1975 Moto Morini 3 1/2

[Canuck750]

I bought a decent 1975 Moto Morini 3 1/2 Strada about five years ago out of Arizona knowing the engine needed rebuilding; the PO had a leaking fuel tap that flooded the crank case with oil and washed the lube out of the big end shells, It has sat forlorn in the corner of my shop, always being passed over by another project. I had the tank and side cover painted when I brought it home, other than its just collected dust.

As bought



repainted parts - 1975 Strada colour scheme



Other projects await parts so I put the little Morini on the lift and tore it down. The bike was well looked after so it all came apart easily



a day of stripping down the engine and vapour blasting all the parts



One con rod big end shell scored



Crank will get reground with 1st over big end shells, I will replace all the case bearings even though most feel ok. Pistons and bores measure up tp spec, I will replace the rings and criclips



Forks are nice, the tapered bearings look new, I will just replace the fork seals and dust caps and the headlight ear rubbers



front and back wheels in real nice shape, good tires, I will just vapour blast the hubs and these will be good to go



I put on a new set of Italian shocks, Sebac I think



Frame components stripped, off to powder coater today for Carbon Black



All the zinc plated parts vapour blasted and rinsed in Muriatic Acid, off for bright cad plating

[Antietam Classic Cycle]

 

[Canuck750]

Yesterday I dropped off the parts for zinc plating and today the shop called to say the work is already done! Talk about excellent servcie, and the shine on the pieces is fantastic.





Dropped the crank, rods and shells off today with the machinist / crank grind specialist, he took one look at the crank and said the crank oil openings had not been properly chamfered and that led to some small foreign debris getting hung up on the crank journal opening. He also ground my 500 Morini crank so he has some experience with them. The factory manual is missing the stock dimensions for the crank journals but the suppliment that Herdan Corp printed lists the main journal as 30mm.

Unfortunatly the shells I bought are standard size and not over so I hope the crank does not need grinding and the new shells I have can be used.

[Scout63]

Great pictures Canuck. I love the plated parts. Interesting thread already.

[Turin]

Looks familiar... did you post before pictures previously?

[Canuck750]

Looks familiar... did you post before pictures previously?

Probably years ago when I bought it off Warren in Apache Junction

[Turin]

That must be it. I can't remember birthdays, but I can remember a motorcycle someone posts on the internet a decade ago. go figure.

[Canuck750]

That must be it. I can't remember birthdays, but I can remember a motorcycle someone posts on the internet a decade ago. go figure.

Yep me too!

[Canuck750]

I have made some decent progress latley on the Morini 3-1/2 and the powder coater called to tell me the frame and associated parts will be ready to pick up tomorrow.

123 Bearings out of the UK sent me all new case bearings, heated the cases in the oven to 300F for twenty minutes and 'plink' the bearings drop right in



transmission gear clusters, shift drum and shift mechanism drops in nicely



Charlie Mulendore gave me this great alignment tool years ago when I rebuilt my Morini 500 (thanks again Charlie), works on the 350 as well, allows me to check the poistion of the shift mechanism relative to the shift drum, pawls engaged



The crank grinder measured my crank then put the new stock shells in the big end, used Plasti-gauge and torqued the rod caps down, the journal is within stock spec, no need to grind the crank journal, he just polished the crank and eased the oil passage opening edges in the crank journal, I have new standard shells to fit



Pulled the crank through the bearings, applied case sealent and joind the cases together, then fitted the main drive, oil pump, etc





New seals throughout



primary drive side cover ready to go on



assembled the clutch





one side done



new cam belt



I honed the cylinders, fitted the new rings to the pistons and filed the rings to meet the specified ring gap, Mdina Italy only had 1st over rings sets so I had to file all the ring gaps. I also got new piston pins and circlips.

I went to fit the pistons to the con rod small ends and then it all went sideways ........  

WHY ARE CON RODS NOT CENTERED IN THE CASE CYLINDER CUT OUTS...????

Of course I had installed the rods the wrong way on the crank. DAMN, I thought I was being so careful following the shop manuals and parts books ...... the con rods shanks (the arm that joins the big end to the small end are NOT centered on the big end, the con rods have to be placed on the crank so that the con rod arms are close to the outside of the cases, of course I have them backwards.

so now I get to take it all apart tomorrow and do it again, correctly this time, hopefully......

[krglorioso]

The phrase, "Better than new" comes to mind.  Wonderful work.

