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2007 450 sx-f - Accelerator Pump Help!

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I've been reading up a lot and found out the timing for the pump needs to be adjusted to a a squirt every second. Apparently it is set to 3 seconds at the moment. There are many methods I can do to adjust this but I am not sure which one if the best method.

Here are the methods I have heard

1) Honda Diaphragm

2) o-ring

3) valve shims on the bottom middle of accelerator pump cover

I am really stuck because I am not sure which mods to make to get the best outcome.

Thanks Fly_Racing

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I responded to you PM. Please, if you are going to make a post do not ask the same question in a PM, instead, simply refer to a link to your question.

First, you are over analyzing and making assumptions as well as confusing carb models.

Next, why do you think you need to do anything? You make no mention of an issue. Never fix what is not broken.

Old style FCRs (slant with external AP linkage) had extremely long squirts that can simply be dealt with by 'the Eddie Mod'.

Newer style FCR-MX (like you have) do not have a squirt duration issue, all have a squirt in an acceptable range. The only way you can time a squirt is to use a video camera with a known FPS. You record the squirt and count the frames to calculate duration. You cannot use a stop watch.

  1. The Honda Diaphragm was primarily used in the old style FCRs, longer rivet = shorter squirt
  2. Oring mod/wired linkage/stiffer AP spring all achieve the same thing (remove slop from the linkage) on the new style FCR-MX and are not needed on Hondas from 2008 forward due to a different designed linkage.
  3. Valve shims are the wrong method (decreases chamber volume in addition to limiting travel) of reducing duration and volume on an old style FCR.

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When I deaccelerate from a good twist it bogs and stalls. It also does this whilst it's idling. I always make sure my bike is warmed. Which leads me to think it's the AP.

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The bike stalls on de-acceleration and at idle? That has nothing to do with the AP.

Either your pilot jet is clogged (replace, do not clean) or the fuel screw is set wrong (or damaged) or the idle speed is set too low.

Fuel Screw/Pilot Jet

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

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The bike stalls on de-acceleration and at idle? That has nothing to do with the AP.

Either your pilot jet is clogged (replace, do not clean) or the fuel screw is set wrong (or damaged) or the idle speed is set too low.

Fuel Screw/Pilot Jet

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

Thanks heaps. Would a JD Jetting Kit be worth while? I am at 100 ft above sea level normal temp is around 70 degrees F.

I have a video that I will post in a minute showing the bog.

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No, your problem is in the idle circuit. Other than that, you make no mention of any running issues. Do not fix what is not broken.

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The video is worthless. Cold bike, just sitting on the stand. I can make any bike do that. No one rides by being at idle, reving it with no load then closing the throttle back to idle, esp. with a cold engine and expects perfect performance.

Do what I instructed regarding the fuel screw. Be sure the bike is FULLY HEATED IE, ridden for at least 20 minutes first.

Put in a new (not just 'cleaned') pilot jet first.

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That was after it was warmed. Should I buy a 42 pilot because in 2008 the 450 changed to a 42 pilot and kept it to 2010?

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No, you should replace the pilot it currently has and do the fuel screw setup I told you about. If after you install a BRAND NEW pilot, the test will tell you if the pilot is right or wrong. Please read what I previously posted.

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Ok thought KTM would know what's best? Anyway thanks heaps. Will let you know how it goes.

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