wont start with the starter but fine pushing it

[55stone]

hey guys i know this has been asked a million times..and its usually just do to how cold bloody these things are and jetting but i bought a 400ex blown up that was already tore down and the guy didnt have money or the know how to put it back together... but a new clutch in it,11:1 piston, sparks key, new stock head and valves, new frame...anyways.. the thing wont start with the starter... it will start fine and easy if i push start it. it runs fine too once its started... anyways i have a stock exhuast on it still and idk what jetting is in it.. but i was anxious to see if it ran...anyways broke it in..and have rode it like 4 times or so.. the battery also wont charge while its running.. it could be a bad battery i have no idea what shape it was in when i got it.like i said it was already tore down and dont know the old owner or have his number.. so what do you guys think? probably jetting and its cold out for the starting issue. what should i do..should i go up wiht the main and take the pilot jet to like a 40... is the stock needle alright??? never had a 400, could a big factor be the fact i have the stock exhuast on it stil or does that not really matter.....but now what about the battery not charging? bad battery or stator or whats your opinion on this... plz give me any ideas you have.. throw everything out there..
thanks a bunch
stone

[bkelley]

The battery is probably the first place I'd start. Also, be careful with that Sparks key and 11:1 piston. Sparks states that it "must only be used in conjunction with a stock [compression] piston".

[55stone]

ya i read that too..but i did alot of research first and anything up to 12:1 is fine.. and even over that sometimes they work..just cant and i mean cant with a rev box...so you think start with the battery???

[bkelley]

Yeah, as long as you aren't riding in 90° - 95° plus constantly you'll be fine. And, yeah, I'd put the battery on a charger or something first to make sure it's not the root of the problem.

[55stone]

ya see thats whats weird though..the battery will take a charge..it will be full..still wont start the thing nor will it charge when im ridding it..so thats why im not sure its the battery..could it be bad if it will charge??

[KISSmyACE]

it's probably really not charging. replace your battery, then check your stator. you could have a drain somewhere, lights, tether?

[bigbad400]

is it just not turning it over fast enough?
you may need to find a rapter battery or a hyabusa battery that has more cranking power than a ex battery. with hi comp. motors and aftermarket cams you remove the stock decompressor mechanism thats there to make it easier to start. you could try removing your battery and just setting a car battery there with some jump cables to it to see if thats the issue. i guarantee if its gonna start with the battery a car battery will spin it over real fast.

i have a hyabusa battery in my 440 it wouldnt turn over fast enough to fire on a ex battery.

[55stone]

it still has the stock cam... but does the different battery really work?? and does it mount up in the same spot??? and no one thinks its jetting??? it has a filter on it now and the 11:1 and didnt before.. so it has to be off..should i just throw and sparks jet kit in it and go from there??

[F-16Guy]

1)Does it crank over slowly and not start, or does it not turn over at all?

2)If it doesn't crank over at all, do your headlights work while you're holding down the starter button? If so, your battery maybe okay and your starter solenoid may be bad. To test, jump the two big solenoid terminals that have hex nuts using a screwdriver and see if the starter turns over. If it turns over, your soleniod is probably bad.

3)If your headlights don't work at all or they dim or shut off when attempting to start, the battery is dead. Jump-start the quad using a set of cables and a car battery. If it jump starts okay, the starter and solenoid are fine, but the battery, stator, or connections may be bad. Check the ground cable first. Make sure the connection to the subframe is tight and that there is no corrosion on the cable at the terminal ends. If all of the connections are okay, does the quad run fine and stay running until you shut it off? If it does, the stator is fine. The stator is similar to the alternator on a car engine. If it fails, the engine will continue to run off of the battery until the battery's charge is depleted, at which point, the engine will die. If the cables and connections are all good, and the quad starts and will stay running for extended periods, the last likely component is the battery. Replace the battery and ride.

[55stone]

wow awesome info man..really awesome..it cranks over..the head lights will stay on..maybe dim a some.. but once i get it started even with the battery all the way dead to where it wont turn the motor over the quad will still run till i shut it off... so thats leaning towards just a bad battery correct???

[F-16Guy]

Yeah, about 99% sure. Double-check connections, though. If you have a loose or corroded connection, it will act just like a weak battery.

Also, if you have an aftermarket CDI (rev box) that is smaller than the stock box, it's probably a re-labeled XR250 bike CDI. If that's the case, the bike CDI has a circuit that prevents spark below a certain RPM so that the engine won't kick back against the kick starter when you're kicking it over slowly. When that box is installed in a 400ex (especially one with a high compression piston and/or a cam with no decompression mechanism), it can cause a no spark condition if the starter can't turn the engine over above the cutoff RPM. If you do have an aftermarket CDI, try slaving in the stocker and see if it starts okay.


As far as jetting goes, that could be playing a big part, too. With a 11:1 piston and a stock cam, I'd do probably a 42 pilot and a 155-158 main jet. As long as you have the choke on and good gas, it should fire up fairly easily. The battery may be getting weak, but if it will crank for 20-30 seconds worth of cranking time, it should be enough to fire it up. When my quad has been ridden on a fairly regular basis, I can go out and fire it up stone-cold with full choke, a couple of pumps of throttle, and a few seconds of cranking.

[55stone]

ya it will crank over for atleat that long as long as i just pulled it off the charger..well maybe that long but im pretty sure..so its either the battery or jetting..actually its both... my battery is probably weak and i know the jetting is off..thanks for the jetting help???so thats where i should start

[F-16Guy]

Yeah, with just an 11:1 piston and stock everything else, I'd start at a 42 pilot with the fuel screw about 2.5 turns out and a 158 main. If it feels a little sluggish, drop down to a 155 and see if that helps. I think a 158 should be really close, but for about $3 a piece, I'd order a 155, 158, and a 160 to give you some options.

www.jetsrus.com for cheap jets.

[texasman20]

I don't mean to hijack your forum but I am having a similar issue but mine does not turn over at all. I accidently left the key on one night killed the battery so I jumped it and ran it for a while to recharge the battery but it not longer held a charge. I then bought a new battery thinking that was the issue but after I connected the new battery the starter does nothing at all. Even when I try to jump it, nothing. I checked the fuse right there and it was fine. Any ideas?

Also not sure if this maters but I was running it in snow and that's when the issues seemed to start.