Getting some power into my Honda cg 125

[dave_manz]

Hi

I have just bought a 2002 honda cg 125.

The plan was to push up the HP a little bit by adding little things like new sportier exhaust and K&N air filter but the problem is im not very mechanicly minded when it comes to bikes. Ive got a little bit of experience with cars but im new to the whole bike thing.

From what i understand there is no performance parts made for the cg because its not designed for high speeds but can anybody tell me if theres any performance parts designed for other 125s that could be adapted for the cg.

thanks for the help.

[Ste]

If you want more power then the best thing to do is to sell the CG and buy yourself a two stroke like the NSR125 as they have ~27bhp when de-restricted.

[dave_manz]

I would love to but the problem is moneyis tight....very tight and a friend sold me the cg for next to nothing.

[dave_manz]

have been thinking of buying something like a honda cbr125 sports exhaust and cutting and welding both exhausts together....anyone see a problem with that??

[Ste]

Money is tight, but it can't be that tight if you're wanting to spend money tuning your CG.

You can spend lots of money on the CG and at best you'll make it a bit faster. Or, you can sell the CG and buy an NSR with that money and the money you would have spent on the CG.

That will work out cheaper in the long run and will give you lots more power than you'd get from spending money on the CG.

It's really not worth spending money trying to tune your CG.

[Irn-Bru]

Just.. no Save your money up and buy a bigger bike. CG's are just work horses really, A - B bikes, not a lot more really.
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KTM 990 SMT & Suzuki DR-Z 400 SM

[Moo.]

Ooop.. double post.
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A2 Passed 18/6/10

[Moo.]

CG's are the kinda bikes you can tune up, they'll plod along at 65mph forever.. and not much else. Everythings been tried, but the fact its a ohv means theres not much performance to be had.

Racing spark plugs, better oil, k&n, rejetting, better tyres, windscreen.. with the cost of all these.. you'd probably get a +5mph at most.. if they even work on it.. you'd be better saving up and waiting for a bigger big.
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A2 Passed 18/6/10

[crackpotterpi...]

I agree with previous posts,cg's are reliable and will keep running wiith very little up keep,however the flip side of this is that its a de-tuned engine.
having previously owned a nsr,I can say they are fast bikes but they need more regular attention,being a 2 stroke.....hope this helps
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1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[dave_manz]

Ok thanks guys!

Just 1 more quick thing and i know its abit off topic but my 2 friends have just bought 2 brand new 125s (megelli 125r) and wanted to do a road trip. The ideal trip would be from bottom to top of uk but my only worry is that the cg wont be able to keep up with these big boys even tho they promise to stay at 60/70. First impressions are the cg wont even make it to 70 will keeping the honda at 65ish kill it very quickly?

Thanks for your help guys.

[crackpotterpi...]

I have done a fair few miles cruisiing around on my cg,they will sit at 65 mph without too much bother are your mates 125's 2 strokes?
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1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[dave_manz]

[Ste]

Those Megelli bikes are 4 stokes so I wouldn't expect them to be much faster than your CG.

[crackpotterpi...]

well if they are 2 strokes they will blow up well before yours anyway................one consellation when they are accelerating away lol
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1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[dave_manz]

[Irn-Bru]

i think theyre chinese things anyway, they'll probably fall to bits before beating your CG
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KTM 990 SMT & Suzuki DR-Z 400 SM

[dave_manz]

[Ste]

2 strokes aren't going to blow up unless they've been abused and not maintained.

I'd be surprised if those bikes do 80mph seeing as they're 4 stroke 125s.

[pepperami]

if they/you are on B-roads a lot, then thier extra "power/speed?" wont do them a lot of good.

i should think that if they are on 125`s you wont be far behind them, especially if thiers are 4-strokes.
a lot of the newer 125`s look like race tuned pocket rockets and go like an old Honda CG
dont be put off.

i`m going touring on a 1980 Honda CG this year (around East Anglia) and i dont care who passes me as long as i get there
hopefuly our paths will cross and we can laugh at each others little honda as we speed off to our next destination

if you come across any go-faster parts for a CG please let me know
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I am the sum total of my own existence, what went before makes me who I am now!

[dave_manz]

Ok thats great! thanks alot and i hope u enjoy your trip! i have abit of spare time on my hands and a friend who can get me a 125cc sports exhaust (not sure what its off) so i might make my own go-faster parts and see how that goes

[pepperami]

can anyone tell me the answer to this??

i was thinking of shortening the exhaust on my one, by doing a cut and shut and taking a section out.
i was thinking 8 to 10 inches.
i am only thinking of doing this because there is so much exhaust sticking out of the side for such a little bike!!

will i need to re-jet? or will it just kill the bike?

some-one mentioned using a carb of one of the old CB200`s?XL185??.... is this just a straight swap??
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I am the sum total of my own existence, what went before makes me who I am now!

[Moo.]

The cg can hold 65mph cruise speed fairly easy (up a hill may decrease to 55-60), and the other two bikes are more likely to blow then the cg, built to last they are They may have a few mph more, say 2 or 3 but it wont be very much, and if they want their engines to last, they wouldnt wanna hold 70 for too long.

As long as those carbs have the same bolt alignments, they should fit on, im guessing they'll have larger diameters and different jetting.


With the performance on cgs, watch you dont push it too much, or it'll start destroying the valves and they'll bend or get knackered
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A2 Passed 18/6/10

[Moo.]

The cg can hold 65mph cruise speed fairly easy (up a hill may decrease to 55-60), and the other two bikes are more likely to blow then the cg, built to last they are They may have a few mph more, say 2 or 3 but it wont be very much, and if they want their engines to last, they wouldnt wanna hold 70 for too long.

As long as those carbs have the same bolt alignments, they should fit on, im guessing they'll have larger diameters and different jetting.


With the performance on cgs, watch you dont push it too much, or it'll start destroying the valves and they'll bend or get knackered
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A2 Passed 18/6/10

[Ariel Badger]

I can make it go faster. Port out the head and fit larger inlet valve. you may have to make your own valve. Buy flat slide carb to suit you new bore.
your compression ratio will be carp., skim and profile things until you get it up to about 12-1 and get a cam built that gives you decent timing. stop using petrol, your compression is now to high so run on methanol. Best add some N02.
Is it worth it?
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Bikers make great organ donors, get 115 on your licence today.

[Noxious89123]

Don't bother tuning it, just ride it and have fun. You should be able to keep up with your friends alright.
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi