 7.00 quarters. NHRA rules allow it to have more weight and gives it other consessions to make it competitive with the Ricers. In bracket racing they would spot your FJR ~4.1 seconds at the lights.

ionbeam...what times do you run at the Valley with your FJR?Last time I ran there I was on my Vmax.Do they still have Saturday test days?

Ed...

 

[ionbeam]

11.0 @ 123 with a 1.7 60 foot. Saturdays are still test 'n tune days. My car club goes to LVD a couple of times a year. Drag racing is a hoot, bet you can't make just one run. LVD is in the foot hills of the Adirondacks and it is beautiful in October, plus the cooler air makes better power. The only advantage to New England Dragway is that the track is at 60 feet; LVD is at ~950 feet.

 

[vmaxed]

Same times I ran at Lebanon Valley with my Vmax in 1992,bike needed a bar.

 

[ionbeam]

Whoa vmaxed! If that was the last time you were at LVD you wouldn't recognize the place today.

This year NHRA changed a few motorcycle rules that make it harder for the general population to just ride in and have fun. Clothing must be leather or Kevlar; if Kevlar it must have a tag SEWN into the item proving what it is. Also, modified this year, any bike running 11.00 or quicker or 120mph or faster has to have a kill laynard. But for these new rules I would have offered to put together a race day at LVD for FJRs. Ironically and pitifully, if you ride in with ass-less chaps and ultra thin dress leather they will let you run, but if you show up with a quality riding suit complete with armor and it doesn't say Kevlar they won't let you run. I now have a pair of Draggin' jeans for the Kevlar label that I wear under my armored riding suit. I'm waiting for my Draggin' Jeans Kevlar shirt to arrive. The laynard is ~$20 - $30 and taps into the red run switch on the right bar.

 

[Ratman]

What? ~250 What!

Err, that would be horsepower. "...~250 normally aspirated HP ...."

Hay I-pod,

I do appreciate the input on shifting, but (Err) is that like some thing you would say to a blond? To me the tilde is used a ASKI code or in digital electronics as a NOT.

You motor heads love to talk.

Than you bring up Helmholtz resonance thing, I though that the only thing you would have aspirated is your lungs from breathing in exhaust fumes??

Again I do appreciate the input, but ERR, I can now say I have been Err’ed by a pre-teen and on the net..

Thanks humbly the Rat.