Hello everyone, I've been lurking the forums for quite a while and a lot of info here has helped me to purchase my first 400SM!  Love it so far, made some minor changes since purchasing and I'm extremely happy with the bike, I've put about 1,200 miles on since buying it not quite 2 months ago   It's my first motorcycle but I'm not new motorsports as I've owned dirt bikes, pit bikes, four and three-wheelers; never-the-less, I'm thrilled to take a bike to the pavement.

Lately I've been noticing a sputter or miss.  It's been a lot hotter and more humid lately so I'm wondering if that has something to do with it, and it wasn't really noticeable right after I bought it.  For motor mods it has a K&N filter, holes drilled in the number plate into airbox (not sure why the previous owner didn't do the 3x3 instead...), Yoshi slip-on, not positive if anything has been done to the carb but I would assume a jet-kit since it runs pretty well besides this latest symptoms.  That's it for motor mods from what I was told and I don't see evidence otherwise.  Also, it's an '05.
It happens only while cruising at a constant speed, usually when I'm holding the throttle steady between just barely open to 1/4 throttle.  For instance, when cruising through town at 30mph in 3rd gear it sputs every few seconds while I hold the throttle steady.  When I open the throttle beyond that the problem disappears.  It doesn't hesitate, surge, or miss under acceleration.  Also, when shifting through the gears (just cruising or hammin' on it) it seems like there is a slight miss JUST as the throttle is opened up after shifting to the next higher gear.  Besides that initial miss off the closed throttle to me twisting it, or around 1/4 throttle-ish cruising, there's nothing.  It does pop on decel a bit as well, but everyone keeps telling me that that's normal.  It's not excessive but it's there, not sure if that matters to know.

So, my best guess would be a pilot jet, but I wanted to hear what you thought.  I planned to tear the carb down and give it a good cleaning this weekend and maybe clean the air filter just for good measure.  Does it sound like a pilot jet issue (maybe needle), or am I over-analyzing things?  Is this normal for this bike?

Thanks for your help!

To me you are describing a rich needle condition...
Drilling side covers without the use of a dyno analysis is usually "hit and miss" when it comes to tuning...
To make tuning easier, I would block the side cover holes and do the 3x3 mod, ....
You really need to check if there is a jet kit installed....An easy check is to remove the top of the carb and inspect the needle...If it's got multi clip positions, it's from a jet kit...if blue or red colour on the needle it's a JD needle..... plain colour = a  Dynojet needle
No clip adjustment grooves, = the stock needle...
You also need to know what main jet and pilot jet you have...
When we have this information and know what air opening size we are dealing with, jetting advice will follow.....

This video may be of some assistance ..

+1......

CraigoDRZ485sm, on 17 July 2012 - 04:41 PM, said:

Thanks for the advice!  I'll dig into things and report back my findings.

Edited by photorider, 18 July 2012 - 06:49 AM.

I dug into a few things today; I don't have a good place to work on it until this weekend so I only did a little bit.

First off, it's about 25 degrees cooler and less humid today and the problem is pretty much non-existent.  I won't say completely gone because now I'm being hypersensitive to symptoms and I'm not sure if anything I noticed tonight was a result of jetting.  Anyway, the steady 1/4 throttle issue is as good as gone, and the hesitation right off closed throttle is pretty much gone as well.  There may still be a slight bit of it but I'm thinking it's carburated and not efi so slight hesitation from closed throttle is normal?  It doesn't sputter intermittently at 1/4 throttle like it did before though, it's acting like it did 3 weeks ago...before it was as hot as the sun...  There might be a slight 'put' in there once in a great while though.

Perhaps the problem was as easy as the heat and humidity, never-the-less I opened it up a little to see what's in it.
First...face palm.... one of the previous owners did indeed do the 3x3 mod.  I'm sure I knew that before but spaced, oh well.  So there's that as well as the holes in the airbox cover.  They did a messy job of it though.
The needle is gold/brass colored, says "OCEMN" stamped on top, has 7 slots, the clip is positioned second from the top...

So yeah, any other thoughts or can I chalk it up to the weather?
I might mess with needle position to see if I can make it better but as of right now I'd say it's pretty good.
Thanks for the help.

OK, cool. (sc) You have a DRZ400SM with a replacement Keiin FCR carb.  Not the original carb.  The FRC is much in demand for performance.  Yes no doubt the carb is jetted too rich for the temp, humidity and altitude.  OCEMN  OC means copper alloy material. EMN is the tuning code.  EMN is quite common but pretty rich.  There are hundreds of needles so it is hard to say what might be better for you.  OBDXP is the stock needle for a DRZ400E.  (OB is aluminum alloy needle and DXP is the tuning code) That would probably work. EMP is also a needle you could try (same taper, same length to the base diameter but leaner just off idle.  Clip position 1 may help a little but a needle change will do more good.  Also need to know pilot jet, pilot air jet, and main jet sizes.  Also you can adjust the fuel mixture screw (under side near the motor)

You might want to post a picture if the carb, there are dozens of FCR carb models all slightly different. Could be an E model carb, an after market kit for the DRZ400 or adapted from another motorcycle.

Yes....We still need to identify which fcr it is....pictures please...

I was not aware that it had an aftermarket carb. I thought some SM models came with Keihin carbs?

http://i3.photobucke...ga/2cb2b483.jpg

http://i3.photobucke...ga/ad503f45.jpg

http://i3.photobucke...ga/9345ba63.jpg

Keihin FCR mx.  Probably adapted from another motorcycle.  That is as close as I can come. Looks good.  I don't see a problem with the install.

