175TS top end stripdown

[ranton_rambler]

Yesterday afternoon was a continuation of the strip & examination of the top end.
I’m trying to exert some control over the cost of this rebuild, so am only replacing what is clearly beyond use, or what would threaten reliability and potentially cost more in the event of a failure. Some things are obvious but as I’ve not worked on one of these, a few queries for the more experienced if I may…..

Exhaust rocker pin looks to have picked up a bit in the bush. No discernible play or notchiness. Looks like it should polish up. Is this too risky?

DSCF5386small.jpg

Exhaust rocker has a wavy spring washer to take up side play, but inlet does not. Which is correct?

DSCF5372small.jpg

All 4 valve springs are worn where the little bridge piece sits on them. I’m guessing this will lead to a crack in the wire eventually?

DSCF5380small.jpg

Valve guides don’t seem worn but I can see a bit of green corrosion inside, so these will be replaced. Presumably from standing so long (>25 years I think). Should there be seals? The parts book doesn’t show them, but people seem to sell them.

PS crankshaft is with Nigel Lacey to be looked at.
PPS piston is already on first oversize 62.4mm, so I’ll be getting a 63mm Sport piston and a rebore to clean the corrosion marks off the liner.

[Rick]

Ranton(?)-
Lots of rocker arm spindles have a helical oil groove, so if the shaft is smooth and a good fit I wouldn't worry about it.
It may be distorted perspective from the photo, but it looks like the valve end of your rocker arm isn't centered on the valve stem end- the rocker arm should be shimmed to be centered on the valve. I'm not sure the spring is any better than using good, hard shims- the spring would add some unnecessary friction, but probably not a big deal one way or the other.
I've never seen a failed hairpin/mousetrap valve spring in the time I've been fooling with these engines- haven't heard of it being a problem- I think they get weak long before they break. The wear on your spring would introduce a potential 'notch effect'- if I was going to use that spring I'd dress any abrupt changes- I think springs are still available, so replacing them probably makes sense.
Rick

[ranton_rambler]

It was centred, but doesn't look it in the photo. Springy washer on the left, shims on the right. Inlet rocker had solid shims both sides, although rather a lot of sideways play.

Springs are indeed available, but all adds to cost. Probably bought the wrong bike for a cheapskate!

Ian

[Samurai]

Both the rockers had each spring washers on my 175TS, but only on one side. From memory (not the best I'll admit!) the parts manual show the same arrangement.

[Ventodue]

Hi Ian,

1. Rocker pin.
Yup, worth trying to clean it up. But check the condition of the bush. Obviously there’s been a lubrication failure at some time, most probably ‘cos the holes in the rocker got blocked/starved. And that suggests the bush may have suffered.

I guess that the only real-world consequence of that might be a certain tetchiness when setting the valve clearances. But if there’s a lot of play between bush and pin, you could consider getting new ones made up - I don't think anyone has them as a stock item. But ask Nigel and/or Barry Jones. You never know - they may be having/have had some made.

2. Rocker shims
As already said, should be spring washer on the left side, shims on ‘tother, both inlet and exhaust. Now, whether you arrange it so that the rocker acts squarely on the valve head; or whether, as I’ve seen argued, it’s preferable to have it striking off centre thereby inducing the valve to rotate at each strike - I leave you to chose (altho’ once again, ‘Ask Nigel’ ).

3. Valve spring
I can understand your reluctance to refit components with obvious wear. But I’m not sure you’re going to find replacements for the 175 anyways? As with the rocker bushes, I note they have different part numbers from the 250s. (But, ‘Ask ….).

4. Valve seals
Weren’t fitted originally ("What's a little oil in the combustion chamber?"), are supplied these days to fit new guides which have the necessary retaining groove. So if you're going to fit new guides, you might just as well fit the seals (unless you like a little smoke for authenticity's sake ).

HTH

Craig

[Ventodue]

Update Ian
Seems Jesus Loriente in Spain has both rocker pins and bushes, 38 euros a set



http://recambiousado.com/venta/index.ph ... &id_lang=3

Possibly valve springs too, 14 euros each. He says they fit all models - but you'll need to check.



http://recambiousado.com/venta/index.ph ... &id_lang=3

[ranton_rambler]

I had a look around the UK suppliers and we can get everything from either Nigel or Barry but Spanish prices look a bit better.
Not sure about valve stem seals, if not originally designed for them. I've been told that big block Guzzis just wear their guides out due to lack of lubrication if they have seals fitted.

Ian