This girl fires right up every time quick as she ever did. I have made passes minus the filter and there was no detectable difference. I'm def not arguing with you Hub, I'm just trying to understand what this problem could be. I think we will see a much better picture of the problem at hand when I can show you a datalog.

Fuel pressure.

click

Nothing wrong with 215 PSI .. I have done a few of them and that is the number or close to the numbers I get .. Now just like dyno numbers are different , gauge to gauge can be different .. I had a guy call me and said his only makes 140 PSI cranking compression with 14.5.1 pistons and milled 25 head.. I told get another gauge and give it a try .. boom 240 PSI ... Sounds to me your motor is solid , so we need to look somewhere else for the problem with you back half ..Could be fuel or lack of PSI , would be the tire you are using and PSI in the tire .. Chain can cause this also .. ok keep in mind this ,when I run 127 in the 1/8 I back half over 160 .. When I front half 133 I only run 159 ..That doesn't mean my motor is bad ..60 foot times and 330 time play a big roll in your MPH on the big end .. The zx14r has one hard pulling motor on the top end , I have spun the tire in 5th gear with ease and when it happens I can't always feel it spinning , sometimes it just enough spin to kill my mph by 4 or 5 mph ..What i'm getting at is you can't always go by your MPH.. If you ETs are there and the MPH is off it tell me you are spinning on the top end of the track ..Spinning on the top end doesn't change ET much at all but will change your MPH ..One thing that can help keep a tire planted on the top and gain MPH is a good shock ..If the stock shock can't handle changes in the track prep or small dips and bumps it will spin .. You may not feel the bumps or uneven parts of the track but trust me they are there ..A good drag shock like mine keeps the tire planted making my mph higher than most bikes .

Just a little story from Brocks , he had a guy making 250 HP on his busa , it ran good ETs but his MPH was way down and he blamed Brocks mapping and a few other things .. Brock told him to get a drag shock , the guy just did not believe brock so he put it off thinking brock was crazy .. Weeks of trying everything but a shock and his MPH still sucked .. He finely did get a drag shock and the bike picked up 8 to 9 MPH just bolting it on with NO tuning of the shock .. He picked up more once he had the shock dialed in ..Brock only had one thing to say " I told you so "

I like I said your motor seems sound .. you need to look else where for the problem ..

BTW....Hi Smokin!Glad you come over and share here....way cool...thanks;)

I'm def not arguing with you Hub, I'm just trying to understand what this problem could be.

I'm not the one with 50 pounds down we both take compression readings. I'm not about to argue the point about getting the correct [leak] number, or it's reach around time. Are we waiting for a fuel pump and we didn't take a static measurement in a beaker [67mL], or shot glass me 3 times in a dixie cup, find [2.3oz.] or more, in 3 seconds we turn the key on and piss it out the tank.

Right now, we either have a bad compression tester, or 126 is booking it, you can do that all day long. Then we have compression. Compression does not drop with more rpm per say. We have grunt numbers but the top end goes belly up? If we backtrack, we were running good numbers up til when?

We ran some other kind of gas and did not remap for ratio? So all of a sudden, you are connecting the dots with the fuel change? So before you swap fuel pumps, my guess is we are not going to check leak, then, might as well match leaks out the tank. For grins, I'd measure the 2.3 ounce or more in a measured cup.

Then, if the new pump shows the same volume, the next reach around is a leak down tester to see a race leak under the 6-7% window. Not only that, you are 4 pounds down on 1 cylinder. And as soon as you dial in that air compressor that feeds over 100 psi and you now bleed off the leak tester to 100% ...

Signed,
NOLTT (when it comes to chasing your own tail)

I can't definitively say when exactly I stopped seeing 152+ mph. My note taking is horrid and memory worse. The last time I remember trapping 152+ was in Louisiana during early August at 97+ degrees with very high humidity. I didn't make any changes to the bike for the few weeks that followed. I have become more proficient at launching the bike and ripping the 330' yet my E.T. does not improve. Belly up on the big end is nixing my better front half no? Perhaps the tire is wearing and becoming less apt to grip on the big end with little prep? As smoking said my shock is def a weak link in my setup and could potentially net much quicker ET. Drop a grand and hope for the best? Fix what I have and then move forward I say... Leak down test will be performed I assure you Hub. Pump vs. Pump volume showdown? Sure. I can dig that.

Signed, Open minded and moving forward.

* Last updated by: maverick1441 on 10/6/2013 @ 11:40 AM *

I don't really have much real word drag racing experience, zilch actually, outside of random illegal shit. But out of curiosity, is it possible for a clutch to start slipping in the back half with all that load and speed on it? Like say the lever is somehow sitting there just ever so slightly with pressure against the master? Or maybe automotive grade oil with slickening agents doing funny things with the plates not allowing them to get a full hard on grip. I know these are issues that would easily be noticed at the launch, but say with 200 horse pulling under full load at 130mph+ with aerodynamic drag on the bike be enough to create a slight slipping just enough to prevent the full 200hp reaching the rear? But at the same time never be detectable at launch? Or a warped sprocket might steal enough power to slow yer azz down. I don't know, I prob asked some dumb questions but like I said in the first sentence.....

