Elite head valve sizes - actual and listed

[LaceyDucati]

Thank you for buying the valves from us, but just a word of warning. Although the Monza/Sebring valves are effectively the same head and length as the Italian 200 Elite valves the collet grooves and collets differ. There are ways around it, either use 250/350 tops or use a conversion collet. We have had most of the original italian collets remade now, there are 3 types 125/160, 175/200 and 250/350 450. We have also had a couple of conversion collets made, one that goes between the 175/200 valves and the 250/350/450 top retainers and one the other way that goes between the 250/350/450 valves and the 175/200 top retainers. This should hopefully help with Italian 175/200 retainer parts which are few and far between.

I would suggest you give the collets a close look at before assembly.

None of these collets are compatible with Mototrans valves or retainers which differ, unless you are changing both valves and top retainers.

Regards Nigel

[Geordie]

Thank you Nigel. I had checked the fit of the collets and it is not good. But as I need other head parts I was planning on getting to you soon. I may now have sourced acceptable rockers, adjusters and cam but they need fully checking before moving ahead.
Regards,
Ian.

[Duccout]

God, this Italian v Spanish is a nightmare! I fitted Nigel's valves to my 250 Strada and never thought that they might be different to the Mototrans items, although they seemed identical and everything fitted properly (fingers crossed).

[LaceyDucati]

If the collets fitted, then they were probably compatible with what you had. Many Mototrans valves have single ring grooves and top retainers with differing diameters and angles. I'm no expert on Mototrans models, but I do seem to spend a lot of time trying to unpick owners comparability issues! I'm not sure whether later widecase models all used ring type grooves or whether some used tapered grooves like the Italian models. Maybe Jon could give a clearer picture of what was used. Certainly many narrowcase models seem to use ring groves.

Regards Nigel

[Jon Pegler]

As a general rule the narrowcase Mototrans bikes use the valves with ring type grooves and collets.
These valves may have been replaced with the tapered collet type, making it vital to check when replacing parts. Both types of valve are available from suppliers.
If Italian valves are fitted into a narrowcase Mototrans bike it is important to fit the tapered collets and possibly change the valve spring bridges as the taper may differ, as Nigel states.
The widecase Mototrans machines all seem to have the tapered collets and valves, fitted as in the Italian models, including the late Strada/Forza/Vento models that came with coil valve springs as standard. The collets for the coil spring and hairpin spring machines are interchangeable.

Jon

[Duccout]

Thanks Jon, that's reassuring.

Colin

[George]

I have noticed that 125/160 valve guides on Nigel's site are 13mm OD and guides on Guzman site are 11mm OD. Another variation to be aware of.

[Geordie]

What started as a query on valve sizes has led me to questions on the whole top end!

I have a Mototrans MD8**** bottom end, 37-33 valves, a piston with pockets to match those valve heads, valves with tapered collets, one bronze and one iron valve guide and a cam ( although extremely worn) nothing like a Mototrans Elite in inlet timing and duration.

A rebore and piston will be required and I have acquired a Mototrans Elite cam. But if that cam and valve size combination causes interference with a piston then that would be better circumvented...

There are external differences to Barcelona v Bologna heads but mine shows a combination of each. I post some pics here in the hope someone wil be able to tell me what the casting was or now is.

HEAD FRONT.jpg

HEAD OBLIQUE.jpg

HEAD TOP.jpg

[Jon Pegler]

The S stamping on the head indicates a Mototrans Elite head, which would be correct for a motor no. 8xxxx

Jon

[Geordie]

Thank you Jon, very useful to know that.

Regards,
Ian.