Strada Camshaft Oil Ways

[Duccout]

I have had another look in the selector box and can see no obvious wear, so I've reassembled it and I'll give it another try out; if it still plays up I'll start replacing things, starting with the spring.

I've also bought the bike (or is it me?) some Christmas presents - a new handlebar to try to improve the riding position, and a Mikuni carb! I don't know if I've done the right thing, especially after Bill's tribulations, but we will see. The obvious thing would be to have gone for a new Amal, but I wanted one rubber mounted really, so that meant Mk11, which I know nothing about, and Mikunis get good reviews, although I hope that Moto Carb know what the correct jetting is. It was a choice between them and Allen's, and I had to pick one. I don't know if there will be clearance in the frame of the Strada either, as the Amal only just clears the frame and that is bolted straight onto the head, if not I'm going to have to make up a cranked manifold.

[George]

I have had another look in the selector box and can see no obvious wear, so I've reassembled it and I'll give it another try out; if it still plays up I'll start replacing things, starting with the spring.

I expect it's something you have already looked at but I found that renewing selector shaft bushes helped. Mine were quite worn and shaft moved up and down a lot.

[themoudie]

Aye Colin,

My friend who runs a 'fleet' of Commandos has always used Moto Carb for their Mikuni single carb conversion kits for his machines and recommends Steve for his knowledge and stocks. As for jetting settings, Dan C published the settings that he is using with a Mikuni 30mm carb that he has fitted to a 350 Desmo widecase engine earlier in this thread. Page3, 4th entry on page:-

On 1969 350 Desmo.
Pilot 30, Needle 6F5 on middle notch, Needle Jet P5, Main 160, Air jet 2.0, Slide 2.5
Similarly these settings on this bike are giving nice tan coloured plug readings throughout the rev range. Bike starts easily, idles and revs cleanly at all throttle settings.

I would agree with George that you need to remove all the play in the bushes and between the shafted components, before moving onto the eccentric, the coffin and the spring. However, there is no doubt that a new spring may help in a worn mechanism for a wee while, before the play between the components overcomes it.

Good health, Bill

[Duccout]

Thanks George and Bill. When I bought the bike I was lucky enough to find on eBay a new splined selector shaft, which tends to wear too, so I thought that with a new bush I would be OK, but surprise, surprise, the shaft is unworn, so a new bush was all that was needed and there is no play at all. On my 750, which uses the same parts, I had to get the shaft hard chromed and ground to take out the play.

There is something not right about the spring in the 250, it sits sideways in the coffin and does not let the boss on the selector shaft sit right down, so if it is still not working right I will get a new one; it is always good to have a spare anyway. I remember crossing the Alps on my 750 years ago when the selector spring broke and I had to climb all the way up and down through all those hairpins, and then do it all over again on the return journey, while returning the gear lever manually.

[Duccout]

I have a Mikuni (no, not a new type of swimsuit) and very nice it looks too. There will be some problems mounting it: the manifold flange has the outside bolt holes recessed, to allow Allen bolts to sit semi-flush, but Ducatis have studs, so I will either have to remove them or try to work something out, possibly turning the nuts down. Is there a downside to removing the studs and replacing them with Allen bolts?

Also, the inlet pipe for the fuel is high up on the carb, but on the Strada the petrol taps are low down, so there may be a problem getting the fuel pipes to fit. And finally there may be clearance problems with the frame, either with the carb itself, or the air filter, so I may have to make up a tapered spacer to go between the head and manifold.

The carb was delivered with two extra main jets and two pilot jets, but for the life of me, I cannot read the size stamped on the pilots, even with a magnifying glass. It's all good fun!

[blethermaskite]

I have swapped the inlet studs out for allen bolts several times, no problems unless you manage to cross thread the allen bolt in the head then of course you are into helicoil territory, the carb/inlet manifold doesn't need to be insanely tight on the bolts anyway.(sure your cylinder studs are just going into alloy and they are ok) So I would just go with the easiest solution.
Cheers,
George

[Duccout]

Yes, George, if I wish to use the rubber manifold, then it has to be Allen bolts. I have the studs removed and am gradually sorting things out, but there is a big break coming called 'Christmas', so it looks like mince pies will take precedence over petrol pipes for a while!

[Duccout]

I'm thoroughly fed-up! What I thought would be a simple job has become a complicated one.

Firstly, the rubber manifold supplied with the carb is intended for a British bike with 2" bolt centres, so the holes have to be elongated to 52mm centres, but the holes are counterbored, to allow the Allen bolt heads to sit partially recessed, so I had to remake the counterbores with a Dremel; then, the original Whitworth Allen bolts have smaller heads, so I had to turn down the 8mm heads in the lathe to get them to fit in the counterbores. Then, because the stud holes in the head are undersized, so I had to run a tap through them, and finally got the manifold fitted. Job done.......

Fitted the carb, then found that the cable inner was too short, so had to remove some of the outer cable. At last all was fitted. Then realised that the petrol taps are below the level of the carb, so I don't know if it will work, and I don't have any clear piping to check if the fuel is reaching the float level. Then, found that the tank covers the pilot mixture screw, so it cannot be adjusted with the tank in place. Grrrrrrrrr! I did manage to get the engine running, but only at tick-over, if I try to use any throttle it cuts out.

Looks like I've wasted my money, I should have bought a new Amal. It is always risky trying something non-original, but I thought that a Mikuni would be an improvement. I can try a dummy tank to get the tick-over mixture adjusted, but I don't know if the fuel taps being lower than the carb will stop it running correctly. I am also worried because the supplied jets are different to the ones that other Mikuni users on here are using.

[blethermaskite]

It won't matter about the taps being lower than the carb the fuel will always find its own level,(as long as the fuel in the tank is higher than the carb)
Cheers,
George

[blethermaskite]

It won't matter about the taps being lower than the carb the fuel will always find its own level,(as long as the fuel in the tank is higher than the carb)
Cheers,
George