Ring Gaps

laverdakeith said:
 All of that assumes no wear on the bore Cam
Click to expand...

Well, not really. I chose my words carefully. I said "a more typical ring gap of 0.07mm" I didn't say a standard or within spec ring gap. 0.07 is a bit wider than you'd expect in a new installation, so i was assuming a bit of wear.

I agree that a rebore or at least the correct rings would make a better job of it. I guess that's something for Rob to work out with his mate. Would probably come down to the bloke's financial resources and how much responsibility he expects Rob to accept for a less than ideal solution.

BTW, have any of you young whipper-snappers heard of Koethurizing? I used to get it done to worn pistons when I was a young bloke and couldn't afford a re-bore and new pistons. It's basically a process where the piston skirt is shot-peened from the inside to expand it enough to reduce piston to bore clearance. Most often used in conjunction with a light hone to the bore. It was a cheap way of eliminating piston slap and would extend the life of an engine before a re-bore was necessary. It was quite an effective fix but I've not heard of anyone doing it for maybe 40 years. I'm wondering if there are still people around who do it.

Cheers,
Cam

 
Cam it could be because some owners might be lawyers.
I have eye withess reports of a "reputable" rebore shop putting a piston in the vice and squeezing across the gudgeon holes to give it a better fit in the bore they had done with too much clearance.
There are many solutions.
 
No responsibililty what so ever!!! I was the guys only hope of getting it back together in Perth, even though I'm in Walpole. I initiality didn't want to get involved but it ended up on some paintshop floor in an industrial area with the barrels off, broken ring and boxes of nuts and bolts, shims, lots of small bits missing etc. Couldn't bare to see the motor end up in another idiots hands. Given the unknown history and the condition I got it in I wash my hands of any future problems. I'm only reassembling. The bike will only ever get ridden to and from the office occasionally. I'm going to get 1 set of 2nd o/s rings and put it back together.
I'll check the cam timing while I'm at it. It'll be a good practice run for when I dial in my cams  :D

Ahh the piranha brothers, and only one post apart!! Good to see you surface piranha junior :D
 
you could have have an inch gap on the rings and it would not make any differance,there was a test done some years ago to even biger gaps it made no differance,i kid you not. :-\ :-\ :-\ :-\ :-\
 
for old Chev engines say from early 60`s when I was buying and driving a succession of low cost beaters in the early 70`s rather than a rebore and new pistons we used to use the old piston in a vice trick, squeeze the suckers hard then bang on a new set of the cheapest rings available, I still have my bore piston ring ridge cutter around here somewhere.... The other thing to try was to turn the piston face down, get a big hammer, and drive an appropriate sized large socket (just slightly too big to fit) into the skirt to spread it, if it didn`t break you were good to go, and if you made it too big to stuff in the bore, a file could quickly cure that....

Used to work surprisingly well, with the reprofiled (okay, bent) pistons the motors would then outlast the rest of the worn out car, cheap effective but mechanically brutal....... I have also seen the trick of knurling the piston skirts to expand the effective diameter of the piston in the worn out bore, but never heard of Koethurizing, I probably would have given it a try if I had known about it, sounds like it could be quite effective, especially if new oversize pistons were not necessarily readily available as was often the case :D

Paul LeClair
 
That piston in the vise trick would have saved me lots of time on the old forklift engine I was charged to overhaul about 38yrs. ago. I was told to use a center punch on the skirts to knurl/raise material up to tighten the fit.It worked pretty well,in spite of the boss hammering in the cam with a 3lb. adjustment tool.
 
Sorry Rob I apologize to you mate for stealing your thread and I hope you get your piston rings issue sorted, but

              Note to Piranha Brother 2,   where is my f.....g Technics turntable and speakers?  I came back to the house in Subiaco 4 years later to collect them and you had moved, typical.
                         I suppose you are still riding that old SF, you used to be quite quick on that thing but now it is old and so are you.
                   The Technics like the SF is vintage now but both sound good eh! Still enjoying them both? Still banging the bongos are you
                                                       Cheers Dave  PS welcome to the site.
 
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