1951 Bianchi Stelvio Will it start?

Published on 9 August 2023 at 08:57

My big parcel of bits for the Stelvio arrived, all present and correct, I got a battery, battery box, handlebars, throttle twist grip assembly, front brake lever, clutch lever, choke lever and ignition advance lever all in one well wrapped package. The quality of the items was all splendid so I am happy to say the company that supplied all this stuff at exceptionally good prices was www.feked.com. I did not get any discount, nor will I receive any award for giving them a plug but they were brilliant, had really good stocks and got the stuff to me quickly.

Anyway, first job was to see if the 70 year old electrical bits would be any good - all the resistances checked out and the ignition timing looked to be about there or thereabouts when static - the advance is manual on this bike. I had turned the tickover up to where I thought it would be about right - just a crack of light appearing under the carb slide.

the choke was on, it defaults to on, which is weird, to turn it off you need to pull the cable. As I was not going to run it for long if it started I decided there was no need to connect the cable up so choke would be full on, if it looked like being a problem I would sort it and try again.

I made up a couple of leads to go from the battery to earth and from the positive of the battery to the coil, I took the plug out, connected it to the ht lead and rested it on the cylinder head. It was time to see if there was a spark so I gave the kickstart a firm schooling with my right boot and was rewarded with the fattest, bluest spark I could have hoped for -- fantastic.

I'm sure my heart rate went up a notch as I put some of Tesco's finest ethanol loaded muck in to the tank and turned on the tap. I waited a few minutes to make sure there were no leaks, it was all good so I flooded the carb with the little button provided until petrol came out the over flow. I dried up the excess and gave it a kick - nothing, a couple more kicks produced the same result. I thought maybe a small shot of easy start may help get things moving, another kick and I thought it tried to do something.  It didn't fire but it felt different on the kickstart, I felt the exhaust header and it was very slightly warm so something had been igniting.

I thought maybe a bit of ignition advance may help so I took off the distributor cover and gave it about 10 or 15 degrees from fully retarded. Next kick and she burst in to life, I was ecstatic. The tick over was way too high but the engine sounded fantastic. I didn't want to run it for long like that so I pulled the positive wire from the battery and after I had finished celebrating I tried it again. She started first kick this time, again I killed it and then set about adjusting the tick over, this is where it got a bit weird. The float bowl on this carb - Dell'Orto SBF22, is separate to the carb body, it is joined by a banjo bolt at the bottom through which fuel flows from the float chamber in to the carb body. With it set up in the correct orientation for this bike the idle adjust screw is inaccessible as the float bowl is in the way. I think it may be the wrong one for the bike, I suspect on the original the idle screw is on the other side. I had t take the bowl off to adjust idle, it's still a tiny bit fast but it's much closer.


With it all back together again I gave it another kick, she started first time and settled in to a very pleasing idle. It was running very rich by now as the engine had warmed slightly and the choke was still full on. I pulled on the cable and the idle settled out a bit, I need to fit the handlebars and all the controls so I can set everything properly but she runs beautifully, I am absolutely delighted. The results can be seen here - https://www.youtube.com/watch?v=iQhzU62Mpug . I need to make up all the cables now and fit the handlebars, to do that I need ot make some brackets that fix the bars to the upper yoke. This is not easy, I was going to use 2 pairs of handlebar clamps but there is a clearance issue. I am thinking some fabrication is in order but I don't have the tooling to make an exact replica of the originals. I need to ponder that a bit and work out the best way forward. I can always do something temporary that will allow me to get everything fitted and tested until I find something better. At least now I know I am not wasting my time with it.

dellorto carb fitted to a 1951 bianchi stelvio 250

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