2018 CBR125R Engine

[Skptical]

Hi all, I'm semi new to biking, but have many people around me who have years upon years of experience.

My CBR125R Fuel injected model (2018)'s engine has fucked its self. The timing chain has snapped. My question is, would be doing a big bore kit be worth it as ill have to do a new top end anyway?

If not, what would you reccomend?

[A100man]

[MarJay]

That's a very loaded question. How you worded the question is not really what you're asking. You know that you have to have the top end apart anyway, so you know that a big bore kit could be done at the same time. What you're asking is: "Is it OK for me to do a big bore kit on my CBR125".

Do you have a full license, or a CBT? If just a CBT then no. Don't big bore it. Do you want it to maintain value? Then no, don't big bore it. Could you just sell it and buy a bigger bike? Then no, just go and buy a bigger bike.

The ONLY reason to do a big bore is if you accept the loss of value, you have a full license and you want to have the fun of doing a project.

IMO, anyway. Remember a big bore 125 is still a 125, it's just now not legal, with the same tyres, brakes and suspension. A bigger bike has better brakes, tyres and suspension (as a rule of thumb).
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Robby]

We all did similar shit back in the day, but back then it was derestricting 2 strokes instead of fitting borekits to 4 strokes. In hindsight, pointless back then because we were only on our 125s until we passed our tests.

Nowadays it's a different calculation. I don't know the precise details of licencing, but I understand you're essentially stuck on a 125 until 19 anyway, and there are more hoops to having a proper licence.

However, if you get caught, you're just as fucked for many years. Assuming it's a 200cc bore kit, it won't be much faster.

I would also want to check over the bottom end before reassembly. Timing chain snapping is rare, I would be surprised if a 125 ever did enough miles to wear one out. It's mostly likely a symptom of some awful maintenance, like someone fitting a manual tensioner and turning it up to 11. I would want to know what else they fucked up before throwing any money at the engine.

[WD Forte]

2018 eh? how many miles has it done for the chain/tensioner to get so fucked it snapped?
As suggested, it sounds more abuse/neglect related than mega miles.

Big bore? nahh there's more to consider than just fitting a bigger piston
for 'moar powah'
How are you going to remap the ecu for starters.
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