DT125R ARCHIVE

GADGET · Guru

Just after some Infor on Cylinder

GADGET · Guru

Depends what brand you buy.mitaka are the nuts and are a very good fit (can get for like £35 and they come with rk rings etc very nice ),get the piston first then give that to the machinist who's boring it with the tolerances so they can make it perfect,Ps u could go up 1mm etc but don't unless u have to coz your just makin it harder if it needs to b done in the future,get it measured first then buy the next size up

-- Edited by GADGET on Sunday 17th of June 2012 09:25:45 PM

DTR_NW · DTR Senior Member

so just bought a standard 1998 dtr

can sumone let me know

what size the standard piston is

what the next size up is (also what size will i have to bore it out)

and how much is it ruffly to have it bored and new piston put in thanks in advance guys

DTR_NW · DTR Senior Member

so can you go up 1mm like put a 57mm piston in ??? and how much is a piston kit either 56.25 or 57 if possible ??

GADGET · Guru

Sorry that's a bit confusing

1: have the bore checked 2: buy the size piston kit you need next 3: give that back to the machinist with the piston kit +tolerances so they can do it right 4: make sure they chamfer ports and hone the cylinder 5: rebuild it yourself we'll help you bud(I can walk u thru it if you need ,youll save loads ,it's not hard) 6:MAKE SURE YOU RUN IT IN AFTER

DTR_NW · DTR Senior Member

nice one mate so dont take it to a bike shop to have it bored ?

DTR_NW · DTR Senior Member

the reason i ask is the bike is a fer few years old and i dont know if its ever had a piston change so would it benefit from a 56.25 piston and a rebore or would just a new standard 56mm piston do the job i have little experience in this but i will tackle it my self at some point is it easy to change the piston alone if that is all it needs ?

Cameron · Guru

Check the cylinder first, if there's no damage to it there's no point reboring it.

NORFE · DTR Trusted Engine Builder

Petrol_head wrote:
Check the cylinder first, if there's no damage to it there's no point reboring it.

may not be no damage but it could be well worn you need to measure it to be honest ull need a dial bore guage to get an accurate reading ....

GADGET · Guru

A local engineer will have the gauge,ask him to check if the bore is out of round and by how much this will give you the next size you have to bore it to so that it's round again ,Norfe bang on £25 for a good honest job all day long ,measure,buy piston,give the whole lot to the machinist with the tolerances and 25 notes,buy a yammy head gasket for like 11quid.."sorted

NorDt · Guru

You can have it bored all the way to 58mm. But at 58 mm the piston hits the powervalve. so you have to dremmel it down.

Cameron · Guru

At +1mm it hits the PV, I know lol.