wanted - moto giro bike

Canuck750 said:
Interesting Gilera Paul. I found this 106SS near Edmonton a couple years ago, didn't reallly want it but it was cheap and I was able to find most everything I needed for it in Italy. This one has no Sears tags on it and was originally yellow / black, I don't have any history on it so no idea if it was a Seras or not but I refinished it as a Sears type. The engine cases on the bike were original hammer tone silver, refinished them to match, looks like the same seat as you found (also form Italy).




I am building a 61 Ala Verde 250 for my Giro bike, I hope to get to Nakusp one day for the Giro hill climb.



Also building a Benelli 200 Sprite (Motobi), may get this one done first



If you ever get up to Edmonton give me a shout
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great to hear from you. I will send you a note through the personal messaging to exchange direct personal contact info. You have had much better luck finding older small displacement bikes than I have, I advertised on Kijii for months which finally turned up the 57 Gilera 150. Many of the Gilera parts I have been getting from Italy, but some from the UK, some from the USA. Your Aeramachi(sp?)/Harley Ala Verde 250 will be a great Moto Giro entrant, I would have loved to find one of those, around 16? hp compared to the Gilera's roaring 7hp. Are you coming this year, mid Spetember 2022 in Nakusp British Columbia.
 
Hi Paul

I keep meaning to get to Nakusp for the Giro event but every year I seem to be out of the country or tied up that weekend. I hope to get to the Hands Held rally near Drumheller this summer, Christian Gordon tells me is going to organize the event on behalf of his father this year. Thinking of taking my 72 Benelli 175 for that ride or my 48 Airone.
My Aermacchi is a bitsa, 66 Sprint frame, 65 Sprint 250 motor, Ala Verde tank and seat, 61 Ala Azzura 17" front end, 17" Sprint rear wheel.
 
PIston ring measurements - measuring as best I can

the rings provided with the new piston result in a ring end gap of roughly 3.5 mm with the new rings in the newly machined bore, when I am looking for around 0.25 mm for top two rings and around 0.20 mm for the two oil control rings. Ring gap is way too big to be useable.

new piston measures pretty much exactly 61.20 mm.

fresh bore measures pretty much 61.26 mm

machinist says he clearanced piston to bore by .0025 inch, which converts to .06 mm, so my piston and bore measurements must be pretty close.

all piston rings grooves measure 2.7 mm "deep" into the piston

the top two rings and ring grooves measure almost exactly 2.0 mm thick top to bottom

the lower two oil control rings and ring grooves measure almost exactly 3.0 mm thick top to bottom

now I don't know what to do with the measurements........:eek::eek::cautious::cautious:

found all kinds of purveyors of piston rings online but no idea how to figure out what to order. Help?
 

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Find a ring manufacturer somewhere in Canada or USA and give them all that info. They should be able to find you a set of rings. The rings don't have to be made for your precise bore of 61.26mm. 2.441" (62mm) seems to be a common size. The slightly larger bore spec just means you'll have to trim a bit off the end of the rings with a grinder to get the correct gap in your cylinder bore.

Not sure I'd bother with the bottom oil ring though. Most engines these days only use one oil ring above the gudgeon pin.
Leaving the bottom oil ring out will provide better lubrication to the pressure faces of the piston skirt. If it was my bike I'd leave the bottom oil ring out and see how it goes. I'd only put it in if the bike has smoke billowing from the exhaust.
 
The 2mm thick rings are the problem. It's an obsolete width. As Cam suggests, go through a manufacturer and see what they suggest.
Local to me an importer also has a line of cast iron rings for vintage/agricultural/small engines which are made here. I've used their cast iron rings more than once on oddball stuff for which nothing else is available. Wouldn't surprise me if there's a similar supplier over there.
Might be worth asking agricultural parts suppliers or the vintage machinery guys who they use.
 
