Carb Removal

I'm currently removing the carb from my 2007 wr450 I've got to the stage where everything (shock etc) is out the way and I need to disconnect the throttle cables etc.


I remember reading somewhere that there is something to do with the throttle or linkages that you should not adjust otherwise it is a nightmare to reset, but can't find the post. Can someone explain to me how I can easily and safely disconnect the two throttle cables and hot start and anything else needed to get it off.



After you have removed the two engine braces above the carb, remove the black throttle wheel cover, and slip out the cables.

Do not remove the throttle wheel from the carb. It will mess up the physical position of the slide.

Do not remove the TPS from the carb, just uplug it at the harness. If you remove  it from the carb body, you will have to re-calibrate it.


That's it.


Replace your hot start nut with a ZipTy racing aluminum nut, and inspect the fuel inlet, hot start, and choke plunger o-rings, and lube them all up, since you are in there.

It's the TPS that you don't want to have to reset. Disconnect it at the harness connector and leave it bolted to the carb.

The throttle cables are the easiest to work with if you disconnect them at the throttle tube first.

Thanks for the replies I have now managed to get the carb off. It has been quite a mission to get it off.


1. I have tried to read up on all the mods and jetting etc but I'm just going round in circles with it all. I opted for the JD jetting kit and am now wondering how to proceed. I am almost at sea level here in the UK and it is currently below 50F temp. The instructions say that you can/may use the blue needle. However, I really don't want to have to strip the whole bike down again to change the needle as soon as it gets a bit warmer.


Can I use the red needle and get away with it all year round. I'm not doing much riding and its not really competition stuff, or would I really benefit from using the blue needle now while it is still colder?


2. I am going to clean the carb tomorrow on the outside before taking it apart and checking the jets. The jets are currently standard though. I don't know whether I should be putting the 48# pilot jet in or whether to keep the standard jet. I know it says that it depends on how many turns the fuel screw needs but again I really don't want to put it back together and find that I need to strip it all down to get to the pilot jet again. Which would you recommend is safer to put in to try with my new JD needle and main?


3. I am in the UK so can't get the ZipTy fuel screw. I have never really done much adjusting of fuel screws and find the issue quite daunting. I can get an RFX fuel screw which seems similar to the ZipTy screw. Is it worth getting one or can you adjust the standard fuel screw while the bike is back together?

Just to clarify it was your guys help beforehand that made me to get the carb off. Sorry for the many questions I'm just trying to learn as much as possible and get things right.


I have looked at the jets now and to my surprise there is a 170 main and 50 pilot jet in there. I was very surprised as the bike seems so stock. I am therefore going to put the JD 48 pilot jet in and the JD 168 main.


I'm still undecided about the Red or Blue needle though...any thoughts?

All the fuel screws function the same I think, it's just that they have  along knurled handle so you can adjust them. I'd go with the JD recommendations, you can always change it later. next time believe me it will be a lot easier. It's the main jet that's really sensitive to changes in temp, the needle less so. It's cut is optimized but I don't think it would make your bike unrideable if it's not correct. All bikes run super lean from the factory, somebody (maybe a dealer even) might have thrown in the larger pilot jet maybe?

When buying an extended fuel screw for FCR's, choose one with a tip the most like the OEM screw.  Some of them are shaped rather oddly and don't trim the fuel mix as well as others do.

Thanks very much.

In the UK, I beleive you can easily get a Steahlys fuel screw. It is stainless I think. Allens carries it too, if memory serves. Just avoid alloy (aluminum) fuel scres.

In the UK, I beleive you can easily get a Steahlys fuel screw. It is stainless I think. Allens carries it too, if memory serves. Just avoid alloy (aluminum) fuel scres.


In spite of the fact that I do agree that brass is a better choice, I haven't had any trouble with the aluminum screws I've used from Zip-Ty.  Just remember to use the OEM spring instead of the one provided with it.

That is a nice part. I like the oring on the shaft to assist in holding the setting and keeping mud out. Nice!

I guess they should be just as easy to get in the states, if you don't make mind putting a KTM part on your bike!

The KTM part number is listed in that link; 590 310 173 00

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