Ralph

[SoCV]

 

 Dusty

[Canuck750]

I tore the engine apart this afternoon and swapped the orientation of the con rods, didn't take as long as I thought. I had to come up with a piston ring compresser for these small pistons, a big jubilee clamp worked great



cylinders tapped down easily and then the hose clamp was fully unwound and pulled free of the piston



I bought a 2-1/2" diameter Flex-hone (ball hone) and put the shaft of the hone in my lathe, oiled up the hone stones and the cylinders and quickly got a nice cross hatch on the cylinder walls working the cylinder back and forth for about 30 seconds while the lathe ran at mid speed.





I need to pick up some valve grinding paste and lap the valves to the seats and finish up the heads.

I picked up the powder coated frame, swing arm etc this afternoon, I can get the engine back in the frame next week and start the reassembly.

Boxes of parts came in from Start Gomma today (rubber parts for many Italian motorcycles)

https://www.startgomma.com

and Guzzino more rubber and carb parts (plenty of Italian motorcycle parts)

http://guzzino.com/

and if anyone is looking for NOS Moto Morini parts this is a great source = Mdina Italy in the UK

https://www.mdinaitalia.co.uk/

[Canuck750]

I got all the powder coated parts back, just a little bit of thread chasing and I started to put some things back together, started with rear fender / tail light assembly then the shocks and swing arm



the fenders are stainles steel, there are rubber washers isolating all the fasteners from the fender / frame tabs





I had all the fasteners and plated steel pieces replated with bright zinc, saved all the washers, nuts and bolts si reassemebly is pretty easy









It was a good day for progress, front end and wheels next

[Antietam Classic Cycle]

 

Just my preference: put the engine in first. Lay the engine on it's side and lower the frame down over it.

[Canuck750]

Just my preference: put the engine in first. Lay the engine on it's side and lower the frame down over it.

I agree, that’s what I usually do and I still might with this one but I can’t find my valve lapping paste and went ahead with what I could work on today until I can get some paste on Monday and finish the motor up. I can use my overhead crane to reposition the frame and raise / drop the frame over the motor on its side. I get impatient when all those bright parts are just laying around.

[Canuck750]

I picked up a tub of valve lapping paste, my original tub is hiding somewhere in the shop, I have a lifetime supply now,
I find the Heron head very odd, the 'combustion chamber' being the recess in the piston top just goes against what little I know of an internal combustion chamber



but it obvioulsy worked for Moto-Morini and Moto Guzzi also used the Heron head on the V35 and V50 motors.



I passed the valve through the head and attached a variable speed drill to the tip of the stem, brushed a healthy layer of paste on the valve and seat and pulled the valve against the seat with the drill running at mid speed, wipe, inspect, repeat until I felt I had it as good as I can get, usually I send the heads out to have the valves and seats cut proffesionally but but I cheaped out this time





assembled the heads and fitted new gaskets, torqued the heads down, then I lifted the frame up with the overhead crane and adjusted the ratchet straps to get the frame to lay horizontal, layed the motor on its side on the lift table



bolted the engine to the frame



fitted the rear wheel, rear foot rests, pedals etc, the rear sprocket and brakes hoes are in good shape



cleaned up the threaded carb intake manifolds, new O rings between the isolator and cast pieces





assembled the replated and powder coated cross over shift mechanism



I cleaned up the triple clamps ready for new bearing grease and to be installed



tires, rims, spokes where all in very good condition, I just washed the hubs and rims with mag wheel cleaner, hot water, soap and a bristle brush, a little aluminum polish and they present real nice

[Huzo]

You are a freaking genius mate..
But I’d be careful were I you, the bike might end up costing you $3.50 more than it’s “worth...” Gasp...!

That would make the whole exercise a waste....(apparently) 

[Canuck750]

You are a freaking genius mate..
But I’d be careful were I you, the bike might end up costing you $3.50 more than it’s “worth...” Gasp...!

That would make the whole exercise a waste....(apparently) 

Thanks Huzo, maybe I should price it in Bitcoin (whatever that is). I got my fingers crossed, this just might turn out to be the least expensive restoration I have done, now that I have said it something will probably go sideways

[Canuck750]

I started on the triple clamps this afternoon, previous owner had fitted new tarpered roller bearings but the overall depth of the roller bearing and race is greater than what would have been originaly cup and cone / loose ball.

