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If you are capable of building a rectifier then you should be capable of finding a good spot to hide it. Most restored British bikes are converted to modern voltage regulators. We just hide them away ( they’re very small ) . Mine has all the stock electrical system in place, but also a modern regulator under the seat, doing the work. We do this because it does a better job of keeping the battery in good charge, which in turn makes the lights brighter . The electrical systems on old bikes can use all the help they can get. Convert to LED bulbs to reduce the strain on the system as well as improve lighting.
 

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Discussion Starter #23
I like the idea of tucking a better rectifier/regulator out of sight, and will go that way.
My second question. How can I determine if my 200 cc engine is a bored 175 or a slimmed 250?
I have a Clymer copy of the Ducati owner's manual from the mid-1960's for narrow case engines, but it never mentions the 200.
Lots of details on the 175 and 250 engines, but I don't know which to use.
According to another book I have, the 200 was a bored 175 until early 1961, when they started making the 250, and, at that time, the 200 became a slimmed 250.
Since I purchased mine in June of that year, it could have been either.
 

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Hi Lee: Are there stamps on the motor that indicate the capacity? Do you know for sure it is a 200? Otherwise, pop off the head and measure the stroke and piston diameter and do the math! This may help determine if it was a bored 175 if you can find the 175 specs for bore and stroke. You are my kinda guy; obviously love your vehicles. Do you talk to them? (I do). Post more pics!
 

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Just looked up the specs:

The 175 has a bore of 61mm x a stroke of 58.4mm
The 200 has a bore of 66mm x a stroke of 58.4mm
The 250 has a bore of 73.7mm x a stroke of 58.4mm

2.5mm each side of a 175 bore could be likely; it's also more likely that the 200 was simply a bored-out 175 and it also makes more sense chronologically.

Beautiful little bikes.
 

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Phone number: Fillmore-60122 HA!

You young-uns prolly didn't know US phone numbers used to start with two letters, signifying two numbers on the telephone dial. All numbers in a given exchange, or geographic area of town, had the same two letter prefix.
I was born in 1991 and I didn't know that; this is coming from someone who grew up reading encyclopedias for leisure.

Clearly, I skipped the section discussing the telephonic history in the Golden Age of Television. Time to bust out that encyclopedia :nerd:
 

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Just looked up the specs:

The 175 has a bore of 61mm x a stroke of 58.4mm
The 200 has a bore of 66mm x a stroke of 58.4mm
The 250 has a bore of 73.7mm x a stroke of 58.4mm

2.5mm each side of a 175 bore could be likely; it's also more likely that the 200 was simply a bored-out 175 and it also makes more sense chronologically.

Beautiful little bikes.
the stroke on the 175 , 200 and 250 is 57.8 mm

the bore on a 250 is 74 mm

Eldert
 

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Discussion Starter #29
I don't think there is any question that mine is a 200. I had the engine overhauled in Seattle in the early 1970's and was concerned that they could get parts for a 200, but they had no problem, including a replacement piston.

Can anyone tell me where to find the engine number? I have the number as provided on my purchase document, but have never been able to confirm it with a number on the engine.
 

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Thanks Eldert: There are a few contradictory specs on the Internet and I quoted from what I thought to be reliable; I also read 62mm x 57.8mm (162cc) for the 175 and 67mm x 57.8mm for the 200.

Probably better to use mathematics; assuming a common 57.8mm bore for all three motor sizes results in the following:
175cc = 62mm x 57.8mm
200cc = 66.4mm x 57.8mm
250cc = 74.2mm x 57.8mm
 

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If you are capable of building a rectifier then you should be capable of finding a good spot to hide it. Most restored British bikes are converted to modern voltage regulators. We just hide them away ( they’re very small ) . Mine has all the stock electrical system in place, but also a modern regulator under the seat, doing the work. We do this because it does a better job of keeping the battery in good charge, which in turn makes the lights brighter . The electrical systems on old bikes can use all the help they can get. Convert to LED bulbs to reduce the strain on the system as well as improve lighting.
aww yr exorcising the original spirit with modern electrics on old bikes. I say, if ya can't fix it with a chisel and hammer on the side of the road, you ruined it. Why do the Brits drink warm beer? Because they have Lucas refrigerators.
 

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Thanks Eldert: There are a few contradictory specs on the Internet and I quoted from what I thought to be reliable; I also read 62mm x 57.8mm (162cc) for the 175 and 67mm x 57.8mm for the 200.

Probably better to use mathematics; assuming a common 57.8mm bore for all three motor sizes results in the following:
175cc = 62mm x 57.8mm
200cc = 66.4mm x 57.8mm
250cc = 74.2mm x 57.8mm[/QUOTE


Hi Rick

a 200 has a 67 mm bore and is 204 cc . the 250 has 74 m bore and a 350 has a 75 mm stroke and 76 mm bore and is only 340 cc . a 450 has the same 75 mm stroke and 86 mm bore and is 435 cc

Regards Eldert
 
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