Honda Spree and Elite 50 Forums

well, not quite a honda. a Lifan ct70 clone.

went out for a ride to the "country side" today. everything was going fine, until i decided it would be a swell idea to do a top-speed run with a tailwind. 64 was the top, btw. immediately afterwards, as i let go of the throttle, it doesn't want to accelerate anymore. would bog down at anything except "barely any" throttle. only way i made it home was with the choke pulled 3/4th the way.

i checked the manifold where it connects to the head and the carb, but neither seemed to have come loose. the air filter's still on there tight.

any ideas as to what could have happened?

thanks for any advice.

Try spraying starter fluid around the rubber manifold while the scoot is running. If the engine speed changes its leaking. The chinese rubber manifolds (if it is rubber on that bike) have a tendency to crack.

Next I'd check the valve clearances to make sure they didn't change with the high speed and resulting heat to the valves.

Next in line would be the carb throttle diaphragm. Provided, of course, that the bike uses a CV carb rather than the PZ style carb.

Could be you seized it also. Had that same thing happen to my 200sx. As long as it was running it may have only soft seized but it would be worth taking the cylinder off, if the above does not work. You may need a hone and new rings at best.

There is a problem with the Shoty China Mikuni carbs they go really lean at the top end on four strokes, Starts at around 6000 rpm then leans out all the way up.

well since then, it seemed to have fixed itself, only happening once or twice more since then, and going back to normal after 20 minutes of running or so. although now i know a possible factor, thanks. now it runs perfectly, although it probably needs a valve adjustment... d*** these four strokes! i miss two strokes...

Four strokes are so easy compared to 2 strokes. Way less finicky and 10 times easier to tune.

no matter what i learned in my highschool small engine rebuild class, i'm still afraid of valves