1965 Benelli / Motobi 200 Sprite

[Antietam Classic Cycle]

Looks great! BTW, 123 Bearing is in France. 

123Bearing
CRT 4 de Lesquin Rue Léo Ferré
59273 FRETIN - FRANCE

[Canuck750]

Looks great! BTW, 123 Bearing is in France. 

123Bearing
CRT 4 de Lesquin Rue Léo Ferré
59273 FRETIN - FRANCE

I guess I wasn’t paying attention to their website, I just assumed they were UK, great service though, I ordered the crank big end needle bearings and cup rollers late last week and less than a week later they arrived. Can’t beat the prices either, I used to have a helpful local supplier but no longer.

[Canuck750]

I got another 200 Sprite parts motor bottom end in trade for some Cardellino parts. The cases are excellent and will be used in my 200 motor. A bunch of other bits will find a home in the 250 and 125 motors.





A night in the ultrasonic tank then an afternoon of vapour blasting.



The bike suffered a broken transmission gear, probably sat for decades after the transmission went bang.



I am hoping I can repair the damaged crankshaft tip with
My MIG and turn it back in the lathe.



The rotor was fused to the crank, someone had tried to get it off before and whatever puller they tried damaged the crank and tore the threads out of the rotor spindle. I cut the rotor brass body off the steel Center (I have a spare) and used serious heat and a big bearing puller to get it off, amazing how stuck it was.

[Canuck750]

It’s taken many months of searching for parts, buying a couple donor engines, and research but I have finally got a rebuilt 200 crankshaft with new rod, pin and main bearing and while I was at it I had a 250 crank rebuilt with new pin and bearing and a 125 with NOS webs and bearing.



So now it’s time to go through all the boxes of parts and build a 200 for the project bike.  I will have a rebuilt 125 and 250 for future projects



Back to work on the Benelli

[Canuck750]

sorting through parts today, I have three sets of transmission pieces and used the best of the gears and dog, getting the snap ring off the output shaft to separate the rotating gear was a heck of a job, there must be a trick or a special tool, this snap ring has no holes in to open with a standard set of snap ring pliers. three small flat blade screwdrivers opened the ring to free the gear, I sure could have used three hands.

A very helpful tool is the Tusk crankshaft puller, not too expensive and it cleanly pulls the crank into the ball bearing without resulting to a soft mallet on the opposite end of the crank and disturbing the freshly trued crank



I pressed in a new small end bush I had made up by a machinist and reamed it to 18mm, drilled the oil passage holes. I also ran a 10mm reamer through the case cam follower bushings, one of the bushing was very tight.

crank set in one case and it spins so smoothly



Once the transmission and gear shift drum were installed I found there was a very stiff / tight fit across one set of meshing gears. I went back through the stash I had and found another gear that fits much better. I tested the shift mechanism with a small vice grip on the shift drum output shaft, it moves easily through the gears and neutral seems to be easy to find without the detent in place,



I should get the cases joined tomorrow and get on with the top end.

[cliffrod]

Looking great, Jim.  How much difference is there between transmissions vs displacement?  Have you accumulated that many spares for each combination or are many of the parts interchangeable regardless of displacement?

[Canuck750]

Looking great, Jim.  How much difference is there between transmissions vs displacement?  Have you accumulated that many spares for each combination or are many of the parts interchangeable regardless of displacement?

Thanks Clint,

As far as I can tell the 4 speed transmission is the same across the 125 - 200 and 250, The 125 and 250 were also available in 5 speed and I think the crank cases are unique for the 5 speeds. There are many small differences between the engines, the 125 and 200 share side covers, the 250 is unique, the heads and cylinders are individual but some head parts are interchangeable. I am learning every day about the differences and I think I now hopefully have all the parts for the 125, 200 and 250.

Today I must have assembled and split the cases a dozen times to shim the transmission shafts, shift drum and kick start shaft. Benelli does not show a case center gasket but on each of the three engines I have put together the cases are just far too tight without a thin center case gasket. I have made my own gasket in each case and I have collected a good stock of thin shims to fit the various shafts.



