CG125 to 150ccm?

[pete3]

I am still drooling about CG125 adds on the internet - it is all Birdys´ fault!

Just a thought, would it make sense to exchange barrel and piston for the 150 ccm variant for some higher performance?

Would the 125 ccm system handle the higher power without losing reliability?

Thank you in advance.

[palace15]

Is an extra 25cc worth the extra cost? and remember if you are doing a big trip, do you think 150cc spares would be easy to obtain?..I think not, and my advice is, keep it standard.

[brclarke]

What you would gain in power you would lose in reliability. IMHO... if you really need a bigger engine, you should get a bigger bike instead of puttering around with an add-on solution.

[backofbeyond]

If you just replace the barrel and piston with the 150cc stuff without changing the head, exhaust, cam etc (and assuming it all fits correctly) then you're unlikely to get more top end power. What you will get is more mid range torque and that'll make the bike easier to ride, more responsive at normal speeds. It'll feel flat at the top end and may vibrate a bit more as the heavier bigger piston won't be balanced as well by the crank as the original.

Probably worth doing if - 1. the bits are original Honda and not some clone or back street engineering and 2. they are cheap or better, free. The performance change is unlikely to overwhelm the rest of the bike as it's mainly mid range, at speeds / revs you were doing anyway. I've done it on a couple of Hondas successfully and a Lambretta scooter where it was a disaster As long as it's just bolt on changes and you don't have to eg machine the crankcases you can always try it for a bit and change back if you don't like it. On a single like the CG it shouldn't take more than a couple of hours.

[Joe C90]

It is quite feasible to put a different barrel on and run at 150cc.
The clutch/bottom end etc are superb. Normal use will not damage them. They will only give trouble if the oil isn't changed and the filters (yes 2) are ignored. The only one I have seen properly killed in action was on the racetrack, where the end of the gearchange shaft by the clutch casing came adrift because the lead footed lunatic was booting it between gears without using the clutch.

We run cb100n gear clusters in cg125 engines, identical apart from lower 4th and 5th gears. End of race season engine strips have shown absolutely no engine wear whatsoever, even with 11,000 rpm thrashing.

[pete3]

Thank you all for sharing your thoughts and insights. Once my initial needs are satisfied I need to find myself a nice CG125 to fool around with.

[oothef]

I'm really intrigued by the race series, what is it? I'm about to drag a CG out of the shed to rebuild with/for my son

[bkm_br]

The 125cc and the 150cc are two completely different animals. The brazilian made 125cc engine (and most of the Chinese knockoffs matter of facts) are OHV. The new 150cc engine made by honda are OHC, almost 100% new engine. Latter on Honda introduced the OHC 125cc but what I know this engine was never exported to Europe.
Here in Brazil we have a lot of Big Bore kits (just like this one) for both engines, 125cc OHV and 150cc OHC. An 190cc OHC CG looks like an interesting bike for city commuting, but I don´t believe this would be an reliable option for travelers.
An other option (and probably a more feasible) is to use the CRF 230 engine on the CG frame.

[pete3]

Alphatechnik sells an electronic kit for the CG125 to boost the speed from 80 km/h to 100 km/h:
alpha Technik - alphatechnik. Spezialist für Homologation & technisches Zubehör für motorisierte Zweiräder

Not bad ...

[Joe C90]

Regarding the race series, Regs are on the Fab Racing website, moto-team pages.

We have a huge variety of machinery racing, from 50cc watercooled minarelli engines (17-20 rwBHP), down to 125 cg engined specials.
A couple of teams have used the standard cg frame with varying degrees of success, but Dans has got about 14BHP (from standard 9bhp), with derbi senda USD supermoto forks.

My machine last year was an Aprilia RS50 with a heavily modded cg125 motor.

Am in harrogate if you fancy a jolly over, plenty of honda 125 engines in bits to see.....

[bkm_br]

Originally Posted by pete3

Alphatechnik sells an electronic kit for the CG125 to boost the speed from 80 km/h to 100 km/h:
alpha Technik - alphatechnik. Spezialist für Homologation & technisches Zubehör für motorisierte Zweiräder

Not bad ...

The carburated Brazilian CG125 don't have any kind of speed limiter.