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Weighing in

Discussion in 'Motorcycle Related Discussions' started by Peavey Jeltz, May 9, 2019.

  1. Craig

    Craig VIP MEMBER

    Joined:
    Dec 20, 2005
    I like to use free weight dumb bells when checking scales for accuracy ... guess you all have heard of vanity sizing in high end women’s clothing , I would say that German scale of Glen’s is carrying that theme over to weight watching ....
     
    worntorn likes this.
  2. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Yes I know what you mean about bikes being too noisy at times. You’ve already got the x pipe though yes? It’d be a crime not to at least fit it and see what you think surely !?
     
  3. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    I do plan to fit it and I'm hoping to do before and after dyno runs, if I can find a reasonably priced dyno operator.
    I tried dyno hill, but sadly it is for obsolete bikes only. I had to abort the mission about halfway up the hill at about 100 mph.
    The old bikes don't get up to any crazy speeds on that hill but both the Triumphs and the Glenli do, so I need to find a dyno.

    Glen
     
  4. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    If the de cat only liberates a claimed 4hp I wouldn’t do it for that reason Glen, frankly a normal rider would have a job noticing +/- 4bhp on a bike like a Thrux.
     
  5. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    True, and is it possible to definitively say that a 4 HP gain has been found, or is this just dyno margin of error?
     
  6. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    That should be provable by doing several runs before and several after. 4bhp should be outside of the normal margin of error IMHO.

    When I look at a cat I find it hard to believe it’s not holding back 40bhp ! All credit to the engineers I guess.
     
  7. ashman

    ashman

    Joined:
    Jul 11, 2010
    Glen I put a Meerkat decat on my Thruxton and got Peter to open my stock mufflers he makes new baffles the same as the baffles in the old Conti exhaust systems back in the 70s, the decat made a big differents with the sound it gave a more of a deeper thump sound but not to loud from stock and the mufflers sound great but still under the legal noise limit and the best thing if I get haseled by the cops I just say well its all stock mufflers from the factory, but so far have had no problems at all and I can tell you it made a big differents to the performance and you will notice that everything will be a lot cooler running, the heat that comes off the stock cat is pretty high.
    If you decat your Thruxton go the Meerkat way, I have checked a lot of decats for the Thruxtons but none come close to the workmanship of the Meerkat decat as well as performance wise, I am lucky as I only live a 100 miles away from Peter at Meerkat, but as you know from the Triumph Rat forum Meerkat has a good reputation for his workmanship and quick service.

    Ashley
     
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  8. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Ashley, I hadn't thought about the heat. Last trip was cold so the heat was useful, but most of the time it's not. There is a lot of heat coming off that engine, so I might give this x pipe a try.
    It's a Tec and they claim the same small HP increase as Meerkat.

    Here's another weigh-in showing 437 lbs.
    BSA doesn't list weights in the A7-A10 Instruction manual. A period road test lists 413 dry for the Super Rocket.
    This one is almost stock and it's little 2.3 Imp tank is full of fuel. Fuel and oil will be right around 25 lbs, so that agrees with the road test weight almost exactly.

    Glen



     
    Last edited: May 14, 2019
  9. ashman

    ashman

    Joined:
    Jul 11, 2010
    Because the cat sits right under the motor and they are designed to get very hot which don't help your motor as it sit under the sump, you will notice the differents straight away as soon as you take it for a run after a decat, helps when most of our temps for 9 months of the year are over 30c, I could even feel the heat coming up the sides of my high boots.

    Ashley
     
  10. speirmoor

    speirmoor VIP MEMBER

    Joined:
    Apr 11, 2010
    are you not required to use a bellypan where you race?
     
  11. KiwiNeill

    KiwiNeill Guest

    Weighed my modified 75 Mk3 Interstate on calibrated scales at work last week with full tank and fluids.
    All road equipment incl. triple discs, wide spoked alloy rims and radials with custom steel swingarm, both stands, original indicators and lighting, FA head, twin horns, large Shorai, std seat, steel mudguards, alloy clip ons and rearsets, usb/12v power sockets etc WOSP starter, no kickstart.
    Average of 3 readings but all pretty close:

    Front: 102.6kg... 225.72lbs
    Rear: 116.4kg...256.08lbs
    Wet total: 219.0kg...481.80lbs

    Less fluids: -21.36kg...47lbs
    Dry total: 197.64kg...434.80lbs

    I weighed all the fluids by volume separately a while back, petrol,engine, suspension, gearbox oils and brake fluid and got a weight of around 47lbs from memory but paperwork needs digging out.
    Will redo fluid calcs when I replace fork oil and brake fluid after tour.
     
    Last edited by a moderator: May 26, 2019
  12. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    I found a similar result recently after weighing the bike on a Commercial scale.
    438 dry was the verdict there.
    My MK3 is close to stock, just has a bit lighter front brake and alloy wheels.
    Still have a heavy lead acid battery, about 6 lbs heavier than a Shorai.
    So with the battery difference allowed for we are very close to the same number.

