350x with 400ex carb cold weather start up question..

[Ddw350]

so after my conversion from a leaking,worn out all but rotted 350x carb to the 400ex carb..ive ran into some start up trouble when its cold[like 35degrees]..now i used to choke..1/4 throttle and 2 -4 kicks and she was purring like a kitten. no more! i kicked till i was worn out,smelled some gas but wasnt pouring out the overflow.choked..1/2 choked..i tried it all. BUT i gave it 3 pumps of the throttle and at least it tried..i finally did get it going.is there a certain method that you guys have discovered for starting these things with the accelerator pump on? i hate to go thru this everytime!

[RIDE-RED 250r]

Now I haven't yet fired my 400ex in cold weather that I just picked up this summer, so I'm not sure the best way with the 400ex carb specifically...

But I do remember my brothers 450r he had liked about 3-5 pumps of the throttle before kicking it over in cold weather like this. Made a WORLD of difference starting a cold engine in cold winter temps. Before we realized it had an accelerator pump we just flipped the choke on and kicked like you would with a 350x. Kicked and kicked, and kicked some more..would not start for anything. 3-5 pumps of the throttle (depending on just how cold the weather is) and it would start right up.

I suggest giving that a try. Treat it like an old carbureted Chevy smallblock.

[Ddw350]

thats what im gonna try next time..a few pumps with choke and see what happens.i was to far into it the other day to stop and try something different. though i did notice the choke didnt seem to make much of a difference once it did fire up...

[sp8twn]

my 06 ex... I need to pump throttle 5-6 times at 1/2 to 3/4 choke,,,starts and stalls out... then repeat a few times till it keeps running..... summer like winter!! Im just glad there's a starter on it and I don't need to kick it!!!

[Blown 331]

400EX's have a pretty lean pilot from the factory as well. I bumped mine up one size and it made a world of difference.

[Ddw350]

i may look into that,i havent tried the new technique yet. ill give that a few goes and see what happens..

[bigmac]

When u switched over to the 400ex carb what differences did u see???

[Ddw350]

it pulls a little harder..but i found it to be a little more of a chore to install than i thought it would be.as of right now im not happy with the swap..mainly due to the new start up procedure i have to learn.if i had a perfect condition 350x carb,i wouldnt do the swap,but thats just me..i know there are some folks who really like the flexibility the 400 carb gives them with big bore kits,high comp piston kits and the accelerator pump and what not.but i was looking for a quality replacement,which i believe i have found..just not used to it yet i guess? its hard to change something after ive had the same thing since 1993! Lol

[bigmac]

If I can ever find a 350x for the right price I'm gonna do this

[Dirtcrasher]

Does every carb with an accelerator pump have a leak jet or just the FCR's ????

Just realized, I REALLY need to go to bed, see ya guys.

[bigmac]

What does a 400ex pipe on a 350x help with?? I just need a straight answe not trying to jack trailprotrailpro theead

[Dirtcrasher]

I'd love to hear a straight answer on that also. The XR400 pipe fits great and appears to be stainless steel so I hop with a mid-pipe to a Super Trapp that I'll be AOK. Many claims are found on the 400EX pipe. Some claim they need wrestling into the head and a bit of heat to align them in position for a silencer, IDK......

I'm gonna go with the XR400 (honestly, owed to Kasey) and see what I have to do. If they are stainless, that's awesome as the stockers NEVER take paint or high temp PC that people actually ride with! The show trikes use that stuff just fine but I'm not a shower, I'm a grower :D

[BleedRed]

I used a 400ex head pipe with a 450r silencer. First thing you have to do to even get it on the head is cut the pipe off right at the Y. (the ex pipe turns towards the motor in a downward angle so you won't even be able to get it on till you do this) Next I drilled out the flange holes to the next size to bolt the flanges to the studs. Then from the piece I cut off, I cut the last roughly 6 inches off that right after the bend. I re-used the last bit because 1-it had the right bend to go through the frame by the brake reservoir and 2-it had the factory flange on the end to insert into the 450r muffler.I clamped that piece into the 450r muffer I had bolted on already then welded In a piece of stainless to connect that piece to the head pipe. Smoothed out welds and it was done.

I did mine as 1 piece head pipe so I tacked it then made sure I could get it in and out properly before finish welding. It IS tight but it can be done in one piece so no need for a mid-pipe.

[bigmac]

What have u noticed on the bike overall after changing pipes

[Dirtcrasher]

The 450R silencer is PRETTY but needs the HRC tip. A 30$ part that opens it up. I paid 30$ for a silencer with the tip.

Now take off the air box (AB) lid and increase the starter or pilot jet a bit and then the main jet should allow you to mess with the rest of the jetting.

NO - It is not easy.

NO - It is not hard.

Make one change at a time BOO HOO HOO!! and write it down.

Do not give up feeling like this use to run perfect!. Spend a day with some jets and get it dead on.

You have 4 STROKE OR A "THUMPER" so relax, breathe and jet. PLUG CHOPS A MUST!!

2 strokes can blow up just testing them, that's why they start FAT!! or with a big main jet. Foul 10 plugs but get it right.

Start a bit (should have said fatter) than the manual but by no means shorten up the oil mix unless the plug is soaking black and the silencer is a mosquito

trap. Drop the main a bit EASY and do some plug chops!!

SAFE TEST!!??

If i runs awesome with no air box lid, you are jetted fat or too large unless you want to ride that way. I hate airbox lids as well as water.

If it falls flat on it's face and worse with the airbox lid off and no balls. it's running lean.

Report back to help other guys please!!

[BleedRed]

Yes the HRC tip is a must. Stock tip is way to restrictive and it even made my engine run noticeably hotter. I didn't really do it for performance, I did the swap fror parts availability and quiet it down. It sounds absolutely great now and the DNR wont bother you and your neighbors won't hate you. Still has some grunt but quieter then a crf450. The 350 came with a cobra and my opinion is it and other exhausts sound horrible, supertrapp can be tuned to sound decent but still not my type of taste.