Head Repair springer 250 bevel drive pass through hole

[graeme]

did this engine run previously ?

The bevel gear on the crank shaft is keyed to the crank shaft.
The timing dot on the crank shaft bevel should be vertical as is the keyway on the crank and bevel gear. TDC....
The lower bevel dot to dot both lower bevels. (crank shaft and lower bevel shaft)
The idler gear and timing gear (straight cut gears) match the dots with the dot on the crankshaft straight cut gear inboard of the bevel.
Then line up the bevel dots on the cam bevel and the upper bevel shaft (long bevel shaft)
This should line up the two flats on the oldham coupling. Head can now be fitted. IF all your shimming is correct ?

If you turn the engine the dots will not line up again until about 14 revolutions. 14 or something like that

If this doesn't line things up,,, either I'm older and loosing the plot or some parts you have are very wrong.

This is for wide case engines, I'm not sure of narrow case timing.

Graeme

[LaceyDucati]

Hi

The key on the crank aligns with TDC, however the dot on the crankshaft bevel gear is a tooth out on Italian models. This is why the timing dots appear slightly out....that's the way they are and as the gear is keyed to the crank, that's the way they will always be. As long as the dots are all aligned when assembled, then all should be good (regardless of whether it is slightly off TDC).

350 W/C top bevels will not fit in a W/C 250. If they do it's not a 250, maybe it's been converted.

The second groove on the lower bevel shaft is never used.....why it is there is one of life's mysteries, maybe a design change in development or a hangover of some type.

The valve is hitting the piston probably due to the mismatch of the piston to valve size, as it is catching the edge of the valve pocket. I sense this engine is potentially an assembly of parts from various models. Increasing the pocket diameter will solve this if this is the case.

Regards Nigel

[insanity]

Hi Chaps,
You people are terrific - many thanks for your patience and sharing knowledge and experience.

Two YouTube vids are below links.

https://youtu.be/8O8LDX_gdvs

https://youtu.be/zf1c1jEr6KM

The bike was apparently a "box of bits" on an olive farm in NSW, so likely Nigel you are right, it's a bitzer as we say,(of unknown parentage).
Could it be a 350 with 250 engine cases (9 barrel fins) ?
Anyhow, I have begun to reassemble with confidence and will carry on, I will certainly update when the big day comes.
Again many thanks

kindest regards
Knut Case

[Hiya9612]

Hey folk! On the same original subject of this thread Can anybody (in the UK) recommend a machine shop who have the experience to machine my 350 head to accept an oversize cup?
(Short version) My head has been sitting with a machine shop since last December. They tell me they've not been able to set the head "square" to machine it correctly, good that they want to do it right, but it's not getting the bike back on the road.

Some might remember I posted a photo of my crankshaft bevel drive gear about this time last year with a tooth missing? Well it turned out that the whole engine had been butchered by the previous "builder" and that gear was the first clue of problems to come (Shims? Pah!!....who needs 'em?). All of the bottom end problems were sorted by the careful attentions of Mr Nigel Lacey (thanks again Nigel), I just need to get the head sorted now.
Cheers
Phil

[insanity]

Phil,
Though I can't help with a machinist, I had the same problem with the people I used - all cnc laser pointer and data off the interweb youthful people (who probably haven't hear of Brunel).

I purchased a used good head that they then used to make a jig or take measurement from the centre line of the cam shaft did align with the
centre line of the bore. In the end the young fellow got his retired father in to do the job. My fault of course, I did stress it was from an old bike and \the shops don't have new ones. It was a automotive head specialist though.

Best of luck

[themoudie]

Aye Phil (Hiya9612),

No knowledge of any engineers that might be near to you. But:

Seager Engineering in Debenham, Suffolk, know what they are doing, but as a two man band, they have a very long waiting time, no much use to you!

Stotfold Engineering in Biggleswade are a second generation, third coming on company, who used to race Mach I's in the 1980's and know their stuff. Having developed a short stroke Mach I 250 of 237cc that revved to over 13,000rpm and stayed in one piece!

I would suggest that you give the latter a call and see what they say? Here is their link: Stotfold_Engineering_Co

If this fails, I could ask an engineer up here, but at 78, he has a lot on his plate and may take a wee while?

Good engineers, who understand their materials and can think on their feet are a dying breed and the "iPad generation" mostly don't have a clue, or want to soil there hands!

All the best and good health, Bill

[Duccout]

Hi Phil,

My local engineers in Hainault, Essex could do it, but are a long way from you, but if you are interested I'll fish out the address. Nearer to you are a company that I have seen advertising in the 'Old Bike Mart' called Matt's Machine Shop, who are in Wales, and would also be worth a try.

Cheers,

Colin

[Hiya9612]

Thanks Bill and Colin, you've given me some good options there, I'll get on the phone and (hopefully) get things moving!! (I knew putting a shout out on Motoscrubs would be a good move )
Phil

[insanity]

Short update,
buggah wont start.
it continues

[insanity]

YAY Donatella Ducati Runs !
Finally got some free time 4 myself.

Oil drip/ leaking from the front valve cover or near there, else good.

I redid the tdc align the dois on all gears etc again, must have fluffed it last time, but yay merrily yay.

My thanks to all concerned taking the time to share the knowledge.