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  • Reading diameter of cylinder?

    A inside bore guage, take it out to read with a caliper? Sounds like two errors accumulating into a mistake?

    How do you do it correctly? Is there a giz bang wonderful tool?

    I just tore down a harley engine, It has 40 over cylinders, and a standard piston in the front jug. It knocked, but the open drag pipes hid it for a while. I read with the inside tongs on my mitutoyo caliper but don't know how close I am.

    LOUD radios and drag pipes hide a lot of engine noise huh? I'll put some oil in the motor on payday, right after I go to the hair dresser.. and get my nails done.. that light there on the dash will remind me.

    No, my wife is not like that, but some of the MRS COFER'S were..

    http://cgi.ebay.com/ebaymotors/NEW-D...spagenameZWDVW
    could buy this one, It comes with instructions.. huh?
    Excuse me, I farted.

  • #2
    Calipers aren't really going to work for you.

    You set that bore gauge you linked against a stack of gauge blocks (with appropriate accessories). I use them all the time to measure some of the boring we have to do that needs to be accurate. Pretty darned good tool, and cost effective. Ours are .0001" and .00005" grad, not sure what the one you listed is. It is definitely more of an inspection/checking tool, rather than a primary measurement tool.

    Another option is a bore mic set - either the two point or three point (tri-mic) variety. This is a more expensive option, way way more expensive in the case of tri-mics, but is really one of the few accurate instruments available if you're trying to creep up on a dimension.

    Comment


    • #3
      Measuring Cylinder Bores

      David the old stick Piston in upside down and use feeler gauges on the thrust face to check clearance. The best way is a Proper bore gauge and maste rbore ring. But the Telescopic Gauge with a properly set Micrometer is also very good. It takes a bit of practice to use the telescopic gauge properly but it works very well. I use them at work all the time for close tolerance bore measurement, Mike

      Comment


      • #4
        HI Mike..

        Yes.. the piston with feeler guage has been used many times here. What I was trying to do this morning was diagnose, "what is there" with the caliper, wiggle and giggle was present. I finally got a measurement I was happy with.

        Looks like.. a 40 over cylinder with a standard piston in one hole. I have always trusted others to do my boring and setup for me. Looks like I don't trust anyone anymore.. THIS is someone elses bike I am working on for cash under the table.
        It has been a nightmare bike, one thing after another. I replaced the headlight hi-lo switch then got to swap out the headlight bulb. I have fixed no less than 30 shorts in the wiring, mounted the breakers.. etc.. got 38 hours in it now.
        Excuse me, I farted.

        Comment


        • #5
          Sounds like your average Harley to me.
          "four to tow, two to go"

          Comment


          • #6
            Hi,

            I have a couple sets like the one you linked to. And for what you want, it's almost the perfect tool for the job. It will give you an excellent picture of the wear pattern of each bore from the top all the way to the bottom. And it can be used to determine actual bore size in an indirect manner. Though not as nicely as a HoleMic.

            I usually set the gauge up using a micrometer set to the target dimension. Say in your case, factory new specs. Then simply add how ever much the dial gauge shows to the minus side of your "zero", (subtract for the plus side of zero).

            And that is a pretty steep price for that set. You can buy the same set from Enco for half that.

            dalee
            If you think you understand what is going on, you haven't been paying attention.

            Comment


            • #7
              Originally posted by David E Cofer

              Looks like.. a 40 over cylinder with a standard piston in one hole.
              Sounds about mid range tolerance for a Hardley Dangerous

              When it gets to 60 over it's time for a set of rings.

              .
              .

              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



              Comment


              • #8
                Yeah what madman said!

                I've had to measure a gob of cylinder bores for small engines and the cheat i used was to take a machinists square to keep the telescoping gauge square in the bore. I don't always eyeball stuff to well so it was nice to have something to kinda referencee off of. Then it's just a micrometer to measure the telescoping gauge. Then i'd measure with wrist pin and against it plus top, middle and bottom to check out of round and taper. Of course these were your basic briggs/tecumseh engine where tolerances are plus or minus 1/16

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                • #9
                  David, Dalee is right on the price of bore guage . You might look up on Ebay #280166672414 for a good price also. Another way to measure cylinder bore is with an inside mike and double checked with a good outside mike over the inside mike. JIM
                  jim

                  Comment


                  • #10
                    NOW John: wore out and in boxes them Harldley motor sprinklers are still worth more than any brit bike made. Just look at the women them things attract, a real iron milwaukee vibrator..

                    I had my old 58 lockwired and locktited, it'd still put your hands and feet to sleep.. balancing and a belt drive did miracles thou.. THIS Police roadking kicks it's ass off to the curb in comfort, ease of riding. and I hate to say it,... fun...
                    the old 58 would do 140+.. this new one.. not so fast.. Lakeshore HD had something to do with that, I had the rest.

                    Telescoping inside guages is what I was thinking I was needing.. I'll look about some more thou.. I am still learning.. I don't claim to be a know it all.. gimme another 50 years thou...
                    Excuse me, I farted.

                    Comment


                    • #11
                      Friend of mine ran across something like this, built by a so-called "professional" engine rebuilder. This was a $6,000 high-performance 4-bolt SB Chevy; knocked, smoked and leaked from day one. There's something very wrong in this photo:



                      Besides that issue, the main problem was this:



                      My scale is 0.021" thick, and I could fit it in there easily between the cylinder and the piston. Block was probably bored 0.030" over (or even .040 or .060") and fitted with stock-dimension pistons. It may have been as simple as the rebuilder ordered the correct overbore pistons, but got shipped a set of stock bore, and he didn't catch it.

