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cota piston exc 250

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Salut

 

Voi ce cota ati folosit pt primul piston schimbat la exc 250/300? A sau B?

 

Pt 250 unele situri dau acelasi piston pt anii 2004-2014, altele nu, cum e pana la urma? e acelasi?

 

Mai am 30 de ore pana la 100 si ma gandeam sa il schimb

Edited by red

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EXC-F250 07-13 4T este un piston

EXC-F250 2014 4T alt piston

EXC250 00-05 2T alt piston

 

:peace:

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2T?

Diferenta intre pistonul pe care il pui si cilindru trebuie sa fie de 4 sutimi pentru un 250 2T. Masoara cu un micrometru de interior cilindrul tau, uita-te ce inseamna la pistoane cota A si cota B si vei sti ce sa iei.

Edited by mircea.cazachevici

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merci Mircea, vroiam sa stiu din experienta celor ce au schimbat pt prima oara pistonul la exc 250/300 2t

 

e mai complicat cu micrometrul, pt ca nu il am :)

 

unii zic sa merg pe cota A la primul piston chiar si la al doilea

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Cota A la primul schimb si la mine (la Husqvarna, dar e aceiasi chestie).

Micrometru de interior nici marile service-uri nu au. Eu am gasit la un atelier mecanic, in spate la United Motors (intrii la United, intrebi la service si te ghideaza ei). Si mai gasesti la TNG, in Ciolpani.

Edited by mircea.cazachevici

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la al 2-lea schimb ai putea sa mergi tot pe A , mai ales ca il schimbi la 100 de ore , daca l-ai schimba pe la 150 de ore ai putea sa treci pe B , dar cel mai bine este sa masori

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eu am pus cota A la 135h, acum am 205 si e f ok,

totusi , urmatorul nici eu nu stiu ce sa pun, A sau B

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Salut

 

Aurel la tine e clar, la urmatorul schimb pui cota B, o sa fie al treilea piston

 

Eu tot stau si ma gandesc ce sa aleg, oricum mai am mult pana la 150 de ore

 

Ted m-am uitat in link uk de mai sus si e adevarat ca se recomanda sa fie B dupa 60 de ore

 

Acum tine si de cum e exploatat motorul, in cazul meu e hoby 100 % si doua ore in we :)

Edited by red

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Greu sa te duci la cineva sa-ti masoare, nu? Dai 30 lei si stii sigur. E mai simplu sa faci un sondaj de opinie, cine si cum a pus.....

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Eu, pe unde am fost sau am intrebat, mi s-a zis ca nu au micrometru de interior. Poti sa ne zici la cine putem masura cilindrul?

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In general nu se masoara cu micrometrul. Micrometrul se foloseste pt a calibra un ceas comparator, insa unii mai folosesc micrometre in 3 puncte ( cu 3 picioare)

Edited by DanKTM

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Salut si La multi ani,

 

In nebunia cautarilor pe acelasi subiect.. trebuie sa imi schimb si eu pistonul acum, am gasit cele de mai jos. Poate va ajuta.

 

*sursa: http://www.motoxparts.co.nz/p/ktm-250-exc-piston-kit-wossner (tabul SPECS)

 

"

What size piston grade (A,B,C) would be advise able to fit to a used 2-stroke cylinder that is in good condition. It’s not hard to work out.

98% of the time a piston the same size, .01mm smaller or .01mm larger than the one that has been removed from the engine will work fine, as long as the cylinder bore is in good condition. (Read above what .01mm measurement is)

Cylinder bores wear mostly right at the top at (ring wear). So over 80-90% the bore is normally unworn, this is where installing a too large of a piston to may course a problem (going from a A to a C) as it may decrease the piston to bore clearance in 80-90% of the bore below the minimum clearance required. What normally happens if a to large pitson is fitted the piston will lock/seize in the cylinder bore due to insufficient piston to bore clearance. It is better to have a bit more piston to bore clearance (-.01mm) than to have to less, as having to less the piston will seize in the cylinder and that is not good as it will destory the cylinder. That should be a no brainer when you think about!