I had not noticed this when disassembling the front end but there is very little bite for the sole top securing nut, 7mm tops for overall thread depth. Unlike a Guzzi or other Italian bikes of the period there is no intermediate nut that is screwed down onto the upper bearing prior to dropping the upper triple clamp.

To try and remdey the loss of thread depth for the top nut I decided to machine the top and underside of the upper clamp, I was able to machine 1.5mm per side for a total of 3mm, this increased the top nut bite from 7 to just over 10mm





I think with the machining and the strength of the pinch bolt the triple clamps should be secure



I polished the Verlicchi headlight stainless brackets, powder caated the black headlight ears, new reproduction rubbers from Guzzino

http://guzzino.com/



Same source for new fork dust boots, originals are perished and fork seals plus other small rubber bits and carb parts for the Dellorto's

I prefer these cast alloy treaded intake manifolds that support the carbs rather than the rubber boots that Morini used on the 500, my 500 carb to head boot sagged and split, reproductions are available from Start Gomma but they are expensive







I powder coated the instrument support frames and just cleaned the holder rubbers and indicator lights and sockets



Tach and speedo faces do not match but both are labeled Moto Morini, the tach on this bike is mechancial, strangely the handlebar clamp bolts are imperial, perhaps replaced by previous owner and passed through the treaded metric holes in the upper triple and had nuts fitted below. I retapped the upper triple and fitted new M8 stainelss bolts but also added the nuts underneath.



I have some work to do for the front fender, the support brackets have been repainted but the paint is peeling, will strip and powder coat, there are some scrapes in the stainless fender that I am going to try and polish out

Loose fitted the carbs, was able to find new parts for most of the internals with the exception of the atomizers, I am going to ditch the K&N pod filters and reinstall a stock air filter box and the mulitiple vent hoses that terminate in the plastic manifold collector, the former North Leicester Motors (NLM, they were the go to guys in the UK for Morini) reccommended running the stock air box as opposed to pod filters.

I also plan on fitting the original type signal lights, stems and support brackets, Mdina Italy had the NOS parts in stock, the signal lights themselves will be reproduction CEV.

Have not decided on the headlight / signal light / horn switch. The Moto Morini 500 uses a unit that is pretty decent but hard to find so I may just go for something multi function like the options MG Cycle offer. I think in 1975 Moto Morini were till using the fiddley CEV type that were of the family of switches found on the Guzzi V7 Sport, Eldorado etc. not the easiest to use from my experience.

[Huzo]

In my view..
You Sir, are the best.....

[Antietam Classic Cycle]

Your top triple was likely from a Sport and was drilled and tapped to accept handlebar clamps.

The mechanical tach is from a later model 350 or 500. Likely the original electronic tach died and a previous owner "upgraded" to the mechanical unit and necessary drive bits. Blue face and black rim look like 350 K or K2.

The original left-side switch was a CEV "snuffbox" type, and had headlight high/low, signals and horn. Mine is an original and works well.

[Canuck750]

Your top triple was likely from a Sport and was drilled and tapped to accept handlebar clamps.

The mechanical tach is from a later model 350 or 500. Likely the original electronic tach died and a previous owner "upgraded" to the mechanical unit and necessary drive bits. Blue face and black rim look like 350 K or K2.

The original left-side switch was a CEV "snuffbox" type, and had headlight high/low, signals and horn. Mine is an original and works well.

Thanks Charlie! great information as always,

[Canuck750]

The paint almost fell off the front fender brackets in the vapour blaster, plenty of rust under the paint, the brackets were once chrome plated but most of the plating is long gone. I drilled out the rivets and powder coated all the fender support pieces, while I was at it I powder coated the metal wire harness wraps, I blast the parts clean and wipe down with acetone prior to powder coating.

If you dont have some type of blast cabinet a wire wheel will do just fine, to get the last of the rust out soak the parts in a 50% diluted solution of muriatic acid (do that outside the fumes are nasty)





there is nothing simpler than powder coating for small parts, all you need is an old oven, a couple psi of air and a 110v outlet, plus its cheap, makes very little mess, no smell and just cleans up with a broom or compressed air, and after 20 minutes in the oven at 400F its done for good, just let the parts cool and they are good to go. I hang the pieces off a metal pipe and use galvanized wire as hangers



Once cooled the brackets went back on, I used 5mm diameter aluminum rivets, easy to fold down the backside of the rivet



steering damper back on



got the last piece of the shift linkage powder caated and mounted



That's a lot of rods and joints to swap the shift pedal from the left to the right but it works

