Engine Backfiring

[strikers]

2003 Predator 500

Recently went to the dunes sucked up a bunch of sand. Unfortunately I had to ride with it poping and running like crud due to the sand until I got back to my staging point.

Got home cleaned the carb. Still popping hesitating and backfiring.

Order a used carb off ebay. Still popping hesitating and backfiring.

Carbs did not pass the vacuum test that the book says to do. So I still think the carbs are bad.

At this point I am ether unlucky and have purchased a bad carb off ebay or something else is wrong internally.

I have ordered a "guaranteed" working used carb off ebay.

We have checked the fuel lines and the fuel pump as well.

My questions is. Is there something Im missing, were not used to these vaccumed carbs and I feel like maybe Im missing something here.

If there is an internal damage, what would cause hesitating and poping and backfiring.

[The Outlaw]

Shane how did you get sand in the carb?

[strikers]

The air filter wasnt sealed properly.

UPDATE : I threw a new carb on and the bike seemingly ran perfect. Took it down the road and same thing started back up.

Popping and backfiring. Now the dang thing doesnt even want to rev.

Ideas?

[snowman48]

If you sucked in sand as bad as i think you might be low on compression. Your carb needs that suction to help draw fuel and work the fuel pump. There might be more wrong than you think. I think you should check the compression.

[ZsPred]

If you "sucked up a bunch of sand" in the amount that you say, looks like its time to pop the top and see what damage is done. Your rings/piston and nikasil are more than likely shot.

Have you drained the oil and pulled the filter to see if there was any sand in it?

Chris

[strikers]

Ok Guys

No Sand in Oil or oil filer.

Could it be a timing issue? Could the timing chain jumped? Would this cause the bike to pop/backfire and miss.

I also ordered a rectifier. Someone told me it might fix it? Will a worn rectifyer be the problem.

[snowman48]

i would seriously check the compression. Cylinder could be scratched from the sand. Valve seats could also be pitted from the sand.

[strikers]

Compression check out to book specs.

It only is backfiring in the mid range.

Idles fine, top end is fine.

Mid range pops and backfires. Tried stock jetting. Tried changing the jets out with jet kit.

Same thing. Seems like whatever i do with the carb it misses, pops, backfires at mid range.

[ZsPred]

If its only the mid-range then its your needle that you need to look at if everything else is running fine.

Chris

[strikers]

The bike ran fine! Then all the sudden it started running like shat. Its not the jetting, Ive replaced the carb, the jets, the whole 9.

I pulled the head to check the cyl and valves no problem there yes the timing is set had to set when i put the head back on. started the bike ran the same..

I am completely confused This thing should run