CG125 OHV Build Oddessy

Re: CG125 clone

I had the valves reground today, all 2 of them.

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Then I found myself stuck at home on a Saturday night, with a bottle of Chilean Merlot, a cylinder head on the kitchen table, and a dremel. ;D

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Should flow slightly easier now.
I suppose it's time to lever open the wallet and order some parts of evilbay.
So far it's just a gasket set and a front sprocket.
(The rear and chain look ok, however the front looks like a ninja star.)
 
Re: CG125 Clone Wars

This is the state on my kitchen table this evening.
It's - 2 outside and the woodburner is keeping it real.
I'm pretty much ready to reassemble the head and slap it back on.
I opened up the exhaust port a tiny bit more as I'd over looked a couple of areas.

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I haven't been able to find out the head torque settings on line, so I'm hoping the Library service will have a manual.
Unless anyone can point me to a link for one?
Carb next, I know the plasticky manifold is split in more than one place, I hope I can salvage it.
I need to check the carb jet size. I'll be restarting this with a mesh type filter on the end of the original air box tube and some sort of exhaust with a lengthened header and a shortened silencer (reverse megaphone ), basically a cone welded on to the end of where ever the original was cut once I can get that muther of a can off it.
 
Re: CG125 Clone Wars

Cheers Glenn

We get down to low single figures, we had the odd -7 last year, but it's the wind chill that's a beatch. But I am up at the top of a mountain valley.

Thanks for the jetting advice!

I only eased the harshness of the lip on the floor of the exhaust port and smoothed it a little, not quite polished.
So I hope it won't have weakened the head.

I got the valves back in today and started to reassemble the top end. I found a Jap/Brazil manual to download for free.
So I've got the torque settings I needed.

I stripped out the back wheel and swinging arm earlier and spent some time flaking of the joke powder coating from the frame.
It looks like it was welded by three people...
The headstock and rear triangle by a tradesman, the engine mount/brake area by his trainee and the tabs by his pet monkey.

The tabs are all coming off but I shall be having some of the other stuff finished properly for peace of mind.

The quality of the tubing used for the rear triangle tubing is utter shite. A marked difference to the front down tube which is very good quality tubing.
I know the low quality of the metal used is prone to rust, and if it starts to rust again after I've refinished the frame .... time for a rethink.
 
Re: CG125 Clone Wars

a lot of this bike is identical to the cb125s - cept the OHV donk obviously
i'd bet on it being 12v
 
Re: CG125 Clone Wars

wow :eek: some good progress,

mine's almost done but the whole garage is under 2inchs of white stuff, going to take awhile now, hopefully be getting some parts i need for christmas :)

any updates.... just to keep this on page 1
 
Re: CG125 Clone Wars

sebatron said:
a lot of this bike is identical to the cb125s - cept the OHV donk obviously
i'd bet on it being 12v

It's a Chinese copy of a CG125.
'Interesting' cam, single lobe for both valves.
Rocker positions give correct opening/closing.
Arial used same system from at least 1950's
 
Re: CG125 Clone Wars

Not much to report here at the mo.
It's snowed, usually we don't get snow till the new year.
It looks exactly like pj's signature picture but much colder!
And my horse has gone lame in his back foot, so that's been my priority.
I need to borrow a torque wrench to reassemble the head and it's treacherous on foot and by truck to get to my mates to borrow one at the mo.
I'm going to refit the side cover this evening but that's it really..
Inspecting the rear wheel bearings revealed they need replacing too. :(
 
Re: CG125 Clone Wars

I got the side case on but failed to change the front sprocket .... I need to be able to hold it still.
I gave the Carb a wipe over and inspection. It's a Keihin PTG.
Where do I measure to get it's size? :-[

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I cleaned out the float bowl and checked the main jet size. It's a Keihin 95.
I will look for a 105 or a 110 .... jeez aren't jets expensive! sheesh :eek:
The cheapest I could find was $9 posted.
I did some research and 2 people were running these engines with open carbs on 115 and they said it was just a tiny bit rich.
 
Re: CG125 Clone Wars

Thanks once again Glenn. That makes it a 26 mm, exactly same as CG.
Ironically the only part 'missing' from this bike was the gear lever!, I'll leave changing the sprocket until one turns up.

Now I've got the engine back together and after much perseverance freed up the front engine mount bolts and got the front mount off to de rust.
From trawling the net I learnt, and subsequently discovered, that the mount bolts are too small a diameter for the casings and this is a cause of vibration at high revs. In fact I think this is a case for all the mounting points.
I'll be taking them down to the hardware store to get chunkier ones and nylocks to match.