I previously had a 200 cylinder bored 2nd over and matching NOS piston and rings, fitted a set of new cylinder base gaskets - paper / aluminum / paper, and fitted re-plated studs.



I will pull the 125 motor out of the frame tomorrow and install the 200 motor then fit all the rest of the parts with the engine in place.

I want to get the engine running and sorted before I pull the bike apart for painting. I need to tackle all the electrical next.

[Canuck750]

swapped out the 125 motor for the 200, just three bolts and the motor drops straight down, so simple and its pretty light without the clutch and primary gears.

the head gasket is just a thick rubber seal for the push rod tubes and studs, the head is sealed by the cylinder liner fitting tight into the aluminum head recess, I think this is the design in many engines, Ducati does similar on the bevel twins.





installed the drive sprocket and the sheet metal cover that keeps dirt out of the stator area, fitted a new condenser and replaced the lighting coil with a spare I had, new wires



I should have installed the shift drum cap and woodruff key with the motor on the bench, twice the key fell to the floor and I spent a long time finding it each time



Clutch is pretty simple, the five springs are put into tension by hooking the top of the springs over a loose steel ring



stripped and cleaned the oil pump, its slides in from below and the gear engages the center of the cam shaft, a new soft rubber seal was installed



this motor was missing the M9 x 1.25 head nuts, I found flanges examples on Ebay from China but the wrench size is 14mm not the stock 12mm, I machined the flanges off and I can just get an open end wrench over the nuts but torque is by feel, I cant get a socket on



The bike deserves a period correct Magneti Marelli plug, love the pink





made up some 6mm studs for the carb flange, I need to rebuild a carb from my stock of used Dellortos,



Next to go through the wire schematic and make some new wire harness sections, fit a 6V coil and connect the electrical up inside the headlight shell. Hopefully I will get a good spark.

I gave up on building a 125 motor, the NIS crank I bought won’t work, it is for a 5 speed. I decided to build up another 200 cc 4 speed with all the spare parts and a gods pair of 200 crank cases. I guess if I do build a race replica it will have the 200 motor.

[Canuck750]

I got some time in on the Sprite this past week, installed a reproduction wire harness I found on Italian EBay, it’s an accurate copy.



I installed a brake, clutch and throttle cable. For the throttle I had to make a solder ball end to fit the throttle, I made a little ‘pot’ from 1/2” diameter pipe, about 1/2 “ tall, melted solder into the pot and then dipped the bare end of the cable, I balled up the strands, and then once cooled I sanded the blob into a ball.



I ordered a NOS light dip switch/horn button and a rear brake pedal switch to finish off the electrical. The CEV speedometer I have had a very small diameter threaded mount for the cable and doesn’t work with he speedo cable I bought, need to come up with something for that.

I used the original type wire terminal connectors used on Italian bikes of this vintage.





I ordered from Detlef Burian what I hope is the last of the parts I need, a new exhaust header pipe, a few little clips and rubber parts. I think I am getting close to completion of the dry build and starting up the motor. Then to strip it down and get on with paint.

[Antietam Classic Cycle]

Sweet!

[Canuck750]

I got a nice pair of Orlandi fuel taps that came with a donor motor, good shape and even the rubber seals remain pliable.



I punched two little indents into the fuel tap faces and dabbed a spot of red paint at the ‘off’ position and an unpainted indent for full ‘on’   I always forget which position is off and on on the various petcocks on my bikes, this little marking makes it easy.

These are the correct taps for this bike and fit the Siamese fuel line to the carb



I sorted out the clutch today, de-burred some plates and reassembled the unit, nice smooth clutch pull now. Many of the Italian manufacturers used bared end cables with the clamp on terminals, the stub end of the cable is then folded back 180 degrees and a plastic tube was fitted over the end. I used a short piece of green fuel line as the plastic retainer.





Next job is to assemble the steering damper, I found a NOS plastic knob and have replayed the compression plates. I had not noticed the steering stop plate appears to be snapped off short of the lower triple clamp stops. I will strip down the front end and weld up a stop tang.

