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CG 125 tuning

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ghbrown125
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PostPosted: 12:24 - 26 May 2009    Post subject: Reply with quote

it would pull that kind of gearin cos mine used to have 14 front and 41 rear, it now has 17 front and 36 rear, pull perfectly fine, if u have a racing cdi box pefrformance air filter and exhaust. Cool
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Newbiker0507
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PostPosted: 19:12 - 26 May 2009    Post subject: Reply with quote

https://hondacg125.awardspace.com/

Check that site, there's a good section on improving performance
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honda nutter
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PostPosted: 07:42 - 18 Nov 2009    Post subject: my cg Reply with quote

i ride a cg 125 03 plate when i got my bike it would not do no more then 50mph i got it in my shed every thing i didnt need went and i mean every thing i put a k&n on it only £20 put bigger carb on off a cb250 put a viper pipe on it its loud and a nice pear of bars it pulls 75mph all day long off the clock 80+ down hill hope i can be of help
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unitybiker
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PostPosted: 22:47 - 04 Dec 2009    Post subject: Reply with quote

CG's after the early 80's used a twin wall exhaust ,changing to a single wall non standard one and a k n N should boost 2hp just remember to adjust mixture .Although a carb swap is a good boost carbs from early 80's onwards have an accelerator pump on the side .I think the concept was ....weak mixture/jetting and richer mixture when accelerating for 11 hp traction.


I would'nt focus too much on top speed ,they just get knackerd valves and springs at top wack all day and you can quickly wear the motor out in 5,000 miles . whats special about the symetrical one cam valve timing is the amount of low down chug in 4th and 5th, by modding the exhaust and air filter they stomp along at low revs,this extra power can be geared in for 5-6mph at the higher range of use ,,,,i,e, 50 -60 mph


remember if your cg's got an enclosed chaingaurd then look after it it's a fiddly fkkkr but it will make it worth buying a decent chain because of the much longer chain life.
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markrolls88
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PostPosted: 22:55 - 08 Dec 2009    Post subject: cg 125 Reply with quote

i have a cg 125 mine is 2002 and mine is standard but i want more accelaration its a heavy bugger is there any where i can save weight thats simple im thin so i dont wanna lose anymore weight so it has to be the bike i can get 75 outa mine i have had 80 screaming the bollocks of going down hill with the head down as far back as i can be on the bike
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johnsmith222
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PostPosted: 00:16 - 09 Dec 2009    Post subject: Re: cg 125 Reply with quote

markrolls88 wrote:
i have a cg 125 mine is 2002 and mine is standard but i want more accelaration its a heavy bugger is there any where i can save weight thats simple im thin so i dont wanna lose anymore weight so it has to be the bike i can get 75 outa mine i have had 80 screaming the bollocks of going down hill with the head down as far back as i can be on the bike


The CG is a heavy bugger?!?

Keep going the way you are at the moment and your engine will be dead in no time...

You don't need to lose weight, you need a different bike.
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The Shaggy D.A.
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PostPosted: 18:39 - 10 Dec 2009    Post subject: Reply with quote

1. Put a screen on.
2. Rebump in another 6 months to make it a 6 year old thread.
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Ben35
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PostPosted: 22:20 - 28 Feb 2010    Post subject: Reply with quote

I put a 15/34 sprocket combo on mine (1988 BR-E engine) and it does have trouble pulling it.

But it has a lovely relaxed rpm when cruising @50mph (approx 5,500).

Down hills that baby really flies ...

Might try the slightly colder plug (9)

Ben
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mrr1
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PostPosted: 00:18 - 22 Mar 2010    Post subject: Reply with quote

I've got a ybr 125 as a winter hack, not a million miles away from a cg. I tried the "for more speed try two less teeth on the back sprocket" thing - what a pile of shite!!!

It took me two days to saw those bloody teeth off that cog and then the friggin' chain kept falling off!
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mrr1
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PostPosted: 00:24 - 22 Mar 2010    Post subject: Reply with quote

and then I burnt the skin on three fingers trying to araldite the bloody teeth onto the front cog!!!!
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smegballs
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PostPosted: 02:03 - 22 Mar 2010    Post subject: Reply with quote

mrr1 wrote:
I've got a ybr 125 as a winter hack, not a million miles away from a cg. I tried the "for more speed try two less teeth on the back sprocket" thing - what a pile of shite!!!