    The idea that the MK3 is 100 lbs heavier than other Commandos is a myth.
    Add an estart to an earlier 750 or 850 and the weights are virtually the same.

    Glen
     
    Last edited: May 26, 2019
  13. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    Sorry for the delay in answering. A bellypan would be required now for vintage racing here, but the picture is from some years ago when they were not required. The bike was retired from road racing, and is now my landspeed bike for dry lakes and salt flats events, which do not require a bellypan.

    Ken
     
  14. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    If I put the electronic scales under the front and rear wheels separately, how can I calculate the total weight of the bike ? The wheelbase is 54 inches. My Seeley 850 weighs less than my 500cc Triton. I know that because it is easier to get up the ramp and onto my trailer.
     
  15. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I've seen some very quiet bikes doing very well in road races. They always seem to be in the hands of the fastest guys. But my feeling is that if everything about your bike is optimised for maximum performance, loudness is unavoidable. With a two into one or similar exhaust system, getting the best out of it means changing the valve timing. Yamaha Exup is probably more about noise than it is about torque. If you use the valve timing which gives best power on a superbike, it probably becomes too loud. Exup probably costs a bit in top end power, but there would be an overall gain in the midrange and the bike would be quiet enough to pass the noise tests. I know some of the guys who race superbikes in Australia, take the Exup off the bike.
     
  16. KiwiNeill

    KiwiNeill Guest

    acotrel
    If I put the electronic scales under the front and rear wheels separately, how can I calculate the total weight of the bike ?

    Just weigh both ends sepatately then add the total. You can also divide each end into the total as a percentage to get the weight distribution, in my case:
    front 102.6 ÷ 219% = 46.85%
    rear 116.4 ÷ 219% = 53.15%
    It,s best to have the bike on the same level as the scales if you don,t have a hoist scale like worntorn.
    At home I have a footpath with a step that is the same height as my electronic scales but the work scales are just about level with the floor and will take the complete bike to confirm the total weight.
    Two of us lightly supported the bike each side vertically for accurate readouts.

    worntorn
    you are right more like 35 - 50lb between the often quoted 415-430 lb range, mainly e start, rear disc, cush drive,and footpeg/ rear master cylinder assemblies possibly.
    You,ve done well to get down to 438lbs with a near stock Mk3, mine is 32lbs lighter than originally but alot of unseen/alloy bits substituted to get that.


    Could lose possibly another 17lb with alloy barrels, fork yokes, mudguards and custom seat but alot of cost and I like the bike as it is in function and looks.
    Just lost 4.5kg to get back to my normal 89kg, much cheaper.

    I,m also around 130 starts into a 2500+ mile tour using an $18 Chinese sprag, will update on your post about these when I get back to the UK.
     
    Last edited by a moderator: May 26, 2019
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  17. ludwig

    ludwig

    Joined:
    Aug 30, 2006
    When going for minimum weight, each and every part has to go on the scale. Some parts are surprisingly heavy, like the side stand, gear lever, clutch spring centre .. for ex: simply replacing damper rods by anodised tubes saves 1 lb.
    Most attention should go to wheels and unsprung mass. STD rear wheel and brake ass. is ridiculously heavy.
    A BT45 front tyre ( criss-cross pattern ) is 500 gr lighter than a comparable Avon RR.
    A great weight saving material I only recently discovered is PEEK:
    https://en.wikipedia.org/wiki/Polyether_ether_ketone
    Half the weight of aluminium. Pretty expensive, but you could use it for fork seal retainers, isolastic collars, etc ..
     
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  18. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    I can't agree more about the weight of the wheels
    I have an apprilia hub with a morrad alloy rim on the back of my commando it's been in there for 20 years
    But recently I have been working on some original commando parts and when I picked the back wheel up complete with the brake hub etc I was shocked at just how heavy they were!!!!
    Cheers
     
  19. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    There are also some stock Commando items that are very light in weight.
    I was planning on fabricating an alloy oil tank to save weight until I weighed the stock steel oil tank. It is 3 pounds four ounces and made of very thin steel.
    An aluminium tank will need to be thicker so I don't see much weight saving here, if any.
    The Commando Transmission ( minus clutch- the clutch is a lump!) is also quite light as transmissions go.
    The powerplant itself is also not bad for weight once you ditch the cast iron cylinder in favour of aluminium.

    Glen
     
  20. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Do you recall the weight of the finished alloy tank?

    I'm not so worried about every gram with this bike.
    The big chunks are in the wheels, as you
    mentioned.
    I have very light wheels, tires, forks and so on plus my goal is around 325-330 on the road, no fuel. I've added up what I've got here, an almost complete bike, and this should be a reasonably easy target.
    If I get lazy on twenty items each weighing 100 grams more than possible, that's only 2 kilos, a bit less than 5 lbs.





    Glen
     
    Last edited: Jun 7, 2019

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