Speeding Up The CG125?

What does "Sorry, this thread has been deleted" mean exactly, and WHY?

 Since I can type here, I'll assume its still "open", in some way.

If you REALLY want to put some effort into this, I'd say you are more likely to get payback (and less likely to break your bike) if you leave the engine alone and try and  improve the aerodynamics.

Since standard naked bikes are so bad, significant improvements are possible with fairing, though the biggest have been achieved with a "feet-forward" configuration that won't be achievable with a CG125.

DIY fairing could be low-tech and quite cheap. For temporary, experimental attempts you could use skin-on-frame techniques, or papier mache. If you get something useful you could do a more permanent job in glassfibre. As a bonus you might get some weather protection, and maybe some crash protection too.

 There are potential dangers, of course, like reduced steering lock, sidewinds, (see the controversy on "dustbin fairings") sharp edges, so you'd have to be careful, and regard it as an experiment, but if you survive your bike should be easily restorable to stock, and anything learned could be transferable to another bike,

Checkout Craig Vetters site

http://www.craigvetter.com/pages/470MPG/470MPG%20Main.html

Or this streamlined Honda Innova. A crude prototype increased top speed by over 10mph, with more to follow (though this is a feet-forward design, and the focus is on mpg)

 http://www.wired.com/autopia/2010/01/streamlined-honda-innova/

http://www.gizmag.com/honda-areodynamic-scooter-conversion/14071/

   

empty your pockets befor eyou get on the bike! loose some weight, go for a jog 3 times a week!!!

leave it alone man, just ride it and sell it on when done and buy a faster bike later. its really not worth the effort

How fast do you want a 125 to go? how much money have you got?!!! you could spend a few hundred quid having the cam reprofiled and maybe a re-jet, bigger carbs, high flow air filters blah blah blah, you could have the head skimmed blah blah blah.........but theres really no replacement for displacement on a road bike. bigger engine; more power to you.

it might touch 120mph if you threw it off a cliff

just thought i would tell you what ive done to my giantco 125 hunter (cg clone), changed the front sprocket from 15t to 17t,rear from 49t to 36t,fitted a 28mm delorto carb and fabricated a new manifold as well as ported the head,machined out the barrel and fitted a new liner,bored to 69mm using a honda g200 piston,also had to machine out the crankcase bore to take the new liner as well as fitting packing under the clutch springs to stop it slipping,the next step is to make a new single walled down pipe for it out of stainless steel,all these mods have taken the top speed from about 60mph to over 90mph,time will tell how long the bottom end will last!,fuel consumption has gone from 100mpg to about 60mpg!

Ha ha ha, brilliant. Completely silly, but sounds like fun You done any changes to the valves / pushrods / cams?

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arrrf.

Not at the moment,there isnt much that can be done with the cam as its a single lobe that operates both the inlet and exahaust,i may grind 20 thou of of the base circle of the cam to increase valve lift but thats about it as far as the cam goes,i have a spare bottom end that i may strip,im thinking of offsetting the crankpin about 4mm to give an 8mm longer stroke,this should strech it to about 238cc,but we will have to see when i can find the time to do it as its not a 5 min job.as it stands its about 197 cc at the moment.

Just thought i would explain the maddnes in doing this!,before i get thrown in a room with rubber wallpaper.the bike is a april 2010 model that i brought with a busted fairing for £200,so its pushbike money,and its only got 6000miles on the clock,im a self employed mechanic and have free reign of a decent machine shop,mills lathes etc,one of the things i forgot to say is,the piston kit for the honda g200 engine was £12 from ebay,the liner was from a 875cc hillman imp,the g200 piston is ideal as its flat toped which helps keep the c.r down a bit,it also has a 15mm gudgeon pin,the carb was scrounged from an italian nsr 125 honda with a homemade flange tig welded on,on the firt run it holed the piston but i tig welded it up and built up the piston under the crown to give it a bit more meat,after machining out the squish band in the head and fitting 2 head gaskets its runing ok at the moment,its only done 100miles since the work so its still running in,the whole lot stands me at about £250 and about a days work,its a small price for a bike which i imagine is putting out twice the power as standard and if it blows up it hasnt realy cost me a great deal,i wanted more umph from 40mph to 60 mph so i wasnt getting stuck behind lorrys without the guts to get by them,i dont think doing anything with the valves is an option as there isnt much room to fit bigger,i take it up to about 9000rpm with no valve bounce and max power seems to be at about 8000 so i dont see much point in lightening the rockers etc,hope this info is some use to folk trying to get more umph out of a cg!,cheers for now.Paul.

Not at the moment,there isnt much that can be done with the cam as its a single lobe that operates both the inlet and exahaust,i may grind 20 thou of of the base circle of the cam to increase valve lift but thats about it as far as the cam goes,i have a spare bottom end that i may strip,im thinking of offsetting the crankpin about 4mm to give an 8mm longer stroke,this should strech it to about 238cc,but we will have to see when i can find the time to do it as its not a 5 min job.as it stands its about 197 cc at the moment.

Yeah - guess you could put in lighter push-rods, heavier springs, and a slightly harder opening cam, but sounds like a pretty fun project anyway.

Of course - there's always super-charging and nitrous

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arrrf.

well time for an update,ive done 3000miles so far and made a few changes,first off i found another head off of a loncin off road bike with a 2mm larger inlet valve and a 1.5mm ex valve and fitted that along with an oil cooler,with this fitted it does 0-60 in about 7 secs,not sure of the top speed but the speedo and rev counter go off the clock (speedo goes up to 87mph) but i think about 95 at 12,000 revs,also forgot to say i ground 2mm off of the base circle of the cam,im running about 20 thou clearance on the valves and piston,not a lot but it seems ok up to yet!,well the problems so far are two blown head gaskets and a busted gearbox second motion shaft bearing!,firstly on the head gasket,well this was fixed by making one out of a piece of copper hot water cylinder and annealed and its been no trouble since,then on to the gearbox,this was a bit hairy as the bike locked up solid at about 65mph!,when the bearing broke up it let the shaft move sidwards about 3mm causing the kickstarter to engage,this shot the lever downwards at great speed denting the silencer,luckily it mist my leg which im sure it would have broken!!,the shaft was scrap as the bearing surface had bits of needle roller welded to it!,i ended up using one crankcase fron the loncin engine as the bearing was about 1mm bigger than the standard giantco crankcase,also the clutch end of the selector drum is supported by a needle roller as the original case it just runs in plain alloy,also the jet in the oilway that feeds the bearing has beed drilled out to 2mm to increase the oil supply to the bearing,was it all worth it?,well as the whole lot has cost me under £100 for all the mods and a few hours work i think so,it comes on cam at about 7500 rpm and pulls to 11000 plus,ive had a few old honda 250 twins from the 1970s and this would thrash them into the ground,so ive got a bike thats light goes like stink looks pretty standard and is fun to ride,so on the whole i think yes,the only downside is the fuel consumptiom,about 45mpg but you cant have it all ways lol.

Ha ha ha - I SOOO need to see that some day

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arrrf.