Author Topic: Best way to launch a cb750? (Read 5327 times)

killersoundz · « **on:** August 31, 2012, 12:21:39 AM »

I'm going to a vintage motorcycle drag racing weekend next month. Mostly just for fun drag racing old slow bikes. I'm probably going to enter on my cb750k4 just for fun, it's $15 why not. I've got my ultra quick power shifting down but not so great at launching yet. Anyone have any tips to get off the line fast as possible? I've tried revving up and releasing the clutch a few times but most of the time it doesn't work out to good. Need to do something a little differently?

shinyribs · « **Reply #1 on:** August 31, 2012, 01:02:50 AM »

Practice brother,it just takes practice. Sadly,all that practice will usually wreck your clutch

Go have fun with it and dont worry if you don't look like an old pro while your out there. It's all about the fun.

dave500 · « **Reply #2 on:** August 31, 2012, 02:13:00 AM »

gear it down for a start,your near peak revs in top gear should be about when you cross the line.

Terry in Australia · « **Reply #3 on:** August 31, 2012, 02:21:22 AM »

Just do some massive burnouts mate, it won't be long before your clutch starts to slip real bad, and that way you won't need to gear it down, just wang it up to 9 or 10,000 RPM and let it rip!

dhall57 · « **Reply #4 on:** August 31, 2012, 03:40:32 AM »

I would love to go to that event and see all the old bikes killer, but me personally I wouldn't abuse my 40 year bike like that. Worse than that taken a chance of crashing and hurting yourself. Enjoy all the classic bikes, but keep your bike off the strip. But each to his own killer

If you do go down the track good luck and be safe and let us know how the old CB does and take plenty of pics of all the bikes

dave500 · « **Reply #5 on:** August 31, 2012, 03:56:34 AM »

its a straight line what could go wrong??insert dumbarse smiley face here?yeah ill bet the sounds will be as good as the sights.

Xnavylfr · « **Reply #6 on:** August 31, 2012, 04:12:40 AM »

Slide as far forward almost on the tank,STAND to start. Slip the clutch some just to get off the line then completely release and hammer down. If you get a wheel spin the bikes backend will want to pull to the left (CHAIN SIDE) just power on and steer into it and it will straighten out. Have Fun
I used to drag a KZ1000 (bored to 1100) It didn't take long for me to get down the 1/4,, average 110mph .

Xnavylfr(CHUCK)

dhall57 · « **Reply #7 on:** August 31, 2012, 04:36:51 AM »

I guess I'm thinking like a old fart (55). Hang on and let it scream killer!!

CrankyOldGuy · « **Reply #8 on:** August 31, 2012, 05:00:08 AM »

Quote from: dave500 on August 31, 2012, 03:56:34 AM

its a straight line what could go wrong??insert dumbarse smiley face here?yeah ill bet the sounds will be as good as the sights.

Dave,

That reminds me of my old Boss. One of his favourite sayings in a difficult situation was "Give your head a shake. What's the worst that can happen?"

Harry O.

cgswss · « **Reply #9 on:** August 31, 2012, 06:39:50 AM »

Back in the day, I went down 2 teeth on my counter shaft . had better valve springs and slightly advanced timing. I would put the bike in 2nd, stand over the back of the tank, take the bike up to 7500. when the last light went out, I'd drop the clutch, twist my wrist, and sit down. BTW I always had a kill button and used that to shift.

754 · « **Reply #10 on:** August 31, 2012, 10:51:38 AM »

Lower gearing, big sticky tire, best clutch you can get, and start learning to ...............sssssslllllliiiiipppppppppp..it..
Hundreds of practice runs.. makes a huge difference

solo 2 · « **Reply #11 on:** August 31, 2012, 11:29:45 AM »

JATO rockets

MCRider · « **Reply #12 on:** August 31, 2012, 11:39:42 AM »

I had a brief experience with drag racing. As a fearless youngster. I often wonder about now.

From a dead stop, takes guts to do it right. Rev it to about 5500-6000rpm. Light turns green, dump the clutch with more throttle. Get some tire spin. Once its spinning you can let off a TAD, to get more traction. Let off too much you hook up and pull a giant wheelie.

I preferred to use bald narrow tires. Easier to control wheelspin. Probably limited ET, but i was a rookie and never progressed. 12.76 on a 900cc CB750 was my best. Pitiful I know. Tucson was 1.5 sec slower than West coast due to altitude.

Oh yeah, skootch forward, grab the seat with your thighs. Once launch is underway, feet on pegs and scoot back a little to control traction.

I had a good teacher and never crashed. But I could have and it can get nasty.

MCRider · « **Reply #13 on:** August 31, 2012, 11:40:36 AM »

Safer way for pure rookie in a race that doesn't mean anything...just slip the clutch.

