Jump to content

2003 DRZ 400 Jetting on Stock FCR

Recommended Posts

Fuel was dumping out of the bottom when you would leave the valve on so I decided it was time for a rebuild. This bike is new to me and I have no idea what has been done to the carb. But when I had it apart I looked up all the jet size and it looks like it is all stock. The only thing we noticed when we had it off was that the accelerator pump seamed to be stuck and that the fuel screw was out almost 4 turns.

Took apart the carb cleaned it and replaced the float valve and o-ring and all the vent hoses (dry rotted) put it back on went 3 turns out on the fuel screw because the accelerator pump was froze and 4 turns is a lot and when its running at low idle and you crack the throttle it will bog and die. So I turned in the fuel screw to 2 turns. same thing. I now moved it back to where it was when we originally took it apart and still bogging and dying. its happening at 0-1/4 throttle. Once you have the RPMs when you are riding it works fine but that off the bottom bog is driving me nuts.

What are you guys using for stock jetting. I am in southern Indiana approx. 400 elevation.

Share this post


Link to post
Share on other sites

Did you get the accelerator pump working?  Have you visually tested it to make sure its working? It sounds like that is your problem.

Share this post


Link to post
Share on other sites

Yes the accelerator pump seems to be working by looking at it on the outside now. It moves now when the throttle moves where it didn't before.

Share this post


Link to post
Share on other sites

I do have a Uni Filter on it now. But when I rode it before the rebuild the uni filer was on it then too and it did not bog like it is now. It does have the stock exhaust on it.

Share this post


Link to post
Share on other sites

You need to pull the air boot out of the way, and operate the throttle to wide open quickly.  You should see a stream of gas spray into the engine from the brass nozzle in the carb bore.  It sounds like that is your problem.  It appearing to work on the outside isn't good enough... you have to check for that shot of fuel.  It should be a strong shot, not just fuel leaking out

Share this post


Link to post
Share on other sites

Ok I just want to be clear. Remove the boot between the carb and the air cleaner. Operate the throttle to full throttle quickly and inspect the brass nozzle in the carb bore to make sure it's dumping plenty of gas. Will this squirt out into my face? Just want to make sure before I stick my head down there and get an eye full of fuel. Hahaha

Share this post


Link to post
Share on other sites

Yep that's all correct.  Except you'e in the clear... it should shoot gas right into the engine lol.  And the stream of fuel should just barely miss the slide as it rises.  

Both of my FCR carbs, slant on LTZ-400 and the MX on my DRZ, shoot a strong stream of fuel directly into the engine.  The stream doesn't hit the walls or 'floor' of the carb or intake manifold at all.  

  • Like 2

Share this post


Link to post
Share on other sites

matt750 Thanks for the help.

Took the boot off last night and was getting very very little fuel from the brass nozzle.

When my buddy helped me rebuild the carb he noticed on the part fiche file that the spring was on top of the diaphragm and didn't think this was right so he put it on the bottom. For some reason I was not getting good throttle response when the spring was in the bottom (which was correct) so he thought maybe the drawing was correct so we switched the spring back like the draw showed. After doing a little digging we found that the part fiche was not correct so we switched it back to right and ground the pin off at the bottom of the diaphragm and it works great!!! I could actually hear the fuel going into the cylinder when we put it back on.

Capture.JPG

  • Like 1

Share this post


Link to post
Share on other sites

The diaphragm number 46 on the bottom the pin is longer so that it stops on the bottom of the bowl number 45. I ground it flush so that it will open further squirting more fuel in. Found it on here some where. I'm going to order another diaphragm just to have one because it could wear out fast due to more movement.

Share this post


Link to post
Share on other sites

Hmmmm - Interesting - I have a bog when I stab the throttle  . . . . . . did you do that mod where you wired the AP arm to the throttle linkage too? I think the grinding the diaphram may have been part of that mod . . . .     

Share this post


Link to post
Share on other sites

No from what I was told this style you can't do that to. It's a 2003 FCR which I guess is different??? My buddy is my Carb Go To Guy and he was going to do the mod but said on the version I have it can't be done.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×