So the answer to what size should I purchase to install in my used cylinder? Is very simple - Any one from 1-2-3 below will be work fine (as long as the cylinder bore in good condition that is)

1 - The same size the piston that was removed will be fine

2- Piston that is .01mm larger = lets say the old piston was 66.35mm, than a 66.36mm piston will be fine in most cases. (say 66.35mm is a A size piston, you can use a B size 66.36mm)

3- Piston that is .01mm smaller = lets say the old piston was 66.35mm, than a 66.34mm will be fine. (say 66.35mm is a B size piston, you can use a A size 66.34mm)

Note: piston grades go up in .01mm, most pistons A is the smallest grade, than B is only .01mm larger, and than C is .01mm larger than B.

We could go on and on about piston to bore clearance, but above is all you basically need to know about selecting a piston. We try to make it easy for all to understand and not make out it is harder than what it is, some people like to make it is a big job but it is not at all.

Two strokes have old long style piston skirts so .01 of a mm makes no different to performance, piston to bore noise or how long the piston will last. I know I used to grade piston to bore clearances and machine cylinders every day for 25 years. So I do know what I’m talking about.

"

 

La mine e al 3-lea piston (nou, cota A, si acum al 3-lea).

Initial eram decis sa iau cota B, gasind pe foarte multe platforme recomandarea asta pentru motoare cu 50h + ... (a mea are 146h, primul piston schimbat la 80h). Acum parca as merge tot pe cota A.

 

Banuind ca sunt destui ce s-au mai lovit de "problema" asta, va multumesc pentru opinie :)

 

Sa ne auzim cu bine in noul an !

 

Vlad

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salut,

eu am decis, a mea are 86 de ore de cand am schimbat pistonul si cilindrul, pistonul o sa il schimb la 150 de ore si merg tot pe cota A

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ceas comparator, dar cum rezultatul e cam acelas mereu poti pune A la primul schimb si B,C la urmatoarele. uzura pe un ciclu este cam de 0.25mm/diametru. exista producatori care merg din 0.5 in 0.5 si altii care merg din 0.25 in 0.25. astfel te poti orienta in functie de ce ai nevoie. groso modo poti masura si cu o lera + pistonul vechi.

cota A este oricum mai mare decat cota 0, aceasta o poti cumpara odata cu kitul de reparatie cilindru.

uzura pistonului depinde foarte tare si de regimul de exploatare. daca motorul a fost incins de multe ori sau a mers fregvent in ture mari uzure este accentuata si vei avea nevoie de cota B, daca regimul de exploatare a fost unul normal (fara prea mult omor, numa asa, oleaca, de control) poti pune cota A. cam asta e criteriul dupa care ar trebui sa te ghidezi daca nu ai cum sa masori cilindrul.

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Si vreo ierarhie a firmelor de pistoane? OEM, Wossner, Prox, Athena?

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Traiasca nenea Jumba. Multumesc ! Asta era sfatul pe care-l cautam :)

 

ceas comparator, dar cum rezultatul e cam acelas mereu poti pune A la primul schimb si B,C la urmatoarele. uzura pe un ciclu este cam de 0.25mm/diametru. exista producatori care merg din 0.5 in 0.5 si altii care merg din 0.25 in 0.25. astfel te poti orienta in functie de ce ai nevoie. groso modo poti masura si cu o lera + pistonul vechi.

cota A este oricum mai mare decat cota 0, aceasta o poti cumpara odata cu kitul de reparatie cilindru.

uzura pistonului depinde foarte tare si de regimul de exploatare. daca motorul a fost incins de multe ori sau a mers fregvent in ture mari uzure este accentuata si vei avea nevoie de cota B, daca regimul de exploatare a fost unul normal (fara prea mult omor, numa asa, oleaca, de control) poti pune cota A. cam asta e criteriul dupa care ar trebui sa te ghidezi daca nu ai cum sa masori cilindrul.

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