kzz1
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posted September 28, 2002 08:59 AM
 Edited By: kzz1 on 28 Sep 2002 10:04
Traction problems? Help!
Went to the track last night. Tempature was around 65 degrees. Did my burn out staged, launch at 6k and the tire went up in smoke. Now I have a shootout tire with 15psi, slammed, 6 over adj. arm set back 6" Rear shock settings set at- compression 10 clicks (stock ) rebound at full stiff.
Questions, How long do I do a burn out on a shootout tire? Is it possible that I am doing too long of a burnout? I figure I am doing a burnout approx. 10 sec. I don't do a dry hop. Should I? I 've always heard that doing a dry hop is hard on the clutches? I personally think that a dry hop is necessary to find out what rpms to launch at?
I know that if you don't get a good 60' which mine are from 1.5 to 1.7 the bike won't et well on the big end such as last night. Trying to stay consistant on my 60' is a problem with me. I know its all in the launch... up in smoke, wheel in the air or I get a good launch. I believe i'm slippng the clutch enough?
How do you guys do it as I want to improve on my launch techniques with the above combo, is there anything wrong with my setup? I know pratice make perfect and the end of the season is near. I live in Michigan and got the month of October to still test and tune 
Should I launch at a lower rpm due to the tempature?
How can you tell when a shootout tire is worn out? I'm thinking that the tire is worn since (I've had it on since spring with quite a few passes on it) and the outside tempature and or setup or all three has something to do with my launches last night. BTW, got to the track late and only got make two passes. Both passes the tire went up in smoke. How about some help from fellow dragracers
  
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CrotchRocket
Moderator
Bracket Racing with Betsy
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posted September 28, 2002 09:10 AM
kzz1...I have heard guys complaining the shootout tire gets slippery at the end of the season!!!...Maybe they needed to spray the track, you do have more motor than most of us,plus the swingarm!!!...Maybe your suspension is too stiff???
CrotchRocket
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kzz1
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posted September 28, 2002 09:16 AM
Well I didn't see them spray the track but I got there late. The motor is a 1270 and I don't know if the suspension is set up right? Mad Mike set up the suspension on the bike last week at Milan which seem to help? I was at a different track last night (shit hole compared to Milan).
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ZRXDean
Needs a job
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posted September 28, 2002 09:29 AM
I bet your tire is gone. Dig into the rubber in the middle of the tire with your fingernails, then do the same at the edge of the tire- if it feels a lot harder in the middle, your tire is toast. The MCR2s last about 75 passes IMO, but once they go, forget it. You can try dropping it down to 8psi, loosening the front strap, but more than likely you just need a new tire. Spencercycle.com has a good price, I think $195 delivered.
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kzz1
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posted September 28, 2002 09:33 AM
I'm unsure about the rear suspension setup? Can someone explain to me how it works for the drag strip? ZRX Dean, I'll check it out!
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INTRA
Expert Class
Posts: 307
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posted September 28, 2002 09:35 AM
My experiences with the mcr2 has been kinda strange,one things for sure,if I put it anywhere below 20 psi,it bounced like crazy,particularly in the shifts,bouncing cuases wheelspin by shrinking the contact patch of the tire,with more air pressure,your patch will stay consistent,and solid.With a street tire,I air down quiet a bit though, but the mcr2 is designed to be run at or near normal pressure.I usually like to have the suspension do all the work as far as weight transfer,soft as possible in the rear,and make sure the strap isn't too tight on the front,that could prevent your suspension from sagging low enough in the rear when you luanch,especially with the stock rear shock,it needs a lot of help from the front to work good,if your 6" over,you can loosen the strap a bit.Also,if you want(and this works),put your bike on the swing arm stand,paint your tire with VHT and let it sit over night,take it too the strip and HOLD ON!!
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kzz1
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posted September 28, 2002 09:42 AM
Intra, what do you set the compression and rebound at? I thought you would want the front end pulled down?
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entropy
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posted September 28, 2002 11:46 AM
kzz1,
I was having BIG trouble with spin until:
1. started doing a smoky burnout (your 10 sec sounds way long enough if you are getting the rpm up there,
2. just recently started preloading the clutch. i.e. move from presatge to stage w/clutch and then keep the clutch out till it is just on the point of grabbing. when the last yellow comes on just slam it out.
3. I never put my pressure less than 20#
4. soft compression hard rebound. I have a Penske so my setting are worthless to you.
I stage at 5500 but am trying to up that
Have you got plenty of room under the tail??? I "paint" mine w/white shoe polish to see when the tire is hitting. If it is I give a little more compression or raise it up just a little.
Please disregard anything above which sounds wierd cause I am still trying to improve the consistency of my launches also.
Good luck, keep us posted!! Say hi to Angi!
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BA
Pro
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posted September 28, 2002 09:18 PM
I agree with the ol' soft compression, hard rebound.
