General Category > Bike Builds, Rebuilds And Restorations Only
1965 Benelli / Motobi 200 Sprite
cliffrod:
Not surprised it’s hard to get stone. My orders for custom granite (raw stock) from the manufacturers are currently requiring min 8-12 months lead time. Even more pedestrian dimensional stone components are comparable lead times if you aren’t ordering a semi trailer load at a time. So I would expect properly lapped surface plate stone to be a long schedule as well and not surprised that cheaper priced stones were bought up to be repurposed. You just can’t get stone right now. It’s an industry-wide issue.
So, while I impatiently wait, it’s to see more of your bike progress, Jim.
Canuck750:
--- Quote from: cliffrod on November 19, 2022, 08:11:01 PM ---Not surprised it’s hard to get stone. My orders for custom granite (raw stock) from the manufacturers are currently requiring min 8-12 months lead time. Even more pedestrian dimensional stone components are comparable lead times if you aren’t ordering a semi trailer load at a time. So I would expect properly lapped surface plate stone to be a long schedule as well and not surprised that cheaper priced stones were bought up to be repurposed. You just can’t get stone right now. It’s an industry-wide issue.
So, while I impatiently wait, it’s to see more of your bike progress, Jim.
--- End quote ---
I shouldn't be surprised that finished stone, like everything else is in short supply these days.
I have been busy getting a bunch of parts ready for bright zinc plating but this time I am taking the extra step to finish the bare steel parts of the visible components to a decent bright finish in the hope that once plated the bright zinc will have that like new bolt look. In the past the plating I get done is very good but it has not been like new in shine. I have three sets of kick start and brake pedal levers and a bunch of axles and shafts with exposed heads. Some pits remain on the pedal components, the depth of the rust was very deep and I have already spent three days getting this small batch of parts prepared.
The kick starter parts should be chrome plated but I am not too happy with the chrome shop I have used for years and until I can find a good shop the bright zinc will have to do,
All of these pieces were rusted and several had very deep pits, I almost considered throwing a brake pedal away but went after these parts with a series of random orbital foam backed sander papers, 100 / 150 / 240 / 400 and then on the polishing wheel with white polish stick
The 'other' parts are mostly inside the motor and not visible, the rest of the exterior fasteners are stainless steel
Most to the engine studs and shaft threaded ends needed attention, everything chased and ready for plating. I pulled the axles and swing arm shaft out of the Aermacchi 250 as well, the bolt hex ends had to be cleaned up on the lathe and mill, just knackered after decades of ham fisted abuse, likely from pipe wrenches and vice grips grabbing the heads.
Canuck750:
I can finally say with confidence I understand the differences between the Benelli 4 Speed 'egg' motors; 125, 200 and 250 cc.
The rumor I have been told a couple times is that all three share very similar bottom ends, this is only partially true to the extent of the transmission parts, even the cases are slightly different across the range. For example a 125 and 200 4 speed motor share the same frame mounting bolts, the 250 has a different lower frame location point.
125 and 200 cases are very close but there are differences in the type of small diameter needle bearings used between the two, including the depth and bearing covers.
My point, which I have now learned the hard way, is that not much actually interchanges with the bottom ends other than a 125 and 200 share the same con rod but the crank webs are not interchangeable.
When Its all said and done I have accumulated a 125, 200 and 250 motor for a 200 bike! One day the 'other' engines may find a home in a chassis.
Nerding out here but for the recorded here are the measurements and diagrams I did to catalog the bottom end differences in my quest to find ONE good crank.
Canuck750:
My friend George, retired professional welder TIG welded replacement aluminum fins on my Benelli 200 engine case and rocker cover. This outer long fin was almost completely broken off, I have just a little bit of cleanup to do and the repair will be almost invisible
Four fins were broken off the rocker, again just finishing to do
Canuck750:
I picked up the reconditioned head today from the machine shop, new guides pressed in and reamed to size and the valves reground.
I dropped the crankshaft off with a NOS crank pin and a new caged needle roller bearing I purchased from 123 Bearing in the UK - 30 mm O.D. x 24 mm I.D, x 15 mm width. I asked the machinist about the suitability of the bearing and he told me he uses similar bearings all the time rebuilding dirt bike cranks so I think I am good to go. Dry fitting the bearing ion the con rod with the pin felt great, almost no play whatsoever.
The 'new to me' pair of crankcases have been cleaned and all new bearings fitted, double row close fit ball bearings, standard ball bearings and cup needle bearings all purchased from 123 Bearing in the U.K.
I have sent the cylinder studs and misc bearing covers out to be bright zinc plated, I will hopefully have the bottom end back together in a couple weeks at the latest.
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