Dooooogster

Bought an early DT125R 1989 about a year ago as previous owner said that it cut out once on a journey and he hadn't looked at in 5 years. Hmmmmm..... Anyway, decided to restore this beauty back to its original glory as well as get me my bike license. Good intentions. This bike has been a labour of love & cost me a fortune! Smokie engine so replaced the worn old engine with a de-restricted mint one. However, after the engine warms up and is put through paces, it cuts out again. so replaced HT lead. Still cut out. The bike starts and idles fine, but when its ridden for a few miles, the engine bogs down ( you can hear and feel it going flat) and cuts out. As if when it gets up to almost correct temperature / going up a hill, it cuts out. It starts again staight away, but will cut out shortly after when putting demands on the engine. I need to leave it for 10 mins before I can at least get another few miles out it before it cuts out again. Journeys take ages and taking your bike for a walk isn't cool!! (Had a few car drivers stop, tell me they are bikers and offer me fuel to get home - the biking community is the best!) After messing about with jets on the old carb, I eventually got a replacement carb, replacement CDI unit and replacement regulator. Thought I had solved it, but hey, same old bog down and cut out. So after all the hassle the thing still cuts out. Checked fuel cap and cleaned air valves to make sure it wasn't a fuel vacuum problem, still cuts out. There is a strong smell of fuel just after it cuts out. Conclusion (it has to be?!). Worn or old wires to the HT leads. I recon if the wires on the loom are old and with the resistance of extra load at high revs or when the wires heat up, etc then it has to be that that cuts the current to the ht lead and the spark plug? Hence the smell of unused fuel from the engine? Any ideas how to fix this without replacing the entire loom? Am I on the right track? Have replaced everything else, so has to be the electrics surely? Any advice help, before i spend more time / effort / cash on another dead end?