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slow idle return on 07 450 EXC

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so i find that when i throttle up hard and let off the engine rpms tend to let down really slow. when going straight and fast this isn't an issue, but riding in the woods i prefer to engine brake. having the rpms hang up causes a lot more clutch work and tends to push me farther into the corners. background; has jd jet installed all smog gone. i love the bike, but this hanging idle makes me a lot slower than my little klx 250. any advice would be great.

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check cable routing and throttle tube to be sure all is right. The 2nd cable is a known issue for this problem. I removed my close cable long ago on all my 4st.

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Pilot circuit in the carb will do a similar thing. If it gets gummed up and is not passing enough gas, you may get a run-on idle. I take all the brass out of my carb twice a year and soak in carb cleaner overnight to really get them clean. Also try adjusting the pilot screw out and see if that helps.

Cheers,

MrHix

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check cable routing and throttle tube to be sure all is right. The 2nd cable is a known issue for this problem. I removed my close cable long ago on all my 4st.

I've not had it happen personally but some have mentioned problems with the cables fraying at the carb end of the cable where it enters the housing.

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its all new brass, just installed JD jet, the KTM (k2) kit was in it, that one sucks by the way. the hanging idle is why i decided to buy the jd jet kit in the first place. i'll check my cables. i did notice there is no play at the grip, so that could be the issue. i have noticed an increase in rpms when bar turned full right. thanks for the advice

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Even though all the jets are clean, make sure the holes they feed in the carb are clean as well. Also, make sure you don't have an air leak around the Carb on the engine side.

Good luck...

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check cable routing and throttle tube to be sure all is right. The 2nd cable is a known issue for this problem. I removed my close cable long ago on all my 4st.

I just put my return cable back on and now have the same issue. 08 450 exc-r:banghead:

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I have had it personally.

frayedthrottlecable-1.jpg

I've not had it happen personally but some have mentioned problems with the cables fraying at the carb end of the cable where it enters the housing.

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Make sure your throttle cables are running above the knob that the gas tank sits on as this will put tension on the cables if they're below the knob.

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thanks guys, i ordered a motion pro cable that should be here tuesday, its supposed to be 3" longer than stock (thats what she said anyway :bonk:) i'm gonna work through each of your suggestions one at a time till it goes away. i'll report back after i get the cable installed with my findings so hopefully this thread will help the next guy.

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thanks guys, i'm gonna work through each of your suggestions one at a time till it goes away. i'll report back after i get the cable installed with my findings so hopefully this thread will help the next guy.

Bump

Where's our promised update? ;)

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Bump

Where's our promised update? ;)

With 17 total posts, the last being over a year ago I don't think the OPer is around here much!

Bruce

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It is the accelerator pump causing the issue for the OP. He needs to install the honda diagram or the spacer from latest JD jetting kits.

The accelerator pump is squirting too long for his operating conditions (altitude, temp, riding style, etc...) and the engine needs to burn off the extra fuel to return to normal idle.

Edited by dot_bob

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Sorry, BDM is right I'm not around much, it's a "I don't have a computer" thing. So for the accelerator pump, yes the JD jet kit did have the li'l spacer to reduce the squirt. No effect other than cleaner acceleration. I've tried every throttle cable configuration and ended up with single pull only. Which seemed to limit it the most. What I have found at this point is that the hanging idle is random so it points toward the throttle cable. I have since installed the acerbis super tanker 6.6 which required a reroute of the throttle cable and that seemed to help the most, though it will still randomly have a hanging idle. I have the top end torn apart right now so as I go back together I'm going to go back to push/pull cable set up and really play with it to minimize the effect of turning the bars on pulling the throttle open. Thank you all for your suggestions, it's been extremely helpful. Oh I almost forgot to mention the running WR sitting next to the Ktm. It's a shame the KTM is such a PITA though I may keep it for my long trips. I haven't decided yet.

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Sorry, BDM is right I'm not around much, it's a "I don't have a computer" thing. So for the accelerator pump, yes the JD jet kit did have the li'l spacer to reduce the squirt. No effect other than cleaner acceleration. I've tried every throttle cable configuration and ended up with single pull only. Which seemed to limit it the most. What I have found at this point is that the hanging idle is random so it points toward the throttle cable. I have since installed the acerbis super tanker 6.6 which required a reroute of the throttle cable and that seemed to help the most, though it will still randomly have a hanging idle. I have the top end torn apart right now so as I go back together I'm going to go back to push/pull cable set up and really play with it to minimize the effect of turning the bars on pulling the throttle open. Thank you all for your suggestions, it's been extremely helpful. Oh I almost forgot to mention the running WR sitting next to the Ktm. It's a shame the KTM is such a PITA though I may keep it for my long trips. I haven't decided yet.

FYI Motion Pro makes throttle cables that are two inches longer. I installed one of there cables on my 450 XC-W since I'm running a 3.4 gallon tank and a gpr under bar stabilizer. Made all the difference in the world.

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Pull the slide out of the carb and check the seal on the vacuum release plate. A worn seal will cause a hanging idle. A new seal is about 15$ from KTMWorld, a seal and plate about 60$ from HondaParts.

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