Honda CG 2007 choking at higher revs

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Honda CG 2007 choking at higher revs

So it's a bit of a story what has happened I will try to summarise briefly.

I heard a grinding noise in engine, took it to a mechanic he told me the problem is in the bottom end probably because the oil was contaminated. I stripped the engine down completely and put it back together, looking for the damaged part, which i basically wasnt able to find but i reassembled it carefully, put it in the bike but it didn't run.

After tinkering around with it for a while I though I'd have a look at the timing on the cam gear even though I knew 100% that I had checked and set the timing correctly. Well when I looked at it I realised that somehow I had set the timing wrong (I don't know how I did this after putting the whole engine back together correctly!). The inlet pushrod got bent and there was a black mark on the piston from the valve hitting it but the cam gear looks undamaged and crankshaft is still silky smooth. The energy was only coming from the starter motor, I don't think the force damaged the crankshaft bearings, it looks as if the pushrod took the brunt of the force, even the valves looked totally fine, i reseated them anyways though. I did a compression test and found with a bit of oil the compression jumped from 110 to 125 so I changed the piston. Probably damaged it when the valve struck it, the gudgeon pin was a bit wedged in there. Fired it up and it sounded good.

Jumped on and rode it it around but as soon as I open it up at all it chokes. It doesn't stall but it won't produce any more power. It feels a lot like a problem I had doing high altitude driving, a bit like driving with the choke on, and just like then the spark plug gets black very quickly.

I have done everything I can think of to diagnose and fix it. Ran it without air filter in, cleaned the carb, put a new spark plug in, changed the fuel, adjusted the carb floats, changed the exhaust gasket, nothing makes a blind bit of difference, it just can't handle any kind of load on the engine. I will change the head gasket but I don't see how it could cause this problem.

Any ideas? I'm really stuck as to what to do next but I love the bike