question 4 carb gurus

[350xorbust]

I did change the main jet to lean it out a bit as the plug was very black. I went to a smaller jet and then the plug looked good. I ran that jet for a week before i had the trouble with starting so i thought nothing of it. I went with a dynojet main jet and i kniw theire jet sizes dont match stock stuff but a buddy of mine crossed referenced the #s and gave me one a bit smaller. I can get the #s for ya but i wont be able to till tomorrow.

[350xorbust]

If i were interested in changing the coil out, does anyone know of a coil from a more modern quad that would work on my x? The reason i ask is the ease of obtaining one up here is always easier if its from a modern bike......would take some time to track an oem one down.....

[350xorbust]

Update: swapped out the coil from a proven 85 bigred and still nothing. Could it be a weak stator? If so should i swap it out for the spare stator and flywheel from my original 85 motor? Is that wven possible?

[Flyingw]

If you have a meter, you can put it on the black/red wire from the stator and take a resistance reading. That value will tell you the health of the exciter coil. Also, The 85 350X CDIs are known for the contacts that run from the plug to the circuit board breaking. Vibration causes this and it is very possible you have this going on in your CDI and kicking it isn't spinning the motor fast enough to get enough current to jump that broken connection as it does when its pull started. Not saying this is the cause but it is a possibility. I have seen electrical problems mask themselves as carb problems so I would put a meter on the exciter and pickup coils and se what the reading is to rule those out as suspects. If you have another CDI, try swapping it out. The factory manual tells you which wires to check for the two coils and what the value range should be.

[350xorbust]

I have already swapped out my other cdi and it didnt help. I will get that reading in ohms in a bit. Fyi the dynojet jet i have now is a 126. Aparently it equals a 135 oem. Stock that came in the kit was a 138. I have a cobra exhaust with a Yzf450r muffler welded on, a k&n filter and the "bolt in performance" cam from web cams. Otherwise the motor is stock.

[Flyingw]

Ok so strike the ignition coil and CDI off the list. Have you tried some fuel in the spark plug hole to see if it burps or anything?

[350xorbust]

Im still leaning towords a feul issue. When i swapped over the 85 bigred coil i kiked the engine over at least 20 plus times with the choke on full. (I know the choke works fine vecause it works when its running)the plug was dry. If all was working properly and i kiked it 20 times with the kill switch off the plug would be soaked.

[350xorbust]

Yes...dump feul down the cyl and it will fire up till the feul is gone...then nothing

[Flyingw]

Hmmmm, that takes me back to the carb and it not supplying fuel or enough fuel for startup.

[350xorbust]

Well all the ohms tests were done on the coil and stator and its components and all were found fine. So thats it....carb is gone. Time for a new one
So...if anyone has a 400ex carb to sell lmk.
BIG THANX to all that took the time to help. Couldnt of done it with out chas.

[DohcBikes]

The carb is not "gone". If you are dead set that is the issue, send that sucker to flyingw.

[350xorbust]

Iv spent all winter building this bike. Our summers up here are so short up here, that if I send my carb across the border, I wont be riding for way too long. I appreatiate the offer, but the new carb was just bought. $150 for a new Kiehien/ honda 400ex carb. If someone wants my carb, cover the cost of shipping and say $20, and its yours. I have spent the last 6 days in a row kiking my brains out...and Im done!!!

[oscarmayer]

do yourself a favor, do a compression test. if it's on the low side that too could pose an issue (enough to run once started but makes it tuff to get started). Another thing to try is a new plug. we had a bad new plug and once we figured it out, and swapped, no more issues.

not sure this could be your issue, but also check your valve adjustment. if too tight it could leave the valves hanging open and lowering compression during start up.

good luck and keep us posted.

[350xorbust]

Well the only part of that i didnt do was do a compression test although i cant see it being low as its a bear to start when the decomp lever is too loose....stops my 265lb advance dead in mid stroke...lol. tried several plugs incl a new one, and set the valves myself this time to the 4 thou that web cams recomended. I have had them as tight as 2 thou then the 3thou recomended by Honda. Iv also tried several different adjustments of the decompression lever and found it easier to kik with it adjusted at the tighter end of the spectrum.
Let me be clear. This isnt just hard to start....it doesnt even fire....well maybe once in a while but its like i turned off the kill switch.....dead!!.The new 400ex carb should be here in a week or so....and i will keep you guys abreast!

[DohcBikes]

I will keep you guys abreast!

keep a couple if you have the room...