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Discussion Starter · #1 ·
Let’s talk clutch springs, I’ve got a I use for drag racing. I’m stretched out 10 over and I’m 205-210 suited. Now I run a Cycle Concepts clutch, mods done too the bike are strap, swing arm,
Schnitz Flash, PC5 with Brock’s street map, Brock’s 3/4 alien head, Cycle Concepts drag pak, Brock’s heavy duty springs with the .250 spacers, 16/43 gearing. I would typically go into 5th around the 1200 foot Mark shifting at 13,500.

Here’s the issue I’m running into.

So last year with all the above mods but stock wheel base and 16/39 gearing, and Cycle Concepts super heavy duty clutch springs I did a best of 9.80 at 143 with mid 1.70’s 60 foot.

I got my arm on at the end of the season and only got 4 passes but went a best of 9.67 at 143 with a 1.65 60 foot.

Fast forward to now, I upped the gearing to 43 in the back, put a fresh clutch in and changed to Brock’s heavy duty springs with the shims. Normally when you install the springs you’ve got to push the spring down some to start the Allen screw. With these springs you do not. The pretty much bolted in. That to me raised questions to if it’s was going to slip. So I got to make a bunch of passes Friday and Saturday bracket racing and I’m down mph at time, using all 6 gears and the bike actually has slowed down a lot while my 60 is killer, from looking at my slips I’m loosing a lot after the 330.

My best pass this weekend was a 1.54 60 foot at 9.62 at 143. Mind you that was the only real fast pass. The rest were pretty much the same 60, but 9.70-9.90 range and saw more of 140 instead of 143.

It feels at times it’s slipping once it’s getting into 4th, I’ve loosened the clutch cable up as much as I could to take that out of the equation. It’s almost like there isn’t enough spring pressure on the clutch it’s self. I also pulled the clutch and checked the stack height, it was good.

Between taking a tenth off my 60 and getting in the 4.teens in the 330 I “should” be going mid to low 9s at 146-148 like my gen 4 was with pretty much the same mods.

Last year I was 118 to the 1/8, I’m now 114. I was 6.20’s to the 1/8 and this year I’m in the 6.40 range. I’m getting out of the hole a lot better then after the 330 seems to feel like it’s falling off. I’ve checked for pinched full lines and any obstruction in the ram air system and air filter.

Does this sound like I’m right on track with this being a potential spring pressure issue? Power delivery feels the same. I’ve got my old springs I’m going to put in to see how it does when I run this weeks test and tune.
 

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i've run all the spring combos u mentioned on different rider/bike weights with zx10's. my friend dj runs a gen 1 with track king clutch 3 gsxr 1000 valve springs and 3 stk springs. holds him fine at 153 mpph, weighs around 235-240 suited. those gsxr springs fit loose, have to screw them in a bit before any tension as u mentioned. geared 15/43 my 07 with dragpac runs stk springs shimmed .080, no problem holding. ur steels reveal slippage, they will be burnt/blued to a degree dragracing, but not like u've had a torch to them. good clutch as dragpac will hold without getting severe on spring pressure. my opinion u are still tall on gearing at ur weight with et/mph ur running. i run over 130 in 1/8, 160 in 1/4 with extended rev limit but i know im still making power at 13500. try 15 front and lower shift points. pretty much stk internal gen 1 engine generally drops power like a rock before/around 12500 which is little over 13000 on tach dyno verified. think ur revving into a range where power has declined ur problem instead of clutch. try a 15, shifting at 13000, work gearing out to max around 13k on tach or less in 6th for 1/4. hope this helps.
 

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Try throwing the drag pack back in and see what it does. Obviously your experience at the strip is far greater than mine but when i ran my 4th gen at the track with the oem clutch it felt like a damn auto transmission once the clutch started slipping. Was like it still held but the "feel" and rpm weren't matching up like how i know it should. Maybe with the new springs being stiffer they create the same force when bolted in as the others do "preloaded"? idk
 

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Discussion Starter · #4 ·
I don’t know how many more teeth I can go on the gen 5, the gearing on the transmission is stupid on these it’s extremely close ratio so with the 16/43 top out mph is 158 I believe per the calculator. Just a 16/39 gearing I was in 5th around 1100-1200 foot. I may be able to get away with a 45 tooth.

I’m running the drag pak clutch. Like I said I put a fresh drag pak in. I’m going to try the old springs to see if there is any change. Because I’m down 4 mph at the 1/8, but still getting the same at the 1/4 within 1 mph. Air wasn’t the greatest this past weekend but nobody wasn’t running that far off of their normal times.


I’m curious about if I can put a gen 4 gear set in instead of getting the recall done with the gen 5. From what I understand the transmissions are the same other then the gearing.

As you were saying about the shifting with power, my limiter is 14,200. Mind you with the Schnitz flash all they do is turn the limiter off, raise the rev limiter, and open the throttle blades a little quicker. Nothing with timing or really any power production. I wish I wouldn’t of wasted my money on his flash and just went to Don originally like I wanted.

But I’ve been keeping the shift point the same as last year to get a back to back comparison of stuff improving with the suspension change over the winter.
 

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Discussion Starter · #5 ·
Try throwing the drag pack back in and see what it does. Obviously your experience at the strip is far greater than mine but when i ran my 4th gen at the track with the oem clutch it felt like a damn auto transmission once the clutch started slipping. Was like it still held but the "feel" and rpm weren't matching up like how i know it should. Maybe with the new springs being stiffer they create the same force when bolted in as the others do "preloaded"? idk
Right! That’s what I’m saying the feel and rpm just doesn’t seem right.
 

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misread ur thread, assumed u said running a gen 1, u are correct. gen 5 completley different. patrick g on here has his gen 4 flying, been thru the clutch problems, think he settled on gen 1 full dragpac clutch complete with judder spring. still think u need more gear. i'm geared really low, especially for the 1/4. bike rips thru gears with 330's averaging 3.65. shifting at 13700 gets me in 6th about 8-900 ft mark, pulls 14300 on tach at traps. so i understand having to thumb that shifter button thru 5 changes in in about 7 seconds, but that's when the bike got really fast. backhalves in 3.03-3.05 seconds. i would gear the hell out of that gen 5 dragracing.
 

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Discussion Starter · #7 ·
I’m definitely gonna see if I can find a 45 tooth, I’m actually still foot shifting. I wish we could get in and adjust the kill time on the factory quick shifter, there’s et to be had there. It’s just so weird I’ve picked up a tenth in the 60, went up 4 teeth and it’s basically right where it was and down mph.
 

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Do you have any issues wearing out the clutch pull rod on the cover with hard springs
 
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