piston change

[Tosh]

having done 500+ miles on scoot stage 4 200,spoke to sean about further tuning he said it would be better to change to a better piston ,now having done the engine from new i`e bearings,seals,had to change end plate but thats a diff story and the like.
what is the best way to make sure i get the right piston/rings as in size wise, prob go for asso or other but with two rings then contact sean again if poss

[shocky]

you could try a replacement "mahle" type piston with thin rings like this one http://cgi.ebay.co.uk/LAMBRETTA-GP-200- ... 3ef52af71d
or a slightly more upmarket one like this http://cgi.ebay.co.uk/LAMBRETTA-GP-200C ... 1c0c7934ae
the asso pistons are now aproaching £90 (the AF web site is way out of date)

[shocky]

are you going to go for a rebore ? reason is your piston will be marked + ,++, 0,- these markings are slight under/oversizes of the standard 66mm piston and any replacement piston(yes even an asso) might not have the correct clearance if your under size then thats no prob as you can have it honed to perfection (dont forget to chamfere those port edges ) if the bore is to big then piston slap and possilble cracking of the piston may occure ,
you seem to have a good working/friendly relationship with sean see if he can give you a better idea as to your needs face to face is so much better

[Tosh]

are you going to go for a rebore ? reason is your piston will be marked + ,++, 0,- these markings are slight under/oversizes of the standard 66mm piston and any replacement piston(yes even an asso) might not have the correct clearance if your under size then thats no prob as you can have it honed to perfection (dont forget to chamfere those port edges ) if the bore is to big then piston slap and possilble cracking of the piston may occure ,
you seem to have a good working/friendly relationship with sean see if he can give you a better idea as to your needs face to face is so much better

no not going for rebore just upgrade piston, then ask sean if he can do is stage 4 then also go with what he say`s as in carb/exhaust would like a fast touring set up if pos might ask if he could sort piston

[Andy Pickering]

It seems Mr Bradys gonna be doing a few stage 4s.. How much difference would an upgrade piston make..? I remember back in the 80s a lot using Hepolite pistons which I assume would have been lighter..

[shocky]

its not so much the piston as the rings those fat 2.5 mm ones are cast and will brake on a large port and are not designed to rev very high .tuning usually means more revs the thin rings are usually drawn and are not brittle some can even be tied into a simple knot most are chrome plated as well which means less friction, higher reving pistons have more silicone in them as this absorbes heat and wont expand as much as aluminium so helping to prevent seizures

[sean brady scooters]

better pistons allow better tuning,
as has been said,indian pistons generally have 3, 2.5mm poor quality rings.....
thinner/better quality rings enable the safe use of wider exhaust ports especially,which give more area without shortening the power stroke.....and so help keep a great amount or torque whilst increasing power also which is great for say touring tunes.

i always do this first before raising ports ,and if its for a touring tune on an indian barrel i often leave it at that,
if someone wants a more sporty/race tune ,then the ex port will be raised also........

and dont forget ,increased inlet timing increases revs even though ex ports are NOT raised.......

[joespeed]

you could try a replacement "mahle" type piston with thin rings like this one http://cgi.ebay.co.uk/LAMBRETTA-GP-200- ... 3ef52af71d
or a slightly more upmarket one like this http://cgi.ebay.co.uk/LAMBRETTA-GP-200C ... 1c0c7934ae
the asso pistons are now aproaching £90 (the AF web site is way out of date)

both these pistons are cheap cheap,both quality and price you really need one from mr broadhirst or an af one

[soosh]

Tosh,i have a stage 4 200 with a Mahle piston and its been in there since 02 with the same ringpieces,the guy who did it said it was the best "standard" piston to use and he also went round all the edges and smoothed them off,it looked like a work of art.This has been probably the most reliable motor ive ever had and it does get caned and goes very well.It only uses the 2 top rings.I did try the the Asso (2 ring) piston but it couldnt handle the bore clearance and nipped up but the Mahle has been bullet proof and the rings have handled the exhaust port even though it shouldnt.Unless i was going for an MB piston,id deff use a Mahle again if i had to replace it.When you look down into the piston,you can see its stronger.

[sean brady scooters]

i,m sure bazman ran the mahle piston.............