starting problems on a 2007 400ex

[kcliff]

I bought my quad used(2007) but I am pretty sure nothing was done to it. Whenever I try and start it(choked and 3 blips of the throttle), it will turn over run a sec die hitting it again 3 times doing the same and then it will run for 8-10 sec and die. I will try again it will run I will give it a little gas(i also take choke off at this time) (barely putting pressure on throttle) and it will run again and die all of the sudden, and it wont start again till after about 20 hits of the starter button. If I get it to run for 10 sec I will take off slowly and run it a little and then it starts fine all day, but the beginning is ridiculous! I have a 42 pilot jet on the way with spark plug tool I will look at plug and replace if needed and also change pilot-duh but I would like to know is this normal? I had a 1996 pos blaster that would run at idle easy and it would also start first kick all most every time. WTF? thanks for any insight.

[hornetgod13]

How cold is it where you are? Have you checked/cleaned the air filter lately? A 40K or 42K jet might help you. If you still have your air box lid on and a stock exhaust than a 42K might be too big. Another thing to do is bump your idle up a bit. The stock setting on the idle is a tad low. Mine wouldn't even idle until it was warm until I adjusted the idle setting.
As a test, try to take your air box lid off and see how it starts/runs cold.

[kcliff]

hey thanks for the quick reply, I figured you would try and help. i am in South texas and it is about 60-75 right now. The filter is clean. I got the 42 pilot because I plan on getting a HMF slip on and a K&N with Outer wear and that lid you have as well. thanks I will try with the cover off. I went out again (shouldnt have because it pissed me off again lol) and I would hit the starter engine would sound like it was gonna run and die every time I tried to start it. i have a dumb question and I have told myself not to ask but oh well for my 400ex's sake, The stock filter- Does it need to be sprayed with a special oil, or just blown out with an air compressor? thanks hornet

[04exking]

I wash mine with soapy water and then oil it with the uni foam air filter oil. So I believe that you do have to oil it. Try checking the idle and the jetting for sure. I don't have a clue why but for some reason people think by just putting a bigger jet in your carbureator make you go faster. What they don't undersstand is how to jet it properly so they get the most out of their engine. They just suspect the bigger the better.

[hornetgod13]

Originally posted by kcliff
hey thanks for the quick reply, I figured you would try and help. thanks hornet

Glad to help. I learned the hard way on my jetting. It was all trial and error until I got it right. If I can help anyone else out than the time I spent will be even more worth it.
Sounds like your mods will be close to mine once you get the EHS Racing lid and Slip-on. One thing to note is you won't need the Outerwears on the filter if you install the Racing Lid, it has Outerwears built into it. I attached a sample picture of a lid so you can see. This picture is not off a 400EX. I only post it so you get an idea what the lid looks like.
The filter DOES need oiled after you clean it. The special filter oil is designed to repel water and trap dust. Be certain not to over-oil it or it will restrict air flow to the carb.

[JDMThoughts]

I had issues with starting and it turned out to be a bad spark plug boot, the wire inside was shot. I have similiar issues with my quad with crappy starting, but I live in the northeast and I haven't seen 70 degree weather in like 5 months. The factory manuals suggests soaking filter in a non-flammable but flash like substance like kerosene. Let air dry then oil filter before re-install. A personal note of interest is to stay away from K&N filters, they are terrible, their filtration sucks, and they are a really big hassle to clean. I was about to get my quad to do better with starting by adjusting the idle screw, now I don't even choke it and it starts up.

[kcliff]

ok, the air filter, What oil do I use and is it the same oil for all filters? I am seeing a trend and I guess I will stay clear from the K&N and stick with UNI. I dont know what type of oil to use though. thanks

[troutman561]

Also try not to use the choke when its warmer out because it shouldnt be needed. I dunno if that was any part of the problem tho but just a suggestion...

[hornetgod13]

I use a UNI filter and I couldn't be happier that I did. It's easy to clean and maintain and it cost less than $25.00 to purchase. Don't buy the filter spray cleaner all you'll need is a good degreasing dish soap and water to clean it. Any spray foam filter oil will work it doesn't have to carry the UNI brand name. Check www.rockymountain.com for the UNI filter and filter oil.

[kcliff]

ok thanks, I will be sure and post when I get that thing going. It starts and all tht but I hate that I have to jump on it real quick and ride it so It will stay running, I cant wait to be able to hit the button and it just sit there and idle, I appreciate all the help

[79400ex]

That's a 400ex for you. It needs to be rejetted and that should fix it. I have several 400ex and they were very cold blooded intil I had them rejetted. Now they start with very little trouble when cold.

[kcliff]

thats what i keep hearing, but a frickin 2007 with no mods and stock it seems outrageous to be that hard to start. oh well i am gonna replace the spark plug and pilot jet when i get the tool and then I will get the other stuff later. the filter seems ok because it still bright yellow and has a oily residue on the filter.