I scrubbed off the underneath of the crank cases. No evidence of leaks but pretty crappy finish.

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Re: CG125 Clone Wars

Slowly slowy, a little bit each evening!
Could go a lot faster with a budget but right now I have to live to the cut of my cloth!
I'm at the point where I have to face up to the frame with a sawsall, angle grinder and wire brush.
I'll extract the rear wheel bearings when I go down to civilisation later this week.

It does feel that it's getting a bit of a soul with all the attention. I know from the boy who I got it from, and his mum, that it had the crap abused out of it and lots of bits broke and fell off and generally is a heap of beans, but the donk never missed a beat. And it had 4 owners before hand, I'm the 6th in 5 years but a mileage of 28k is only 5k a year. i bet half of those owners barely used it.
 
Re: CG125 Clone Wars

Hmm. I've just spent an hour or two this evening chipping powder coating off the frame.
It's too freaking cold out to have got the wire brush on it.
I can only assume that before the frames went for coating, everyone took turns to piss on them for luck.

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I am seriuosly resisting the urge to grind off the utter pile of low grade scrap called the rear triangle.
I've been telling myself to just de-lug it, get the rust off and leave it in primer for the re-build and MOT test.

I like the Honda diamond main frame/engine design and I'm exploring the idea of monoshocking it and having an ally bolt on seat subframe.
I'm thinking along the lines of using the stock swinging arm, (which is good tubing) attaching a 'mono triange' to it then putting plates either side of where the present seat tubes attach, and mounting the other end of the shock there. I would aim to reproduce the current geometry.
Does any one perceive and problems with this train of thought?
Any pointers for research?
There is a rash of shocks available for pit bikes ranging from 250mm to 280mm
 
Re: CG125 Clone Wars

Hey Glenn, I've already been down that line of enquiry ....... all the ones I found were either
Too narrow at the frame mount
Too narrow at hub
Long enough, but braced across the arm allowing only for a small wheel

My conclusion was that it would theoretically be easier just to reuse the original arm

So update.

I cleaned up the swinging arm and errrrrr I've now run out of stuff to clean off and inspect.
That must represent some kind of progress!

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Re: CG125 Clone Wars

Just a little reminder for crazypj why he's better off over there.

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Picked up a potential fuel cell ...... a Villiers stationary engine tank, some M5 bolts to blank the starter orifice and a flapper wheel for the angle grinder.

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Re: CG125 Clone polishing the turd

I spent several hours attacking just one part of the rear triangle.
I reckon I used enough electricity just removing a couple of tabs and trying to get the tubing smooth, to have welded a whole new frame!
Lord knows what the tube thickness is like now :eek:

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Re: CG125 Clone Wars

It warmed up to -2 degrees today so I got the angle grinder out and removed the rest of the lugs and the rear frame mounts.

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Another pound of weight in the scrap bin

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Re: CG125 house special chow mein (Cantonese style)

Back to moving forward. Got a lump of weld on the kicker to build it back up.

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Found this stuff in the pound shop ($1.59 shop) so I thought I'd try it. How wrong can it go?

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So am soaking the engine cradle in it overnight.

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I've got some vice time tomorrow so plan to de-lug the swinging arm, cut off the steering lock from the bottom tree and do the kicker.

I've amassed a generous budget of $40 dollars towards the rebuild.

I intend to squander this on ball bearings for the head race, rear wheel bearings, a main jet and fork oil.
Maybe some engine mount bolts with whats left. Hey ho, it is Christmas after all.
 
Re: CG125 house special chow mein (Cantonese style)

Yesterday's list taken care of, and the rust remover did in fact get rid of the crustiest stuff.
I've swapped the indicators for a bit of welding on the frame before I finish the triangle and slap some primer about the place.
I'm calling in to a bike breakers yard for a little mooch tomorrow ;)
The day I can actually start the interesting stuff must be getting nearer?

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Re: CG125 house special chow mein (Cantonese style)

looks like fun!

that frame should be fine with some bracing and cleaning up.

its probably mostly just re-named honda parts, with the costs savings coming from the electrical components, frame quality, and small nick nacks. stuff people wont notice when test riding the two brand new, side to side.
 
Re: CG125 house special chow mein (Cantonese style)

Looking good man, keep posting pics/progress and don't freeze to death!
 
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