77hotrodhonda · « **Reply #14 on:** August 31, 2012, 12:44:52 PM »

Once your staged, hold it at about 5000. When the last light goes give a little more gas as you give more clutch and hammer down. USE THE CLUTCH LEVER going into second gear, or you will not go into second gear. Even with the clutch make sure you kick that shift lever like you mean it. For the rest of the gear nevermind the lever by your left hand, let of the throttle a little and kick her up. Drag racing is an abusive sport. You can go fast, or save some life in your machine for the road. Post your times! Reaction time is critical

Xnavylfr · « **Reply #15 on:** August 31, 2012, 01:37:19 PM »

Way back in the stone ages (60s) I drag raced a CB160. I only used the clutch for the launch then layed down on the tank and shifted with my left hand, I'm suprised I never thrashed a tranny as hard as I crammed them gears!!!

Xnavylfr(CHUCK)

seanbarney41 · « **Reply #16 on:** August 31, 2012, 03:03:18 PM »

hey killer, I was a drag race newby earlier this summer...don't be scared, it's pretty easy, although all my reaction times were terrible. I would try to get rpm's around 4500 and then slip the clutch, not the best launch but it's do-able for a newby. I really enjoyed making some of my Harley buddies eat crow and I got the timeslips to prove it...my best time on a basically stock k7 750 was 14.2 at 93mph...

chewbacca5000 · « **Reply #17 on:** August 31, 2012, 03:20:02 PM »

Quote from: seanbarney41 on August 31, 2012, 03:03:18 PM

hey killer, I was a drag race newby earlier this summer...don't be scared, it's pretty easy, although all my reaction times were terrible. I would try to get rpm's around 4500 and then slip the clutch, not the best launch but it's do-able for a newby. I really enjoyed making some of my Harley buddies eat crow and I got the timeslips to prove it...my best time on a basically stock k7 750 was 14.2 at 93mph...

That had to feel good! Did anyone of them want to trade their 20k Harley's for a 40 year old machine with more power? I love it! Reminds me of one of my rides when I blasted by hundred of Hogs doing about 80! They all just looked at me. That was my day at the strip!

To me a Harley is like paying for NY Strip Steak and getting a chicken pot pie.

lucky · « **Reply #18 on:** August 31, 2012, 04:38:29 PM »

My first drag race I ever went to was a Don Gartlets Special weekend.
I took my Honda Benly 125 twin with megaphones.
I beat everyone in my class.
I came home with a 1st place trophy that was 3 feet tall. I rode the bike to the event so it was very hard to carry it home and drive the bike at the same time.

I was so happy because the trophy said Don Gartlet drag meet on the trophy, and it was the first time he went 200 MPH in a 1/4 mile that day!!

killersoundz · « **Reply #19 on:** August 31, 2012, 07:18:01 PM »

Thanks guys I took some of the tips here and tried them out today. I'm not too concerned about burning up this clutch since it's going to need replaced soon. When I had the discs out out there wasn't much left to them. It hasn't slipped yet though!

Yeah I know it's abusive but the way I built this bike is as a beater machine made to be beaten

Just so you guys know it's no where near a 'nice stock k4' or anything. It's more like a giant turd with a legendary motor lol.

What seems to happen a lot when I rev up and then slip the clutch to take off. Well you guys know just how grabby these cb750 clutches are, they have some slip to them but not like a lot of bikes. I'll let it out and get moving but right at a certain point it grabs real hard and then the bike kind of stumbles for a second and hesitates sometimes. I'm working on letting it out as smoothly as possible but it's hard with these clutches!

I may also need to tighten up my chain again that could be contributing to this. I've tightened my new chain up like 3 times so far!! Keeps stretching

phil71 · « **Reply #20 on:** August 31, 2012, 07:59:06 PM »

I'd add 2 teeth to that rear sprocket, bet it'll run in the high 12s if you holeshot right

Stev-o · « **Reply #21 on:** August 31, 2012, 08:19:08 PM »

Quote from: lucky on August 31, 2012, 04:38:29 PM

My first drag race I ever went to was a Don Gartlets Special weekend.
I took my Honda Benly 125 twin with megaphones.
I beat everyone in my class.
I came home with a 1st place trophy that was 3 feet tall. I rode the bike to the event so it was very hard to carry it home and drive the bike at the same time.

I was so happy because the trophy said Don Gartlet drag meet on the trophy, and it was the first time he went 200 MPH in a 1/4 mile that day!!

Pics or it didn't happen!

phil71 · « **Reply #22 on:** August 31, 2012, 09:00:45 PM »

That trophy did not say "Don Gartlet", (though that would be funnier)

Stev-o · « **Reply #23 on:** August 31, 2012, 10:06:05 PM »

Quote from: phil71 on August 31, 2012, 09:00:45 PM

That trophy did not say "Don Gartlet", (though that would be funnier)

Actually, it probably did say "Gartlet"!

shinyribs · « **Reply #24 on:** August 31, 2012, 10:11:56 PM »

Quote from: Xnavylfr on August 31, 2012, 01:37:19 PM

Way back in the stone ages (60s) I drag raced a CB160. I only used the clutch for the launch then layed down on the tank and shifted with my left hand, I'm suprised I never thrashed a tranny as hard as I crammed them gears!!!

Xnavylfr(CHUCK)

That sounds like fun,doing it that way.lol Makes me wanna give it a go

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Author Topic: Best way to launch a cb750? (Read 5327 times)