Did a little bit of a refresh on the old GS a few weeks ago. She was running really well but starting to use a bit of oil, with smoke obvious when booting it. So thought I ought to do the obvious, change valve seals and check rings. Really enjoyed taking the top end apart, but it was a real struggle to get the head off the block. The block shifted first so I had to resort to careful prying with my trusty 3' tyre levers. Took ages and a lot of sweat! But once you see that little gap open, you know you have it beat! Gentle nagging got there in the end.
Anyway, all exhaust seats were pitted but the seals looked fine. Replaced with IMD Japanese seals anyway and reseated all valves, best I could. They passed my leak test, so I was happy. I think the previous owners forgot to do valve clearance as when I got it, there was no clearance at all on most exhaust valves.
With the cylinder removed, I removed all pistons. I checked bore dimension as per Suzuki workshop manual and they were all well within tolerance. As were pistons. No gummed rings and they all measured like new. I thought the best thing to do was put it all back together and hope the smoking was cured by old seals.
Did a quick hone on the bores with me 3-stone springy thing and they all looked good. Checked bore dimension again, just to make sure, all good.
Pistons back on, barrel back on. Tried some homemade ring compressors but rubbish, so just used my fingers to feed the rings in. Not too bad, but then noticed first skoolboy error. Barrels on back to front. Brilliant. So, off they came and second go went a bit quicker.
Head back on and then fitted some newly acquired GS1000S cams (exactly the same as E cams) as one of my intake lobes was a bit under spec. Once they were in, I could shim it. Had to order a few smaller sizes to get them all good. I set them all to the top of the spec as they will only go one way!
All torqued up. Ready to fire. Starts straight away and sounds lovely.
Took her for a little spin and it rides great too. Let it cool down overnight and then re-torque head (got an extra quarter turn on all nuts) and check valve clearance still good. Now off for a good thrash to see where we are with the smokiness. Bit disappointed to be told by a mate that it was still smoking.
Resigned myself to either fitting new standard rings or going the whole hog and getting a rebore and next oversize pistons/rings, but, I thought I would just ride it for a bit and see what happens. After 200 miles, I don't seem to be using oil, so the old rings may have bedded into the honed bore. Maybe I won't have to split the engine again? I'll keep my eye on it.
When checking out why it might still be smoking, I saw vids of engine builders recommending fitting barrels dry. That seems odd to me but they were claiming that oiling the bores was not good practice. Can that be right? I smeared oil over the bores and coated the rings and pistons but maybe this is wrong?
I also discovered that you should always fit new rings if you hone. I didn't want to replace mine as they were all so well in spec. Should I have left the bore semi-glazed?
Anyway, I don't mind the thought of sending the block to IMD and fit their piston kit, but I would be happier to keep the original pistons if they bed in OK.