Definitely agree that the tire may be gone too, or just not enough tread on it. The ol' fingernail press test works for me. It's easy to tell a hard tire that way for me. (now-a-days, anyway)
I think that more pressure is better than to low as well. You ever seen an under inflated car tire? It doesn't wear in the middle. Do a hard, short burnout on some pavement and look at your mark. Is there one wide tire mark, or two 'outlines' of your tire? I'd say that two outlines *may* suggest too low of a tire pressure.
Are you maybe overheating the tire? Too much is as bad or worse than too little.
I'm not sure how you are used to launching, but it sounds like with a 6" arm, that you can afford to scoot your arse back in the seat to shift your weight rearward. (something I cannot afford to do, I gotta be up on the tank)
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ZRXDean
Needs a job
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posted September 28, 2002 10:46 PM
I run 12-16 psi all the time, but I'm not too concerned with mph, I just hate spinning. The 8psi number came from my last bald-tire experience in Rockingham, when I asked Ryan Schnitz what he had in his tire to hook up on what I thought was a slippery track. His tire was brand new, on his 60" ZX12, and he said "I just put 8 pounds in it and it hooks". He didn't spin all weekend that I can remember, and his 12 goes 174mph. I think the biggest worry of low tire pressure is the tire moving on the rim - I have read that some guys have marked their tires & wheels and recorded slipping - sometimes unevenly from side to side. I think this is rare however, and prolly due to using soap to mount the tire, as opposed to Windex or water. Anyway, I think you're safe with 10psi for sure, and it's worth a shot until a new tire arrives.
Kevin was at the track tonite and ran 1.60 60 foots on a stock wheelbase Busa, with 30psi BT56 - 6.20 1/8 miles.
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kzz1
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posted September 29, 2002 04:51 AM
Edited By: kzz1 on 29 Sep 2002 05:55
I checked the shootout tire in the middle with the finger nail test. barely left an impression on the rubber but on the edge of the tire it left an impression. Also, there are no grooves/ tracks in the middle of the tire. Does this mean that along with barely leaving a finger nail impression that the tire is worn out? I also notice when I put the rear on the stand and spin the tire that it is out of round? Could this also cause problems? I mark the tire and rim with white shoe polish and it has move about a 1/4 " no more.
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ZRXDean
Needs a job
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posted September 29, 2002 07:15 AM
Yeah, if you can feel the difference in hardness, and the middle tread lines are gone, it's time for a new tire. I guess half of the MCR2s out there are out of round - the carcass is so soft I guess it's difficult for MT to make a consistently round tire. That and they have the market absolutely cornered.
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entropy
Moderator
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posted September 29, 2002 08:11 AM
ZRXDean,
VERY cool tip on digging yr fingernails into the rubber.
Jeez, I should have thought of doing that  Oldtimers disease hits again, good thing we have this forum and guyz like you!
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BA
Pro
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posted September 29, 2002 09:11 AM
Ken, I'm not sure if this will relate to your tire but here's my little story. 
I've almost never had traction problems on my 12R at my local track, except on the rare occasion that I hit a spot of oil from some cage at the starting line or something.
Lately, I've been saving quite a few of my rear tires for some hooligan activity. Then, one day I put on my previous Michelin Pilot and went to the track,.....ended up having lots of traction problems.
Following week,....same thing. A very odd thing for me!!
So, I switched tires.....to one of my other spares.....this one a tried and true Dunlop 207. AGAIN, I had traction problems.
Then, it occurred to me that these tires were SOO low on tread, that they had *NO GIVE* to them. I broke out the fingernail test dead in the middle of both tires and damn'ed if the center wasn't pretty hard.
I put on my "regular street riding" tire, a Michelin Pilot 190, full tread, and the next week didn't have any problems.
This kind of lead me to believe that you can actually take a street tire down too far,...and just because it "LOOKS" like a slick, don't mean it's going to act like one!! (slicks have full contact side to side, yes, but they also have a 'thickness' to them)
My buddy who races a 67 Goat at 11.50's on big slicks has noticed the same thing with slicks. Once you get them down to where there's no tread, or 'cush' to them, they're useless.
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ZRXDean
Needs a job
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posted September 29, 2002 09:43 AM
I should say that I picked up this habit watching Kevin sharpen his claws on shootout tires.... I think this is how you can tell if a slick is going, since there is no tread to watch. That and the spinning of course
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kzz1
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posted September 29, 2002 10:36 AM
BA...Thanks for the tidbit Now I got to make up my mind to either buy a new shootout tire or Shinko being that the end of the track season is the end of October or try some VHT on the tire 
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flite leader
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posted September 30, 2002 10:16 PM
all tires have a definite number of heat cycles they can go thru
when a tire gets old ...... it gets slick(no pun),,,, loses traction
if its been on a whole season ...... traction may be gone
yes you might be actually overheating you tire
burnouts & chirps look real good...... try easing up a bit
cant hurt..... you can always go back to caning it
most guys i know keep a log book
wont give you all the answers .... will let you see trends
temp....humidity.... rpm launch etc
that will help you make decisions
you might be able to set some good times right at the end of the season
you & your combo should be sharp.....put on a new tire at your next good meet
may give you the kind of results that you can improve on over the winter
good luck
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