81 atc 200 backfiring

[polabareus]

I have an 81 atc 200 that everytime I slow down after going fast it backfires. It can also be a pain to start (the warmer the weather the easier) but once warmed up runs very well. I know Im being pretty vague here but does anyone have any clue why it would back fire?

[atcmatt]

I have the same thing happen on my 200es. Ive been told it does it due to 2 diffrent reasons;

-Loose header pipe
-Timing out a fraction

Im not sure if these are genuine reasons! Anyone want to elaborate???

Mine does it wose in cold and wet weather............ (its easy to start even when cold though)

Maybe that will help!

[slowmo]

Check the intake for cracks, poor sealing- that would explain the hard starting, (sucking air) and an overly lean condition when you close the throttle will cause backfiring. The engine sucks in air after the carb, and the idle circuit supplies a small amount of fuel. Easy test is to spray some WD40 around the intake with the engine idling and listen for a rise in RPMs.

[smokinp]

I've got a 83 200 and when i first got mine it had the same problem,i tightned up the exhaust and it seemed to be fine

[Tri-Z Pilot]

Whenever you have a backfire on deceleration it is caused by a lean idle mixture (this is also the problem why it is hard to start in the cold). All you have to do is increase your idle mixture strength (go with a bigger pilot jet or richen your your idle mixture screw).

[timex69]

i just fixed my freinds XR100 and it did taht alot...make sure the intake [the little peice that holds the carb onto the cylinder] has gaskets that are in good shape and their are no cracks in the intake...also make sure your floats arnt sticking and for best results run Hi test gasoline [supreme] or [premium] or [gold] thats what we call hi test here in Canada :P