1984 honda 200x auto x backfiring after WOT?

[d.walker43]

Hey guys. So my Auto X consistently backfires after letting off the gas after being at WOT or close to it. Thinking its carb jetting, I need to go up a few sizes right? The trike has a Supertrapp exhaust and a K&N filter, along with some vents cut in the air box. Im not too good at carb rejetting so I don't want to waste my money. What sizes should I go with? Thanks

[yaegerb]

What is your current jetting and how many discs are on the pipe?

[knappyfeet]

along with some vents cut in the air box.

Fix this^^

Modern airboxes take into account inlet size, length and volume in order to optimize resonance frequency. This may be a contributing factor....along with the jetting to your current running condition.

[d.walker43]

stock jetting, and I have no idea how many discs lol ive never messed with it

[knappyfeet]

stock jetting, and I have no idea how many discs lol ive never messed with it

The major cause of exhaust backfiring off deceleration is a lean condition in the pilot circut. There are a host of other reasons but this one is the primary. So messing with the idle mixture or up sizing your pilot jet (slow jet) may cure the issue. Your type of exhaust can be tuned for a certain improvement in running conditions.......hence the reason to find out the disc count.

But I would say this....did this happen all of a sudden? Did you just install the exhaust recently? Have you been in the motor or did any valve adjustment yet? Compression test? Certain engine conditions can lead to a lean situation as well.

[Rob Canadian]

Any exhaust leaks?

Another thing to check is an air leak at the intake manifold.

[yaegerb]

stock jetting, and I have no idea how many discs lol ive never messed with it

Well, count the discs and open the carb to ensure it is stock jetting.

[d.walker43]

yea as much as I don't want to I should just tear into the carb and verify. I do know there is no exhaust or air leaks. And knappyfeet to answer your questions, no I did not just install the exhaust recently, its done this ever since I swapped the motor into it. When the motor was in the original 200s it did not have this problem, so I am 99% positive that there are no engine problems or valve adjustment that needs done, the problem is somewhere in the exhaust/carb areas, I'll start with adjusting the mixture screw and if that doesn't work I will up the jet size and report back. thanks for the help