MadMike
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posted April 26, 2004 07:24 AM
I see you squish is safe but what was your exhaust valve to piston clearance? also what was your cam settings on your adjustable cam sprockets. sounds like your valve was hanging and you were loosing HP for the couple of passes. untill she finally broke off. I have a bent valve here in my office as a reminder to you can never check everything to many times and if you feel in your gut something could be wrong, It probably is.
hey Vince, expand a little on your exhaust valve cooling technic? I had SS valves put in my bike and I am getting ready to put everything back together. how can this help me if I pull the seals off? thanks!!
   
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entropy
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posted April 26, 2004 09:35 AM
Angi,
Are any of the other valve stems bent???? Like Mike said, valves slightly hanging could cause the drop off in power without making a racket so loud you'd hear it tapping.
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VincentHill
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posted April 26, 2004 09:55 AM
The only reason street bikes have exhaust valve guide seals is to stop them from smoking when you let off the gas or for a second after you get on the gas. In a race bike, the amount of smoke is very small because after start up, you gas it and there is no smoke until you let off and then that is a good thing because it is cooling the valve even more. Nothing is getting into the combustion chamber and all stays clean there.
On my race engines, I used the best possible guide seals on the intake side and none on the exhaust. For Daytona, I would need more cooling so I would make the top of the guide concave with a small place for the oil to build up and cool more (I actually had 1 head that I used for Daytona, Talladega, Charlotte, Elkhart Lake and Ponoco. The other head was for Loudon, Mid-Ohio, Riverside, Sears Point, Summit Point, Nelson Ledges, Thompson CT, Road Atlanta, Cleveland Burke Lakefront Airport and Bridgehampton.)
Ask Doug if they are using seals on the exhaust side on their 4 valve heads? This was all on 2 valve heads and I am looking into this right now because my engine will be apart in a few days.
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ra12r
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posted April 26, 2004 11:08 AM
 Edited By: zx12girl on 27 Apr 2004 18:35
quote:
ECU is not the problem
1) Did your adjustable cams slip?
2) Cam chain breaking of stretching?
Note: Sorry ra12r....I must have hit the edit button instead of the quote....I have to watch this moderation status!!
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VincentHill
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posted April 26, 2004 11:55 AM
quote:
If all the valves were hitting the pistons on all cylinders, then the ECU is not the problem it is something with the cams.
1) Did your adjustable cams slip?
2) Cam chain breaking of stretching?
3) I would put in new bearing.
Entropy, would the stiffer springs bend your retainer lips??
RA, I think the ECU came into play because of the higher RPM Ceiling they were using. This makes everything get a lot closer together because the valves start to get behind the Piston crank movement because of chain stretch,valve bounce and the clearance in the valve train. If you have .007 in clearance, .040 between the vlave and piston plus 6 or 7 degrees of play between the crank rotation and then add maybe .005 to .010 in piston growth, things can get very close indeed!
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MadMike
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posted April 26, 2004 12:12 PM
If you find out vince! dude let me know. I am willing to try? but in Dragracing do the valves really get that hot? when you have a good 1/2hour to 45min between rounds?
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VincentHill
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posted April 26, 2004 01:56 PM
Thanks Mike, you just answered the question. It is not the rest and cooling that is the problem, but the usage at very high revs and the duration. This is "NOT" Road Race but it is High Revs and some severe usage. The extra Oil in the guide will stop the excessive wear, but is it necessary for the 10 to 30 seconds (Drag Race and Land Speed Racing) Maybe at Bonneville but not at Maxton or a 1/4 mile. I have seen People that had no problems at Maxton die a short death in the Salt flats. I think I will still ask Dr. Doug and see what he thinks?
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krexken
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posted April 26, 2004 02:17 PM
I think I'd definitely like to see the spring pressure of your current springs versus your used stockers. The aftermarket ones may not be as good as we think.
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zx12girl
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posted April 26, 2004 04:43 PM
quote:
"Cam chain control"! It needs to be checked for length between Pins and the tensioner checked. You do have a stronger after market tensioner in the bike??
Tensioner - Check
New cam chain last year - Check - will have another new cam chain this year...
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VincentHill
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posted April 26, 2004 04:48 PM
I remember some tensioner problems the Early Busas had. WHat are you using for a tensioner? Manual or self adjusting?
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zx12girl
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posted April 26, 2004 04:53 PM
quote:
Angi,
Are any of the other valve stems bent???? Like Mike said, valves slightly hanging could cause the drop off in power without making a racket so loud you'd hear it tapping.
Might have a very slight bend now. I can not tell for sure with the valves still in. We sent the head off today to make sure that it can be repaired and then re-valved.
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zx12girl
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posted April 26, 2004 05:01 PM
quote:
I remember some tensioner problems the Early Busas had. WHat are you using for a tensioner? Manual or self adjusting?
Updated (2nd or 3rd generation) factory cam tensioner...
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VincentHill
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posted April 27, 2004 03:51 AM
Take a careful look at it. I saw the factory Kawasaki (Which have not had a problem) back up a notch at Gainesville and he "Lost an exhaust valve".
I use a Manual Tensioner that cannot back up. I would "Seriously" look at doing this.
The other thing I would do is check the spring pressure on the spring at that valve against another vs a stock set of springs at the install height.