[Canuck750]

I removed the front end to get access to the steering stop, cut a piece of plate to add to the broken stub,



A quick splash of primer to keep it clean until painting



fitted the damper parts, needs another piece of strap to engage the damper stationary piece



Tha'ts done for now



I fitted the steering stem ball bearings and set the triples, I had to machine down the top of the triple at the stem to get enough good thread out of the stem for the top nut, only had to shave off about 3mm, good bite now picked up a few parts I had sent out for powder coat primer, chain guard, side covers, now everything has been media blasted and coated with a thick base of sand-able primer ready for final prime and paint.



The to do list is getting smaller:

- install light dimmer / horn switch
- install rear brake pedal switch
- install rotor, set points and timing, install engine side cover
- Install drive chain
- strip shock absorber, paint bodies semi gloss black
- install speedometer and cable
- install exhaust manifold and muffler
- install 6V battery

Then start up the bike and tune it, followed by stripping it all down for painting, this little Benelli / Motobi has taken more time and effort to source parts, repair, rebuild etc than anything else I have restored in the past.

I did a summary of what I started off with from the initial parts bike in a crate I bought off Ebay:

Frame / swing arm with axle / rear fender loop / triple clamps, forks and shrouds / head light / seat base / right side cover / center stand / gas tank / front hub / brake pedal / kick starter / rear axle

What was not correct for the bike that came in the crate:

engine (was a 125 bottom end with a 250 top end and a miss matched crank) rear hub / right side cover / front fender / front axle /

Things I found:

200 cc complete engine / oversize piston and rings / valve guides / gaskets, seals and O rings/ engine case bearings / big end rod bearing, small end bush / repro seat cover / NOS handlebars / repro exhaust pipe and header / NOS speedo and cable / rear hub / spokes / rims / tires and tubes / shift pedal / headstock steering races / carburetor / chain guard / front and rear fender / licence plate bracket / tail light / wire harness / brake and clutch cables / air pump / horn / braided fuel line / grips / foot peg rubbers / tank rubbers / front and rear sprockets / Dansi 6v coil / stator lighting coil / condenser / levers and cable adjusters / front brake cam and brake cable lever / rear shocks / battery strap / steering damper knob / passenger foot rests / front brake shoes ....

There is truth to that old saying to never buy a disassembled motorcycle in boxes, I should have just steered away from this bike when it came up for sale as a 'Project that was 95% there'.... but here we are nearing the end of the dry build, I got in too deep but when its all done I think I will be happy with it.

[cliffrod]

Man, Jim- I’m loving it.  That bike is going to be great!  Thanks for all the pics and details.

[Pescatore]

Hey Canuck, I knew I had seen that motor on this forum.
I found this Motobi at a museum in Beverly, MA.

[Canuck750]

Hey Canuck, I knew I had seen that motor on this forum.
I found this Motobi at a museum in Beverly, MA.

Thanks for posting that picture. I think it’s a 5 speed with a gear driven tach and it’s a sport model with the clip ons and shorter fork shrouds, very cool.

[Scout63]

Great work and wonderful photography/ descriptions Jim. I agree re buying disassembled bikes.

[cliffrod]

Hey Canuck, I knew I had seen that motor on this forum.
I found this Motobi at a museum in Beverly, MA.

Jim, do you know what approx diameter front hub/brake or wheel rim (17” or 18”)  that bike would have?  Looks like a  grimeca sls twin panel 4 shoe brake, but if 17” brake looks smaller than typical 180mm version.

[Canuck750]

Jim, do you know what approx diameter front hub/brake or wheel rim (17” or 18”)  that bike would have?  Looks like a  grimeca sls twin panel 4 shoe brake, but if 17” brake looks smaller than typical 180mm version.

Hi Clint, the stock Sprite rims are 18” front and rear. The race bike in the picture has a non stock front hub, looks a lot bigger than the stock hub



A couple of the Motobi race bikes at the Pessaro museum.

[cliffrod]

Good info.  Thanks, Jim. 