It took me two days to saw those bloody teeth off that cog and then the friggin' chain kept falling off!


Laughing

I truly hope you jest!
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mrr1
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PostPosted: 20:37 - 26 Mar 2010    Post subject: Reply with quote

errr.....jesting, oh yes, of course - I was jesting, ha, ha
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markrolls88
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PostPosted: 13:54 - 05 Jun 2010    Post subject: Reply with quote

i have a 2002 cg125 i can get 75 on flat head down screaming it on the back pegs
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Howling Terror
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PostPosted: 14:16 - 05 Jun 2010    Post subject: Reply with quote

^^^You can get the clocks to show 75mph. Wink


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Frost
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PostPosted: 17:47 - 05 Jun 2010    Post subject: Reply with quote

The Shaggy D.A. wrote:
1. Put a screen on.
2. Rebump in another 6 months to make it a 6 year old thread.


You sir predicted the future.
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The Shaggy D.A.
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PostPosted: 19:53 - 05 Jun 2010    Post subject: Reply with quote

\o/
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Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5
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Old Thread Alert!

There is a gap of 2 years, 56 days between these two posts...

v6413
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PostPosted: 12:22 - 31 Jul 2012    Post subject: Reply with quote

make sure your magnet is ok check ..for the governer and cam..within magnet....to set the point take it too a highly qualified mechanic who uses the proper equipment like "ignition timer" ,"timing light"...
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DMCpro
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PostPosted: 13:27 - 31 Jul 2012    Post subject: Reply with quote

v6413 wrote:
make sure your magnet is ok check ..for the governer and cam..within magnet....to set the point take it too a highly qualified mechanic who uses the proper equipment like "ignition timer" ,"timing light"...


nice job bumping an 8 year old thread...
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Alpha-9
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PostPosted: 15:58 - 31 Jul 2012    Post subject: Re: cg 125 Reply with quote

bluezedd wrote:
i have a cg 125 mine is 2002 and mine is standard but i want more accelaration its a heavy bugger is there any where i can save weight thats simple im thin so i dont wanna lose anymore weight so it has to be the bike i can get 75 outa mine i have had 80 screaming the bollocks of going down hill with the head down as far back as i can be on the bike


Not as heavy as a YBR! Dance! Gagged

The bike does the speed it's designed for, you're just killing it faster with that shit
you might aswell put NOS on it and melt the whole damn engine, it's not hard

bolded the lulz
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tahrey
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PostPosted: 17:11 - 08 Oct 2012    Post subject: Reply with quote

Mild thread necromancy (on a truly ancient original post)!

I ended up at this after somehow being inspired to look at TL150s etc (I think I was looking for XR gear ratio lists or something? weird how the internet works)... a "Miller conversion"?

Has anyone actually tried some of the TL125 capacity increasing tricks and found if they also work on CGs / XRs / CRXs etc? Assuming the engines are at least vaguely related?

Seeing as I will hopefully have a bottom end to play with soon (indeed, one that NEEDS the crank taking apart to repair - in which case I can look into stroking it a little), and top ends aren't anywhere near as hard to get hold of. It's not so much of a problem if you knacker one trying to bore it out if it's not actually vital to the continued running of your everyday bike...

They don't say explicitly on the site I looked at what the stroker comes out as, just that it's "about 150cc". The additional stroke is 9.5mm, which I assume is overall (so 4.75mm additional radius, and a 4.75mm shorter rod) ... 56.5 x 49.5 goes up to 56.5 x 59.0 = 124.1cc goes up to 147.9cc.

