1982 Yamaha XT550?

Question

Bike runs until i get to 2nd gear then starts to backfire and has no pickup will only run about 20 miles an hour. whats going on. carburator??I changed the float and it stoped leaking gas now another issue. helppp

Answer 1

It is indeed an induction problem as you've concluded. Start with the airbox and make sure it is clean and free of dirt and debris(mice just love to build nests there during the off season) as a clogged or ubstructed filter will choke off the air suppy and thus rob the engine of any power potential.
Next make sure your fuel line is clean. I'd replace it as it's probley due anyway, besides which you should pull the petcock and flush the tank as rust and assorted 'stuff' from years of use can clog the mesh filter screen that is located on the tank side of the petcock. No gas-no power!
Lastly you should thouroghly clean the carb. If you've already replaced the float then you obviously aren't afraid to get your hands dirty. The culprit in the carb is usually varnish which builds up over time. A thourough soak in some parts cleaner is the best place to start, then a bit of scrubbing with a good bristle brush or some Scotch Brite and blow it out with compressed air should clear things out.
One part in the carb which should be replaced are your jets and needles. A look in the owners manual or better yet a clymers, hanes or chiltens manual will give you the proper sizes required (as well as directions and pictures). Don't bother trying to save the jets via cleaning as they're not expensive and are critical components in the system. Even a little scratch from a slipped screwdriver can and will have a major impact on these so pony up the $3 and buy new.
After all this is done it only makes sense to chuck a new spark plug at the beast as well. More than likely it is also due for new and as fuel issues usually equal plug fouling as well. Besides, it's another cheap, easy and effective way of insuring you've got all the bases covered.
Lucky it's the weekend cause you've got a couple of hours of maintinence ahaeed of you so get at it, the sooner you're finished the sooner you ride. Good luck.

Answer 2

1982 Yamaha Xt550

Answer 3

you need to confirm that ignition timing is correct as it will result in the same symptoms if spark is retarded,
if ignition timing is spot on then you have probably a weak mixture, if it backfires when accelerated then the mixture is weak (or timing is wrong) this can be confirmed by taking a spark plug out to see if it is white or grey, if it is weak then either you have one of the following,
incorrect float height, an air leak, incorrect adjustment of the air screw in the carb.
If the backire occurs when slowing down you have a rich mixture once again look at the plug electrode to see if it is black and sooty.
If you look in any car or bike manual you will find a spark plug chart with photos of plugs and what they mean.
you should have a brownish tan colour on the electrode if the air/fuel mix is correct
black and sooty is rich grey or white is weak but there are lots in between so just get the plugs out and compare them to the plug chart in any manual it will give you a better idea than anyone on here can.

Answer 4

Does the problem happen at any throttle position? If so, it may be an electrical problem, not carburetion.

Defintely clean the intake and carb, but keep in mind it may be the CDI or points (can't remember if the XT is CDI or not).

The fact that it's actually backfiring actually points more towards a timing and/or electrical issue - or problems with the cam or valves.

Answer 5

This is an issue only with the Carb! U need to get it changed to get ur problem fixed once n for sure. The carb is jus clogged or the lining of the carb is gone for it to run max 20miles. Get it completely replaced.