From old posts in ThumperTalk. If the XL250 has a battery ignition (i.e., not magneto) then you will probably also need a 12V ignition coil and appropriate resistor:
"Hi Thumper folk. It is very easy to convert to 12V on these old bikes. In the old days regulating voltage was a hassel. They used high resistance 6V bulbs to do most of the regulating. With modern solid state regulators it is easy to convert to 12V. Just purchase a 12V regulator like the " Moose " 12V HD regulator. less than $15, install it ( easy two wires and one goes to frame ).
Then install 12V bulbs and you will have good basic lighting for enduro type or off road vehicles. There is no need to rewind for 12V because the output of most magnetos is about 20 to 30 VAC at just above an idle. 12V bulbs have a lot less resistanc than 6V and will be brighter. I have done several now and this has been tried by other friends and with great results. I have been using this on several bikes from Hodakas to SL100 Hondas. If these regulators were available years ago there would not be many 6V systems. The regulator I have been using is the Moose Parts unlimited # 2112-0090 anda should cost less than $15 from your local dealer. TRY IT ! it works very well, wayne huff "
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"Hey, Wayne,
That's great info. I have both a Hodaka 250SL and several early SL/CL Honda 100s and 125. I've read about doing it, but it's always been "my brother's roomate's cousin knew a guy who..." :thumbsup:
I'm curious about the hookup: the early Honda's are two wire, where each wire is one end of the long multi-coil charging/lighting circuit. Each wire goes to half of a full-wave rectifier, which inverts half of the DC. With the Moose type, with a single input and one side grounded, it must just be a half wave rectifier, which just clips that other half. Where do you hook up the second wire from the OEM system?
Anyway, sounds interesting. I may give it a try...
Kirk"
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"Kirk, forget about rectifiers and DC current. The regulator simply plugs into your lighting wire and the other other wire has an eye made on to it, that goes to ground. If you have two wires coming out of the mag( other than the wire for ignition) just use one of them. the other may need to be grounded but I think it usually can be just taped off or something. This is something I have tested and currently use and is not some rumor. It works and works well. If it matters to anyone, yes I do have a degree in electronics and am a long time proffessional motorcycle mechanic. The regulator is small and bolts to the frame. prefferably where it can get air although I have had no over heating problems with the ones I am using. The regulator works so well it is impossible to tell when it kicks in and doesn't seem to care what rpm or load you put on it. I know this all sounds too good to be true but the availabilty of a good cheap reliable regulator has changed everything about simple reliable lighting on these vintage bikes. I say again, you do not need to rewind for 12V. The windings are already wound to produce enough AC to run 12V bulbs. I know it seems backwards but the 12V bulbs have little resistance and do not put near the demands on your magneto output as 6V bulbs and rectifiers.I will try to write this up in more detail and post it on my web site when I get around to it so I won't have to do it for every forum I am in.By the way, Dwight Rudder is using this method on one of his bikes that I wired for him and is well pleased. Also this is so much fun to get rid of the corrosive battery,unreliable rectifier and there is no need for a fuse!! Just a light switch and a kill button. Try it you will like it. have fun ,wayne huff"
thanx for your comments! Quick question! I have a 4.0 x 18 rim what tire fit better, the 120/80-18 or the 4.10-18? I think bigger is better! Which one is bigger? Do they both fit and how?
