Benelli 250 2C

[Lotus54]

That would be fun!

[Lotus54]

Waiting on something for the 250 SS, so I installed the shift ‘desmodronic shaft’ and forks. Then dropped in gears to make sure I got everything lined up and it shifts well.
Now I will install the new bearings/seals- crankshaft and kickstarter after that.

I already ran a tap through all the threads to clean them up, shot some of my favorite Maxima suspension clean and blew them out.

[Lotus54]

I got the new kickstart shaft (reason for tearing it apart) installed and made a tool to preload spring. I tried out some of the silicon bronze, it seemed to work quite well. I have not brazed in decades and it took me a bit to get heat right, but not too much. Since it didn’t really matter I figured a good time to try it out.

The top case it on and the clutch cover is just sitting there to support the kickstart, so I could test it and make sure I did it right. I did put the top nuts on - just snug. Next I will install all bottom and torque everything. I’m waiting on a part for the 250SS- I could have made something, but figured to just get the original part and I have this one to work on anyway.
At this point, I will probably finish this engine/bike first. Maybe by mid-may or sooner, depending on if I find any other issues and what other stuff comes up.

I will be cleaning up that clutch cover of course. I don’t have the primary gear or clutch in yet.
I did put the part that collects oil flung off the clutch gear and routes it to a passage with holes over the gearbox. This assures good lubrication.

[John H]

Looking good. What is the reason for the additional flywheel near the right connecting rod?

[Lotus54]

Both or the cranks have that- the left is just on the other side. Maybe a combo of balancing and ‘crankcase stuffing’?
I don’t really know. But I speculate it is easier to manufacture having a separate piece, and easy to install with a built up crank.
They also make a 125cc version of this engine- stroke is different, but perhaps the crank is the same other than the crankpin location and so separate piece makes it cheaper/easier to fit proper weights for different engines?

[Lotus54]

This bike in Europe did not come with turn signals, but often the importer would add them to the bikes when they came in. I do not remember if the one I got in new when I was a dealer had them or not. I don’t think I have any pictures either (which was dumb).
This one had Stanley brand signals, which the Japanese bikes used. I didn’t really like how they looked and how they were mounted. I’ve decided to put some CEV ‘knock offs’ on that would be period correct for Italian bikes. I didn’t feel like spending how much real CEV ones cost (quite a lot) and these are fine considering I’m not doing a restoration, rather just getting it into good operating condition and looking pretty good for an old bike.

The ‘simple’ install for the headlamp ones turned out to take me quite some time. These have two different threads, signal side and mount side. Well the mount side was too large, but turns out the signal side was just right. BUT the threads were too short to just screw in with a washer. So I spent way too much time making a special spacer. It is threaded but also relieved inside so the signal stalk and recess, giving the length. I goofed up making the ‘bolt head’. It works, but not right and only later I realized I did it all wrong. Oh well, next time I will get it better. Perhaps I should take some scrap and work it out.

Anyway, I have a pair all made up, drilling out the signal for the larger thread- and it didn’t seem to match anything I had. The small one is metric, but turns out the large one is SAE. That had me on the run for awhile. So I threaded the plastic signal, then made a threaded spacer so I could ‘bottom it out’ and allow the inner nut to tighten up.
Jeessh. Even at that it is a lot cleaner setup than what someone else did and it will work. I thought about leaving them off, but later ones did come with them and while I use hand signals also- how many people even know what they mean anymore? Plus I like all the visibility I can get.

[John H]

Someone actually makes mistakes like me??? Interesting that you find a mix of metric to sae threads on a German bike. Be glad you aren't dealing with Brit bike that has combos of all threads.

[Lotus54]

It is an Italian bike, and the turn signals are aftermarket- made in Taiwan I think. The original type CEV are Italian and I’m sure all metric, but cost a bunch. I didn’t feel like spending that much on something that wasn’t even original anyway.

Yes, having metric and imperial mixed on the same part had me on the run. I didn’t even consider that it would be that way at first. Finally, nothing worked and I tried an imperial thread and it worked. Jeessshhh.

I have a small rotary table, so getting the flats at proper angles was easy. BUT it took me a bit figuring how to hold it- then I somehow decided to have the table flat and rotating. Well- that doesn’t work well at all and not until I looked it up I found I should have had it 90º to the mill table and then it is fairly easy. Oh well, I am learning as I go. Usually I try to look up ways to do things before I start- since I know nothing about machining. I probably should have done the bolt head first, then do the rest of the operations. That way I would have more to hold onto- plus I discovered the Vertex rotary I have- the centre is a Morse #2. That could have saved a bunch of time perhaps.

[John H]

Oops, I meant Italian.
I find that if I 'zero' the chuck on the rotary head with a pointer then I can move the 'x' or 'y' axis to the cutting position. I've only done simple machining with the rotary, never any odd number cuts like in some splines.

[Lotus54]

Pistons, cylinders, head on and fitting the Vape ignition/charging.

The measurement tool I have for mm BTDC is a 12mm thread, so I have to make an adapter from 12 to 14mm so I can screw it in the sparking plug hole. I could use something else, but it does such a nice job.

EDIT: I found I had a 14mm one also, so didn’t have to make one.
Ignition all one, side covers on temporarily. Pics soon