In motorbike?

My 150CC bike is more than 2 years old and I noticed it that it would not anymore reach its speed the way when it was still new. A day ago, we went with the group and joy riding was really great. But I full throttled my bike and it could only full throttled to 108kph and I noticed misfiring (short of fuel perhaps). Prior to that I changed my air cleaner to a more free airflow..can somebody help me explain to me, do I need to go to shop?

Hi!

I guess you want to say that you have got a high-flow air filter. I suspect that is the reason why you are having probs. with attaining more speed.

When you go for a performance filter, it throws in more air in the engine but to gain out of it, you need to increase the fuel flow too as you can't just burn air alone. What you need to do is increase the fuel flow by tweaking the Carb. If that doesn't fix things either, you will have to upjet the carb.

YOu need to go to an experienced mech who has some exp. in perf. mods and ask him to adjust the fuel-air mixture. Do NOT go to the authorized service station, their mechs know only one setting i.e. the stock/default one. Also, it would help if you could specify which bike you have. If its one of those gulsars, then I would not be surprised. It's a common prob. in them.

One more thing, if you didnt complete your running-in properly, then its just your engine getting old. If you dont run in a new engine properly, it tends to show its age after around 1.5-2 yrs.

You can write to me if you need more details /help.

For future reference, always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.
In your case, the mileage of the bike would have been helpful.

Check the cylinder compression.
If it's a 2 stroke engine, the top end may need to be rebuilt (cylinder, piston & rings).
If there's no damage, just installing new rings will bring the power back.
2 stroke engines wear out much faster than their 4 stroke counterparts.

Everthing both of the guys above me said is right. I'm just posting to agree with them and to make what they said the majority answer. Especially listen to the first guy 'cause he said exactly what i thought the problem is.