* Last updated by: nasty on 10/6/2013 @ 12:21 PM *

There is some merit to your suspicions Nasty, but I have already investigated and make changes in those departments. I have switched back to a full synthetic wet clutch compatible and increased my static clutch spring pressure while also eliminating the slipper mechanism. Steels and frictions are fresh and have been inspected after every trip to the track. Stock front sprocket with an aluminum Vortex 40t rear sprocket and it spins like a bicycle tire while on the stand. I'm running the stock chain with the O-rings removed and the rear wheel bearing seals pulled. I also pulled the rear rotor and brake assembly to experiment with pad drag and rotational mass. I'm going to adjust the shock settings and see how that helps me on the big end. I'm a little apprehensive about doing so because I'm cutting very consistent 1.51-1.53 60's I wonder if I could break into the 1.4X range with a dedicated drag shock... hmmm... That's a whole other can of worms...

You have been beating the living shit outta them valves, maybe a bad seat? Somebody out of spec? Weak spring/s? Vac leak around TB? Leak down?

Bad seat? - Won't know until leak down Out of spec? - Possible but at 3500 miles I doubt it Weak springs? - See previous Leak around TB? - Possible as I swapped for all short stacks a good while ago.

That's the only thing you have changed, motor wise? Short stacks in the middle. Did you use stock OEM shorties? Aftermarket not making a good seal? A vacuum leak at the throttle bodies could easily have an adverse effect on high speed performance. Loose clamp?

* Last updated by: nasty on 10/6/2013 @ 8:34 PM *

Factory shorts. Took my time. Had already planned to double check that or even switch back to factory longs. Current mods are : Brock's Alien Head 2 full system, Brock's clutch mod with high pressure springs (.180 shims), PC5 with Brock's pump map, forks slipped and strapped, rear dog bone link slammed, all factory shorts, Shinko Hook-Up, stock chain with o-rings removed, Guhl's ECU flash (Note of interest: Original flash included fuel map and later left instructions to ONLY reset the fuel trims to stock), super slippery cleaner/wax, calibrated clutch hand... I thought about wafting propane around the TB's to listen for uptick in RPM to eliminate pesky leak from list. Belly up on big end points to ram air loss of air box seal?

Keep with the simple things first. Check for a vac leak. Then a leak down will tell you right off the bat if something is wrong internally, all you need is an air regulator with a gauge, a valve, and a little bit of MacGyver like ingenuity. What do your plugs tell you? Any of them have a glazed look? Anything out of the ordinary? What kind of temps was she running at the end of a run on that 97*+ day?

And a shock just might be your ticket. A grand ain't gonna do you no good if you don't check them things first.

* Last updated by: nasty on 10/6/2013 @ 9:47 PM *

Indicated water temps have never breached 205 after a run. My new fuel pump came in today so we'll find out this weekend if that phantom power returns. I'm aiming for a leak down test before the weekend but that may not occur due to scheduling and work conflicts. Swapping the fuel pump takes 15 minutes vs. the 2-3 hour leak down. (That's strip bodywork, pull all plugs, perform leakdown, replace all plugs, inspect wiring harness while I'm in there, replace bodywork, detail the bike) The detail part adds a good bit of that time but any self respecting rider isn't going to ride dirty.

I mean, 126 all day doing those, is not compression. You'd think the old fuel pump would keep sending in those 126's too. It's not the pump... You'd think

I'm aiming for a leak down test before the weekend but that may not occur

Right out the hole, I'duck&tuck all over that bike like I came out of one of these.
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS_uRvWiVo2EoVVoMUUtW6UAizy_YlL2draGINn_E2OqlcBC55V

* Last updated by: Hub on 10/7/2013 @ 6:35 PM *

It's interesting to mention the tuck Hub. On the very day that I ran my personal best of 155 I had recently adjusted my tuck position. The old slide your ass to the bump and drop your upper body down to the tank as flat as possible. I can easily replicate this tuck position but I cannot seem to replicate the mph. Hmmm..... It's more than a hobby for me Hub. I'm in it to win it and I won't rest until she is running at full capacity.

TB sync might net you another MPH or two?

If I was in your shoes I'd be doing all these inspections maybe once a month depending what your schedule is like. Fucking in it to win it! I grew up around sprint car racing bro, these people did it as a hobby but they were still in it to win it. That car rarely sat untouched during the week between shows; plugs, compression, leak down, valve lash, etc, etc. The basic requirements to remain competitive on the grid while keeping catastrophic mechanical failures to a minimum, dirt track racing is wildly competitive around here, the rest is up to the operator after that.

I want to see you dominate the competition out there bro!

