175TS with 125S engine project

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LaceyDucati
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Re: 175TS with 125S engine project

Postby LaceyDucati » Thu Aug 20, 2020 7:01 pm

George

Those pins are tricky to remove, my method involves building a small ball of weld with my tig set onto the broken tail end of the pin. Then weld a small screw onto that and use a side hammer to tug it out, works every time. Unfortunately not really a DIY job, unless you have a tig set.... Anyway I have some pics somewhere, I'll see if I can find them and put them up for general interest.

Sorry I haven't responded to your request yet, but I don't have any arms that aren't worn. The usual repair (as Brian describes) is to oversize the hole to 3/8" / 10mm then sleeve it with a bronze bush. I often use old valve guides to make a bush, again I think I have some pics of that repair. As long as the casing is not worn, 8mm silver steel is ideal for making a new pin (cheap and readily available). I have the 2.5mm roll pins in stock if you need one and if you need any assistance with the pin or sleeving give me a call.

Nigel

George
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Re: 175TS with 125S engine project

Postby George » Sat Aug 22, 2020 8:33 pm

I am going to fit bush to clutch arm. With regards to the broken drift pin the only answer I can think of is to grind it out with Dremel diamond point. Half way down before tool wore out will order two more. I won't be using drift pin replacement but think of some other way of securing shaft. This is a cheap Micky Mouse idea.
Don't mean to upset all you Ducati fans but I have been disappointed with the engineering ideas, or lack of, on this machine. I am speaking with a working life of 60 years engineering experience plus many motorcycle restorations. The concept of the engine design is very good let down by some poor minor details done on the cheap such as drift pin, top bevel bearing housing etc. etc. To me any engine that requires so many shims indicates poor construction with parts manufactured on worn out machine tools. I am wondering if I should have stayed with my well engineered Moto Guzzi's.
Rant Over
I have spent to much money to give up now and just hope the finished bike will be worth it.
George Essex UK

Duccout
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Re: 175TS with 125S engine project

Postby Duccout » Sun Aug 23, 2020 1:17 pm

Certainly, all those shims meant that the engine would not have been economically viable!

DBDBrian
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Re: 175TS with 125S engine project

Postby DBDBrian » Sun Aug 23, 2020 3:13 pm

Like you George, I worked in engineering all my life before retirement, but not in mass production. I think we must not overlook these machines were designed and manufactured well over half a century ago, on very basic machine tools.
The biggest part of my time was spent rebuilding heavy earth moving machines, including engines, injection equipment, hydraulics, transmissions manual and hydraulic.
None of which did not have some form of adjustment, including shims, were tight tolerances on assembly are required.
Crown wheel and pinions for example (bevel gears) are machined to a very high standard, but still require setting up on installation. Multi cylinder injection pump camshafts, also machined to a high standard, require shimming for injection timing / phasing . It would be a very tall order for it to be otherwise. But with modern electrically controlled systems it's a different ball game.
I think if you look at the little Ducati engine of the time, in general it is well thought out and made, but accepted the roll pin retaining the clutch lever pivot is not the greatest arrangement.
I'm sure with your engineering skills you will get it sorted, but without your own machining facilities it obviously makes things more time consuming and expensive.
Brian
Made in England

Duccout
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Re: 175TS with 125S engine project

Postby Duccout » Mon Aug 24, 2020 9:09 am

Certainly modern Ducati engines, in spite of being machined on CNC, laser equipment, still require the gearshafts and crankshaft to be shimmed. It would be a tall order to be able to machine to tight enough tolerances to obtain zero crankshaft clearance.
Last edited by Duccout on Thu Aug 27, 2020 9:13 pm, edited 1 time in total.

George
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Re: 175TS with 125S engine project

Postby George » Thu Aug 27, 2020 8:31 pm

I have noticed that ignition points cam is very worn. The felt pad was bone dry and stiff, it looks like the felt has worn the cam at start of opening points.
Looking to replace cam part only as back plate and springs are in good condition. Would anyone have one in fair condition that I could purchase. Graeme has offered to have a look for one, not sure about postage from Tasmania
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George Essex UK

George
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Re: 175TS with 125S engine project

Postby George » Tue Sep 08, 2020 7:13 pm

Time for a catch up.
Have had positive results. Nigel Lacey found a good used points cam. I find Nigel very helpful, sure sorting cam was more trouble than it was worth to him. Hard to get service this good now.
Clutch arm bushed and fitted.
I found that front sprocket shaft was still a bit tight after tightening nut (see earlier posts) decided to split crankcases again to investigate. I found that the ring clip between 3rd and 4th gear is loose in shaft groove and perhaps when tightening sprocket nut the shaft was pulling 4th gear on to .50mm shim. Changed for .30mm shim, reassembled shaft in R/H case and fit sprocket. Spinning without binding. added L/H case tightened up, sprocket still spinning, gears selecting. Reassembled kickstart gear, alternator and clutch. Engine turning smooth by hand. Bottom half finished. :)
Gear selector box dismantled, gear lever shaft worn bushes replaced.Working parts in good condition, reassembled and no amount of adjustment to eccentric could get the lever to return all the way when changing up. Stripped again to see what I had done wrong. I noticed that the tangs on spring return are bent to one side, rotated 180 degrees with end of tangs pointing outwards, to gear lever, eccentric put in centre position, reassembled and works perfect. No mention of this in the two manuals I have? Thought it might be worth mentioning as may help someone else.

Still waiting for top bevel bush to be machined. One of the effects of Covid 19 is that everyone is working on their bikes and not riding them, the good tradesmen are all busy. If I had access to a lathe i would make it myself. Same with my paint job not expecting that back for few weeks.
Not much I can do now apart from fitting piston and checking clearance with head.
George Essex UK

Duccout
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Re: 175TS with 125S engine project

Postby Duccout » Tue Sep 08, 2020 7:58 pm

Hi George,

That sounds really positive.

Colin

George
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Re: 175TS with 125S engine project

Postby George » Mon Sep 14, 2020 7:59 pm

More progress made. Discovered replacement barrel I had bought is shorter than original and new piston is hitting head. Adjustments made to base gasket. Piston / head clearance 0.65mm minimum to 0.75 maximum with compression ratio of 7.8 to 1. I will settle for this unless anyone thinks it should be different. Unable to check valve to piston clearance until I get top bevel bearing housing, hopefully at end of this week then I hope to finish engine. Could be another month before paint job is finished. Got chrome parts back from platers, why do shiny parts make you feel better. I feel that things are coming together at last.
George Essex UK

Duccout
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Re: 175TS with 125S engine project

Postby Duccout » Mon Sep 14, 2020 8:24 pm

Motorcyclists are suckers for a bit of bling!


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