2003 400ex needs jetting?

[300exBorg]

I just purchased a 03 400ex this past week. I also have a 300ex and when I start the 300ex I do not need to use the choke or anything. I just turn it over let it idle on its own and it warms itself up. But with my 400ex it likes to stall ONLY when the engine is warming up it seems. Once the engine is nice n warm it'll sit and idle all day. I have to keep the throttle a little bit above idle for it not to stall out. Seems like choking the motor fully does not help BUT half choke does seem to help. What do you guys suggest? I am running some Sea Foam through the gas tomorrow and I am thinking about taking the carb off and having it cleaned since I know the P.O. did not ride it much at all. The engine is completely stock by the way. Should I up the jets at all to help? I have never played with jets before and am not too sure what jets to bump it up to on a stock motor.

[Stickman400]

Most will tell you to bump the main up 1 or 2 sizes since it's jetted lean in stock form. Also install a 42 pilot, that should eliminate the need to use the choke in cold weather.

[TheAwesomehonda]

Well when i start my 05 in cold weather i pump the throttle 5 times to get some gas in the head but if i do that on my 01 it will flood out right away. Then start it up on full choke and stand there and hold the trottle alittle open for about a minute cuz if i don't it stalls like your does. So i don't think there is anything that can be done about it but if you mod it the starting may get better or worse depending on the jetting and stuff. So it just takes some getting used to. It is normal to stand there and hold the throttle open alittle on the 400ex.

[TheAwesomehonda]

Originally posted by Stickman400
Most will tell you to bump the main up 1 or 2 sizes since it's jetted lean in stock form. Also install a 42 pilot, that should eliminate the need to use the choke in cold weather. Yeah your right to the 42 pilot helps even for a stock motor for the cold starting.

[300exBorg]

Thanks for the replies! I think I'm definitely going to try a 40-42 pilot out to see if it'll help aid the cold starting which I'm sure it will. I just got the bike the other day so I plan on going through the whole maintenance section in the manual. So when I got my gas tank off to adjust the valves I'll play with the carb. Where can I get some pilot jets online? Only place I found was rocky mountain but it said they were out of stock until 5-22-12.

[CJM]

www.jetsrus.com

[300exBorg]

Well I went to take off the bowl on the carb today and completely MANGLED the last of the 4 screws holding on the bowl. I can't get to the damn jets without getting this last screw off and there's absolutely no way I'm getting it off with a screw driver. I tried to cut a little slice down the middle and use a flathead but I do not think I did it enough. How can I get this damn screw off? Should I just cut the head of the screw off and replace them with allen head screws? I am just nervous about taking a dremmel to that carb for some reason.

[GAZ-V-21]

Originally posted by 300exBorg
Well I went to take off the bowl on the carb today and completely MANGLED the last of the 4 screws holding on the bowl. I can't get to the damn jets without getting this last screw off and there's absolutely no way I'm getting it off with a screw driver. I tried to cut a little slice down the middle and use a flathead but I do not think I did it enough. How can I get this damn screw off? Should I just cut the head of the screw off and replace them with allen head screws? I am just nervous about taking a dremmel to that carb for some reason. i had same problem yesterday i used a cutting tool on drill and made screw a flathead then sprayed off with cleeaner to make sure no little metal pieces were around worked out perfectly.

[CJM]

Drill it out carefully, the screws are brass.

Then take a trip to home cheapo or lowes and buy replacements with allen heads.

[dxcody]

Before you drill it,

Can you get to it with vise grips to turn it just to break it loose?

Once you break it loose you could turn it the rest of the way out with your fingers.

[300exBorg]

Originally posted by dxcody
Before you drill it,

Can you get to it with vise grips to turn it just to break it loose?

Once you break it loose you could turn it the rest of the way out with your fingers.

That is actually what I was planning on doing. If I can't get it this way then I'm going to use a dremmel to cut a slice in the head and try to use a flathead to get it out. If this does not work either then I will drill it out. My bike does not seem to idle when when it starts until you give it a good riding (running past idle for a good 10 min or so) then it will idle no problem. I am going on a trip to go riding this Friday and really want to straighten this out before I go.

[300exBorg]

Just got back from my garage and was working on my 400 this morning. I was able to get that screw out with some little vice grips thankfully. The pilot jet was pretty much completely clogged up (bike sat for who knows how long before I purchased it). I wanted to adjust the valves while I had the tank off but I could not find a metric socket big enough to fit the valve covers! I am willing to bet the valves have not been adjusted in a long time if the carb was like that. My buddy told me to not even worry about the valves if I do not hear them "ticking". What do you guys think about this? Should I take the plastics off again and purchase a 24mm socket (i think that's the size i need for the covers at least) and check the valves?

