measuring pistons

[twostroker]

after stripping my mk2 125lc ive noticed the piston has been heavily modified,the 2 oval holes on the inlet side have been machined out huge.im not sure if this is a good or bad thing but ive been advised it will probaly crack and cause piston faileur so im going to replace wiht a std one.
problem is i dont know how much it has been rebored by is there any marking so i know how oversize it is?

[mellow]

usually it will have an "s" on top or nothin if standard.if bigger piston i think it has .5 etc on top

[scott]

take the barrel to the place where ur gettin the piston from m8 and they'll measure it.or u need the special measureing thingy-ma-bob

[mellow]

thingymajig

[scott]

NO i think u'll find it's a thingy-ma-bob

[twostroker]

i was going to order one from norbo,if i cant find any markings it will have to be the local bike dealer

[mellow]

do he sell thingymajigs then

[twostroker]

ive herd he does a complete range of thingmejigs

[scott]

THING-MA-BOBS

[mellow]

;D

[twostroker]

theres a "every thing for £1 type shop" full of useless junk round this way called thing~me~bobs ;D

[twostroker]

i took my barrel to the local yam dealer to gat measured which involved leaving it with them for a few days.
they phoned me today and said bad news its been rebored between 1.25mm and 1.5mm so they cant supply me a new piston unless i get it bored to 1.5mm oversize,as its been bored out by 1.4mm .
what i dont get is the old piston(with modded piston skirt) fitted fine.they also said that i will have to get the rebore done my self then go back for a 1.5mm oversize piston.
does this sound believable of am i being ripped off?seems a shame to get a perfectly good barrel rebored

[jacobeana]

twostroker said:

i took my barrel to the local yam dealer to gat measured which involved leaving it with them for a few days.
they phoned me today and said bad news its been rebored between 1.25mm and 1.5mm so they cant supply me a new piston unless i get it bored to 1.5mm oversize,as its been bored out by 1.4mm .
what i dont get is the old piston(with modded piston skirt) fitted fine.they also said that i will have to get the rebore done my self then go back for a 1.5mm oversize piston.
does this sound believable of am i being ripped off?seems a shame to get a perfectly good barrel rebored

Sounds like a load of bollocks to me if they have measured the bore they should be able to tell you the exact size why not post a pic of the piston so we can see the hole size as it may not be a problem, also if the piston has been tuned the barrell could be

I would go to a local engineering company and ask them to measure with a vernier to get the correct size

[twostroker]

i think its a load of bollox too,the lad who spoke to me is 17 and doesnt appear to know his ass from his elbow
i will take it to a mate of mine whos a welder/fabricator for a measure up tomorow.
i havent got a digi camera at the mo so i cant post up a picture.
in comparison to pictures in the haynes manual my piston has the 2 holes in the back enlarged by around 2mm each hole.
the barrel is defenetly standard.
if any bodys got a standard 125lc piston could they measure the 2 holes in the back please so i can compare the measurements to mine?

[pablo]

last rebore i got done,the guy needed the piston before he could bore the cylinder

[racerd]

when had my barrel re bored over size done the bike shop supplied the right size piston for the re bore i said 1mm over size but the machine shop said the bore needed to be 1.50mm because of a few scores and this was the only way to get rid of them was by going out that extra 0.50mm over size,
that shop is talking crap there is no way you can get a rebore with out the piston, they bore it out to nearly the right size then hone the bore to the proper spec for the piston kit you are using

[billbott]

Feb 27, 2007 19:09:24 GMT 1 twostroker said:

i took my barrel to the local yam dealer to gat measured which involved leaving it with them for a few days.
they phoned me today and said bad news its been rebored between 1.25mm and 1.5mm so they cant supply me a new piston unless i get it bored to 1.5mm oversize,as its been bored out by 1.4mm .
what i dont get is the old piston(with modded piston skirt) fitted fine.they also said that i will have to get the rebore done my self then go back for a 1.5mm oversize piston.
does this sound believable of am i being ripped off?seems a shame to get a perfectly good barrel rebored

That is total bollocks.
1. If it takes a couple of days to measure a bore, they really don't know what they're doing. I measure and draw things for a living.
2. Bored out to 1.4mm - thats funny - piston sizes are in increments of 0.25mm
3. Get it bored and go back for a piston? Most shops bore to SUIT a piston (as said before)

Where are you - if you are local i will gladly measure it up for you - shouldn't take me more than a day ;D

[racerd]

Feb 27, 2007 22:09:19 GMT 1 twostroker said:

i think its a load of bollox too,the lad who spoke to me is 17 and doesnt appear to know his ass from his elbow
i will take it to a mate of mine whos a welder/fabricator for a measure up tomorow.
i havent got a digi camera at the mo so i cant post up a picture.
in comparison to pictures in the haynes manual my piston has the 2 holes in the back enlarged by around 2mm each hole.
the barrel is defenetly standard.
if any bodys got a standard 125lc piston could they measure the 2 holes in the back please so i can compare the measurements to mine?

i have got a 2mm over size standard lc piston the windows are 24mm wide and 26mm high both windows and also there are no oil holes for the gudgeon pin also the inlet windows on the piston are slightly
tapered from the out side to the inside