GregT said:
The 2mm thick rings are the problem. It's an obsolete width. As Cam suggests, go through a manufacturer and see what they suggest.
Local to me an importer also has a line of cast iron rings for vintage/agricultural/small engines which are made here. I've used their cast iron rings more than once on oddball stuff for which nothing else is available. Wouldn't surprise me if there's a similar supplier over there.
Might be worth asking agricultural parts suppliers or the vintage machinery guys who they use.
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Also piston air compressor spares may come up with something too.
 
2mm rings can't be that hard to find. The first place I looked was Hastings in USA, and they list them.

Hastings Piston Rings – Piston Rings Manufacturer | Made in the USA

www.hastingspistonrings.com www.hastingspistonrings.com

I went to their diametrical list and found 2.441" rings x 2mm thick. Not sure what the numbers after the thickness mean (eg. 102, 362). Probably identify the style of ring such as a bevel on the inner edge, stepped, or whatever. I note that the listing is a set for a 4 cylinder engine with 4mm oil rings, but if you tell them what you need they should be able to rummage around and put together a kit for your piston.

Hastings Piston Rings – Piston Rings Manufacturer | Made in the USA

www.hastingspistonrings.com www.hastingspistonrings.com
hastings rings.JPG
 
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thanks for the replies. Weird world of piston rings where bore size is in inches, ring thickness is either in mm or Imperial fractions, often in same piston ring description. Add to that trying to find rings for a single cylinder.....

For now, as backstop a few minutes ago I just bought a Dinamin piston from Italy, looks like same era and similar piston design with four rings, seller does not know what the piston is intended for (and thus cheap except for shipping), but it comes with all four rings and is 62.8 mm diameter. Supposed to be here International Shipping by April 11, 2022. As same era of piston and same brand hopefully the rings are correct other than needing a bit of trimming for proper gap.

am still going to continue to try and find rings from a north american based supplier in proper size if I can figure it out.

in other news, painter has delayed, again, asking for more time.... what am I going to say, no I am coming to get the parts even if not finished..... Frame and all other parts have been with painter since January 2, 2022, pushing ten weeks now on an original promise of 6 to 8 weeks.:rolleyes::rolleyes::(:(
 
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2-stroke rings will will have the cut-outs in the ends for the ring locating pegs. But you'll have to file about 2.3mm off the ends of a 62mm ring to get it to fit your 61.26 bore, so the peg cut-outs will disappear.

I reckon you could get away with your existing oil rings. The end gap is more important for compression rings than for oil rings. Even with compression rings it's not overly important. A 3.5mm end gap is less than 2% of the piston circumference, so it'll scrape 98% of the oil off the cylinder walls. The remaining 2% will serve as upper cylinder lube. :)

If you use both oil rings, the chance of the end gaps lining up is negligible so you'll scrape almost all of the cylinder walls. I say "almost" because the lower ring doesn't travel all the way up the bore.
 
painters wife texted today Friday March 11, 2022 saying all paint work will be ready for pick up afternoon of Sunday March 13, 2022, we'll see. has postponed pickup several times now. Going to clean up the tools and work bench and garage generally in anticpation of possibly being soon able to begin assembly, needs to be cleaned up and organized anyway......;)
 
Sunday evening. I have a clean and organized garage and no painted Gilera parts. Not “perfect” enough yet apparently. Painters wife texted half a dozen times today that painter still working on everything then a final text that not available for pickup today. Not really that big a deal but these repeated failures to deliver are becoming a bit trying…
 
killing time waiting on the painter, garage is clean, now working on small misc bits, cleaning the used chrome header pipe, etc.. I also added several more holes to the exhaust pipe where it sticks inside the muffler

One of the vintage bike group guys referred me to a Calgary based brake shop called Fleet Brake, looks like a big operation. When I called them today the guy I talked to says no problem, they do lots of old bike stuff, shouldn't be a problem..... https://www.fleetbrake.com/ He wants me to bring the brake drums as well as brake plates etc so they can build the new linings to suit proper clearances. Sounds promising, I am dropping the wheels off tomorrow.
 

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