Ahoy the forum. I've got an EU spec 2009 Lifan LF250B, a copy of the Yahama Virago, with the 2V49FMM engine.



It's done around 5000km and had been stored outside and neglected slightly, but I have no reason to believe that it's been abused.

It's running smooth, is great low down and pulls strongly to 55mph, but the bike tops out at an (indicated and actual) 65mph / 105kph on the flat. Since the original Virago claimed 85mph / 137kph, I'm hoping to get more like 75mph / 120kph out of mine.

What I've done so far:
Oil change to semi synthetic 10W-40 motorcycle specific oil. Change oil filter.
Clean air filter.
Ran through a couple of tanks with Redex to try and clear any jet blockage.
Adjust tappet clearances (aka valve lash) to the Yahama recommended gaps. It was set up too tight, and now idles faster (with no other adjustment), usually a good sign.
Freed up a slightly binding front brake and checked the rear isn't binding. The wheels both spin freely.
Change the front sprocket from 16 to 18 teeth - I prefer the longer gearing and think it makes the lower gears more usable, but top speed is exactly the same with both gearings.
Clean, lubricate, and correctly tension the chain.
Check and correct the rear axle alignment.

The bike now feels great, but it just runs out of steam at 65mph.

What I haven't tried yet:
Check that the throttle is actually opening fully.
Strip, clean and inspect carb.
Increase the main jet size.
Any modifications to the exhaust. It's a catalysed Euro 3 exhaust, very convoluted, and I suspect it's not doing the engine any favours. The (real) rear pipework and cat box are also rusted to hell after just 18 months and 5000km, so I'll need to get it off and sorted before winter anyway.

If anyone has experiences with these bikes, or the Yahama original (Virago / Dragstar XV and XVS 250) then I'd very much appreciate your suggestions about where to find the hidden performance. I'm not looking for a rocketship, just another 5 or ideally 10mph for motorway use.