400ex Carb on 350x PROBLEM

[350xx]

It does backfire. yes.
When i let off the throttle.
That does mean it is rich..
should i try going down on the needle, aka up 2 clips.?
The only thing confusing me is the fact that the plug remains white and dry.. Hmm.

[3wheely]

Did it back fire with the stock carb? I had an exhaust leak once and it backfired like crazy until I fixed it. Is the float level? Still seems lean to me at least that's what the plug shows. It's all trial and error especially with a different carb.

[350xx]

It only popped when i was going downhill before, or if i got it really high in the rpms and then let off and let the compression slow it down.

Im thinking of going to a different pilot. I will buy a 42 and a 34 or 36 and try those.
Thats very time consuming though.

IF it doesnt sputter at WOT then my main jet shouldnt be too big right???
I think my idle is too rich or too lean. since it dies by itself sometimes. hmm.

[350xx]

Okay guys.
I think the pilot jet is the culprit.

I turned the fuel air screw out to like 3.5 turns
Got rid of most of the backfiring, however there is still some popping at very low throttle, under 1/4.
Pilot effects idle thru 1/4 and thats where I am seeing issues.

A smaller pilot jet it is.
Then i will have to re-adjust my fuel air screw possibly.

If there are any disadvantages of having a huge main jet please speak up. Because my throttle response is perfect and it doesnt sputter anywhere throughout the throttle range, and WOT has no sputtering whatsoever.

[3wheely]

Sounds like your on the right track. Just remember the spark plug will tell you all you need to know. A goldish tan color is what your aiming for and obviously a good running bike.

[350xx]

Yup :]
Getting a pilot tomorrow.
Right now im at 38..so i will try a size or two lower. im thinkin, with the amount of sputtering i will only need to go to 36. so we will see. depending on price i may pick up more.
The plug trick isnt working for me. no matter what ive done it says lean. So i will do this, see how the sputtering goes, and get a good half hour of riding or so. and then check the plug and see what it looks like.

[350xx]

First off, I will try to bring the clip up, lowering the needle.

[3wheely]

Yes, I would say 4 down is still low.

[350xx]

stock setting on needle is good. Now i just need to go to my local dealer and get a smaller pilot jet.

[350xx]

Still waiting on a response to: If there are any disadvantages of having a huge main jet? WOT doesnt sputter at all, it just rips!!

[3wheely]

You could always switch it out with a smaller one to verify. Only takes a few minutes. If it doesn't sound right then your probably on the right track. Doing plug chops you really need a few new plugs. There's no real answer. Every bike is different.

[Dirtcrasher]

My 3560X carb has a 50mpilot and a 160 main an is still off......................

I give ya credit for trying

[350xx]

Okay, went to my dealer and they didnt have any!!! they could get it shipped and my total cost for one slow jet would be 20 dollars. Screw that.
EBAY HERE I COME!!!
This will work.
I know it will.
Going for
168 main (may drop to 160)
35 pilot (should lean out the bottom end some)
3rd clip on the needle AKA stock.
Currently 3.25 turns out on fuel air
NEED TO GET CORRECT STOICHIOMETRIC RATIOOOO haha


By the way 3 wheely and twilight, thanks for the help.
After some good reading and tests I have a better understanding of these overcomplicated carbs.

Total invested: 39.50 for carb (needed work), 7 for main jet, new slow jet will be 7. And some hours of testing and work past and yet to come.
Better than paying 100+ for a perfect carb and still having to go through the grueling jetting process.
Vid and pics in a new thread maybe sometime.
Ill keep ya updated. Thanks again.