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Thread: ESE's works engine tuner

  1. #5866
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    Quote Originally Posted by Grumph View Post
    Torque plates are always a good idea -
    I can see torqe plates and a decent hone for our GP cylinders going on the to do list.

  2. #5867
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    Quote Originally Posted by TZ350 View Post
    cylinders like RG400's and RGV250's that don't have through studs may not have the same problems with crush distortion but bolting a dummy head and base wouldn't do any harm.
    Think it's even more gooder idea where there's bolts threaded into the cylinder, you've got the axial distortion from friction in the thread, it forces a sine wave shape into the cylinder wall. In those cases it used to be said you should use the same bolts too, and that the blanking flange be the same thickness as the head, (the distortion in the cylinder wall changes depending on how long the bolts are). Where there's a bolt hole used as an oil gallery I've even gone to the extent of using the old copper washers under the bolt head.
    Go soothingly on the grease mud, as there lurks the skid demon

  3. #5868
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    I guess if we are aiming to push the performance level of Buckets up a notch then we need to adopt better workshop practices too ... suits me.

  4. #5869
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    Quote Originally Posted by TZ350 View Post
    I guess if we are aiming to push the performance level of Buckets up a notch then we need to adopt better workshop practices too ... suits me.
    Be nice to think modern FEA systems would allow designers to eliminate such quirks, but almost everything is a compromise, and if you had enough mass in the cylinder to effectively eliminate distortion it'd weigh far more than is nescessary to do it's primary job.

    Machining a cylinder with a blanking plate may be even more important in a modern engine elevated to competition spec's, chrome rings and cylinders don't have anywhere near the dimensional run-in allowances the old iron jobs did.
    Go soothingly on the grease mud, as there lurks the skid demon

  5. #5870
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    20th January 2010 - 14:41
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    offset

    Fits/Wob can you spell out if there is any real tangible advantages with offsetting the cylinder to achieve Asymmetrical timing.

    Also can anyone figure out how the Garelli engine was a split single cause it seems a little odd with 2 x exhausts. As all the other split singles i have sees have one pumping cylinder. The second pictures exhausts were getting close to expansion chambers in my opinion, because even the traditional fishtails of the era stopped a lot short of these.
    The singers my need a little work though
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    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  6. #5871
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    Quote Originally Posted by husaberg View Post
    Fits/Wob can you spell out if there is any real tangible advantages with offsetting the cylinder to achieve Asymmetrical timing.
    Also can anyone figure out how the Garelli engine was a split single cause it seems a little odd with 2 x exhausts. As all the other split singles i have sees have one pumping cylinder. The second pictures exhausts were getting close to expansion chambers in my opinion, because even the traditional fishtails of the era stopped a lot short of these. The singers my need a little work though
    If I remember correctly (1926 is some time back) the Garelli 350 Competizione was a split single allright, but unlike the later DKW split-single racers it did not have forked or articulated conrods. The Garelli was a normal 360° (both pistons rising and falling simultaneously) parallel twin with three transfer ports in the left cylinder and two exhaust ports in the right cylinder. Both cylinders shared a common combustion chamber. Each piston commanded two carburetters. Also unlike the DKWs, the Garelli had no auxiliary pump cylinder or blower of any kind.
    I do like the look of the Garelli's exhaust pipes. It is the oldest bike I know of with such modern-looking pipes. Using diffusers to promote suction was not yet common practice then, and adding end cones would be regarded as revolutionary 26 years later! But I suspect that neither the exhaust timing nor the blowdown time.area of the Garelli did the end cones much justice; they were probably shaped like this just to accomodate the fish-tails.

    I would not bother with offsetting cylinders or piston pins to achieve asymmetrical timing. The effect is very small and who needs the complication.
    The pic below shows a calculation I did on the Aprilia RSA125. I gave it an offset of no less than 10% of the stroke in order to enhance the effect.
    It is obvious that the maximum conrod angles become asymmetric. What may be less obvious, is the increase in piston stroke for a given crankshaft stroke!
    It is also remarkable that it takes more than 180 crank degrees from TDC to BDC, and less than 180° from BDC to TDC.
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  7. #5872
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    The Garelli is a real oddball split single. Most are tandem cylinders with either two rods or a forked rod. the garelli is side by side with a very long gudgeon pin. You're looking at the right hand cylinder which has the inlet ports at the bottom and two exhausts - one at the front of the cylinder and one at the back. No problems doing that as the transfers are all in the other cylinder.

    So - sucks in on the right hand pot, transfers in the left hand one from a common crankcase , common combustion chamber , exhausts from the right hand pot as it's transferring fresh mix up the left barrel.....

    Wob would approve of the long blowdown possible - and the uncontaminated fresh charge.

    Frits - I see we overlapped - no factual differences which is pleasing - and no, I'm not old enough either.

  8. #5873
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    Cylinder offset - either deliberae or accidental can have some funny consequences...

    When Hans von Marwitz (spelling sorry) as FIM observer measured the Britten after the world record setting runs here in Canty, he noted that the cylinders on the motor used had different strokes....didn't suprise some of us here.

    60 degree V twin with a single pin crank - and a certain amount of machining error...

