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oh yeh i for got to explain these are my posts cut from the “drowned bike thread”
each post is indicated by having “>>>>>>>>>>”
between them.
i hope it’s not too hard to follow. i tried to put them in the order they were posted in.
>>>>>>>>>>>>ECKS-Man wrote:
Quote:350? Pfffft, go the whole hog, bolt on a 450, they have a common bottom end I’m told! :laugh:.
um the 450 barrel and piston on the 250 makes 350.
to get 450 you’d have to put the 570 big bore kit in it. but i have not done the numbers, i doubt you’d get 450 cc out of it.
you are correct ux-mon ( he he Jamaican eccant)
in 06 i think? a dealer said the 250 t4 through 525 all shared the same engine cases.
so in theory you can bolt on the 525 top end.
hhmmm now the Husaberg is supposed to be the same cases as the 4t exc’s so you could do the 650 berg top end:huh:
>>>>>>>>>Moto wrote:
Quote:xy-transit wrote:Quote:yes Moto you’re correct. but if you put the 450 cylinder, barrel etc onto the 250 exc-f it increases it’s displacement to 350 mls. = millilitres.Ummmmm……I don’t think so!!
Firstly whatever the new displacement is it’s measured in cubic centillitres which is a volumetric measurement. ‘mls’ isn’t even an engineering unit, I assume you mean ‘ml’ which stands for millilitres. If the bike was indeed 350 ml the piston would be faaarking tiny!
EXC 250F bore and stoke is 76mm x 54.8mm giving a total displacement of 248.6cc
EXC-R 450 bore and stroke is 95mm x 63.4mm giving a dispacement of 449.3ccPlease note the units, there are no ‘mls’ or even ‘ml’ involved
If you put a 450 piston and head on the 250 without changing the stroke you get 388.59cc
If you put a 450 piston and head, new conrods etc, so that the stroke is the same it will be 449.3 just like the other 450’s.NB:- Values above were based on ’09’ models, older models will have different bores and strokes but the principals are the same.
WELL i’m not one much for book lernin’
but CHEW on THIS moto!
>>>>>>>>>>>>>>>Moto wrote:
Quote:XY – That is exactly what I said in my post? I qouted values in CC. You said ‘mls’ and I corrected you and said ml.ECKS – your post is great, but look at my post that you quoted and you will see I said 388cc??? Why am I worng when I got the smae answer as you?:huh:
Moto wrote:
Quote:If you put a 450 piston and head on the 250 without changing the stroke you get 388.59cc If you put a 450 piston and head, new conrods etc, so that the stroke is the same it will be 449.3 just like the other 450’s.well moto you’re right if working with ’09 specs. but i referred to info i gained in ’06.
here is the info i’m on about
http://www.ktm-parts.com/mm5/merchant.mvc?Screen=PROD&Product_Code=SXS04350000&Category_Code=PPEHConvert your 250 EXC RFS into a fire breathing 350 EXC RFS and enjoy huge torque and power gains. Kit comes complete with piston , cylinder, and gaskets. Fits KTM 250 EXC 03-05 ONLY!
NO Mention of stroke being changed!
So WE are BOTH right!!!
and i put one little S in the wrong place and your all over it thinking you’re the only one that has the correct info:P
Now Admin, ( i assume AKA MOTO trying to be authoritative :silly: :silly: :silly: :silly: )
we are sorted!!!! 👿OH yeah SORRY AB for turning your thread into a bun fight:blush:
>>>>>>>>>>>>>>>Moto wrote:
Quote:, new conrods etc, so that the stroke is the same it will be 449.3 just like the other 450’s.[/quote]
crank too!! just top end and 450 con rod Dose not get you 450 ml!
i think you should take this argument up with your KTM dealer!
did you actually read the part numbers on the web site i linked?
it references KTM part numbers.
>>>>>>>>>>>>>>>>>>>>>>>>>Mr Blue wrote:
Quote:I would very much doubt that a manufacturer such as KTm would make a “one bottom end fits all” setup as husqvarna did this and revolving mass kills the power and response on the smaller revvy motors, I would believe some of the cases are interchangeable, but there is very little market benefit to be gained from this style of engineering, as you can save weight by design to brief or end use. Otherwise a KTM 250excf would weight almost as much as the 450, no advantage there.BTW Moto somewhere in that argument you sounded Austistic, but being literal, both are acceptable reference terms of displacement, bloody anorak :laugh:
BC
yes that could be the case Mr Blue.
however the 250-450-525 weight differences would be accounted for in the extra material needed fro the longer stroke crank, thicker conrod. and counterweights etc.
so the weight difference between them would me minimal. but some difference none the less.
Hausaberg’s 450-550-650 do this too. well the 08 models, were all the same engine cases. just different crank, bore diameter/ length, rod, heads? i’m not sure on. and diff. carb size.
the dealer i go to most said the 03-05 exc 4T’s were the same cases, just diff. internals. the lc4 was the only one that was diff.
Cheers XY, I thought Moto may have done it being a mod :laugh:
Now you guys can thrash it out till the cows come home, by the way Motos not exactly right
AnonymousMr Blue wrote:
Quote:Doesn’t matter anyway bloody 4Ts all just waiting to chuck a valve into a piston anyway, that really dimishes the displacement advantage.The optimum size according to several reliable sources for a single cylinder OHC dirtbike motor is somewhere around the 350CC/ML mark, a tade off between torque/power and revability, such things as harmonic distortion and other characteristics are nicely balanced, sorta like the old 54x54mm 125cc formula.
BC
Yeah, I always went along with thwe premise that 300cc was the best displacement so close enough. Just take a look at Formula 1 engines
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