Landracing Forum
Bonneville Motorcycle Speed Trials => Bville Motorcycle Speed Trials Rules Questions => Topic started by: hawkwind on March 19, 2013, 01:34:49 AM
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How is this done? bore gauges or head removal ? I have an inline 4 with center spark plug holes but motor is in a special construction frame so space is at a premium. how does the bore guage work ? what type of access is needed for it to work?....removing the head is out of the question as it would require an engine removal and many hours of work to do . Before I trek over from Australia if you use bore gauges what brand /type so I can check if its possible to use them on my bike.
Also how pedantic are they with maximum bore size: I have taken my engine to the maxium limit for its class ,if it were say 2 or 3 cc over would it be required to go into the next class up?
cheers
Gary
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The techs in impound are great to work with and will try to accomodate you. Most center sparkplug engines (like Hayabusa) can be measured with their bore measuring tool. However when I brought my Kawasaki ZX-10 in for measuring, there was not a straight shot for the tool to get into the hole. Taking the head off there on the salt was just not an option as it would take all day even if we had all the tools. So I took an angle grinder and ground the frame down enough so there was enough room.
If you don't want to take the head off, you must provide straight line clearance up from the top of the spark plug holes - all four.
Good Luck,
Don
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Gary, the answer is yes... For center spark, they have tools to measure bore and stroke without pulling the head. Of course you need access to the area above the spark plug holes for the tool. Both organizations SCTA and Bub use them (SCTA does the measuring at USFRA events).
If you bring your own tool, as long as you can demonstrate accuracy I'm sure they would use it. That is how they came to use the tool they are using now.
The tool is very accurate... every time I have had a bike motor measured it comes out within a cc, +/-. Most bike motors are typically within 2ccs of class limit, and they seem to measure just fine.
If you are 1352 in the 1350 class it will depend... In special construction you are allowed a clean up over bore of .020 or about a half mm larger than stock bore for the motor... if you already are 3mm over stock, you will not be allowed any extra ccs for clean up overbore. The extra cc allowance can only come from the .020 over stock bore. That means a new busa motor at 1352 moves to 1650 class...
So be aware, the limit is the limit, if you are over, you will have to reregister in that class $$ and start over.
This is my experience, the way I read the current rules... when in doubt, contact the scta bike chair for the final say.
Don beat me to most of it....
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Speaking as one who had a stock displacement of 1352 ('09 Kawasaki ZX14) -- yup, that puts you in the 1650 cc class -- with a butter knife against the machete-wielding big bikes. Good thing we were in production -- it didn't hurt as much.
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Jon, that would have been the perfect time to bore and stroke that motor to 16anythingunder50... don't have to stick to stock bore and stroke, just has to be in the same class as stock size.
Then you could take your big gun to the knife fight... :cheers: :cheers:
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You damn betcha, sir. It's now a 1532 cc engine. Still -- it wasn't enough to get the record. Jack Broomall's newer ZX14 made even more hp than does ours, and now he's got the record. Ah, but Nancy held it for a while. That's good enough for her -- and everyone, for that matter. They don't give those records out and then cancel the class so that nobody can ever break the record, do they?
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No, but they will change the rules and make it easy for the next guy to go faster... or they will change the rules and make it harder for you to go faster.... depends on your point of view... :roll: :roll:
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Well, say what you might -- Jack's bike made more power than ours and he was able to get more of it to the ground. That's how you set records in this game, right?
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Just checked.... cylinders 1,2 and 4 I have a straight shot down the plug holes, #3 is under the main backbone frame rail I can get a shot but at an angle of aprox 15 deg from vertical ? no way im altering the main rail or cutting holes in it. does that cut the mustard ?
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pretty sure that all cylinders are measured.
I helped swing a ZX 6 motor forward and down from a rear stud at a bub meet.
this was in the modified or production class. 2 people. couple of hours.
if it was easy, anyone could do it.
