Thumper Club Forum
Club House => Chatter => Topic started by: Steve Lake on April 18, 2014, 07:31:54 PM
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what size does an engine have to be, to be classed a 'thumper' ?...
will my beezer bantam make the grade (if I ever finish it) ?
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Not sure about engine size, but surely the definition of a Thumper has to be a single cylinder four stroke? so the Bantam wouldn't cut it ( though a Tiger Cub might!).
Not being anti two stroke here - My old MZ was probably the best motorcycle I've ever owned.....still miss it!... :'(
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Technically a Thumper is any 4 stroke, long stroke, single, size dont really make a difference. So modern singles really are not thumpers as they are short stroke
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well, I can go with 2 strokes not being thumpers... but don't think length of stroke should make a difference... if we are to exclude short stroke engines (what indeed constitutes 'short' stroke... anything oversquare?)
we would exclude may famous old bike from being classed as a thumper... some highly tuned manx's and G50's were oversquare.. and I've seen a couple of Vincent comet's tuned to be oversquare, and I'm sure there were plenty of others
discuss
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Exactly my thoughts.
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Yes....Me tooo !
Jethro
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Well my XBR is a short stroke motor and on race pipes at tickover it definitely goes 'thump, thump, thump......'
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Technically a Thumper is any 4 stroke, long stroke, single, size dont really make a difference. So modern singles really are not thumpers as they are short stroke
So on this basis a GB400/500 is also not a Thumper, I guess we built a club around a Myth (no, M Y T H Mark)
Furry
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Technically a Thumper is any 4 stroke, long stroke, single, size dont really make a difference. So modern singles really are not thumpers as they are short stroke
So on this basis a GB400/500 is also not a Thumper, I guess we built a club around a Myth (no, M Y T H Mark)
Furry
Nasty speech impediment there John !
And your Thruxton doesnt cut it either ! But Molly's Mac and Viper do ! ;)
Jethro
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Technically a Thumper is any 4 stroke, long stroke, single, size dont really make a difference. So modern singles really are not thumpers as they are short stroke
So on this basis a GB400/500 is also not a Thumper, I guess we built a club around a Myth (no, M Y T H Mark)
Furry
Nasty speech impediment there John !
And your Thruxton doesnt cut it either ! But Molly's Mac and Viper do ! ;)
I
Jethro
Yeh, sorry, it's my teeth. I have got a thumper though, the Evans Manxman, the least practical, usable, sensible bike is long stroke and it must thump but it's too loud to tell, 119db at Brooklands. Though you were camping at Llantony?
Furry
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I was only repeating the conclusions that came up in a conversation with a couple of people from the vmcc, I put up a video on youtube entitled thumper sound (one of my XBR videos) and had quite a few messages from people saying that a short stroke motor is not classed as a thumper, this conversation was continued on a few facebook sites, and the consensus was a thumper is a long stroke motor, but the word is now used generically to mean any single cylinder 4 stroke
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Technically a Thumper is any 4 stroke, long stroke, single, size dont really make a difference. So modern singles really are not thumpers as they are short stroke
Technically a Thumper seems to be a 4 stroke single who's bore is less diameter than the length of it's stroke ie undersquare, by your definition. I think the majority of my vmcc and voc colleagues take the term to refer to the ability of an engine to pull at very low revs, my Dr 650 Ses will never be a thumper, it is really lumpy below 2500rpm. Molly's GB400tt will however be rideable smoothly at 1500rpm however to get real thumpability you would need a Panther PM 120 which will pull a sidecar at 750rpm cheerfully. You pays your money and takes your choice. I like to think it is based on exhaust noise, distinguishable bangs makes a Thumper, never mind the technicalities.
My 2p's worth
Furry
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Sounds reasonable to me
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Mantra for the club Has Always been....For Those With An Interest In Four Stroke Singles !
Not forgetting Landies,Petrol Stoves,Weather Girls,Side cars and East European 2-Strokes !!
Dont understand any of that myself !!!!! ;) ;D
Jethro
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I always thought this forum was based on wife beating. :-\
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I always thought this forum was based on wife beating. :-\
.....and Rabbits in Disney films ;)
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I always thought this forum was based on wife beating. :-\
No Mark, that is just sick. There is no humour in wife beating. :(
Bill.
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I'm with Jethro "Mantra for the club Has Always been....For Those With An Interest In Four Stroke Singles !"
Anyway I always thought that to "thump" like an old Panther probably involved a heavy flywheel. If you wanted a quick reving engine, for instance in a racing bike, a lighter flywheel was needed. As usual I have probably got it all wrong and some one will come forward with their physics "O" level and talk about torque etc.
Having long since been an admirer of large heavyoil standing engines with large flywheels which only fired when the revs dropped below a set RPM, that is what I understand as an engine that Thumps, SWMBO says I cant have one though or a T20 fergy.
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In which case the club desperately needs to visit the Museum of Internal Fire during the next trip to Cwmdu.
Thundering great engines with flywheels bigger than people, some singles.
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Well, as a Cornishman (celebrating our new found position in Europe), I am of course familiar with Trevithick's Beam Engine...
which powered/drained/lifted& lowered miners all from the one reciprocating beam.... (you can see one working at Wheal Jane near Redruth (sadly powered by compressed air now.... ) the flywheels of these engines reached 20' (but no flywheel in Trevithick engines, just relied on a single huge piston) in diameter.... one complete cycle .... anything from 15 to 30 seconds!... now THATS a thumper :-)
pip pip
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Now a proper thumper engine is a Bollinger engine found on some older narrowboats.
Could listen to them all day long.
Another thumper is the BSA M21 side valve engine. Now that would climb up the side of your house on tick-over.
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Well, as a Cornishman (celebrating our new found position in Europe), I am of course familiar with Trevithick's Beam Engine...
which powered/drained/lifted& lowered miners all from the one reciprocating beam.... (you can see one working at Wheal Jane near Redruth (sadly powered by compressed air now.... ) the flywheels of these engines reached 20' (but no flywheel in Trevithick engines, just relied on a single huge piston) in diameter.... one complete cycle .... anything from 15 to 30 seconds!... now THATS a thumper :-)
pip pip
Thats brilliant but NO thump-thump now sadly but phut=phut!
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I didn't notice that rabbits in Disney beated their wife ....
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I didn't notice that rabbits in Disney beated their wife ....
Have you seen Thumper in Bambi ?
Always Banging his other half behind the scenes.... ;) ;D
Jethro
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Now thats a thumper !!!
and another although to be fair this a non compressing gas engine, but it sounds great and if it were possible to fit it in a bike frame it would probably fire once a mile
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As well as the XBR I have a Gilera Fuoco 500cc single cylinder four stroke three wheel scooter is it or am I eligible?
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If it goes bang on every fourth stroke, as far as I'm concerned.... you're in
it'd be a bonus if the bike did the same ;D
pip pip
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I didn't notice that rabbits in Disney beated their wife ....
Have you seen Thumper in Bambi ?
Always Banging his other half behind the scenes.... ;) ;D
Jethro
In France, Thumper is called "Pan-Pan" which can be traduced as "Bang-Bang", silly too ...
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Thanks SteveL the wife is happy so I guess that means I'm in.
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Found this 20 RPM RnsIw&index=12
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My Mountfield HP470 lawnmower is a thumper too...can he join the club?
Runs a very nice engine with an exotic habit of destroying carburettor gaskets. fleabay does a roaring trade in replacements for my mower.