Lost about 40% of my power

[Guest]

I have one of these chinese things to get me to work and back, a Huatian HT125 twist and go. Used to run fine at about 55mph, then "something" happened and I lost lots of power. A local yard replaced the air cleaner, and this seemed to work for about 20 minutes. I was travelling home along a dual-carriageway road at full throttle and nearly 60mph when I had to let off for a lorry in front of me (I had been at full throttle for around 15 minutes). When I pulled throttle on again the engine was again instantly down about 50% power and I couldn't get above 30mph so I went straight back to the garage. After a few days they couldn't find anything wrong so I went to another garage.

This garage said that the previous garage had not reconnected the air supply to the carb correctly and it was ll working fine as it should, however when I rode it straight away I realised it was still sick. Couldnt get above 40 so it was a tiny bit better than before but still way short if the usual 55. Accelleration was sluggish and it could nto maintain speed going up hills that it did before.

It feels like it's suffocating somehow, or could it be running rich? I'm told that the throttle cable is a little stretched, however because the power loss was instant on the way home from the first garage I don't reckon this can be the cause.

To summarise, symptoms are:

1. Loss of top-end power (used to do 55 easily, now struggles to do 40)

2. Loss of acceleration, less noticeable than loss of top end power but still very evident.

3. Sometimes when applying full throttle from approx 20mph the bike hesitates (cuts out or suffocates for about half a second) and the jolt throws me forwards a little.

I'm inclined to have a got at fixing this myself by taking off parts and cleaning them up etc. I own the necessary tools and I'm up for the challenge. My limited knowledge of engines tells me it's the fuelling system but I guess I should also consider the exhaust? It's really wierd how it was fixed for 20 minutes and then lost 50% again instantly. Any ideas welcomed.

And yes, I will be aiming to purchase a different (non-chinese) bike soon.

[Guest]

Fuel? Fuel tap on reserve?

Or fuel blockage from running it too low on reserve?

[Guest]

No fuel tap on this machine. And I've been through 2 full tanks so don't suspect the fuel itself. I do feel it's something to do with fuelling. Just wanted to get a vibe from experienced peeps before I start dismantling stuff.

[Guest]

check both hoses on the tap, if no tap fitted as you say then the vacuum hose is not fitted properly, could be kinked or trapped, or the fuel hose is..

[Anthony]

or its broken

or seriously

[Bill_on_a_bike]

Given the carbs a good old clean out?

[stelmer]

Drain float bowls. Could be water in the carbs.

My GSX did a similar thing after I put it on reserve.