Bike's acting funny after a filter change

Hi all.

Any advice is much appreciated:

I changed my air filter about a week ago. Mistakenly I left the key inside the ignition in the on position, but all the lights were off and the engine was not running. It was left like that over night.

The next day I try to start the bike and of course the battery is flat. I had to restart the bike off the car. No problem. although I took it for a ride that evening the next morning again the thing would not start. So again I had to start it off the car battery.

Here's where things get worrying. After I start it off the car battery I try to ride off. It immediatley loses power (while I'm trying to ride it)...so I try to keep reving so the engine wont cut out...it struggles to keep the engine going...then suddenly the bike has full power for a few seconds...again I try to ride away and it loses power again. At most it could take me up to a speed of 10mph. I get to the main road after 1 minute of riding like this and at that point I decide I need to just take the bus.

Today I thought I'd try to have another look and so jump started the bike again (yes the battery went flat again). After a few mins of idling there was a very loud explosion/ bang at the exhaust letting off a pume of black smoke, after which it automatically turned off. At that point I thought right this is more serious than I thought it was and here I am posting.

Any experience ideas? all advice appreciated.

Thanks in advance.

Check the air filter and the surrounding area, is anything being blocked? A bang is usually unburnt fuel in the exhaust; sounds like your bike could be running very very rich, like not enough air is getting in (but since its carb, I dont see how it would be pulling through lots of fuel if there is little air flow...anyway, check). Maybe pull out the spark plug from the rear sylinder, if the engine is having fueling problems then you can tell alot from the spark plug

[Sid Squid]

Before going looking for a problem - check everything you've disturbed - I suspect that something isn't connected properly.

Do you still have the old filter? Refit it to see if the new one is somehow faulty.

[punyXpress]

Choke isn't stuck fully on is it?

Thanks all.

Alpine- will check surrounding areas.

Sid - I suspected it might be because of the new filter...but thought it's such a straight forward replacement part it might be something else. Will check again with old one.

Puny - No choke is not stuck

[gruntygiggles]

The way it's behaving when you try to ride it makes it sound like too much fuel is going through and flooding the engine, hence the power loss and suddenly power back.

I'm no mechanic by any sense of the imagination...lol, just had that thought so shared it. I agree with the guys though, check out everything that you've done and work back from that. Actually.....what's it been like since the bang and big plume of black smoke? Is it garaged? Could kids have stuck something up the exhaust?

Feel free to laugh at me if I've said anything stupid! I laugh at myself often enough

Well if it needs jumping off the car everytime you come to use it, the battery is knackered.
You could try leaving on a optimizer type charger overnight.

The running issues maybe related to that, see your bike is 2002, have you ever put a new battery on ?

If you have access to another bike battery, try that on it, is worth checking out.

[yorkie_chris]

That surging "where's the power... BRARRRP... there it is ... pft... gone again"
Is what you get when it's running very lean, like if you didn't seat the airbox properly.

However that could also be caused by an electrical thing causing misfiring, battery or charging.

First check everything you might have disturbed, just a cursory check that the crank breathers are all fitted properly, the airbox drains are sealed and it's snug on the carbs.
Then check the battery and charging system, sounds like you killed it.

Originally Posted by gruntygiggles

Feel free to laugh at me if I've said anything stupid! I laugh at myself often enough

I dont think anyone will laugh at you for trying to be helpful.
Thank you

Originally Posted by Shadow

Well if it needs jumping off the car everytime you come to use it, the battery is knackered.
You could try leaving on a optimizer type charger overnight.

The running issues maybe related to that, see your bike is 2002, have you ever put a new battery on ?

Yes it had a new battery put in less than 6 months ago. But I also done the Optimate thing. It helped.

Originally Posted by yorkie_chris

...if you didn't seat the airbox properly.
First check everything you might have disturbed, just a cursory check that the crank breathers are all fitted properly, the airbox drains are sealed and it's snug on the carbs.
Then check the battery and charging system, sounds like you killed it.

I took out the new air filter and replaced it with the old one again and the bike is working again. Seems like the most plausible reasons would be i) I didnt seat the new one properly ii) the new air filter is faulty.

I will re-fit the new one- properly this time. If it still does not work I guess I'll have to conclude it's a dodgy new air filter.

Well, at least I didnt kill the damn thing.

[yorkie_chris]

Originally Posted by abdul.aziz

I dont think anyone will laugh at you for trying to be helpful.
Thank you

That's where you're wrong, I'd laugh at anyone for almost anything