FIX OR 2ND HAND ENGINE?

[dou91e]

I have a real bad knocking noise from the bottom end on my cbf125.
I have been told it is more than likely the crankshaft bearings but until its opened up we cant tell.
So I will have to pay for 2.5 hours labour to be told what the problem is.
If its the crankshalf bearings the parts will cost £70 then the fitting time on top. If its the whole crank needed its gonna cost a shed load more
So do I buy a 2nd hand engine if I can find one or spend between £300-£750+ on mine and get it rebuilt.

Is the cg125 engine the same as the cbf engine? I know the cbf is injected and the cg i think isnt but is the block the same?

[G]

Pretty sure the CBF is totally different.

I would go for a new engine, then look to take the old one apart and have a look yourself.

[Nobby the Bastard]

I rebuilt a X5 about 20 years ago, just having the crank rebuilt after dropping the crank off off cost £200.

Let alone all the gaskets etc I had to get and the hours of stripping and rebuilding (plus the two piston kits and rebores).

I would have done what G said, but back then X5 engines weren't easy to find and there was no internets...
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[moonzoomer]

The CBF is a 2 valve OHC engine with fuel injection, the CG 125 is a 2 valve OHV engine with a carb. The electrics on the bikes are totally different due to the fuel injection system on the CBF. Go for a good low mileage S/H engine from a crash damaged CBF from a good breakers who will give some kind of guarantee on the engine. These little bikes need good clean oil with regular top ups and regular oil changes, the most likely cause for a crank or main bearing failure is lack of the slippery stuff, oil changes with quality oil is the best and cheapest maintenance you can give these 125 cc 4t engines, if ignored they will self destruct.

this might give you an idea of replacement engine costs
https://www.ebay.co.uk/itm/CBF125-2009-M9-COMPLETE-ENGINE-VERY-GOOD-RUNNER-STARTS-1ST-TIME-V-SMOOTH-/201186123738?pt=UK_Motorcycle_Parts_13&hash=item2ed7a09fda

[Rogerborg]

Given the chances of a replacement engine also shitting the bed, best result might be if it burns to the ground or gets stolen.

Not even joking though.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike