wanted - moto giro bike

That looks like a good match to me, but then, I’m not a mechanic. With the basic tools I have, I would put on the ball protector and trim off the 3mm side skirt on the linisher. What could possibly go wrong?
 
If the crank is still together, assemble the new piston onto the rod and see if the skirt clears at BDC.
If it does, I wouldn't touch it.
Any weight difference can be cured by omitting the extra ring on the skirt.
 
Hi Greg

I already tried the piston on the rod on the bare crank. Straight up and down at BDC the new piston clears, but if tilted even a bit it scrapes. I guess I will leave the piston alone until the crank is back in the cases and the cylinder is fitted (after boring) and turn the engine over to be sure.

I had already asked Wolfgang about omitting the extra oil ring on the skirt, he warned me against leaving it off, but I don't know why.

I am going to weigh both the old and new piston to see what, if any, difference there is.
 
update - although I have found and purchased valve guides, 7 mm valves, etc from Italy and they are on there way, I have now talked to the local machinist expert with vintage Italian bikes, mostly Ducati's, but also others.

I am taking the local expert the head and cylinder barrel tommorow after work. He proposes to use modern Suzuki 5.5 mm stem valves cut to length and make custom guides. He will also overbore the cylinder for the new piston. He tels me he did the same with the only other Gilera I am aware of in Alberta, (a 124 built last year for the same local moto Giro), and he has already figured out valves and fitment on the 124. Apparently it had the same problem as my 150 with the valve keepers fragmenting, then the head of the valve mushrooming, and the valve guide being damaged.

I have used this expert before, and he himself has a small displacement Ducati highly prepared for the Moto Giro. My experience in the past wth him has been very high quality work but not quick turnaround..... I guess you can have it good but not fast, or fast but not good, depending on who you deal with....;):sleep:
 
Paul LeClair said:
update - although I have found and purchased valve guides, 7 mm valves, etc from Italy and they are on there way, I have now talked to the local machinist expert with vintage Italian bikes, mostly Ducati's, but also others.

I am taking the local expert the head and cylinder barrel tommorow after work. He proposes to use modern Suzuki 5.5 mm stem valves cut to length and make custom guides. He will also overbore the cylinder for the new piston. He tels me he did the same with the only other Gilera I am aware of in Alberta, (a 124 built last year for the same local moto Giro), and he has already figured out valves and fitment on the 124. Apparently it had the same problem as my 150 with the valve keepers fragmenting, then the head of the valve mushrooming, and the valve guide being damaged.

I have used this expert before, and he himself has a small displacement Ducati highly prepared for the Moto Giro. My experience in the past wth him has been very high quality work but not quick turnaround..... I guess you can have it good but not fast, or fast but not good, depending on who you deal with....;):sleep:
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I have a relative ,retired now, who was very high end at specialty fabrication/welding,, engine building etc.. If you asked him how much, or how long,, he simply said take it somewhere else|.
Stu
 
psg said:
I have a relative ,retired now, who was very high end at specialty fabrication/welding,, engine building etc.. If you asked him how much, or how long,, he simply said take it somewhere else|.
Stu
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Hi Stu

when I took the broken Gilera engine case for welding repair to Derek at https://trillionindustries.com/ , the very very best in town or area, having dealt with him before, same story. I did not even ask Derek how much or how long, just discussed the repair and left the bits with him. Derek did mumble something about maybe turning it around in a week or two....... Been about two weeks now, I have not even called him for an estimated time frame.

the machinist doing the Gilera head, I also have not asked him how much or how long. Strange way to do business, but when you have skills no-one eles does, and more work available to you than you could ever possibly complete, you take the work, or not, on your own terms I guess.
 
Paul LeClair said:
He proposes to use modern Suzuki 5.5 mm stem valves cut to length and make custom guides.
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I can hear the voice of Strother Martin in my head "What we have here is failure to communicate."

