Valve Stem Seal Replacement Without Removing Head

What were your compression readings and whats the PSI range for your bike?

As said, be more concerned about the cleanliness of the mating surfaces between block and head etc. For cleaning I'd use a rag for a initial wipe over then some Scotchbrite pads (or similar scouring pads) combined with WD40 (or a similar product) and gently clean the surfaces ensuring you are not to agressive. Once done check surfaces with a straight edge.

Check the piston to bore clearances and put petrol in the ports to check valve sealing. Clean everything to a high polish.

Cheers, all

It’s rough as ass on top of the pistons, with burnt on deposits. And the valves are very sore.

I have used carb cleaner and WD40 for the most part, and getting there.

I gave up on the pistons since it started hailing, despite the met office saying <5% chance of rain. Well, hail isn’t rain...

Here’s the so far;

Still cleaning...

Your doing well

Its looking less scary

Put each valve in the valve guide with about 25mmabove the seat. Wiggle valve side to side in the guide to check for ovality. Tolerance will be in manual.

I finished one valve. Re-seated, lapped with coarse and fine grit, new stem seal, and put back.

Those retainer pins are a nightmare.

I am too hungry and tired to continue more.

Gimme a bell when you have time mate.

Remember to clean the grinding paste off ... don't leave any it will have fun on the cyclinder bores !

Looks good matey!

Gimme a bell when you have time mate.

Cheers, mate. Tomorrow evening ok for you?

Only done one valve, due to already being totally knackered. The first was only a faff because of being my first. I popped my valve cherry . I feel like a real biker, now.

I'm going to buy some more stem seals. I only ordered four, just to be a cheapskate. But, if a job is worth doing, it's worth doing right.

Yeah, after, 2000 tomorrow.

I have a machine for lapping valves in.

What were your compression readings and whats the PSI range for your bike?

From what I remember, 1=165, 2=190, 3=170 just before I took it apart.

Something like that. But, no idea what they're supposed to be, until I can find that pesky Haynes book.

What were your compression readings and whats the PSI range for your bike?

 

From what I remember, 1=165, 2=190, 3=170 just before I took it apart.

Something like that. But, no idea what they're supposed to be, until I can find that pesky Haynes book.

I did search and I think 170 psi is what its supposed to be lowest

If one was below that your bike will run a bit "funky" when its cold.....until the heat expands the parts a bit and then seals properly

Its happened to me

And best to replace all the seals or you could be doing the same job twice

One like this.

Couple of points.

Why don't you strip all the valves out,lap in one at a time and give a final clean then reassemble?

Keep all the parts in order to where they come from.

The lapping paste can spread around and get under the valves just have just put back in and cause wear later.

Be careful when handling the valves you don't transfer any paste onto the stem.

Are you able to check the run out or bend of the valves?

Trying to lap a bent valve is futile.

Can you get anyone to do a vacuum test on the seats once lapped?An engine recon place can help with this.

Failing that,some engineers blue can show up any dodgy seats.

When reinstalling the collets,use a pair of tweezers or stick then to a small screwdriver with a bit of grease.They can be fiddly little jokers.

When cleaning the top of the barrels,be mindful of any dirt,old gasket or bits of scotchbrite dropping down the side of the piston.

I have send Sprint Manufacturing another email. This will be the third lot of bits I have ordered from them. Need another 8 valve seals.

I also need to find suitable exhaust studs and bolts.

The carbon is so thick on top of pistons 2 and 3 that it took me a long while to reduce it, even a small amount. There is still around 1mm thickness on top. I have to spend more time on it, outside. I am particularly worried about getting any material down the sides of the pistons, or in the coolant gulley. It is going to be a "approach with care" job, all the way through.

I sprayed a lot of WD40 on top of the pistons during cleaning, and am definitely flushing out the oil when it is patched up.

That head gasket looks to have been leaking, with earlier photos showing rust deposits around where the gasket had sat.

Hopefully, none of the valves are bent. I did a valve clearance check a couple of months ago, which proved that the clearances were well in spec.

I have had the bike ten months and so far;

- Paid £180 for a mechanic to do an oil and filter change, and change the plugs. I didn't think I had the skill to work on the bike, at that time.

- Had both tyres replaced.

- Diagnosed a burnt stator and replaced it.

- Replaced the fuel pump.

- Checked valve clearances.

- Repaired broken wiring to fuel sender.

- Renewed coolant.

- Oil and filter change.

- New spark plugs.

Now, I have done all this!

I will hopefully have a chance to do the rest of the valves tonight.

- All valves are coming out, being checked, scrubbed, re-seated and lapped, with new seals. One by one.

And, to think - the mechanic I first visited thought that the compression ring missing from plug 1 was to blame...

After a good long chat with megawatt the other night, I now have a methodical and logical process mapped out, on how I am going to get this job done.

I had already assumed a few things, for example, lapping valves only taking a few minutes, when it takes time to make sure everything is sealed correctly. And, tips on techniques that I would never have thought of, without countless years of experience.

I have a lot of food for thought and a lot of reassurances on things that I thought were going to be a major problem. It really helps having advice from someone with such knowledge and skill.

If you ask a shop mechanic for advice, you will be very lucky to get it, and even luckier to get advice as good as what I have been given.

So, big, big thanks to megawatt for once again helping me out. Your expertise is greatly valued!

Bring on the weekend for some more oily fun.

Happy Saturday, bikers and pretend bikers. Only kidding. I know everyone in this forum is a true biker...

After a hard graft of a day, me and my lady have both got all six exhaust valves done.

She did two, replaces seals, lapped and seated in, even grinded off the carbon, and cleaned the ports out, on one cylinder.

For someone who had no idea about engines before she met me, she’s picking it up faster than I ever did.

Those collets were right gits, but I managed to get my technique by the last couple, and was getting through a lot faster than the first.

I made a crude lapping tool out of a stick, mini plunger, and screw, powered by electric drill.

All in all, really pleased with how it went.

Tomorrow will be the intake valves, which hopefully will be much nicer to work on...

beer time!

You're doing great but if you have come this far have you considered going a little further and removing the barrels and pistons ? Imagine doing all this work only to discover that you have cracked rings or scored bores. Just a thought.

Good prompt.

...have you considered going a little further and removing the barrels and pistons ?

YouTube time! No idea what I’m doing, there. That is a very good prompt, indeed.

I need to get a torch down the walls of the pistons to check, and try a feeler gauge down the sides.

To date, I have only focused all of my attention to the valves and cylinder head.

The bores in 2 and 3 could be inspected, as I left it at TDC.

The cylinder walls were mildly scored.

Should I drop the crank half out and get it on a bench? This is a good job to drop me in the deep end, with a huge learning curve.

The cylinder walls were mildly scored.

 

Make sure you dont mistake cross hatch for scoring

Make sure you dont mistake cross hatch for scoring

There were a few very noticeable vertical scores in 2.

What really worried me, is that around the shim bucket, on the second valve for cylinder 2 has major scoring. The bucket was fine...