Which is pretty good as far as I'm concerned, so long as the crank and rod adjustment work isn't too involved or expensive, the big end still has enough clearance in the block (and the rod has clearance in the casing mouth/barrel), and the gasket/pushrods/valves/carb can be adjusted to suit. Saves all the messy reboring business, is larger at the end of the day than the "146cc" big bore kit using CB550 / CB750 parts (liner and piston) plus some risky modification of the barrel, and just seems simpler and cheaper overall. And it still stays within the £16 tax band! Laughing

As well as being something different. No-one tends to make strokers any more :p

All things being equal it'd be a potential 19% torque and power increase (vs 17% for the rebore). Or an extra 2hp and 1.8NM (10.8 -> 12.8 and 9.8 -> 11.6), and probably 5mph on the top end, with hill climbing power increased by and cruising revs reduced by about 9% each (the gearing would have to be lengthened, but not by the full 19%... though this also means it could be lengthened 10-11% whilst still enjoying improved acceleration/climbing).
(IE I could likely regear it for a sustained 70 at 8500 instead of the near-9400 at present, and see a very strong 60ish cruise at a little over 7000. That would be just dandy for my purposes.)

Fuel economy might also drop 9 ~ 19%, but I somehow doubt it, given the amount of time the bike spends at full chat or very wide throttle, vs low-fractional throttle or idle - plus there's the altered gearing (124 x 9375 = 112.5k ; 148 x 8500 = 125.8k ; 125.8 / 112.5 = 111% overall airflow). It'll still use more almost certainly, but maybe more in the perfectly acceptable 5% range except when going flat-out. May even depend on jetting etc.


And of course for those just going for all out capacity on a death weapon esque project, both together would be 174cc (+40%, 15.1hp and 13.7NM, could be another 10mph there...) just with these mods, ignoring the possible 185~200cc (16~17.4hp. woo.) increases with the more exotic and risky rebores. Though one wonders why, if you were then thinking of going higher to the "theoretical 223cc maximum", you wouldn't just upgrade to an already more sophisticated 250 :p
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Jamie S
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PostPosted: 22:03 - 08 Oct 2012    Post subject: Reply with quote

TL125 = OHC
CG = OHV

Two very different engines.
Jamie
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tahrey
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PostPosted: 00:39 - 09 Oct 2012    Post subject: Reply with quote

tittyballs. of course i read the one source that says they're pushrod, and then skim the (very buried) clues on the actual tuning page that shows that they are in fact cam + chain...

all the same, would the theory hold in terms of increasing the stroke, ignoring the boring-out? given that the parts being altered aren't affected by what kind of timing system is in use? crank out, knock pin out of flywheels/counterweights, replace with (or just alter into) a slightly more offset one whilst changing the bearing on the rod... shorten the rod... tweak the effective deck height and its effect on the valve clearance... bobs yer uncle?

not that it would be at all cheap or worth the money, but it's a nice thought exercise. I'm sure someone on this board will be mad enough to eventually try it.
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kramdra
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PostPosted: 02:23 - 09 Oct 2012    Post subject: Reply with quote

why would you want to?

125's sound like they are about to explode. thats because they are. none of them, CG's included, are made as well as bigger engines.

wonder if you could chop a 600cc...no. CBR250RR IL4 engine in half to a 125? would be a LOT of work, if its even possible. but rev to 19k, half of 45 horses... but probably lose a few in the hackery.

Perhaps, you could just disable two cylinders, remove two pistons... remove the valve gear for them? probably be reversable.
get it tested by dvla (SVA test?) to make it leaner legal..


if thats possible, its about the same effort as tuning a shitty cg, with a lot more reward.
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Teflon-Mike
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PostPosted: 03:25 - 09 Oct 2012    Post subject: Reply with quote

kramdra wrote:
wonder if you could chop a 600cc...no. CBR250RR IL4 engine in half to a 125? would be a LOT of work, if its even possible. but rev to 19k, half of 45 horses... but probably lose a few in the hackery.


Honda CB125Twin engine in full power guise offered 17bhp... bit under the 22.5 half of a CBR250R.... but close enough and not bad from a thirty five year old, two valve per cylinder air-cooled motor!

Be easier to tune one of them up, rather than cut a 250 in half and work backwards..... but, ultimately? 125 Four-Stroke? anything over 12bhp is good going, and little engine, never going to find big gains.
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Old Thread Alert!

The last post was made 11 years, 173 days ago. Instead of replying here, would creating a new thread be more useful?
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