WRF won't run

[bentbarz]

Heres the deal.

Raced an Enduro, at the end the bike was running great. I tweaked a radiator, but not bad (thanks Devol). I have all the free mods, YZ timing and jetting is 178 main, 42 PJ, 105 LJ and the rest I have not changed. The needle is stock in I think pos#4. PS at 1 turn.

Two weeks later I had the tank and shrouds off to install a graphics kit. While it was accessable I decided to remove and clean the carb. I have had problems with the rpm hanging if it is set so that the bike will actually idle. This did not bother me as I simply set the idle down like you would a 2 smoke. I removed all jets and sprayed the orifices with carb cleaner then blew them out with 30 PSI air.

At first I could not get it to start at all. I took the carb back apart and double checked that everything was assembled correctly and tried again, no dice. I tried all the starting variations, cold, hot, prime etc. Finally I backed teh PS out to two turns and pulled the choke and it came to life with the idle set high. As soon as the choke goes off it dies even with the idle set high. I can get it started, remove the choke and keep it running with the throttle as long as I keep it above about 1/8th throttle. It does pop on closing the throttle. At this point I am convinced that there is something clogged in the pilot circuit. I once agian disassembled and cleaned the low speed circuits. I did notice the LJ appeared to have something in it, which I was able to blow out. I also cleaned the choke and hot start to be sure there was nothing allowing extra air in. I still have the same running condition. I did try taking the PS to 2.5 and 1.5 turns with no effect.

I am wondering if I have a nuetral sensor, or possibly a TPS problem. I have not yet thrown a meter on them. I still believe it has to be related to my carb cleaning. Also, when I had the carb off the first time I found that there was a screw missing from the pump, which I replaced. It is an '01 right at a year old well maintained with probably 150 hrs.

I did check the valves and they are still well within spec'.

So, where do I look next?

 

[Mathew]

I assume you have changed the spark plug? I sounds like it is fouled to me.

 

[bentbarz]

The plug has been changed.

 

[ACS]

I think its a blocked pilot jet or passage. Your problem with the idle being uneven or "hanging "relates to the pilot jet being off a bit. Probably lean but 42 is about right. The PS or is that fuel screw generally needs to be at least 1 2/2 to 2 1/2 turns out. You need to set up the fuel screw and pilot to get them to start easy and idle properly which is a very fast idle if you are used to other bikes. As it will idle at 1/8 throttle the problem since the clean out it most likely would be in the pilot jet area. TPS seems relevant at wider throttle settings and the neutral sensor is to stop over rev in neutral. Try riding with it disconnected. Some bikes run a lot better, others seem the same.

 

[webbrace]

I would also go with a pluged pilot circut. Replace the pilot jet, and check the hole that the jet screws up into. Do not blow air up it, try to blow it back down and see if you get any crud out.

 

[Sage]

make sure you didn't snap the end of the fuel screw off in the carb body when you "lightly" seated prior to setting it 2.5 turns out. I f you have cleaned the pilot jet 2-3 times now it should be clean or you've got the wrong jet in your hand?

 

[bentbarz]

The fuel screw is not broke off. I know that I did have the correct jet in hand, but I am still not confident that I am getting the pilot circuit clean. I am going to take the carb to the shop, they advise me that they have some stuff that they will soak it in that should for sure get it clean. I am wondering of my can of Gunk and compressed air just isn't doing the trick.

Thanks for the input, keep trying.

 

[smarttoys]

Did you remove the fuel screw when you were blowing through the passages? It would be hard to get the pilot passages in the carb completely clean with the fuel screw in place. Be carefull that you don't lose the tiny washer and o-ring under the fuel screw when removing and blowing through the passages.

 

[bentbarz]

I did remove the fuel screw for cleaning, and was careful to replace the oring and washer.

 

[BikeDstroyer]

bentbarz,

Did you by chance take the slide out while cleaning your carb. I've heard of a few people doing this and accidently putting it in upside down...very easy to do. This caused their bike to run like crap.

 

[bentbarz]

I did take the slide out, but did not remove the needle from it, so I don't see how I could get it in upside down. Or, by upside down to you mean turing 180 with the needle still down? If this is physically possible I could have done it. I do remember that there is a plate that comes of the lide and that is towards cylinder side of the bike. I plan to tear back into it Fri afternoon, I will definately check that. Thanks for the hint.

 

[XR400RMan]

I also have a problem with my 1991 Honda XR250R's throttle hanging, I can be at an idle and blip the throttle and I will have the throttle closed all the way and where ever I let off the throttle the RPMs will hang there and then finally start dropping back down, What is wrong? Is the pilot jet being off a bit like mentioned above? Thanks Matt