[chevymanrick]

It would be a good idea to check them especially if your riding for a long period of time, but you need a socket I just use a set of channel locks, the valve covers aren't on very tight they have o rings under them, just put a little oil on the o rings when u put them back on.

[chevymanrick]

Oops sorry, you don't need a socket*

[chevymanrick]

O and they all tick, its normal unless you've upgraded the timing chain, some tick louder than other especially with a larger cam, cjm will tell u!

[CJM]

They all tick, some worse than others. Mine with the stage 2 hotcam sounds like a damn sewing machine.

The large caps are a 24mm socket, or just use a large adjustable wrench. Most are on VERY tight b/c no one has ever bothered to adjust the valves since day 1.

[300exBorg]

Well I should be riding for a good amount of this weekend so maybe it is a good idea that I check those valves. I don't hear any "abnormal" sounds in the top end but I would like to do it just for the peace of mind. I am pretty sure that these covers have NEVER been off (bike was completely stock and owner used it to go down to his local lake and go fishing LOL). Other than that it just sat in his garage. I wish I had some of those feeler gauges that had the curve at the end of them to make this so much more easy. I am afraid I will break one off in the valves and it gets stuck in there.

I do have one question about adjusting them. I have never done this before so how do I know when there is enough "drag" on the gauge? Do you basically just want it to have a little bit of resistance when pulling the gauge out? Also any tips/tricks to doing this would be greatly appreciated! Thanks everyone!!!!

[chevymanrick]

Yea just slight drag on your feeler gauge, I just bought a set of feeler gauges from the local auto parts store, and the metal is thin enough you can bend it to a 45 degree angle to check clearances I mean kt never even tried breaking, I'm sure if you tried to bend it in half it will snap but just slightly bend it till u get the curvature you need to get it.

[TheAwesomehonda]

My 01 that i just put the new chain in doesn't tick noticeable but like CJM that hot cam has a loud tick to it but my 01 was so bad before i put on the new cam that i was alot louder then a hot cam so i knew it needed a new cam chain. For the valve clearance i like to have quiet a bit of drag b/c i think they tick alittle less if you gap is alittle smaller so i like to make sure they are good and tight on the feeler.

[CJM]

WARNING: Too tight and you can bend/break a valve, better to be looser.

[300exBorg]

Originally posted by CJM
WARNING: Too tight and you can bend/break a valve, better to be looser.

HAHA I was just going to ask if there are any negative effects of having them TOO tight!. Looks like you just cleared that up for me though. I am going to grab a 24mm socket for these covers on Thursday and adjust them. I already have the gauges so I just need this damn socket. I swear I've taken these plastics off so many times in the past week. Thankfully they're wicked easy to put on and off but I just worry about wearing out the clips from so much on and off.

[300exBorg]

Oh and guys I have a quick question. Would an 2005+ bottom end (want reverse) work on my 03 top end? Just curious since this is the absolute ONLY thing I miss about my other bike.

[CJM]

Yep, will work no problem. Every engine up until 2008 is pretty much the same. 2008 has slightly different engine parts-so far it is known the cam has no decompression mechanism.

2005-2007 had slightly different gearing in the transmissions and different sprockets. 14/39 (05+), 99-04 is 15/38.

[300exBorg]

awesome I'm hoping to be able to score some 05-06 plastics down the line so I don't have to "rig" a hole in them for reverse. I've got a chance to grab a bottom end from a 06 for a decent price and it would be nice to have reverse. I would just keep my 03 bottom end as a spare I guess.

[300exBorg]

I never got a chance to adjust my damn valves. I just got back from my trip last night and I ended up getting hurt pretty badly. Went up a hill that I guess was too steep and my 400 flipped backwards and landed on my left leg when I was on the ground. Thankfully my helmet saved me from getting knocked out also since I wacked my head on a big rock. This actually happened the FIRST day I got to the mountains so I did not ride much at all. Anyways, back on topic would the valves cause the bike not to idle well when cold or hesitate to start? Just wondering if this could be part of the idle when cold issue. I see other 400's idling after a good 5 minutes of holding the throttle a little but on mine you literally have to start it up hold the throttle a little open for a few minutes then go out for a little ride to get her really warmed up for the bike to be able to sit and idle. Like I said I am going to up the pilot and main jet. The bike is COMPLETELY stock except for a K&N air filter on it so I am not too sure how far to go up. I do plan on putting a new exhaust system on it also in the near future so I will probably grab a bunch of jets once I get some suggestions on what sizes to use right now.

[Drfat400ex]

If you're going to bump the main just for a K&N it's probably going to put you at a 150 but grab a 152 also just to be safe.