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Zygotic |
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Zygotic L Plate Warrior
Joined: 24 May 2004 Karma :
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craigT19 |
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craigT19 Jolly Green Giant
Joined: 09 Feb 2002 Karma :
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Posted: 23:35 - 24 May 2004 Post subject: |
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errmmmm tow it
seriously tho...thats all your gunna get, the honda 124cc 4stroke dohc engine is pretty....ermm weak to say the least.
regards ____________________ Bikes owned :- 2001 nsr125, 1999 zx6r, 2006 yzf-r1, 2009 xmax 250, 2012 yzf-r1, 2015 MT-07
Current bike : - 2016 MT-10
BCF member pops. sadly missed 1945-2003 |
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jimbo |
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jimbo Borekit Bruiser
Joined: 23 Aug 2003 Karma :
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Posted: 11:55 - 25 May 2004 Post subject: |
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Heehee, the venerable cg125 Like most bikes, someone, somewhere in the world, tunes and races them. I looked into them a while a ago. They are raced in the US and Japan, but have never been able to find off-the-shelf tuning parts for them.
Problem is, it's mostly machine-shop work to modify the engine bore, stroke, port size, cam profile. Nothing simple like you're looking for.
Basically the CG125 is designed to be a rock-solid commuter, and is very good at it's job. The trade-off is that it's pretty detuned and won't take much tuning.
Putting a larger front chain sprocket (1 or 2 teeth) or smaller rear sprocket (less 3 or 4 teeth) might give you a bit more top speed. It depends where the power is on the rev range.
There might be a K&N filter that would fit your airbox or could be trimmed to fit. Usually gives a better feel but not much more power. Carb jet might have to go up a size with this. A sock filter isn't an option as there is no protection from the elements on the CG.
Getting complicated:
There is a big brother of the cg125, the cg150, not sold in Europe as far as i know. I'm sure the barrel would bolt straight on to a 125 engine.
There are plenty of 4-stroke motocross 125s around, so an engine tuner who tunes these will probably be able to give you an idea what can be done. For example, there might be exhausts that can be altered to fit (at a price).
The cg125 can easily be adapted for nitrous oxide injection, though i saw this in a bike mag and the engine blew after a few miles. On the other hand, it was a clapped out banger of a bike. I'm sure it would be ok if installed properly on an newer engine.
A simple way for silly thrills is to run the engine on damp-start (comes in a can from any motor shop, mainly methanol and expensive). Saw this on a GS125, and it wheelied like crazy for a few miles until the head gasket blew. Not great for long term modification, as the methanol attacks some plastic parts (and little details like jetting and the lack of valve lubrication)
On the bright side, the CG125 puts out a stonking 11hp, which is equal to the new CBR125! So you can find a CBR to play with
Some tuning parts may appear if the CBR gets established.
Hope this doesn't dissappoint too much. Let me know if you do find anything that can be done to the CG. I'm always interested |
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badlydamaged |
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badlydamaged Spanner Monkey
Joined: 29 Apr 2004 Karma :
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Posted: 12:06 - 25 May 2004 Post subject: |
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My friend has a brazillian CG 125 with a "racing exhaust" apparantly, we found it on an old CB125 field bike. I would guess its given him 2 hp more than he had, hes a big bloke (19 stone) with the aerodynamics of a 19 stone bloke in a waterproof coat that resembles a snowman suit whenever he goes above 40mph, and his CG will do about 70 - 75 mph on the flat now (suprised me with the difference considering its a 4 stroke), and I belive it had standard gearing. It may be worth trying it without that baffles, as its not too loud (quite quiet unless the throttle is wound right up, although it may be relitive to the shockingly loud exhuat less two strokes we have run in the past). Other than that like jimbo says, put a bigger diameter carb on, and try a performance airfilter. Hope you have some luck with it, and enjoy it! ____________________ My bike: 1988 Kawasaki KH100 Status: Polluting Devon with two stroke smog and noise pollution!
"Its not your engine size that matters!, It's what you do with it that counts"
Add me to MSN if you want! badlydamaged@hotmail.com. |
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mr.z |
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mr.z World Chat Champion
Joined: 04 Feb 2004 Karma :
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Posted: 15:34 - 26 May 2004 Post subject: |
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The only way you will get the cg to go any faster (legaly) is to loose some weight off it and yourself, even that won't make a tremendous difference, even if you did make it go any faster it would explode in a short time. apart from that trust me you don't want to go any faster than that, 73mph (indicated) on a cg125 is NOT something you'd want to make a habit of.
So - either go and buy an nsr 125 (which will cost you allot less than a cg wich will explode within 2/3 miles)
or just live with the snarling beast that you have, it will keep you going till you can move up to something biger, appreciate it for what it is... cheap, easy to live with and relyable, if you want expensive fast and not quite so easy to live with there are allot of 2stroke 125s out there waiting to scare the liveing **** out of new riders and old.
Trust me, been there done that, as many here have, the cost and difficulty not to mention explodeing engines is simply not worth considering.
Ride for half a year, book test, do test, pass test, buy new bike. ____________________ >RidingSkills<->Tech Tips<->MyBikes< |
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Robby |
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Robby Dirty Old Man
Joined: 16 May 2002 Karma :
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Posted: 18:23 - 26 May 2004 Post subject: |
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Tuning a CG is something i'd love to do.
First thing though - Craig, its not a DOHC single, its an OHV (pushrod) single.
Well it all depends if this is a project or your day to day ride, but here are the things I'd do if i had one to play with. Bear in mind the aim would be to get it to go as fast as... a rover metro.. until the engine blows.
In no particular order.
