I have been working on bayou 250 for a friend.Installed carb kit.Carb was in good condition.Complete tune up.Set everything to the right settings 1.5 turns.Cranks right up but has a backfire through the exhaust.Thinking I had it to rich, I turned it a 1/4 back in.Rode it and it runs good but has this backfire when I let off the throttle or if I rap it sitting idle.Thinking I did something wrong I tore the carb back apart.Got back on, it hauls butt..first thing in the morning I have to leave it half choke until it warms up then it idles fine.Thinking it might be a baffle.I called this cat up and asked him did it ever backfire.He proceded to tell me that the exhuast came off a yamaha.That it did some..backfiring..My question here is is this normal to backfire like that.and also the needle valve where it drops in the slide under the clip I used a plastic washer.do I need to leave it as the diagram shows or take it back out.One more thing noise where the oil filter-in crankcase.Thinking the clutch needed adjusted..but shifts good.Do I loosen locking nut and screw the adjuster out until it's snug and back in till it's snug then lock it back down.Or will it hurt to turn in a round and drive it till it smoothes out.Going to put 20/50 in it.Was told 10/40.I'd sure appreaciate any input.

 

I'm so thankful for all the help on this site...No replies so I found the answers myself.Here goes.

Clutch Adjustment
Remove the clutch adjust cover.
Loosen the clutch adjust screw locknut.
Turn the adjust screw clockwise until resistance is felt, then stop.
From this point, turn the adjust screw counterclockwise until resistance is felt, then stop. Hold onto the adjust screw and tighten the locknut securely.
NOTE: Make sure the adjust screw does not move when tightening the locknut.
Install the clutch adjust cover.
Test ride the vehicle to make sure the clutch is operating correctly. Readjust if necessary.

Noisey Exhaust
Its caused by a free flowing exhaust.
Some aftermarket exhaust systems, are so free flowing , that its hard to adjust the carb so it will idle correctly and not pop.

Plastic washer under jet needle down in the slide.Since there is only one setting you cannot adjust it up or down.The diagram is correct.
Washer,Needle,clip,Ring Snap.

Maybe someone else can find this information useful