Launch Tips

brad black · 05-03-2002, 02:17 AM

going to the drags on sunday. anyone have launch tips for gettting away well. never done the drag thing before.

what sort of times should i expect if i can manage to get off the line witrh any decency?

brad
drag strip fool

Rapt · 05-03-2002, 05:04 AM

Times in the 12's stock, in the 11's modded (at least thats what I recall other memebrs have posted)

Good drag launches require slipping the clutch a fair bit. You want to keep the rpm up and ease the clutch out as fast as possible while keeping the front wheel on the ground and the rear wheel from spinning.

Thats the theory, I haven't ever done a series of timed runs to determine what the best RPM is for launch but I'd bet its at least 5500 rpm.

brad black · 05-03-2002, 10:09 PM

unfortunately, not going on sunday.

bob from work was going to bring his sb6 along. however, when he went home last night and told his girlfiend very excitedly what him and brad were doing on sunday, he was reminded sunday is her birthday. needless to say, his arse is going nowhere near a dragstrip.

told it happens every 2 weeks tho. might have lennies cams in for the meet in 4 weeks. got the bmw master tech meeting in 2 weeks in sydney. junket weekend at their expense. gotta love that.

brad

Trevor Rossack · 05-07-2002, 12:05 AM

For a good launch - start feeding the clutch in at maximum torque rpm's and change gears at maximum horsepower rpm's. You will need to keep you weight over the front, to prevent the bike wheelstanding, but not too much to get wheelspin. If the bike does either too much you can use the clutch to control both without closing the throttle. It is a delicate balancing act. I think the quick clutch take up is bit of a problem and I am not sure it is up to a lot of abuse over several runs. It would be nice to be able to practice your start techniques before you have to make some serious passes.

CHEERS
TREVOR

PS Good luck on your runs!!

Neil Paterson · 06-17-2002, 09:44 AM

Took my S to the local drag meeting (RAF Portreath). Before it got rained off (nice weather here is heavily taxed so we don't have any) I managed 12.5 @ 115 and a stumpy bit mph. I was quite chuffed as mine is standard, extra weight of ABS, centre stand, Ventura rack and I hadn't been to the toilet either.

The guy on the ZX10 (Tomcat in the US, I think) didn't get a look in till right at the end where he pipped me.

I kept the revs around 5000-5500 and fed it out reasonably quickly but with no wheelie or spin.

The smell of friction plates hung around for a while so I wouldn't want to make a habit of it. There was a grey S with what looked like a Vanderlinde set up but I didn't see what he managed as I left before the monsoon.

Are you lurking here? What time did you manage?

Anyone got comparison times?

Neil

cliff randall · 06-17-2002, 10:34 AM

Hi Guys........Too run in the 11's, take a trailer to get it home!
This type of racing is hell on your stock clutch.
Tip - shift without the use of the clutch at approx. 8,000 rpm in ever gear, including 1st to 2nd. You will actually be doing the bike a favour!
Cheers,
Cliff

Neil Paterson · 06-17-2002, 10:54 AM

Cliff

I only used the clutch for the launch and it still smelt like a fire at the a.p. lockheed factory.

Neil

markjenn · 06-17-2002, 11:04 AM

I've also heard that the R11 clutches REALLY don't take well to drag-strip abuse. There was a recent story in one of the mags about burning up a clutch in one launch. I suspect they are a lot harder and more expensive to replace too, although I've never done it.

- Mark

CarlosT · 06-17-2002, 12:37 PM

I kinda got away from doing burnouts because the burnt clutch smell worried me. Prolly more to do with the fact that it's a dry single clutch as opposed to a wet clutch. I wonder if Ducs get the same smell.

718Rider · 06-17-2002, 01:02 PM

I was beating the crap out of my clutch yesterday. Rode from Pittsburgh to NYC, and didn't get under a 100 except for gas. Hit an indicated 155 mph on the speedo on a straight w/hardcases - Vanderline pipe/chip/lennie's in duct sj-powerfilter. This bike keeps getting better and better the more miles I rack on it. My back is pretty sore and had to have the girlfriend walk on it to straighten out the kinks. I have a feeling I'm going to need a new clutch before too long. Does prolonged high speed thrashing on the hwy beat the clutch up?

T

cliff randall · 06-17-2002, 02:35 PM

718........You only hurt the clutch when you slip it, i.e. - leaving a light etc, otherwise these motors love to run WFO baby!
Cheers,
Cliff

roger albert · 06-21-2002, 01:23 PM

Hi all,

Carlos, yeah, duc clutches do that too. Much easier to replace than on a beemer. (though about everything else is easier on the beemers)

Hard use on the highway is not at all hard on the clutch. Next best thing to having the bike parked. The wear only occurs when the disc is spinning at a different rate than the pressure-plate(s)
When the relative rate is zero, the wear is also essentially zero.

I was just reading where Porsches new automatically shifted 'manual' (i.e. it does have a clutch, but doesn't have a pedal or a torque converter) transmission allows one such power launch per hour, and like 80 over the life of the clutch. The computer won't allow more. And some of us think ABS is intrusive. Zikes.

roger

brad black · 06-21-2002, 02:09 PM

for one reason or another we never got to the drags. but if i do, my clutch has at least got the benefit of my bike being back in std trim all round. what a ****ing slug. and that std front suspension is just crap. oh well, onto the next one.

go and pick up a 888 this morning. an ex english import. i have never seen a bike with so much corrosion. anything steel - bolts, hose clamps, thermostat, oil hoses - are all corroded.

unbelieveable. nothing i can't fix without way too much money and a **** load of time tho.

brad the compulsive

moose · 06-21-2002, 05:20 PM

Motorcyclist magazine had an article on dragstrip launches a couple of months ago. I can't find it, or I'd tell you more. I remember wheelspin at launch as a good thing.

My old Honda 750 did the best times with lots of wheelspin at the launch.

Cars typically benefit from wheelspin at launch, too.

A side benefit is slightly less clutch abuse.

wamo · 06-22-2002, 03:24 PM

Did BMW put a stronger clutch in the R1100S than other models? It would make sense to go with the bike's 'sporting' bias.

Does anyone out there make a 'racing clutch' replacement? Performance clutch plates are usually part of the 'hot up' parts list.

Maybe the stock item is strong enough. It certainly smells awful when you give it a bit of stick, but there don't seem to be too many stories of clutch failure coming through.

FWIW ....
Wamo

CarlosT · 06-22-2002, 07:35 PM

This is kinda a stupid question but is there any adjustment on the slave side of the clutch. I swear my engagement point keeps moving further out every 1,000 miles. I'd hate to fry a clutch due to a poorly adjusted throwout bearing or sumpin'

brad black · 06-22-2002, 09:59 PM

if the clutch master is overfull, or the piston in the master is too far in and the compensating port blocked, maybe. as these clutches wear, the pushrod moves back. on the cable ones, it decreases the clearance, causing them to slip.

it would take a problem to do it on the hydraulic system, but it could happen. no adjustment tho, as it's automatic. maybe implicit is a better way to describe it.

brad