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Jetting thread # 78934789

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I recently picked up an '07 X, California bike, jetted for the high desert (I think) with only a ride or three on it.

When I picked it up, it ran like @#$&. Way to lean, and it would "hang on" (like a lean condition or air leak---rev/blip it, and it'd stay tach'ed up for a few seconds).

Existing mods:

Dynojet kit (needle, jet)

Boyesen QS

Yosh header & can

Smog block off, smog removal

Idle adj screw, flexible

I have been researching this site for best configurations to start with since it ran so poorly, and I wanted to start from a known good level.

I cleaned the carb, bowl, float needle, seat, Boyesen QS. Assembled it all back correctly.

I removed the DJ kit, and added:

NVCS needle, clip @ 4th position (7 positions, I think. 4th from the top, 4th from the bottom--which is it normally referred to, top or bottom?)

170 Keihin main

148 Keihin pilot

WC fuel screw

These are still on it:

Boyesen QS

Yosh header & can

Smog block off, smog removal

Idle adj screw, flexible

Re-assemled the bike to normal. All air/boots tight.

Now, it runs like @#$&. Way to lean, and it would "hang on" (like a lean condition or air leak---rev/blip it, and it'd stay tach'ed up for a few seconds). Yep. Same as when I picked it up. I just took it down the alley and around the block, and the idle is all over the place--shifting into 3rd with no throttle is almost a wheelie. I turn down the adjustable idle screw, but it still idles and/or revs like it can't make up its mind. Unrideable, to say the least.

I'm stumped, and I need Higher Help. 🙂

Anything sound familiar? Ideas of where to get in over my head next? :D (I'm comfortable working on bikes, etc.---just lost on this one!)

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Where is the fuel screw setting at?

If there is something wrong with the fuel screw, missing an O-ring or spring or washer, that would cause the hanging idle.

If the hot start is hung up, that would cause it.

Has the carb ever been apart to the point where the slide has been removed? If the slide plate were installed upside down, that would cause it.

The jetting sounds perfect for the desert, there is just something causing a vacuum loss in the carb.

I set the WC fuel screw to the instruction-recommended 1 1/4 turns out initially, but played with it ( also per the instructions) for best idle.

The factory spring, washer, O-ring are intact, and installed in order.

The hot start lever does move the cable; however, I have not ascertained what actually happens at the carb when the HS lever is pulled in.

I'll also pull the carb, and verify the slide plate positioning.

Thanks for the clues---I'll check them out, and report back. 🙂

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Where is the fuel screw setting at?

If there is something wrong with the fuel screw, missing an O-ring or spring or washer, that would cause the hanging idle.

If the hot start is hung up, that would cause it.

Has the carb ever been apart to the point where the slide has been removed? If the slide plate were installed upside down, that would cause it.

The jetting sounds perfect for the desert, there is just something causing a vacuum loss in the carb.

Fuel screw is a WC. Sequence is o-ring on top, then washer, then spring.

Hot start checks out---cable is adjusted well, has some adequate freeplay, and I can see th plunger/valve in the carb actuate when I use the lever.

Slide plate is installed with the hole down.

I changed the pilot to a 45 (from a 48) and the main from a 170 to a 165. All new jets. Moved the NVCS needle's clip to the 3rd position (3rd from the top).

Made sure the slide returns all the way down, and the throttle cable has a slight amount of freeplay at idle position.

Bike ran a little better, but not much. Just when you think it might be getting close to being OK, take it fore a short ride, and it is still having the hanging high idle, popping.