                      But, for a so-called "professional" rebuilder, not catching a huge piston mismatch like that- to say nothing of the glaring error in the top photo- doesn't say much for the guy's professionalism.

                      Doc.
                      Doc's Machine. (Probably not what you expect.)

                      Comment


                      • #12
                        Ruff'n'reddy - but tit werkz

                        Originally posted by David E Cofer
                        A inside bore guage, take it out to read with a caliper? Sounds like two errors accumulating into a mistake?

                        How do you do it correctly? Is there a giz bang wonderful tool?

                        I just tore down a harley engine, It has 40 over cylinders, and a standard piston in the front jug. It knocked, but the open drag pipes hid it for a while. I read with the inside tongs on my mitutoyo caliper but don't know how close I am.

                        LOUD radios and drag pipes hide a lot of engine noise huh? I'll put some oil in the motor on payday, right after I go to the hair dresser.. and get my nails done.. that light there on the dash will remind me.

                        No, my wife is not like that, but some of the MRS COFER'S were..

                        http://cgi.ebay.com/ebaymotors/NEW-D...spagenameZWDVW
                        could buy this one, It comes with instructions.. huh?
                        David.

                        If you have dial indicator that will fit down the bore/s and a micrometer - over - horrah of horrahs - a set of digital calipers, you can do it pretty well with what you've got.

                        Fit bit of anything handy to the mounting hole on the back of your DI so that it forms "dog leg" with (small-ish) "rounded-over/part sphere" end on it so that when this bit of stuff is fixed to the DI mounting hole the "rounded-over" end is in line with the "moving/measuring" plunger on the DI so that the "rounded end" and the plunger are aligned.

                        Compress the DI and feed it into the bore and hang onto it.

                        Now let the plunger go and see that it hits the cylinder wall.

                        Now, keeping the DI end in one place - "near-as" is good enough - move the DI around in ever reducing circles until it is near stopped. Then finish off more carefully and note the reading on the DI at the center of it movement and write it down.

                        (Note: it doesn't matter which end you "hold" and which end you "move" as the principle is the same - just use it to suit yourself).

                        Remove the whole she-bang from the bore and using you micrometer or calipers, close it slowly over the whole "DI and ball on -the-end bit" assembly until you get the DI reading as it was in the bore.

                        It will surprise you just how accurate you can be with this set-up - a "thou" or better is quite achievable.

                        I know - and I hope, 'coz I'm ready for 'em - the "usual suspects" who haven't seen it in a book" or haven't done it etc.etc. will likely jump on this/me - OK let 'em.

                        But if it works - job done.

                        And if it doesn't?

                        I will have "come a gutser" and be wrong again - better still proven by myself.

                        But that's OK.

                        I am sure you can see the thinking and the principles behind this - and it has worked for me - after I saw somebody else - a Motor Mechanic - do it.

                        It was a classic "hit-palm-of-hand-on-forehead and "Oh sh*t yeah" stuff" by me.

                        Motor Mech couldn't see anything out of the ordinary in it as he does this sort of thing pretty often when its needed and if he's "stuck" for the "proper tool".

                        But I guess you realise that.

                        Let's know how you go with this.

                        I hope it helps.

                        Comment


                        • #13
                          Dave -- if someone already posted this please disregaurd, As bore sizes go up so does the posibility of error due to a teliscoping gauge actually riding to one side of the "cresent" or the other -- its the nature of a larger bore, the self aligning angle starts to get less and less, this means the teliscoping guage is able to wander a little off to the sides ------ The solution that iv seen is the triple gauge --- there are two lightly loaded teliscoping mechanisms that keep a solid mounted mechanism centered in the bore, On the other end is a single teliscoping gauge thats either hooked directly to a readout gauge or you can grid lock it and use it like a typical teliscoping guage and remove and measure, the single floater end is a heavier spring and will out-power the two lighter alignment ones on the opposite side till the center mechanism on that side touches down on the inside of the bore...

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                          • #14
                            Ugh, David, have you checked the prices on Vincents lately?, ain't any Hardly Ablesons bringing them kind of bux.
                            "four to tow, two to go"

                            Comment


                            • #15
                              Don't tell me!!

                              Originally posted by speedsport
                              Ugh, David, have you checked the prices on Vincents lately?, ain't any Hardly Ablesons bringing them kind of bux.
                              Thanks speedsport.

                              Magnificent Vincent - how true it was - great machines.

                              Don't tell me what they are "worth" now, I'm not sue I'm up to the shock of finding out.

                              I came to close too often to killing myself on my Vincent "Comet".

                              Nearly bought a 1,000cc vee-twin Vincent "Black Lightning/Shadow/Rapide" instead but I sure am glad that I got the smaller single cylinder 500cc Vincent "Comet".

                              Nothing wrong at all with the bike - just me.

                              Scared the $hit out of myself pretty often but I over-did it one day, and took it straight to a Dealer, sold it for what-ever the Dealer offered (bugger-all) and caught a train or bus home. I've only been on a bike 4 times since - all small ones in a paddock.

                              That Dealer must still be laughing his cock off at me yet for the deal he got!!!

                              But its "still there" - 50 years on.

                              I spent a couple of hours at a Vincent Club display at a Shopping Mall near here not so long ago. Those bikes were in "new/mint" condition.

                              I asked what they were "going for" to which the reply was along the lines of "Dunno - none of 'em on the market to find out - but we're looking!!

                              And you will be pleased to know that I sold another classic to buy my Vincent - a 1943 H-D 750cc WLA - still in its Army livery. Great bike too but the quality of design and construct was streets behind a Vincent which was an engineering master-piece at the time.

                              And this is not so OT as I was an Apprentice Fitter and Turner (now Machinist) and I learned a lot as regards machines and machining and fitting etc. on those bikes.

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