" it's not as easy as it looks. "
~ franey 9/07
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So should i reserve a space in the container Gary ? looks like 6 so far
Try Drew directly if he does not answer here
you need 8-10 " above the plug in a straight line for the bore tool to work
i removed the extended ram air sections from within the frame on the 750 and Busa just to be sure it was easy access
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What event are you planning? The SCTA rarely measures every cylinder, usually they pick 1 and multiply. The AMA requires every cylinder to be measured if I remember correctly
The FIM measures 1 and multiplies.
This is the way it was as I remember it, rule changes in the last couple of years could alter the AMA and FIM, I don't keep up on those very well.
I would check with the orgs you plan to run.
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In 2010 at Bubs they only measured 1 cyl. on a V-twin. They came up about 25cc's short also. I've had the same engine measured twice by SCTA and they only measured 1 cyl. as well. From my experience 3 outta 4 should be plenty.
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They measured both of my cylinders and being a 2-stroke I had to pull the head.
Don
Oops, I just noticed this is a Bub thread and I was at Speedweek.
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You can make your own tools for the inspectors. When they only fit your bore and stroke, you dont need as much room as the universal checker tool.
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I was concerned by 2 issues for running bubs ...... measuring the bore in impound,if a record was set .....and a capacity overlimit issue seems I have 2 strikes .......my bike was built under the older SCTA rules which allowed a cylinder overbore of 20thou/.5mm over the 1000cc limit which I took advantage of ...the stock size bore 74mm and stroke of 58mm = 997.8cc after a .5mm rebore of each cylinder its now 1011.3cc. So if the AMA rules require all cylinders to be measured and a max of 1000cc no rebore allowance im sunk. Each piston was custom made for size and CR as well as head gaskets and the head and block are o'ringed. My budget wont allow changes any time soon ,Ill give it a miss untill such times as I can meet the rules.
Thanks everyone who responded and keep the shiny side up :)
PS.Question an option would be to run in FIM Whats their policy on cc limits is there any allowance if one is just over the limit? as is the case with SCTA?
Cheers Gary
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It is the inspectors option on whether they want to check all the cylinders or not. You have to be prepared that they will.
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I have had one cylinder measured and I have had both cylinders measured. It appears to be the inspectors option and so be it.
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It seems to me that if one cyl is over sized both of them will be.
From what I saw of the FIM years ago they have no allowance for oversize within the class.
FREUD
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Having once been involved in motorcycle racing and, later on, inspection, the old rule about a .0.5mm overbore turned into a can of worms and was dropped. I believe it was pretty much only an SCTA rule anyway.
You had, in the motorcycle classes, an aggregate total of allowable oversize of 1cc...... In the car classes, you had a theoretical aggregate total of allowable oversize of 1 cubic inch (16.387cc)..... DON'T CONFUSE THE TWO OF THEM!....
NOW, for any car guys reading this thread, in practical application (and Stainless may remember this), in some of the car classes, the cubic inch breaks did not exactly corelate to an exact equivlent cubic centimeter size - specifically the 750cc - 45 cu. in. class ..... 45 cu. in. equals about 737.5cc - so you actually have less than .3 of a cubic inch of "grace" in that class.
One other option for testing swept volume is the use of a burrette, which, after the valve gear is deactivated, can be pumped into a cylinder with an adaptor into the spark plug hole.....once the air is expunged from the cylinder and the piston is taken to bottom dead center, a slow turn over of the engine will pump the oil back into the burrette and establish the swept volume of the cylinder being checked. The amount, when multiplied by the amount of cylinders, establishes the "as inspected" displacement of the engine it is accurate to about 1cc (or less per cylinder - and usually shows the displacement as being on the smaller side of "as measured and calculated")..... SCTA uses this option on motorcycles and smaller displacement car engines if the owner of the vehicle is okay with this procedeure.... it can be a time saver and, if you have expensive head gaskets and o-rings etc, it can save both time and money on a teardown... You do have to run the engine a bit after with a slightly hotter plug so as to burn the residual oil out of the cylinder as well....