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OK, updates:

  • Unplugging the TPS proved that it was not the culprit, or at least not the sole culprit. Bike still did not idle well, rev well, or respond to throttle input well at all. Very discouraging at this point.
  • Had a come-to-Jesus meeting with myself, and realized this would not be a quick fix, and would require methodical and patient steps to get to where I wanted the bike to be.
  • Pull the sideplates, tank, raised the subframe, and got to disassembly, mostly per the .pdf manual, some by seat of the pants.
  • Pulled the carb per the manual
  • Disassembled the carb entirely (I disassembled the whole carb-- 3 pieces--venturi body, midsection, and bowl), and used an egg carton for organization. If you do this, do not use a foam one. Foam, rubber carb parts, bad gas, and Gumout carb cleaner do not mix well, even if parts are dried with an air hose before placing them into the foam carton. Accel pump diaphragm and float both tried to become one with the foam.
  • Cleaned the entire carb---all removeable pieces, jets, sections, orifices, capillaries, etc. with Gumout carb cleaner, an old toothbrush, Q-Tips, and an airhose and left overnight.
  • Rebuilt carb with new 170 Main, 148 Pilot, NVCS needle, original Starter jet, original Accelerator Nozzle, original air jet.
  • Works Connection fuel screw at 1.5 turns out
  • Lubed the idle adjustment screw with marine grease. It no longer twists half a turn, then snaps back. Now it is smooth, like buttah. Minute changes are easily attained with zero effort.
  • Went to the hardware store and bought stainless steel hex head fasteners for the slide lever/retainer (1 screw to replace the security Torx bit), midsection-to-venturi body (2 small, and 4 medium screws), accelerator pump cover (3 screws), TPS sensor (1 screw to replace the CA-issue security screw), bowl (4 screws), slide chamber cover (2 screws). Flat washers and split washers in stainless as well to match as closely as possible the factory dimensions. Blue Loctite on all fasteners, especially the slide lever/retainer.
  • Re-install carb on bike, but leave subframe in the up position.
  • Adjust the TPS per the manual, and in TT Thread # 469401. Mine I set to finally read 588 Ω, as the .pdf formula showed on mine as (4.53KΩ x .13 = 588Ω)
  • Hook up my homemade, yet bodacious gravity-fed gas tank fashioned out of a plastic Ragu jar (metal/rubber lid seal like on a Mason jar) and some plastic tubing.
  • Fill jar, suspend above engine level to prime the carb.
  • Pull choke out, pull in clutch lever, hit the Happy Button.
  • Bike revs to life, and is quickly coaxed into a smooth idle.
  • Blipping the throttle, the bike is very responsive, and rapidly settles to a smooth idle
  • Buttoned up the rest of the bike, and went around the block. No issues.
  • Hit the trails this w-end, and could not find one performance glitch anywhere in the rev range.
  • Bike is hot and heavy off idle, revs quickly and powerfully, and runs WOT as a bike should.
  • Now, my buddy wants one. 👍 (But, I want a 650R like he's got, so it's all good)

Cost for stainless fasteners was about $15. Easy choice for me as Keihin recommends these be disassembled each season, and cleaned. All I need is my Allen wrench set--no oddball security bits anymore, and no more cussfests after stripping heads on the God-forsaken Phillips factory fasteners.

This w-end, I also took my CR500, and while the 450X can't match the overall hit, I can tell it is going to be one hell of a fun and worthy bike. I venture to guess it will be the best and most fun bike I'll ever own.

All I need to do is get on with the suspension tweaking.

Some pics are below:

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Excellent! Glad it worked out for you. It gives me hope as my leftover 07 X is doing the same exact things. Both my 02 and 03 R's always ran fine, except for valves.

So it sounds like the combination of cleaning and adjusting the tps did the trick?

Thanks for the write up and pics.

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Thanks AS...I hope it can help others who are in a similar situation.

These are tricky carbs, but once into them, they make sense, and a level of familiarity comes out of it that helps the owner make a molehill out of the apparent mountain.

trail_racer...it was definitely a combination as the bike ran a little better with out the TPS (2D mode vs 3D with the TPS on-line), but it takes both to be right. I feel that the complete disassembly and thorough cleaning is a worthwhile endeavor because it will either fix part of your performance issues, or rule that aspect of the possibilities out. Either of these will help you solve exactly what is out of line on your machine.

Keep us posted.

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