Is that a good carb for this bike?  I'm new to these machines and have limited info on the history of the machine.  I wasn't aware the carb was replaced.  Are there modifications that have to be made to get this carb to work?

The 39Fcrmx is perfect for your bike
Ok... for the hot weather ,it does seem you need a leaner needle, but the main jet and pilot jet size do have some effect on the needle setting....
You really need to see what is installed, but you could just try installing the leaner needle....
With the 3x3 mod with open pipe at near sea level ,..
160 main jet..
45 pilot jet...2 turns fuel screw
EMP needle , clip #3
Do the O ring mod with wire....http://www.thumperta...-mx-o-ring-mod/ ...
http://i5.photobucke...ds/DSCN4146.jpg
When the cold weather returns the EMN, clip #3 should work ok..

Edited by CraigoDRZ485sm, 19 July 2012 - 03:16 PM.

Awesome, a mod I'm glad I won't have to buy down the road then
The elevation range I ride in most is between 500-1,500.

I'll crack it open this weekend when I have a better area to work on it; no garage where I'm currently living....
Hopefully things are about where you're specifying.  I think I want to get a different air box cover without holes drilled in it.  I know it'll make a difference in performance, can't be much though... And I'd feel better if I get caught in the rain too.



Not the cleanest cuts I've seen...


Also, one of my buddies is telling me that my head pipe isn't stock.  Can you guys verify for me whether it is stock or aftermarket?







Thanks for all the help so far!

It looks like it has a ceramic coating, possibly a E header?

Anyone else on the header?

Also, where can I buy the different needles for my carb?

Did you measure the diameter of the head pipe?  OD of the S head pipe is 38mm and the E is 41mm

npm, on 20 July 2012 - 07:48 AM, said:

OD is 38mm so must be stock header for my bike.  '05 400SM  Thanks for the info.  I think eventually I'd like to move to a full system.  Either an FMF Powercore/powerbomb combo or RS-2 full system.  Right now it's got an RS-3 slip-on.

I bought the bike used and I'm the 4th owner so I'm learning a lot about it as I go.

So I tore apart the bike over the weekend to do a number of things as well as verify jetting.
While I had everything apart I did the o-ring mod with wire, did I do it right?


Here's what I found in the carb.
Needle: OCEMN, clip positioned second from top
Main: 165
Pilot: 45
Fuel screw: 1/2 turn out
And what's this jet with 85 on it? I'm new to flat slide carbs.


Also, I pulled the plug for reference...


While inspecting the air box I learned someone got drill happy before me...
They were all covered with tape already so they wouldnt affect anything anyway so I left them covered.


These were not covered so I left them open.


Also, I cleaned up the 3x3, idk if it mattered but I wanted it more presentable.



A recap of the motor mods are 39mm FCR, K&N filter, stock header with RS-3 slip on, 3x3 mod with additional holes in air box lid. That's it as far as I know...
After cleaning the carb and reinstalling there is still a little stumble when I goose the throttle. The 1/4 throttle stumble is gone but that was only happening in really high temps.
When the motor is at a higher rpm than idle and I stab the gas it revs fine but when it's at idle and I stab the gas it wants to die, like a lot of other machines I've owned in the past, so is that normal?

After everything my throttle is sticking really badly now, and it didn't before. It matters which way the bars are turned (less sticking when turned right), the spring in the carb works great when nothing is hooked up and I took the throttle housing apart and cleaned it really well. My thought is its the cable, does that sound probable? I really doubt I did anything wrong with the carb. Although, I will say that thing is a b*tch to get in and out of there haha!

All in all it runs alright, could be better though. Would putting the different needle in make a big difference?  Where should I get that? The JD kit?
Thanks for all your help so far! And putting up with my newb questions.

Wire is good...Turn IN the AP timing screw in 1/2 a turn (the screw inside the spring with the green paint...)
The jet with #85 is the starter jet..Spark plug looks old , replace with new....
To adjust your fuel screw setting...
When engine is warm...turn the fuel screw in until the revs drop and then turn out until the idle peaks...you want to be between 1 and 2.5 turns...less than 1 turn you need a smaller pilot jet, more than 2.5 turns you need a larger pilot jet...
An R&D Flex jet remote fuel screw makes tuning the pilot circuit  easier...(available at TT store)http://shop.thumpert...w-p4678896.html
Free revving bog at idle is normal..
Your cable routing may be the cause of your throttle sticking...also You should have both the top engine mounts on the left hand side to allow more clearance for the throttle wheel..
Needles and jets are available from Eddie, Sudco, Jetrus etc.......You don't need a jet kit..
If you had a more free flowing pipe your EMN needle would be fine, but I think you need that EMP with the stock head pipe....

CraigoDRZ485sm, on 23 July 2012 - 02:19 PM, said:

Thanks for responding.
What does turning in the AP timing screw do?
I picked up a new plug today and am going to order a new needle and the R&D flex jet so I'll install all that when everything comes in.
Is the starter jet good with a #85?
You had mentioned earlier going to a 160 main, should I still do that with the EMP needle?
I also plan to replace the airbox lid with one that doesn't have hole drilled in it, will that affect what I should do with the jetting?

I'm also thinking I might order the SSW Single Pull Quick Turn Throttle, any thoughts on that?  I'm not completely sure how I feel about eliminating the return cable.  I'm also unsure if I would like the 1/4 turn throttle...
I'll double check the engine mounts regardless.  I noticed the carb was extremely close to the frame when mounted, looks like it may have even rubbed at some point...

Just to double check, this is the needle I need, right?
http://www.jetsrus.c...017_264_su.html