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PettyRage

2001 400EX Crank No Start When Cold

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So the past two times I've gone out riding, my 400, for the life of it, won't start cold. It'll crank until the battery drains completely without ever starting. Choke on or off, it doesn't make a difference. If I give a little throttle, it'll crank faster and maybe backfire. I've also noticed my choke doesn't seem to do anything regardless, idle doesn't change etc. This past time we went riding, I had to have another rider pull me so I could roll start it in 2nd gear. It fired up and idled fine after that. It also starts without issue once it has run for a minute or two. It only started doing this recently, now that the weather is cooling down. Is there something I should be adjusting, or maybe just a carb cleaning?

Edited by PettyRage

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I'm not sport guy... so I'd check with slammedranger ... he's (IMO) the best sport Honda guy we have. 

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Hey PettyRage. From what u are saying it will fire up jump start but not electric? Once warms fires rite up? If that’s the case it sounds like your pilot jet to me.. or possibly weak battery, but u say it will crank till it dies.  u say it just started to do this and had recently just got colder. Once running have u tried to adjust the fuel screw? Did the choke work before? 
 

sorry I k ow I sound all over the place, but I’m thinking as I type.. I personally would pull the carb, clean it, see what jets u have in it & go from there. 

Edited by Wheeler
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First thing you will want to check is if it is actually turning the crank and not just free spinning. This would indicate a slipping starter clutch. Which i have had them only slip when cold before. Best way to check is for pulse at the exhaust tip. You should feel air pulsing out it as it turns over. If you check that and its good i would next pull the carb and make sure it has a 42 pilot jet in it. Stock is 38 and will make them impossible to start when it gets cold out.(and choke make no difference). The 42 IMO should have been the jet they came with out of the box. But emissions regulations made them jet lean. If you have pulse and a 42 pilot jet i would next go through the whole carb and clean it up. Pull the mixture screw and clean the needle tip(count turns from where it is inward to light seat before removal so you can put it right back where it was). Spray carb cleaner through all passages and jets followed by compressed air. If none of this works you could have a stator issue or cdi box problem but those would be long shots.

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5 hours ago, Wheeler said:

Hey PettyRage. From what u are saying it will fire up jump start but not electric? Once warms fires rite up? If that’s the case it sounds like your pilot jet to me.. or possibly weak battery, but u say it will crank till it dies.  u say it just started to do this and had recently just got colder. Once running have u tried to adjust the fuel screw? Did the choke work before? 
 

sorry I k ow I sound all over the place, but I’m thinking as I type.. I personally would pull the carb, clean it, see what jets u have in it & go from there. 

Yes, it will start via roll/bump start, but will just crank when trying to electric start. When it was warm, I'd just turn the key and it would fire right up. The first time it did this, I was able to give it throttle and get it to start, but it took a while. If the fuel screw you are referring to is the one next to the idle screw, it is 2 1/2 turns out from seated. The choke never seemed to do anything.

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2 hours ago, SlammedRanger said:

First thing you will want to check is if it is actually turning the crank and not just free spinning. This would indicate a slipping starter clutch. Which i have had them only slip when cold before. Best way to check is for pulse at the exhaust tip. You should feel air pulsing out it as it turns over. If you check that and its good i would next pull the carb and make sure it has a 42 pilot jet in it. Stock is 38 and will make them impossible to start when it gets cold out.(and choke make no difference). The 42 IMO should have been the jet they came with out of the box. But emissions regulations made them jet lean. If you have pulse and a 42 pilot jet i would next go through the whole carb and clean it up. Pull the mixture screw and clean the needle tip(count turns from where it is inward to light seat before removal so you can put it right back where it was). Spray carb cleaner through all passages and jets followed by compressed air. If none of this works you could have a stator issue or cdi box problem but those would be long shots.

It's cranking the engine over, I can feel the exhaust and you can hear it thumping. I just started stripping the carb, it has a 38 pilot jet it seems. Of course I did fail to mention, if it makes a difference, it has a stage 1 Hotcam and a 416 kit. I also noticed the top lid to the carb was all wavy/warped, letting all sorts of junk into the top of the carb....I assume the mixture screw you're referring to is the same one wheeler had mentioned? The one next to the idle screw? There's one more screw like that on the bottom of the bowl cover, idk what that does.

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Well that’s part of ur issue rite there.. u answered part of the equation with that pic I bet! Get that cover down & sealed!

Edited by Wheeler

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Hmmm that lid looks like someone tried to pry it off with a flat tip screw driver?!?!. With those mods i would be going to a 45 pilot jet. I ran a similar setup at one point and the 45 was money. Honestly the seal at the top is pretty thick i would bet its still sealing good enough. The mixture screw is where this arrow is pointing. Should be flat tip with a spring, o-ring and a small washer on it. Make sure all of that comes out of the hole. It can get stuck down in. The tip will probably be black. It should be shiny brass. Take a 3m pad or steel wool and shine it up nice and bright.

Screenshot_20201025-192302_Chrome.jpg

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While your at it what size main jet is in it? Should be somewhere around 180-190 depending on you elevation compared to sea level. The screw on the bowl at the very bottom is the float bowl drain. It will drain all the gas out of the carb.