[Canuck750]

A few things off the to do list today, I picked up some clear braided vent hose; 5/8" I.D., for the crank case breather,





The CEV horn and high/low light switch came in the mail yesterday,

[Canuck750]

A reproduction exhaust pipe arrived from Italy on Friday, looks to be correct



The fit to the cylinder head exhaust studs is very tight on one side, I can get the special long nuts just in



The hanger bracket is a long ways from the frame



I made up a stainless steel spacer



The exhaust pipe seems far too long and the reproduction muffler has only one hanger bracket



The muffler is supposed to slide over the exhaust pipe but the outside diameter of the muffler matches the inside diameter of the header



I decided to trim the header length and slide the muffler into the header



With the muffler clamped tight to the header and the rear hanger in place it’s all quite rigid. I may make a 3mm thick stainless steel bracket and weld it to the back of the muffler with a TIG



I installed some more reproduction rubber parts

[Pescatore]

Great job, looks like you're almost ready to crank it.
Is that how the crank breather hose used to run?
Seems like it could hide under the seat.

[Canuck750]

Great job, looks like you're almost ready to crank it.
Is that how the crank breather hose used to run?
Seems like it could hide under the seat.

I need to tuck the breather hose under the tail light bracket, that's how it is routed on the bike in the Beneli / Motobi museum in Pessaro.



I am just waiting on a few small things before I cross my fingers and crank it over.

[Pescatore]

I need to tuck the breather hose under the tail light bracket, that's how it is routed on the bike in the Beneli / Motobi museum in Pessaro.

I would not have guessed that's where it vents.

I am just waiting on a few small things before I cross my fingers and crank it over.

Best of luck   

[Canuck750]

I picked up a woodruff key to mount the rotor but before doing so I took an old rotor I had for this bike that was damaged from being seized to a donor engine crankshaft, the taper bore is not the best but the advance sleeve moves freely and the advance springs mechanism is good. I hate trying to set points and timing through the small access slots in the rotor so I milled off most of the brass on this donor rotor, just keeping the timing marks and the attachment points for the advance springs.
This is going to be used for quickly setting the point gap (0.16), ( 0 on the rotor) and the points opening point (A on the rotor)



so much easier to access the points adjusting screw and the three points plate screws that thread into the crankcase. And I can torque down the points plate and still check the points opening in the event the stator plate flexes as the screws are tightened.



pulled off the 'timing tool' and fastened the rotor, popped the side cover on.

[Lotus54]

I just read through the thread- great work!  I appreciate the specs on the cranks.  I’m splitting a 250 5 speed due to shifting issues, even though it only have some 1500 miles since new. 
I may have to cut off the flywheel also- but I’m going to give it a few more heat/cold cycles and try some of the ‘freeze and loosen’ penetrating stuff.  I guess get it hot, freeze it and hope it gets in there and maybe I can get it loose.

 

[Canuck750]

I just read through the thread- great work!  I appreciate the specs on the cranks.  I’m splitting a 250 5 speed due to shifting issues, even though it only have some 1500 miles since new. 
I may have to cut off the flywheel also- but I’m going to give it a few more heat/cold cycles and try some of the ‘freeze and loosen’ penetrating stuff.  I guess get it hot, freeze it and hope it gets in there and maybe I can get it loose.

I have rebuilt a couple 200 - 4 speed engines. In both cases I assemble the selector drum, input and output shafts only, then bolt up the cases. Check the end float of each shaft. You can wiggle a screwdriver under a gear and feel how much the input and output moves. I have had to add shims to the shafts to get the gear surfaces to align and the shaft to have very little movement. Too much slip and the shift digs will bind.

[Muzz]

Again, appreciate the work you do Jim. Excellent with the photos and the descriptions.

Fingers crossed that it fires up perfectly.

[Canuck750]

Again, appreciate the work you do Jim. Excellent with the photos and the descriptions.

Fingers crossed that it fires up perfectly.

Thanks Muz!
As soon as my doctor gives me the ok to swing a leg and try kick starting I am on it.

[kballowe]

Excellent thread !  Thanks for sharing !