Total Motorcycle Community Forums

i got this 1981 yamaha xj650j in deplorable condition. the air filter box is open and empty. WHAT GOES IN TEHRE!!!! and where can i buy one that's not high performance!!!
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Stroke Forum

I think it takes a paper type air filter. Try to get one at the autoparts store. If not go to the cycle store. If they don't have one they can order one for you.

yup, just go to your local cycle shop and they should be able to hook you up. If there isn't one nearby, you can use servicehonda.com or hdlparts.com for honda parts

I'm suprised the bike ran correctly without the filter. I would assume that it would be running very rich and stall out after a while.

that's just the thing...its not starting and its acting as if its not getting fuel. there is great spark and great compression but it will not start. if i let it sit for 20 secs it will really try and goes up to 2000 rpm and back to idle for a max of 5 seconds. then it dies. if i try again it doesnt start or even try as much. if i let it sit again it will almost start.
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Casualty insurance Forum

Sorry, I retract my previous post because of stupidity and working a long day yesterday!

It should be running LEAN not rich. It is actually getting too much air because there is no filter.

If you want to be cheap, you can try to buy a furnace filter at home depot or something like that and cut it to fit your air box. I'm not sure how your bike would react to that, but it can't be any worse than your no filter situation

I know in theory it should be running lean, and that sounds like the problem.

But why then did my bike run rich as hell(its a 2-stroke) when I fitted a free-flow filter??

Sorry for changing the subject, but this problem has always boggled me as it goes against any normal rules of airfilters and engines...

Either your engine is flooding and when you let it set some of the fuel evarorates and it will try to start or, you have a fuel restriction and when it sets it has time for the fuel to fill the carbs and it only runs a little bit. Does this make sense????

i dont think so, because just 10 seconds isnt enough for it to evaporate enough to make a difference. it was a good idea, but i dont think that will do it..thanks for the input, but im still stuck. im cleaning the carbs over the next few days because i think that the sitting for 10 yrs played havoc with the carbs. ill keep you up to date after i clean it whether or not it works.
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recession history

Cleaning the carbs will so the trick, if you clean them throughly. If it still runs bad after you cleaned the carbs, take them off again and just take the carbs to a shop. They will soak them and that will take the carbs out of the equation.
Just remeber to check your fuel tank for rust before you restart it. It would be a shame to get debri from your tank into those freshly cleaned carbs. If it is questionable, install a inline fuel filter from the tank to the carbs. Also completely drain the tank and add fresh fuel before starting.
New plugs and she will be good to go.
If it idles rough, take to shop for a carb synch.