Actually it's more a case of asking for advice, getting it, and then ignoring it. I suggested you do exactly that about 10 pages back, before you ordered the valves and guides. 🙄

But what would I know? I'm not a mechanic. ;)
 
Not so sure about 5.5mm valve stems being used under stone-age tech rockers. I'm guessing the Gilera valves at around 25-28mm head diametre.

These thin stems are meant to take axial loads only, usually under bucket tappets, copious lubrication and with comparitively short lift figures (mostly being 4-valvers). The Gilera will have a comparitively crude rocker geometry and hit-or-miss lube to the top end (often only oil mist rising from the crankcase). The rockers will induce radial loads into the stem, attempting to bend it under the down and sideways force when the valve opens. No big deal with a thick stem that is able to withstand the bending forces despite the sparse lube, but a rocker bearing on the tip of a thin stem, with just a hint of lube, will surely start to bend the stem, with excessive guide wear following. Bearing area within the guide is also greatly reduced, magnifying the lube issue.

No worries, it will probably last long enough to get you through a 5-day event, but I wouldn't expect any long-term reliability from such a mod.

I used re-worked 350/500 valves for my 100 Tourismo, both have 6mm valve stems in stock form.

piet
 
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Hi Piet

Stock valve face diameter 26.5 mm. Interesting, forced pumped oil feed to rockers by way of direct oil feed from a hollowed out head stud fed directly from a pipe from the oil pump. Well lubricated rockers believe it or not. I note your comments about skinny modern valves and will discuss with the machinist when I take him the head later today. Worst case I still have the stock parts en route and can wait and just use the stock bits if appropriate

Cam, yes you told me so. It has taken me this long to resign myself that this is the only fellow who can do the work and willing to do the work, and I am just going to have to suck it up and wait for the work to be done on his terms and his timeline. I suspect the bike will be fully built except for the barrel and head before I see the head again, bloody hell. I am hoping to be surprised by prompt turn around but not holding my breath.

If I get really desperate I found a used head on eBay Italy claimed to be in useable condition…….
 
Paul LeClair said:
Hi Piet

Stock valve face diameter 26.5 mm. Interesting, forced pumped oil feed to rockers by way of direct oil feed from a hollowed out head stud fed directly from a pipe from the oil pump. Well lubricated rockers believe it or not. I note your comments about skinny modern valves and will discuss with the machinist when I take him the head later today. Worst case I still have the stock parts en route and can wait and just use the stock bits if appropriate

Cam, yes you told me so. It has taken me this long to resign myself that this is the only fellow who can do the work and willing to do the work, and I am just going to have to suck it up and wait for the work to be done on his terms and his timeline. I suspect the bike will be fully built except for the barrel and head before I see the head again, bloody hell. I am hoping to be surprised by prompt turn around but not holding my breath.

If I get really desperate I found a used head on eBay Italy claimed to be in useable condition…….
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Force-fed valve gear in italian tiddlers is quite rare for the era, Laverda reserved such luxuries for the works racing engines.

I find a lot of wear on valve/rocker interfaces, showing there's a lot of friction and therefore quite a bit of sideways force.

Recently completed a rebuild of a 500 Saturno head, the wear I found was mind-blowing, ie, completely shagged! Mainly through dodgy lubrication, reckoned a little 150 wouldn't be much better.

piet
 
sfcpiet said:
Force-fed valve gear in italian tiddlers is quite rare for the era, Laverda reserved such luxuries for the works racing engines.

I find a lot of wear on valve/rocker interfaces, showing there's a lot of friction and therefore quite a bit of sideways force.

Recently completed a rebuild of a 500 Saturno head, the wear I found was mind-blowing, ie, completely shagged! Mainly through dodgy lubrication, reckoned a little 150 wouldn't be much better.

piet
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Hi Piet

the oil pump feeds directly to a cavity behind the crank bearing, lubricates the crank and cam, then is further force fed through the plumbing channel straight up through a passage to the hollow head stud and exits in hte head by the rockers, then dribbles back down through passages in the head and barrel into the bottom end where it must splash around like crazy.