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3 minutes ago, SlammedRanger said:

Hmmm that lid looks like someone tried to pry it off with a flat tip screw driver?!?!. With those mods i would be going to a 45 pilot jet. I ran a similar setup at one point and the 45 was money. Honestly the seal at the top is pretty thick i would bet its still sealing good enough. The mixture screw is where this arrow is pointing. Should be flat tip with a spring, o-ring and a small washer on it. Make sure all of that comes out of the hole. It can get stuck down in. The tip will probably be black. It should be shiny brass. Take a 3m pad or steel wool and shine it up nice and bright.

Screenshot_20201025-192302_Chrome.jpg

I'll go and pull that screw out in just a few and see what it looks like. Unfortunately, the gap was too big, there was sand down in the carb from the dunes a couple weekends ago. I hammered it all flat now and will get a new gasket set for the carb. I'll try to hit up a local shop for the jet too.

 

Just now, SlammedRanger said:

While your at it what size main jet is in it? Should be somewhere around 180-190 depending on you elevation compared to sea level. The screw on the bowl at the very bottom is the float bowl drain. It will drain all the gas out of the carb.

 

I haven't pulled the main jet yet, I'll do that now.

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10 minutes ago, SlammedRanger said:

While your at it what size main jet is in it? Should be somewhere around 180-190 depending on you elevation compared to sea level. The screw on the bowl at the very bottom is the float bowl drain. It will drain all the gas out of the carb.

So it looks like a 175 main. The fuel mixture doesn’t look terrible. We ride the dunes which is sea level, but also up in the mountains around 1,500 feet. 

EB5E722F-5F4F-4E0E-A838-F0B3D586A6C6.jpeg

BF24AAC6-A802-4985-8123-B12F5310909A.jpeg

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I would up that to a 180 expecially running in dunes aka "the oven" lol. Mixture screw didnt look bad. How many turns out was it from light seat? And did you get the spring washer and o-ring out?

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Just now, SlammedRanger said:

I would up that to a 180 expecially running in dunes aka "the oven" lol. Mixture screw didnt look bad. How many turns out was it from light seat? And did you get the spring washer and o-ring out?

I'll step that up then. The mixture screw was 3 turns out, and I was able to get everything out, cleaned, and put back in. The carb is all clean and ready to go back together once I get parts. I will call a few local shops and see what's available for jets and new gaskets. I appreciate the help. I'll update once it's all back together.

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3 turns will be probably more than you will need once you put the 45 in. I was running a 416 kit, magnum stage 2 cam. No airbox lid, uni filter, slip-on hmf and i was running a 45 pilot. Mixture at 2 1/4 turns. And a 185 main jet and plug was a perfect light tan. Pull the plug and snap a picture. That will tell us alot. You may even need to step more up. Running dunes is hard on air cooled engines. They will over heat quick!

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So I was able to source a rebuild kit and at least a #42 pilot a few towns over. Got it rebuilt at work today and installed it a few hours ago. It was about 55 degrees outside and it started right up at full choke. I appreciate all the help!

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On 10/25/2020 at 3:23 PM, SlammedRanger said:

First thing you will want to check is if it is actually turning the crank and not just free spinning. This would indicate a slipping starter clutch. Which i have had them only slip when cold before. Best way to check is for pulse at the exhaust tip. You should feel air pulsing out it as it turns over. If you check that and its good i would next pull the carb and make sure it has a 42 pilot jet in it. Stock is 38 and will make them impossible to start when it gets cold out.(and choke make no difference). The 42 IMO should have been the jet they came with out of the box. But emissions regulations made them jet lean. If you have pulse and a 42 pilot jet i would next go through the whole carb and clean it up. Pull the mixture screw and clean the needle tip(count turns from where it is inward to light seat before removal so you can put it right back where it was). Spray carb cleaner through all passages and jets followed by compressed air. If none of this works you could have a stator issue or cdi box problem but those would be long shots.

It is starting to get cold here in missouri and my 400 is not starting as well when it is cold. Would you still recommend the 42 pilot if my quad is stock? 

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37 minutes ago, Dude22573 said:

It is starting to get cold here in missouri and my 400 is not starting as well when it is cold. Would you still recommend the 42 pilot if my quad is stock? 

40 or 42 will work for 100% stock 400ex's. With a 42 you will have to put your mixture screw in further is all. The 40 you will be close to stock setting on mixture screw. Also with the 40 you may still have to use your choke. The 42 makes the choke useless unless you have alot of mods. Internal and external.

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9 minutes ago, SlammedRanger said:

40 or 42 will work for 100% stock 400ex's. With a 42 you will have to put your mixture screw in further is all. The 40 you will be close to stock setting on mixture screw. Also with the 40 you may still have to use your choke. The 42 makes the choke useless unless you have alot of mods. Internal and external.

Do I need to go up a size in the main also? 

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51 minutes ago, Dude22573 said:

Do I need to go up a size in the main also? 


You shouldn’t have to adjust ur main.. I’m sure u be good there. 

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