* Last updated by: nasty on 10/7/2013 @ 7:25 PM *

I'm the only guy around here carrying the ZX-14R flag and I want to completely obliterate any who oppose me. Rally 'round me brothers and salute this banner of power and prestige! Push me forward until my feet bleed, pile on the weight until my knees buckle. I won't be appeased until I hit the 8s at stock length and that will only bring a brief moment of peace.

It's like a golf swing and a bucket of balls. You are chasing that perfect swing thru. That means, straightest hit, farthest drive. I see guys wind up and all that 5 swings before hitting the ball. I stand there, look down at that ball, let my body do it's thing. I'm literally keeping my eye on the ball. It's all about the head game.

When you are up at that line, there is so much shit happening, but you've done it so many times. It's when you head game it all down to the what/where/am I?

What I want to hear/feel is my feed in, right?
Where is my body and how fast did I settle in, right?

You better start exercising the head game. If it's not the pump, if it's not compression, it's your head game, fella. If your best was some tuck, when was the last time you tucked? If you played the bike out, it's now your shoe laces breaking wind. I'd break wind so my guts sit lower. {jk]

If No, put those down. Are we more a bread basket than our best pass, or are we the same weight, same day, scale for scale?

If I don't think a change in diet is going to play with the head game. How serious are we? You've got till Sunday to chop a few pounds off.

If one wears the race face that says:

I want to completely obliterate any who oppose me.

Weight stays above 160 and below 170 year round and has been that way for 10+ years. Weight since personal best is exact. Ask yourself though; if two bikes 330' identical and one starts to leave the other, what has happened? We say less than 10lbs is negligible, especially on a bike with as much power as ours. We say mod for mod these bikes "should" make very close to identical horses. We say something has happened AFTER the 330' such as aerodynamic drag OR power is not identical OR traction issues down track. I can 60' and 330' with some of the best on a SWB cycle but why won't the run come together....

I'm getting confused here. Mav, are you at a 9.1, and on a no air day, 'The Hand' is a 9.01? Is that who your bike and the other, 'mod for mod' bike is who's bike you are taking about? Are both pc maps and ecu burns the same? Is that how smoke got his 8.40's on a stretch or stock swing arm? And what map/burn if any were smoke's setup for the 8 run?

* Last updated by: Hub on 10/7/2013 @ 10:04 PM *

I've got a couple buddies that run IMCA hobby stocks. The IMCA recently changed their rules to allow an alternator to be ran on the motor but they are dead set against running an alternator. I guess 12.39 volts from the battery to the ignition system during the last half of the race is better than a steady, constant 14.7 volts coming a power robbing alternator...

Hub I ran a 9.02 stock wheel base ( only tried 3 times one night ) .. Same bike and same tune with a long arm ran 8.43 ..I think maverick1441 bike has the same tune as mine as well as the rest of the mods but for my drag shock .. But different tracks and DA for sure .. I'm lighter than him also (15 to 20 pounds) My best guess from all the track time I have is 30 pounds is about a 10th of a second and 2 MPH ..He is very close to my numbers at stock wheel base ( ET anyway ) but his MPH is very low compare to mine .. My tuck is everything to me as far as MPH , I get under the wind screen and turn my head sideways on the top end to get out of the air stream ..That is how I hit 164.95 at long wheel base in the 1/4 mile .. Now I don't know his track at all but I can say I see some pretty wild swings in MPH at our track and from lane to lane ..One lane I can see 158 and the other 162+.. It seems to me looking at his 1/8 mile times he is right on the money as far as MPH ..But off on the big end MPH , BUT his ET is on the money from the front half numbers..Could just be the clocks at the track he goes to , could be track prep and spinning on the top end .. He could be shifting right before the MPH trap and dropping MPH .. I have mine set up to use as few shifts as possible and not have a shift right before the traps ..I put a lot of time figuring out the best set up to run that 8.43 , trail and error ..

I guess it comes down to this , so far the testing he has done shows the motor and clutch to be fine , unless he finds a problem with the leak down test I think his motor is fine ..I don't think he will find a problem with the leak down test . These motors are tuff as dirt , I can tell you I had 5000 passes on my very first zx14 and it even ran faster as it got older ..So if not in the engine or trans and clutch it has to be something else ..Track ? tuck ? fuel ? tune ? Maybe all of them at the same time .. I would reload the Map , make sure I got good fuel from a gas station that sells a lot of fuel so it's fresh ..Lube it snot out of the chain , 50 psi in the front tire ..If all that doesn't work I would start looking at my track as the problem ..A good data logger will show a lot of things , like A/F , tire spin , shift points and so on ..It just may help him pin point the problem if there is a problem .. GPS would not be a bad idea either ..Recall the fastest MPH and see if it matches what the timing clocks say ..

I know we all want to help him find the problem with his MPH but we just can't do it without seeing , hearing or smelling it first .. So we can't do that.. So we need real time data ..Point is we can't diagnose over the Web ..We can give him things to look at but that is about it ..