[Canuck750]

Front wheel back on, again the bike came with these excellent tires, rims and spokes, just cleaned the tire and polished the rim a bit



I bought these Morini signal light stems and repop signal lights form Mdina Italy a couple years ago



Front



Rear, the seat has a repro cover (I think, it came like this)



I painted the tool tray with a semi gloss black vinyl trim paint



I got repro rubber air intake boots from Startgomma, but the stock carbs are missing the threaded flanges that spin onto the carbs



Carb threaded flange is 32mm



rubber boot I.D. is 37mm



I can probably make some up from 38mm (1-1/2" O.D. plastic pipe or delrin rod)

I looked at a period factory brochure and noticed I have the Verlicchi headlight bracket black legs upside down, need to flip them over



I broke down and ordered a new repro set of chrome headers from 'Moto Storiche' in Italy, I have bought muffler and headers from them in the last year for my Aermacchi 250 and Benelli Sprite projects and the quality seems very good, the painted balck headers that were on the bike just don't do the Strada justice.

One last (hopefully) order from Mdina Italy today for a couple cables and four carb manifold gaskets.

parts boxes are almost empty, then the long job of checking / rebuilding all the wiring, fitting cables, and getting it sorted out for start up

[Antietam Classic Cycle]

I may have those threaded adapters on some spare carbs here, will check later today.

I need a pair of those "U" shaped backing plates for the rear signal mounting. Mdina didn't have any when I last ordered, stainless fender washers are working okay for now.

[Canuck750]

I may have those threaded adapters on some spare carbs here, will check later today.

I need a pair of those "U" shaped backing plates for the rear signal mounting. Mdina didn't have any when I last ordered, stainless fender washers are working okay for now.

Thanks Charlie!

[Canuck750]

I found the shift mechanism was too tight, I thought I had it ok but when I hooked up the linkage its way too tight, I pulled the motor, split the cases, and changed out the shims on the shift mechanism shaft. I tested the mechanism with the cases torqued together and then tested it all again, then split the cases and sealed them, put the motor all back together. the shift pattern is now smooth up and down

I reinstalled the motor, the chain and chain guard



I stripped the horn, repainted the metal parts and installed it



the shift pedal / bracket is badly worn, I could not get the bracket tigth enough to take out the slop so I welded up the bracket

and milled out the slot to take the pedal, 8.5mm wide







the pedal slot faces were rounded and basicly a mess. I clamped the pedal in a vice and shaved the flats vertical and to 8.5mm width



I heat treated the pieces after I milled them, got the steel cherry red and quenched in oil

[Canuck750]

I had two Moto Morini stators rewound last year in the UK - Westcounty Windings, very good and quick service but I only had the 5 charging coils done as I was using Eletronic Sachse couil battery ignition on my Morini 500, but on the 3-1/2 I am going to keep the original Ducati Electronica. I had one new ignition coil on hand so I added that to the stator body, soldered the ground lead to the stator frame and attached the stator to the bike, then the rotor





Valve lash set and rocker covers / gaskets installed,

Installed rear brake pedal cable and the right hand engine case cover



I need to review the rear brake cable / arm position or perhaps the cable is just stretched but the adjuster is near its limit



cleaned up the ignition pick up device



Insatlled it



the mechanical tachometer is not stock to this model, there is something missing between the inside of the pickup cover/ tach drive mechanism and the tip of the camshaft, or perhaps the models that used a mechanical tachometer have a square slot in the end of the camshaft to matre to the drive mechanism??



speedo cable installed

[Antietam Classic Cycle]

I had the same issue with my rear brake cable and ended up putting two slotted spacers on the cable - one at the pedal end and the other at the brake backing plate. You can probably see them in my photos.

The nut that secures the pickup rotor to the end of the cam should have a square "socket" to drive the tach.

[Canuck750]

I had the same issue with my rear brake cable and ended up putting two slotted spacers on the cable - one at the pedal end and the other at the brake backing plate. You can probably see them in my photos.

The nut that secures the pickup rotor to the end of the cam should have a square "socket" to drive the tach.

Thanks Charlie, I will take a look at your pictures for the rear brake.

The nut that secures the pickup over the cam, is this square sloted nut unique to the mechanical tach drive or is it common to all?

I am pretty sure it didn't come with the bike, the pickup and cover were bagged up in a parts box when I got the bike and the nylock nut I used was in the same bag. It does sound like something I could machine up.