Topic: Best 1/4 mile times on your bikes?

[old750]

Anybody out there drag? Just wondering who might have the best 1/4 mile times if any at all. I'm guessing most 836 bikes with mild headwork and cam might get in the 12s?

[Irishguy]

According to Cycle Magazine in 1979 a stock 1979 CB650 like mine went 12.993 in the 1/4 mile.  After riding mine for a while...  I have no reason to doubt their numbers.  My turbo Miata will run in the high 13's and my bike seems way faster.

http://www.myhonda650.com/cb650roadtest.htm

I'm just curious what are the fastest magazine published times for the CB750's?  Are they much faster than the SOHC 4 stepchildren  ...   The 1979 CB650's?   

[my78k]

Wow I can't believe Sam hasn't jumped all over this...

Old750...look for a member named samcr750 and look for his post...if memory serves at the last even one of the CR's ran around 12.17 or so. Not sure if Mrieck has run his on the strip but I know his dyno numer was 98.0 BHP at the whell...so yeah some of these bikes still have some haul left in them...unfortunately mine is nowhere near ready for a drag strip (unless it is downhill the whole way and has some way of stopping me gently at the end since my front break needs to be rebuilt).

Dennis

[bwaller]

I don't have anything recent but this is from the summer of 74, first time out. I thought I should have done better but never went back. A new K81 rear was $40 and I crippled home with thread showing. By the way the engine was punched to 810cc with a stock cam, and stock gearing.

[petercb750]

I distinctly remember my stock production racer/every day K2 (apart from K1 pipes) pulling 13.2 back in 73/74. I remember my rear K81 was near bald, and my chain was stuffed. I did a couple of passes flat out on the tank and pulling the gear lever up through the gears with my hand - yes, no clutch and full throttle. Oh that poor bike . (the one in my avatar). I was young and brash, and obviously had no respect for machinery!! But what a testament to their toughness 
It was actually fastest time recorded at that street meet, and I had a little trophy for it. I don't have anything to verify it now, but the memory is very clear. My mate at the same street drag meeting recorded the next best time of 13.7 in his V8 kitted LJ Torana show car (a mid size people's car of the 70s for all you non Aussies).
I have no real clear memory of my terminal speed on that run, but think it was mid 90'smph.
Peter 

[scunny]

14.47 sorry no terminal speed recorded.....500/4 
my glory days were on a suzuki 

[Geeto67]

I did 13.72 and 13.86 on my bone stock cb750 at the new defunct westhampton dragstrip. If you are wondering why the numbers are kind of eh, you have to remember I weighed 275lbs at the time (2002) I ran the bike.

[old750]

Scunny, nice fish. Is that some sort of salmonid / whitefish? Caught on the beach?

[Heironymous Josh]

My bike, a 77 750F, with a curb weight of 545 lbs and an original factory rating of 67 HP (crank or wheel, not sure) would run a theoretical "11.7" quarter mile.  That's based on physical mathematics to include coefficients of friction and wind drag.  What that figure assumes is A - all 67 HP is still there and being put to the wheel.  B - the tire compound is transferring all of that "power output" into real world linear acceleration (at no point does the tire fall short of or exceed the coefficient of friction between it and the pavement) C - Power output remains a constant through the entire power band (which we know isn't the case) D - all shifts are made perfectly.  E - No adjustment for elevation or air density.

So, if we ran our bone stock bikes in a vacuum, they may run a 12 second 1/4 mile but I've yet to get mine on the track!  I've thrown many a car down a straight line to the tune of -12 seconds and +100 mph and I've always used theoretical calculations to rate my "driving performance" at the strip.  To be more accurate, gradients of HP @ differing RPM intervals will give a better look at theoretical 1/4 mile times.  I've always used those theories as a benchmark to tell if I'm driving like s***.  Because of that, I've beaten tons of faster cars in handicapped events.  Like I said, I haven't taken my SOHC to the strip but when the phoenix emerges this spring, I'll post my ticker from Bandimere Speedway (where the men are divided from the boys at 6000 ft above sea level).

[old750]

If you're only using peak HP at 9000 rpm how do you figure out your theoretical time?

[Sam Green Racing]

Wow I can't believe Sam hasn't jumped all over this...

