FFJMOORE Big Blue Engine rebuild

[Flying J]

Well i picked up another 125 the other day. Wife was not happy. The bike came with 2 retro helmets so i told her i bought the 2 helmets and the guy threw in the bike for free!.....I dont think she believes me but i still have the bike so life is good.



got the bike home and introduced Her (lets call her Lola for now) Lola to her brother.



Needs a new tube.
I was told compression was 40 psi.
Put some oil in the motor, cylinders and head and got a reading of 200!



Rebuilt the carb and i would not start.
Did the timing and checked the spark. Spark was weak. So i swaped out the coil and condenser from my parts bike put in a new plug and it fired up. Re checked compression its at 175. The book says 170. so im good. Just need to try and put a new tube in, i have never done that before, then i will spin it around the block a few times. Will post video.

[Flying J]

New Tube. New points, adjusted valves, replaced bent foot brake and it fires up first kick even without a battery. I need to get a battery so it doesnt die every time i hit the brakes.

[Flying J]

Starting to sort out the parts i need for a 12v conversion. I have the new stator, i have a 12 regulator/rectifier and i know how im going to wire it. Blinkers are easy and i have a 12v led taillight im going to run. The hard part is the headlight. I would like to keep the bucket and just swap the light but its not that easy to find a replacement light that is 12v. Im looking into a CB160 light or possibly changing the whole thing out for an RD125 bucket and light. ANybody got any leads on that kinda stuff?

[Rimmy]

I'm not too sure if they have the same headlight bucket size, but the '84+ models are 12V, so you may want to look into finding a new bulb for it.  Also, I've been getting some parts from various eBayers in Thailand, so they might have a 12V light that'll fit.

[Flying J]

Still working on finding the right headlight but since the registration at the DMV turned into a mess i jumped right in and tried the 12 volt conversion. Swapped in the stator and the new reg/rec and then fired the bike up. It RUNS! so then i decided i would wire in my LED tail light. It WORKS! Now i need to go get a battery that will fit and then test to see how much output the bike has with the 350 stator.

[surffly]

the 350 stator just bolted in and worked?
125 rotor?
would love to hear some more info
but what do you really gain by changing to 12V?
coil ok with the new found voltage?

[Flying J]

Still sorting out the details on regulators and rectifiers and maintaining the proper voltage to the battery.
but to answer your question
 350 rotor does bolt right in but there are a few small differences.  A) the rubber plug on the stator wires is different. B) the connector on the 350 is round and not square. You need to use a 12 volt rectifier as well as add a 12 regulator.
I started off with used parts from other old bikes so its been hard deciding weather the issues im having are due to poor performing old parts or not. Im going to update the regulator and rectifier i think. The gains you get for switching to 12 volt are really not much. You can run 12 volt led brake and blinkers. 6 volt equipment is not easy to find. The other reason is you can run a 12 head light which tends to be a little brighter. You may also be able to run the new H4 bulb headlight but i can not confirm if the system will support that much draw yet. As of now i would say that its not a huge benifit to switch unless you are building a cafe racer and will be running a different headlight and blinkers. Coil seems to work fine.

[Erskine]

When you've sussed this all out, is there a chance you could sketch out a wiring diagram showing how you've connected up the regulator/rectifier? Please?
I'm running ignition only at the mo with the horn running off a disposable 9v  battery. but I'm looking onward to the winter and want to have lights by then.
Thanks if you can!

[Flying J]

This is basicaly the setup that im running.

[Flying J]

Im going to replace the old rectifier with one off these

[Erskine]

Cheers for that. I've only got two wires coming out from my genie though damnit.
The Yellow kind and the white kind. Do they carry different types of electricity?

[Flying J]

What bike are you working on?

[Erskine]

What bike are you working on?

Generic Honda CG 125 (push rod OHV) CDI version, Fundamentally the same as the CB125 but a different top end. It has a separate generating circuit that powers the pulse emitter for ignition. My first attempt at wiring up a reg/rect was a non event and only served to reinforce the fact that I am an ignorant twat when it comes to anything electrical. I did suss out how to wire it ignition only and it's never missed a beat but I think that was my 'Everest' moment!

[Flying J]

I am completely unfamiliar with CDI. What i would do is find a wiring diagram and copy that or find one from a similar bike.

[Erskine]

CDI rocks! Pulse generator to CDI box, CDI box to earth, stop switch and coil, coil to plug, bang!
Wasted spark principle. Piece of piss, I'll never do points again! No battery, condenser or timing plate.
Kick - spark - go