1. Get the head and base gaskets out. Make sure the surfaces are good and clean, and mate well. Use silicon sealant on reassembly. Or araldite. Should be a laugh.
2. See about getting some roller bearings into the bottom end. I'm sure some kind of size would fit, and cut down on friction a bit.
3. Skim the flywheel down a bit. Might help, or least make it vibrate more and feel faster.
4. Get a racier cam. Or attack the standard one with sandpaper, see what profile you end up with.
5. Bigger valves. Its such a simple head, I'm sure you could squeeze some bigger ones in. Clean up and polish the ports while the valves are out.
6. Colder plug, just go up by one number and see.
7. 8 inch long exhaust pipe. Point it at the road, no baffles.
8. Rip out the airbox. Run an open carb with a metal mesh over the mouth.
9. Bigger jet. Maybe bigger carb, but you may have to spend money here.
That should give you an engine gauranteed to fail quickly.
Shave some weight off the rest of the bike too. Ditch the indicators, battery, starter motor if it has one. Try a smaller headlight. Ditch the side panels - No need for them if you remove the airbox and battery. Cut the foam out of the back of the seat, remove the rear pillion footpegs and hangers.
That would be cool. Well it appeals to me. |
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Kickstart |
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Kickstart The Oracle
Joined: 04 Feb 2002 Karma :
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Posted: 23:23 - 26 May 2004 Post subject: |
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Hi
65 isn't bad for a CG125. The engine is in a fairly low state of tune, and it would not be easy to get a serious amount of extra power out for it. For example the engine only has a single cam (no I don't mean cam shaft, I mean cam), with 2 rockers operating on different parts of the cam to open the inlet and exhaust valves. That greatly limits what you can do with the cam.
Probably the best thing to do would be to remove the air filter (which will dramatically shorten engine life), jet the engine to suit, play with the exhaust, increase the compression and maybe clean the ports up.
Or far easier would be to buy an XL185 engine and slot that in.
All the best
Keith ____________________ Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing |
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cagiva gezzer |
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cagiva gezzer World Chat Champion
Joined: 17 Mar 2003 Karma :
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Posted: 01:41 - 27 May 2004 Post subject: |
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If you're really serious about getting stupid power out of a cg, join the forum on www.macdizzy.com .
The forum is mainly 2 stroke, but there is some SERIOUS cg tuning going on. There areople on that who know which year head to put on due to it having better gas flow and petty things like that.
The 'boxes in various 4 stroke hondas are interchangable aswell
Its $10 to join (i think), but could be well worth it. ____________________ "because one stroke isnt enough and four strokes waste two" |
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jimbo |
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jimbo Borekit Bruiser
Joined: 23 Aug 2003 Karma :
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stevo as b4 |
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stevo as b4 World Chat Champion
Joined: 17 Jul 2003 Karma :
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Posted: 00:24 - 31 May 2004 Post subject: |
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I agree with keith, that the XL185 motor should drop in easy enough, or even the XR200 engine (20bhp) thats nearly twice std! Erm for serious tuning, your better with the OHC 125/150 Honda engine as used in the CB and Xl/XR's. The ohc motor can rev higher without the worry of snapping/bending a push rod etc. For any real increase you need to go to 150cc or more as you wont get much extra power of the ohv 125 otherwise. The area you want to concentrate on is the head, it should be skimmed slightly and gasflowed. wouldnt bother fitting bigger valves or going to alot of trouble unless you have the OHC engine. its a simpler job then to swap the cam, and if you can get a CB125J cam or else an aftermarket performance XR125 cam, that would make a difference. to increase the Compression ratio on a 4 stroke like this you need a different piston with a bigger crown, and valve cut outs. Other than a head job, id use a sports silencer or a small megaphone (awesome sound) on the std downpipe, and fit a clamp on filter. The carb is only worth changing if you have a big valved modified OHC head with larger ports to suit. A Mikuni TM24 or VM26 would be a good carb to use then. The CG with the head done and some sort of sports exhaust set up may make another 2bhp, but thats another 5-6mph i would say on a light bike like the CG. The old CB125J similar to the CG, but with a tuned OHC engine made 13-14bhp and could do 75mph. If you went for a 150cc bored out OHC motor with tuning and bigger carb, i reckon you could see 16bhp, which in a CG chassis would be alot of fun. The XL185 has 18bhp, but i dont think id want much more, the CG's brakes are very weak, and the suspension would struggle too. |
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Old Thread Alert!
There is a gap of 3 years, 88 days between these two posts... |
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cg_deano |
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cg_deano L Plate Warrior
Joined: 27 Aug 2007 Karma :
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Jamie S |
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Jamie S World Chat Champion
Joined: 28 Dec 2006 Karma :
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Posted: 21:30 - 27 Aug 2007 Post subject: |
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CG125 are not pushrod engines they are cam chain SOHC.
My old one was any way.
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Jamie S |
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Jamie S World Chat Champion
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Jamie S |
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Jamie S World Chat Champion
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Blau Zedong |
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Blau Zedong Banned
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Kickstart |
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Kickstart The Oracle
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cg_deano |
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cg_deano L Plate Warrior
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cg_deano |
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cg_deano L Plate Warrior
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.Chris. |
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.Chris. World Chat Champion
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Maxx England |
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Maxx England Derestricted Danger
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ms51ves3 |
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ms51ves3 Super Spammer
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Maxx England |
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Maxx England Derestricted Danger
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Old Thread Alert!
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Nigel_NS125F |
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Nigel_NS125F Derestricted Danger
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lydanial |
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lydanial Brolly Dolly
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Kickstart |
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Kickstart The Oracle
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Old Thread Alert!
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