With a new set of stainless valves, this is all you can do.
"The other possibility is the valve was just weak when new and failed provided the other pistons were "NOT" touched">
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zx12girl
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posted April 27, 2004 05:30 PM
Vince,
All the pistons were tagged. You can see the slight imprint from the valve left on the pistons. That valve still could have been weak....
Will check the springs!!!
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zx12girl
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posted April 27, 2004 05:41 PM
quote:
ECU is not the problem
1) Did your adjustable cams slip?
2) Cam chain breaking of stretching?
I agree - The extended ECU was not the problem. The tolerances were too tight to take the extra rmp's!!
Cam slip = NOPE
Cam Break / Stretch = NOPE
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ra12r
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posted April 28, 2004 03:45 AM
When you say tolerances were too tight, what do you mean?
When a motor last for more than 5 miles under pressure, then things are generally okay. I have a motor with the cams Mis-degreed and it did not last more than 5miles/8passes to be about exact. ALL exhaust valves hitting the pistons and only ONE cylinder breaking a valve. So please don't rule out the obvious.
1)What were your cams degreed before the break?
2)Did you see MPH change that day?
3)Does your busa "pop" when airshifting?
4)The answer is still right in front of you with the right questions.....
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VincentHill
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posted April 28, 2004 03:50 AM
Angie, let us face it, it was a fluke  Put in the mechanical tensioner and stainless valves and back in business. Then Spank thise young men again!
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MadMike
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posted April 28, 2004 03:52 AM
what were you cams degreed at?
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kzz1
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posted April 28, 2004 07:03 PM
Edited By: kzz1 on 28 Apr 2004 20:05
quote:
When you say tolerances were too tight, what do you mean?
1)What were your cams degreed before the break?
2)Did you see MPH change that day?
3)Does your busa "pop" when airshifting?
4)The answer is still right in front of you with the right questions.....
The shaved head decreased the piston to valve clearance. I think if this would have been a stock motor or at least stock head, we would have had enough clearance even if the valve's were to float a little. From the imprints in the pistons, It did not hit hard and probably would have cleared with a stock head!!!!
1) - I know allot about how engines work, tolerance and clearance but the cam degree is only "The man", My hubby Kzz1. I know enough to make me dangerous with a wrench !!!!
2) The MPH changed on the last pass the previous Friday. I was running in the 140's which is unusual for me. This past Friday when I "broke" it, the mph started to decrease (142, 138). This was a very shitty track! No traction till well past the 60 ft. So, we were not really sure if it was in the bike, the cool weather, the track or the "new" tire. Allot of variables that day. I do think that the valves touched the pistons the previous week because the bike just was not pulling like normal.
3) No "pop" with the shifter.
4) Hey....ask away, we want to make sure that this DOES NOT happen again. I am sure that the valve that broke was weak but that does not answer the question on why the valves touched the pistons in the first place.
I'll ask Ken to post the cam timing!!! Thanks for all of your assistance....
ZX12Girl
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kzz1
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posted April 28, 2004 07:08 PM
Edited By: kzz1 on 28 Apr 2004 20:09
quote:
Angie, let us face it, it was a fluke Put in the mechanical tensioner and stainless valves and back in business. Then Spank thise young men again!
Could be....but I would really like to insure that this does not happen again so that I can start spanking folks this year!!! I have two on my list that I can not wait to line up with....
ZX12Girl
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kzz1
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posted April 28, 2004 08:04 PM
cam timing 106/108. PTV @ .058 which should be safe. I didn't check the cam timing after the bike broke. I believe the problem is the extended ecu with a higher rpm ceiling causing the exhaust valves to hit the pistons. Did the exhaust valves float? Possible but I know that the problems started after we tested the extended ecu.
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MadMike
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posted April 28, 2004 08:10 PM
on the PTV, was that your intake or exhaust? at .058 you should not hit.. even if you rev higher? well I dont think so anyway?
Mad Mike
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kzz1
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posted April 28, 2004 08:22 PM
PTV- exhaust
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entropy
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posted April 29, 2004 12:09 AM
how much was the head shaved???
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kcadby
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posted May 04, 2004 05:00 PM
With the right springs...AND or enough valve to piston clearance...it is hard to hit the valves on the pistons...it is almost alway the exhaust that break also...
You NEED to check valve to piston clearance when building motors like these (shaved head)...
I've seen many a stock exhaust valves break over the years...
If I was bulding an old Z-1 motor (years ago) for anyone...I would stress the fact that IF...they couldn't afford all-new-STAINLESS-valves...
PLEASE...at least get just the exhaust...
STOCK valves don't like to be bent AT ALL...(as you have now seen  )...
I've seen Stainless valve stems bent into an S and STILL not break...
Sorry to see this Ang/Ken...I know you will get her fixed though 
Think about it...ZX12s rev to 11,600 STOCK without hitting/breaking valves...a "few more" RPMS on a Bbusa shouldn't be a big issue if the clearances and springs are OK..
It's all about having GOOOD valve springs/and ENOUGH clearance when you start pushing the limits...
Apples and Oranges but...ProStocks replce valve springs a LOT so they can keep the Valve-to-Piston clearances TIGHT on those motors...
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