125cc 4 stroke valve stem seals

Morning all,

I was wondering if anyone had a guide on how to replace the valve stem oil seals on a 125cc 4 stroke.

Mine is smoking a lot on start up and I need to replace them. the bike I have is a tw125 but I would imagine a guide/diy on another bike with the same size engine wont be too different.

thanks in advance

darren

Remove head, cam and valves. Pull seals off with long nose pliers. Push new seals on with a thumb. While head stripped, have valve seats and valve faces refaced for more power. Clean ports with rotary wire brushes. Easy job. Where are you based?

Hi,

make sure you Lube them well.........put them on Dry and they wont last five min

thanks for the replies guys.

I don't suppose anyone has a step by step guide on this do they? im mechanically minded when it comes to cars so wont have any issues doing the job myself but with motorbikes I don't really know where to start.

thanks

darren

Ive just done this job on my bike .....took me 4 hours .(with head off and on desk).JUST removing valves and adding new seals.....but that was with 16 valves

A single cylinder (2 valve??) will be fast and easy compared

You are gonna need a valve spring compressor and valve grinding kit...........you will be able to get away without grinding valves BUT

as said it will increase your compression sealing and directly increase power IF its needed to be done...........and seeing the age of your bike I would say you will benefit from it

you Will need timing instructions ....haynes will have all the info you need

(if you feel resistance when turning over engine by hand STOP and recheck timing)

you "May" need a fresh head gasket.....Again a good clean and possibly a light spray of copper coat will probably work Ok on a 125

If you decide to change head gasket look to see if Cometic do one for your bike......this will increase your compression a tad....again = more power

The Key is Patience and NOT rushing anything

Oh and you will need a Torque Wrench to get the head studs to the right Lb's

Again that info will be in a haynes manual

hi all,

Got all the bits needed for this now. in a previous comment it was mentioned to make sure they are lubbed up well.

do you mean the oil seals or the valve stems or both?

Thanks in advance

darren

Put a drop of oil on the valve stem before you slide it into the guide. It won't stay there long anyway.

going to tackle this tomorrow,

just another quick and possibly stupid question.

Am I worth while removing the left side crankshaft case when I do this and also if I do remove it do I need to drain the oil?

thanks

darren

Why?

Why?

He doesn't know that's why he is asking!

just thought it may be easier seeing the full crank when re-timing the engine.

just another quick and possibly stupid question.

Am I worth while removing the left side crankshaft case when I do this and also if I do remove it do I need to drain the oil?

thanks

darren

There aren't any stupid questions, just verification to put your mind at rest.......nothing wrong in that

Dont you have a window (inspection cover) that removes so you can get to a bolt/nut connected to the crank that you turn to get TDC?

Cant say about Oil but it wont take more than a few minutes to drain it anyway

Do you have all the info on doing it?

I print out what I need and keep it in a plastic sleeved folder.....which is turning into a Book Now

Torque specs,

Head Bolt Torquing Sequence,

Cam Sprocket Markings,

Valve Timing adjustment,

Do you have to drop engine or Tilt it forward?

TIP:- Do the "work" in your head first, then do same in your head backwards before you even pick up a tool

Its instantly going to be a LOT easier than a 4 cylinder liquid cooled engine so thats good already

There is also a TW owners forum that will be a lot more knowledgeable about your engine at

www.tw200forum.com

You will def need head bolt torque setting because they are more likely to be TTY bolts and over doing them will make them stretch and need replacing

TTY= Torque to Yeild ....meaning they stretch when they hit their limit

I asked why because theres not usually anything useful on the left hand side/alternator end of the crankshaft. You can use the large nut and timing marks on the right hand end of the crank to do what you need to do.

I asked why because theres not usually anything useful on the left hand side/alternator end of the crankshaft. You can use the large nut and timing marks on the right hand end of the crank to do what you need to do.

The following is said in a nice way!

If you'd put that in your first post it might have been more helpful

well I tackled this job yesterday.

Had a bit of a nightmare as I couldn't figure out how to remove the tappets(not sure if that's what they are called), because I couldn't remove these I couldn't get the springs out so I had to replace the valve seals with the springs in place which was a right pain!!

Good Job!

Is it all back together yet?

all back together mate and I took it round the block lastnight.

seems fine however need to give it a proper run and check for any leaks.

Excellent!

Well Done mate!

Feels good when you do a job a garage would charge an arm and a leg for and take 2 weeks to fit in dosnt it

it does mate. ive always done all my own work on my cars, ive done every job you can think of but when it comes to bikes im a complete novice. fingers crossed all is okay with it haha.

Well done..

Remove the valve springs and collects with a valve spring clamp and tweasers or a magnet. An easy job and rewarding.

i couldn't get the springs out mate. they were stopped by the tappets bit(I really don't know what its called, its the little arm that holds the screw for adjusting the valves.

So how did you get the Collets out!!! if you couldn't remove rocker arms! you would have had to compress springs, surely to remove collets and spring top to remove valve stem seal?

i was able to compress the spring so I could get the collets out but then I couldn't remove the spring because of the rocker arm so I had to somehow remove the seals with the arm and springs still in place.