Old750...look for a member named samcr750 and look for his post...if memory serves at the last even one of the CR's ran around 12.17 or so. Not sure if Mrieck has run his on the strip but I know his dyno numer was 98.0 BHP at the whell...so yeah some of these bikes still have some haul left in them...unfortunately mine is nowhere near ready for a drag strip (unless it is downhill the whole way and has some way of stopping me gently at the end since my front break needs to be rebuilt).

Dennis

    78k  I only have internet access at work

OK, old stock motor, bike 100lbs lighter than stock, rider 285lbs, slight wind asisted 13.3 around 98mph, no wind mid to high 13s around 93mph.

New motor, 12.17 and 117mph, running rich.

Chris loses 35lbs bike has mixture corrected ran 12.3 and 110mph smoking the rear tyre to the 60 foot lights.

I'm  sure it has an 11 in there somewhere

Dragman836 Dennis has had his in the 11s but the bike is set up for drag racing with slick and bars.

Sam.

[Heironymous Josh]

If you're only using peak HP at 9000 rpm how do you figure out your theoretical time?

distance, in this case 1/4 mile, is equal to 1/2 acceleration (which is a factor derived from power to weight ratio) times time squared.  Here's a good site if you want to play with some numbers.  Also, you can find various coefficients of friction and drag all of the web if you want to get really technical.

http://www.ajdesigner.com/phphorsepower/horsepower_equation_power_to_weight_ratio.php

[RRRToolSolutions]

Just for you Bob -

[Bob Wessner]

Ilbikes,

Is this some sort of new eye test?

[RRRToolSolutions]

Bob, save it to your computer and then zoom in. It's the only scan I have of it and I'm too lazy to dig out the 1970's magazine article it came from...

Gordon

[Bob Wessner]

Thanks, I'll cancel my eye appointment.

[petercb750]

If you're only using peak HP at 9000 rpm how do you figure out your theoretical time?

distance, in this case 1/4 mile, is equal to 1/2 acceleration (which is a factor derived from power to weight ratio) times time squared.  Here's a good site if you want to play with some numbers.  Also, you can find various coefficients of friction and drag all of the web if you want to get really technical.

http://www.ajdesigner.com/phphorsepower/horsepower_equation_power_to_weight_ratio.php

And why wouldn't you take gearing into account............

[bwaller]

And getting a good start, etc.etc. Through the calculator away and go make a few runs!!

[Sully_PA]

Ilbikes,

Is this some sort of new eye test?

LOL 

[Heironymous Josh]

If you're only using peak HP at 9000 rpm how do you figure out your theoretical time?

distance, in this case 1/4 mile, is equal to 1/2 acceleration (which is a factor derived from power to weight ratio) times time squared.  Here's a good site if you want to play with some numbers.  Also, you can find various coefficients of friction and drag all of the web if you want to get really technical.

http://www.ajdesigner.com/phphorsepower/horsepower_equation_power_to_weight_ratio.php

And why wouldn't you take gearing into account............

You absolutely would, I've never had the ability to tweak my gearing.  I'm a total amateur, but being mathematically inclined, I like to formulate theoretical yard sticks. 

[Heironymous Josh]

And getting a good start, etc.etc. Through the calculator away and go make a few runs!!

Personal bests are always good yard sticks!

[okie]

In theory, Suzanne was a millionaire movie star.  In reality, she was a hooker on 'K' street in DC.  Go out and ride your bike and then come back and tell me about real performance.  As for me and my bike, today, we are going to a non-theoretical, vintage bike show.  Now understand, this is only a theory, because I haven't actually tested it, but I believe my 350F will do the 1/4 mile in about 16.5 seconds (4 seconds slower than my VF500F but 2 seconds faster than my wife's mini-van).

[ekim98]

Wow I can't believe Sam hasn't jumped all over this...
Dennis

Sam lives in the real world and knows how it really is.

[Sam Green Racing]

Thanks ekim, you're so kind

There is a place for maths in drag racing but like has been said, there is no substitue for hands on experience.

I am 124lbs lighter than Chris but he has posted the faster times on the bike.

I know why I am slower, perhaps the maths can let everyone else into my secret.

Sam.

[paxtonpony]

The big problem with 1/4 mile calculators and bikes is the drag coeficient.  On a car it's a fixed varible that you can look up and plug in.  On a bike, you might get a general idea of your drag but it also depends on your body type and positioning (which can change on any given pass).  I really wish I had a drag strip close to me, I've never raced a bike but I did spend 8 years bracket racing my stang.  I would think there's alot more varibles to getting a bike down the track consistently.  My hat's definitely off to the pro riders out there.