  9. #5874
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    since everyone reads this how many mm of front travel are you guys needing and what weight oil trying to sit here andfigure out a new front end for my build but want to know how much travel im going to need first was thinking 20w oil would be abit hard but should slow the front end dive down under braking and reduce the ammount of travel the bike would use
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  10. #5875
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    Ivan what your asking is like asking for a pre arranged script that’s guarantied to chat up a girl, it doesn't work, you have to play it as you find it.

    Engines on the other hand pretty much follow a formula, frames suspension and handling is something else.

    For what its worth my bike is about 98kg with gas, and 200kg with rider aboard. It has 100mm of travel at the front(shortened from 120), taper roller head brgs, 150mm travel at the rear, emulators to control dive and 5wt oil in reconditioned forks, the rear shock is from a 2007 GSXR600 with compression and rebound adjustment fitted with the original spring from my FZR 3LN frame. The front chatters ever so slightly when pushed and the back tyre shows signs of the rear suspension not being complient enough so I expect it can be improved.

    I have not put much time into sorting it out but expect that with some effort and experiance from playing with setups it will become a good ride.

  11. #5876
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    Quote Originally Posted by TZ350 View Post
    Ivan what your asking is like asking for a pre arranged script that’s guarantied to chat up a girl, it doesn't work, you have to play it as you find it.

    Engines on the other hand pretty much follow a formula, frames suspension and handling is something else.
    Yes I know that but im wondering what people are roughly getting in there travel so I can work out roughly how much im going to need its going to vary of course like I knowhow much we are getting on a 675 daytona but the travel is going to be a shit load more in that due to the speed and sudden loss of it under brakes were as on a bucket the speeds are not as high so the braking down force will not be as much,


    I was thinking somewere around 100mm of travel would work
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  12. #5877
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    Ivan, you may be surprised at how hard you can brake on a bucket, accidental rolling stoppies aren't unusual. I'd be looking at whatever travel the bike you are basing your frame on has and try for something close to that.

  13. #5878
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    Quote Originally Posted by Ivan View Post
    on a bucket the speeds are not as high so the braking down force will not be as much, I was thinking somewere around 100mm of travel would work
    100mm is what we use, but there is more to it than just fork travel.

    Check the physics on kinetic energy, wether the object is big or small, fast or slow its the rate of change that’s important. For instance it takes a lot of force to stop a light thing quickly, stand in the way of your average bullet to see what I mean.

    Under heavy brakes (rapid rate of change) you want to control the rate of (amount of time for) weight transfer to the front wheel, regardless of actual suspension travel. As sloppy springs take to much time, and with hydrolicly locked compression dampining it happens too fast.

    Fork emulators do this better than plane old compression dampening holes in the inner fork tube. If the compression dampening is to high then the forks lock and the back wheel tends to lift of the ground as the whole shebang tries to rotate around the front axel.

    Compression dampening holes are always a compromise, usually what’s good for comfortable riding becomes to harsh for hard braking, but fork emulators when set up properly for the bike adjust to the damping demand.

    And fork travel is more about the size of the bump you expect to negotiate, not the rate of weight transfer to the front.

    And under brakes the spring rate will be about how much weight has to be supported by the suspension and still have some movement left.

    So this is how I think it plays out under brakes.

    Spring Rate ... is about how much weight needs to be supported and still have some suspension left for small bumps.
    Fork Travel ... is about the size of the bump and movement needed to compress the spring (see Spring rate).
    Compression Damping ... is about the time it takes to transfer weight to the front wheel. (not to fast, not to slow).

  14. #5879
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    Quote Originally Posted by TZ350 View Post
    100mm is what we use, but there is more to it than just fork travel.

    Check the physics on kinetic energy, its the rate of change that’s important, wether the object is big or small, fast or slow. It takes a lot of force to stop a light thing quickly, stand in the way of your average bullet to see what I mean.

    Under heavy brakes (rapid rate of change) you want to control the rate of weight transfer to the front wheel, regardless of actual suspension travel.

    I think Fork emulators do this better than plane old compression dampening holes in the inner fork tube. If the compression dampening is to high then the back wheel tends to lift of the ground as the whole shebang tries to rotate around the front axel.

    Compression dampening holes are always a compromise, usually what’s good for comfortable riding becomes to harsh for hard braking, but fork emulators when set up properly for the bike adjust to the damping demand.

    Fork travel is more about the size of the bump you expect to negotiate, not the rate of weight transfer to the front.

    And under brakes the spring rate will be more about how much weight has to be supported by the suspension and still have some movement left.

    I think this is how it plays out under brakes.

    Spring Rate ... is about how much weight needs to be supported and still have some suspension left for small bumps.
    Fork Travel ... is about the size of the bump and movement needed to compress the spring (see Spring rate).
    Compression Damping ... is about weight transfer to the front wheel.
    Yip I thought 100mm would be right I might look into making my own emulator setup but wont be buying any for it I think Glen had said he changed the sized of his damper rod holes on his bucket and it handled like a dream when i rode it
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  15. #5880
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    Quote Originally Posted by Ivan View Post
    Yip I thought 100mm would be right I might look into making my own emulator setup but wont be buying any --
    Making your own, your a true Buckateer.

    The ones you buy look fancy but I am sure with some carefull work you could make something that works just as well. TeeZee recons, if your making your own, something made of steel and welded to the top of the damper rod would be better than the store brought ones that just float on top.

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