drag racing

so i took the 07 vfr800 to the track last friday and will be again this friday, to run some 1/4 miles. i got a best time of 11.9 at 120. the thing is i can not for the life of me launch with a rpm above 3000 with out the clutch turning into an on/off switch. i dont know whats going on with this bike, if its just a characteristic of the hydraulic clutch or theres some thing else going on. the clutch works fine for normal driving, but when i rev the bike up, the clutch has no modulation. i would really like to be able to launch in vtec...

please help guys

 

Video006.mp4 video by candyredrc46 - Photobucket

 

11.90 is not bad, the best I've gotten my 93 VFR is 12.03 at 110, it seems whatever my time is 110 is always my trap speed.

 

im going to try to polish the hydraulic pushrod today, if that doesnt fix it, im going to bleed out the clutch line again.
this time i will do it the "proper" way and remove the slave cylinder and clamp it fully compressed the time while im bleeding it out.
see if that helps at all.
i have a feeling that A LOT of people are dealing with this shit, but as its a touring bike 90 percent of people dont care and will never see a 1/4.
come on guys i want to figure this out and need to drop my 60 foots a lot.

 

okay today i changed the oil, and pulled out the slave cylinder pushrod. i sanded out all the groves and polished it up. upon test ride, absolutely nothing has changed. i talked to a mechanic today and he said he thinks the discs are either damaged or warped. this is kinda weird, being that i bought the bike almost new(8000 miles in 09) and i now have 27000 miles, and its been the same the whole way through...

honestly i dont know if i should buy a new clutch, or not. my 750 night hawk had an awesome clutch. i could launch that bike at high revs all day. then i put in a barnett kevlar clutch and it turned to shit(actually it felt exactly how this one feels now)

 

well i went out friday night, and despite the shity clutch, i beat a couple of 600s. a gixxer a zx6r and a cbr600.
my best run of the night was an 11.7 at 119.6
i couldn't seem to keep the front end down in the beginning
and on one of my last runs i spun out a little.

 

You could shim the clutch springs like.020" or so for more clamping grip. I don't like Barnett stuff. I've never had good results with them. Seems like their advertising is better than their product.

 

the problem is definitely not a lack of grip. after 3000 rpms the clutch turns into an on off switch. honestly it feels like the barnett kevlar clutch i put on my nighthawk.....

 

What does it do, slip or bog the engine? You said it has plenty of grip so I'm at a loss of the on/off comment. If it slips then it definitely needs more pressure or new friction/steel plates. Hard to believe a stock motor will over power the stock clutch.
What type of oil do you use?

 

I think I understand what CandyRedRC46 is trying to say. I have the same issue with my '98. Feathering the clutch is almost impossible. No matter how slowly I let out the clutch it just suddenly grabs. It does not slip under power, but it is definitely not a smooth engagement.

 

i have been using proper motorcycle oil purchased only at motorcycle stores since day one.
okay by me saying an on/off switch, that is exactly what the clutch becomes after 3000 rpm's.
below 3000 rpms the clutch feel perfect.
but above 3000, no matter how slow i let the clutch out, it is the same as me just dropping the clutch.
it just suddenly grabs with no warning.

say i stage at the light, i rev it to 4000, i slowly let the clutch out
and then this is what happens:
slowly slowly nothing nothing nothing them BAM!!! as if i just dropped the clutch lever.
and what usually happens is, it bogs and i punch it and pull the clutch back a little, till it hits vtec and then i let the clutch out again

but sometimes it wheelies or spins the back tire off the line.
i can never get a nice smooth consistent launch.
at medium rpms there is zero modulation, and horrible engagement.


its honestly like the guy i bought the bike from had a full race clutch installed
or at least a Kevlar barnett clutch
but the bike was completely stock when i got it.

 

omfg thank you for understanding! i feel like ive been speaking a different language since i started this thread!
okay so what do we do to fix this?
any ideas?!

 

Hell, if I know. I did the same things you did. I polished the clutch rod, bled the clutch slave cylinder and I found no improvement.

I am runnning Rotella T 5w40 synthetic. It didn't help my clutch issues but the transmission does go into gear a lot better after I made the switch from conventional oil.

<zips up flameproof suit>

 

sorry if I missed it, but you are running -1/+2 for drag racing...:wink: I've heard they go under 11 seconds at that ratio and little other mods. (170 pound rider of course).

 

I have a statement, a few questions and a idea to throw your way.

The statement:

1. You are not getting many responses on VFRW because you are drag racing a ‘sport touring’ street bike. This isn’t a drag racing BBS (Thought maybe you missed the memo and should be informed).

The Questions:

2. Have you talked to any of the local drag racers? I don’t mean the local “Bikerboyz” crowd, but the actual guys/ gals who are truly bracket racing and trying to cut consistent times on a true drag bikes? Maybe they know something about hydraulic clutches and launching more smoothly. I have gotten the best engine information from these types albeit on a road racing course, but die hard aficionados usually share good information.
3. Have you removed the case cover to see if you have Barnett clutch plates installed just to confirm?

The Idea:

I have used this company WPC - Metal Surface Treatment / Micro Shot Peening for a few things and so far have been very impressed with their price and results. I would think the part you cleaned up would not cost more than $10.00 bucks to do plus shipping to get it to and from. Great customer service and as I said I am impressed.

Hope this can help.

BZ

 

Ok got it. I don't have that on my first gen with my hydraulic engagement. I don't know the difference between your mc/slave and mine. But I'm just wondering if your lever may have some thing to do with it. Using a different angle which will slow or speed engagement by changing length/rate of throw.

I know what I'm trying to say but my not be getting my point across right. Say when you let your clutch out and your lever moves 1" at the grip and 3/16 at the mc plunger. Change angle or length at pivot. Then 1" at grip would only move plunger 1/16". Gives you more throw to play with to make the mc piston travel slower. So you can slip clutch. Make sense?

 

just read, I'll throw my thoughts in. I've been down the track a few times on my F3. Not on this bike, it's not made for it. I am also not responsiable if you screw up your bike trying these things.

launching - best way to launch little harder is with a tie down strap. Yes. A tie down strap. If you can, take it from the bottom of the left fork, over the triple tree, and hook it on the bottom of the right fork. Cinch it down as tight as you can get it. Why? Because the springs are compressed and when they unload is when the front wheel comes up. HOWEVER, this does cause problems as to when you try to turn. SO BE CAREFUL!!! Get your rear shock as hard as you can.

shifting - don't let off the throttle between shifts. Just pin the throttle open, and hold it there. Don't let off. just pull the clutch lever in, shift quick, and let the clutch fly. This is also excessive wear & tear on your clutch. It will not last as long as it should shifting this way. Pretty much guarantee that. I went through three clutch packs on my F3, whereas on my 900 I never changed the clutch out, and it had pretty close to 30k when I let her go. the 900 went down the track a whopping 3 times.

 

no just a one down 520 kit
but it definitely help the bike get into vtec sooner when "launching" at 3000 lol

 

oh well thanks anyways... you really think were going to get flammed for this? probably people just saying get a gixxer.... lol