It may be worthwhile to ask if this is also an acceptable method.
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Yep, scared the crap out of us in impound when we ran the zx-7.... motor measured over with oil, took the head off, measured 45.7 inches in the 45 inch class... 749cc... luckily it was a car motor and the next class started at 46 cu... too close
the class breaks can be fun, but no overbore allowance in cars either....
always thought the overbore was legal cheating....
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I don't see how the burette method can be accurate at all. There will be some leakage of oil past the pistons and rings even with the best of sealed cylinders. And the longer you take to do the measurement, the more volume will be lost.
How can the cylinders be sealed enough to get an accurate measurement?
Don
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Freud said: "It seems to me that if one cyl is over sized both of them will be."
I remember Scott Guthrie talking about his Yamaha 2-stroke multi-cylinder bikes. To get to various classes he DID run different size cylinders/pistons some of the times. Sure, it was a tad unbalanced, but it ran well enough to get him records. He mentioned that one time he was in impound and the official measured one cylinder - and was about to do the multiplication to get total displacement. Scott told the guy to measure the other cylinders - and the official was quite surprised to learn that indeed, the cylinders were NOT the same.
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I don't see how the burette method can be accurate at all. There will be some leakage of oil past the pistons and rings even with the best of sealed cylinders. And the longer you take to do the measurement, the more volume will be lost.
How can the cylinders be sealed enough to get an accurate measurement?
Don
Don.... It is a little difficult to explain but being that I am the co-owner of one of the burrette's that was used in the past, I have shown a few people..... showing is easier than telling.
The actual check of the swept volume takes only a few seconds of the actual inspection time..... due to the fact that, after the entrapped air has been purged from the cylinder, the engine is slowly turned so that the cylinder being checked is at bottom dead center.... the engine is then slowly turned over until that cylinder is then at top dead center..... and surprise surprise, when the graduations on the burrette are read, the engine displacement is calculated, the size is confirmed and it is so close to actual size that it is and has always been good and accurate enough for even World Records.... and one other little thing about using a burrette or "burrette-like" instrument for checking displacement..... NASCAR, NHRA and the SCTA, amongst other organizations, use an "air pump" type of size checker....air has about 1/5000th the amount of viscosity as oil and not enough air slips past the rings for it to be an issue.... Having said that, while using the burrette with oil, over the years, we HAVE diagnosed holed pistons for more than one competitor.... at which point, we ask that they check other cuylinders to see if they have compression and then we will subsequently check another "good" cylinder or, at the competitor's option, the head gets removed to directly measure the bore and stroke.
BTW, Stainless.... that was me who made you pull that 750cc cylinder head off.... and, if I recall correctly, you also showed us the fact that the cylinders were a bit "barrel-shaped" from ring wear - which was the real contributing factor to that engine pumping over-sized....
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Freud said: "It seems to me that if one cyl is over sized both of them will be."
I remember Scott Guthrie talking about his Yamaha 2-stroke multi-cylinder bikes. To get to various classes he DID run different size cylinders/pistons some of the times. Sure, it was a tad unbalanced, but it ran well enough to get him records. He mentioned that one time he was in impound and the official measured one cylinder - and was about to do the multiplication to get total displacement. Scott told the guy to measure the other cylinders - and the official was quite surprised to learn that indeed, the cylinders were NOT the same.
Scott was using a TZ250 on one half and a TZ350 on the other half of a TZ750 engine ....for running the 650cc classes..... I recall checking his bores and strokes in his pit area and sealing his engine prior to him running.... It sure saved impound/record certification time....
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Don.... one other thing.... you ARE allowed to refuse the use of a burrette to have your engine checked AND to pull your own cylinder head and have the bore and stroke measurements checked..... if you feel that another competitor, who has set a record and had his engine checked with a burrette is not legal, you ARE allowed to protest.... (it costs money to do so though..... and, in recent memory, nobody has done so due to how close the burrette method of measurement has actually proven to be)
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Thanks for the reply Fastman. I only run at BUB now, and I don't think the techs have the burette equipment. But I will do ANYTHING rather than take the heads off my bikes. That would virtually be a whole days work, then the bike would not be able to run again for the rest of the meet. Way too complex to put back together on the salt.