Went to the specialty machinist after work today, he lives in a rural area south of Calgary, has a gorgeous shop on the property full of fancy machine tools, and stuffed with motorcycle engine rebuilds and machining in progress. Herds of gorgeous bevel Ducati's scattered about, piles of Ducati bevel heads, and various high dollar exotica. I left the Gilera head and cylinder and new piston in his capable hands. Don't know what this is going to cost or when the work will be done. The positive is he is truly enthusiastic about the local Moto Giro and interesting small displacement bikes to run in the Moto Giro.

The new Raedelli Aimon Sport rims arrived, they are WM1 x 19 but appear a bit wider than the corroded original rims, hoping that does not become an issue. Waiting on the new spokes from the UK. Most of the bike is now thoroughly scattered, between the painter, chromer, welder, machinist, etc., etc.

Paul LeClair
 
chrisk said:
Usable condition head on EBay ...... buy it anyway. If the smaller dia valved head shits itself, you have a spare. Two heads are better than one.
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Hi Chris

yes, I already bought the used head off of the Italian eBay vendor, 195 Euro all in including shipping to western Canada but subject to import and customs when it eventually gets here. It shouldn't be be any worse that what I already have, may even be more useable. In any event, if the Gilera 150 head at the machinist doesn't hold up in the extended flat out running in the Moto Giro once fitted with modern skinny 5.5 mm valves, swapping a head on a Gilera 150 single could be done at the side of the road in probably less than 15 minutes with a couple of basic hand tools. I will have spare control cables, spare tires and tubes, spare spark plugs, etc. no big deal to add top end gaskets and an extra head to the spares stock for the race. :rolleyes::ROFLMAO:
 
sfcpiet said:
Recently completed a rebuild of a 500 Saturno head, the wear I found was mind-blowing, ie, completely shagged! Mainly through dodgy lubrication, reckoned a little 150 wouldn't be much better.

piet
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I did a race Nordwest engine a few years back. Lots of HP but I came to the conclusion they had trained a metallurgist to always pick the cheap option. Replaced a lot of rubbing/rolling parts in that one. Reccommended that the owner run it on castor base oil in the end. Best stuff where lubrication is marginal.
Valve stem OD. Millions of Honda SOHC singles with quite agressive rocker ratios happily get along with 5.5mm valve stems.
 
Paul LeClair said:
Hi Chris

yes, I already bought the used head off of the Italian eBay vendor, 195 Euro all in including shipping to western Canada but subject to import and customs when it eventually gets here. It shouldn't be be any worse that what I already have, may even be more useable. In any event, if the Gilera 150 head at the machinist doesn't hold up in the extended flat out running in the Moto Giro once fitted with modern skinny 5.5 mm valves, swapping a head on a Gilera 150 single could be done at the side of the road in probably less than 15 minutes with a couple of basic hand tools. I will have spare control cables, spare tires and tubes, spare spark plugs, etc. no big deal to add top end gaskets and an extra head to the spares stock for the race. :rolleyes::ROFLMAO:
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You could fashion some leather to carry the spare head around you waist.
And saved yourself buying the ball protector.

And any further comment on head shall remain a thought.
 
Paul LeClair said:
Hi Chris

yes, I already bought the used head off of the Italian eBay vendor, 195 Euro all in including shipping to western Canada but subject to import and customs when it eventually gets here. It shouldn't be be any worse that what I already have, may even be more useable. In any event, if the Gilera 150 head at the machinist doesn't hold up in the extended flat out running in the Moto Giro once fitted with modern skinny 5.5 mm valves, swapping a head on a Gilera 150 single could be done at the side of the road in probably less than 15 minutes with a couple of basic hand tools. I will have spare control cables, spare tires and tubes, spare spark plugs, etc. no big deal to add top end gaskets and an extra head to the spares stock for the race. :rolleyes::ROFLMAO:
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If it drops a valve, you'll need more than a spare head.

Take your time.

Paul
 
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