Forum

[Norm]

If the oil ring moves freely in the groove I would say the piston is ok. Is there any up and down movement in the big end that you can feel. I wouldn't expect so but check anyway If this is all ok back to the valves. You are doing well, any problems just ask, somebody will help

[Norm]

Silly question should have asked earlier, do you have a head gasket?

[PeteF]

You'll need to remove the valves (tool required but it's possible to do it with a big G cramp) If the valves aren't too bad you just need to grind them in. Check the fit in the guides too - should be a sliding fit.

[Riggers]

I hope this tip isn't too late, but it's about methodology. It will be of enormous benefit to you when you come to assembling everything back together if you take it apart properly! Take your time and don't force anything - there's a really annoying saying which is usually true and that's - "If the job is difficult you are doing it wrong". Use the right tool for the job, and as things come apart use your mobile phone to take photos of where everything goes. Keep your work area clean and free from grit and muck, and wash parts off in paraffin, dry with a clean rag and store in a clean box, or tray. If you're undoing a multiple assembly (the valves say) write down the order in which it came apart (it may be obvious to a trained eye but not to a first-timer). When you come to putting everything back together cleanliness is everything. Make sure all your parts have been properly cleaned and are spotless. And then OIL, OIL, OIL!!! Oil the piston, oil the barrel, oil the rings, oil the valves, oil the springs, and oil the rockers - no need to overdo it but the last thing you want after all your hard work is everything running dry until the pump catches up. Finally the thing that we all need, including the finest expert, is a bit of LUCK so I wish to plenty! Cheers. Tony.

[Alan R]

Hi guys--------- OK, I'm probably going to get well and truly CASTIGATED for this --- (please note the spelling as I don't want a falsetto voice at my time of life), but here goes anyway}---- NORDICGLOOM, As you have now already removed the head and barrel I want you to seriously consider purchasing one of our hosts FORGED pistons.. These are now available in Standard Compression Ratio... Both NORM and MIDGE have indicated the very real chance that your OEM piston may well "let-go" of its' crown....Please don't think that I'm scaremongering, NO--not at all but as you have just found out it's not a 5-minute job to get at that piston, so now would be the time to change it...and from this comes the idea that the cylinder bore could benefit from being measured as well ??.............Also, the original Cast Iron valve guides are not all that strong and can break-up in service.... A change to BRONZE ones will give a much longer and trouble-free life, with a stem seal on the inlet helping to reduce oil consumption.........Finally, although you can always measure and re-fit the originals, a NEW set of valve springs would help, given the age and mileage of the bike.................OK, now that I've got your attention, you'll need to measure the height of the lip on top of the barrel and also the depth of the matching recess in the cylinder head OR, alternatively}---Having cleaned them, place the head on top of the barrel and see if the gap between them is SMALLER than the thickness of the new head gasket...It must be smaller otherwise the gasket won't be compressed between them and can't form a gas-tight seal.....HELPFUL TIP}---- You don't need a piston-ring compressor as the bottom, inside lip of the barrel has a very generous taper to gather the rings and compress them when lowering the barrel back onto the engine...... Hope thats given food for thought ??

[Norm]

Getting the rings back in I find a coule of long screwdrivers under the piston holds it steady as you use your fingers and finger nails to ease the rings into the barrel. Somebody else steadying the barrel certainly makes it easier

[Alan R]

Oh NORM, and you with those delicate little pinkies as well !!-------- Have a look at this >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Just me, the screwdriver ----- and a SEXY little wiggle of the barrel----and it's done !!........... I live on my own so there's no one to ask for help anyway, and my fingers are stubby little rascals that still won't do as they're told after these past 64 years or so....................................

[nordicgloom]

thanks Alan R it is certainly food for thought. I have to at least purchase the replacement gaskets for the head so I will see how it all adds up and certainly think about the overhaul while I am at it. As to the cause of the issue, I think SImon had it at burnt valve, I am going to have a crack at the g clamp removal so I can actually get to them, there's certainly a real carbon build up so I guess the reason for it all is I am running rich. There's no up and down in the piston at all so that's pretty nice, I have to try and fit the procedure into the evening and will keep you all posted. Hugenthanks again

[simon]

If the valve is burnt you either need to replace it with a new one (easy and quick) or have it re faced (not so easy and quick) you will grow old and tired trying to lap it in with grinding paste and a suction stick otherwise. If you have a good old fashioned local engine reconditioner he may be able to reface the valve for you but they are cheap as chips from our hosts and you have a nice fresh valve stem too. Take great care when lapping it in that you get a nice even grey finish right around the valve seat and you can test it by filling up the port with water and seeing if there is any seeping. I totally agree with Riggers regarding methodical tidy practice having been a rip-shit&bust type most of my days and having suffered horribly for it. Clean everything scrupulously and don't get grinding pasted where it shouldn't be!
S:)

[simon]

Also do yourself a favour and borrow a proper valve compressor. The simple Terrys ones are the best for Brit singles and they will potentially save you endless frustration the loss of collets and even drastically your eyesight, they can go sproynge in a most uncompromising fashion if not well managed.