Don
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Don.... It is a little difficult to explain but being that I am the co-owner of one of the burrette's that was used in the past, I have shown a few people..... showing is easier than telling.
Did you buy it or make it Fastmam?
Would you have any pictures?
Thanks
jon
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Fastman, yes it was a junkyard piece we were throwing N20 at if I remember correctly... needed to know how to get it apart anyway....just scared us when it measured over. Yep that class is really close to the limit.
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Don.... It is a little difficult to explain but being that I am the co-owner of one of the burrette's that was used in the past, I have shown a few people..... showing is easier than telling.
Did you buy it or make it Fastmam?
Would you have any pictures?
Thanks
jon
Jon, It was a surplus piece of laboratory equipment that came from, IIRC, The University of Utah.... (not important in and of itself though).... It is a glass unit that is one liter in capacity and the valve spigot (what you would attach a hose to) was broken off..... the valve itself also leaked....A friend of ours was able to "weld" glass.... we had him put a large diameter (3/4") valve on to it. The reason being is that with a smaller diameter (they are usually 1/4"), the oil will squirt out of the top of the burrette like a geyser erupting.... with 9 times the area to the 3/4" diameter, the oil does not develop the velocity to erupt (unless some cranks the engine over with the starter or something, that is - ask me how I know that one)....Also, a good quality plastic one will work well too.... I recall from chemistry classes in high school that the teacher favored taller ans smaller in diameter as the separation between each 5 cc graduation was separated widely enough to "ACCURATELY guess" one or two cc above or below each 5 cc graduation mark. The real trick with a "store bought" plastic one is the installation of a large diameter tube with bulkhead nuts and O-rings in the bottom after removing the standard sized small valve and spigot.
Don,,,, I think that the present SCTA/BNI bike inspectors have one or two of them.....Do any of them come up to BUB and help? Also, ask BUB's chief of inspection about whether they have one, whether they accept that as a legiimate method of measuring the swept volume and, if they accept it but don't have on, whether if you brought your own, would they accept it as a a true method of checking the displacement of your bike....Back in the sixties and seventies, when the AMA certified all motorcycle records set at the SCTA/BNI National event (Speedweek), Earl Flanders was the AMA steward in charge of this...... He used this method....After the AMA was no longer involved, we (my brother and I) used our burrette for doing this.....Having said the first parts of the above now, and, if they WILL accept it, you may find yourself "pressed into service" as a cubic displacement inspector.....
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Thanks for the reply Fastman. I only run at BUB now, and I don't think the techs have the burette equipment. But I will do ANYTHING rather than take the heads off my bikes. That would virtually be a whole days work, then the bike would not be able to run again for the rest of the meet. Way too complex to put back together on the salt.
Don
Don.....Your comment reminded me of our travails in 1972 with our Honda 750..... In order to pull the cam, we had to remove the engine from the frame....We could NOT leave the cam in with it deactivated as we would bend valves.... IT was a whole day deal the first time but we had them seal the engine and inspection was a breeze the next two times....And I DO know about NOT wanting to unduly "disturb" the head seal on a good running engine!
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In '71 I watched Earl use the oil method at least 2 or3 times, maybe more, on an entry following record runs. Kept coming up just a couple or so cc over so he suggested they pull the head for measurement which they did, mic'd out the same couple or so cc over. Earl was as disappointed to have to disallow the record because of being so close on the wrong side as they were to have missed the mark.
Granted there is no replacement for displacement but I think just as much, if not more, additional power from a .010 over bore comes from making the hole round again after an engine has been heat cycled a few times as from the displacement increase. If possible I'd stay away from the absolute upper class displacement limits just to make life easier all around. Just my 2 cent opinion.
Ed