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coxey2

yet another wr450 jetting problem? Help

25 posts in this topic

I give up. O7 wr450 with the bogg 1/4 to 1/2 throttle. I have been chasing the problem for a month now. It had a 162 main, 68 pilot, 70 air jet and did not check the leak jet yet. I did change to a 168, and did the oring mod and put two shims under the stock non adjustabe needle. It seems to have lost power and the bogg got a little better. ANy ideas, I am at 500-1000 ft at sea level. :smirk:

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Try the stickies at the top of the forum. The search feature will probably provide most of what you need.

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Try the stickies at the top of the forum. The search feature will probably provide most of what you need.

I got as far as I have by reading the stickies. Im at the end of my abilities w/o someone suggesting something specific. Is will back fire on decel now with the changes. :smirk:

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JD jet kit will get your bike running better guaranteed. If you've got a pipe try 168/R4/45. Works great in my 09.

Clean out accelerator pump passages. Even if you drain float bowl fuel still sits in acc pump resivoir and can gum up the acc pump passages.

John

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Come on guys; there's at least 10 members here that could fix this one in their sleep!

SLight bogg after oring mod; it did get better. With 168 main and two shims under factory WR non adjustable needle and it started to backfire on decel from higher rpms not low speed. Starts good when hot and starts with choke ok. I did block off the ais system. Should I raise the needle more? Go down in the main to a 165. The pilot screw has no effect on idle; is it too big?

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Come on guys; there's at least 10 members here that could fix this one in their sleep!

SLight bogg after oring mod; it did get better. With 168 main and two shims under factory WR non adjustable needle and it started to backfire on decel from higher rpms not low speed. Starts good when hot and starts with choke ok. I did block off the ais system. Should I raise the needle more? Go down in the main to a 165. The pilot screw has no effect on idle; is it too big?

68 pilot? You mean 48, right?

You have to put in a smaller leak jet. It dictates throttle response.

The stock needle is pretty lean, go one size richer.

Have you replaced the slide vacuum plate seal yet? They go bad.

Is your fuel screw complete with oring and washer?

Don't bother with an oring mod, do the merge racing linkage spring upgrade.

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68 pilot? You mean 48, right?

You have to put in a smaller leak jet. It dictates throttle response.

The stock needle is pretty lean, go one size richer.

Have you replaced the slide vacuum plate seal yet? They go bad.

Is your fuel screw complete with oring and washer?

Don't bother with an oring mod, do the merge racing linkage spring upgrade.

48 pilot, 168 main and two shims under needle and the oring mod. What size leak jet? Which needle? YZ adjustable? The oring and spring and washer are on the fuel screw. I can turn it all the way in and it does not effect idle. thanks

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First off....set up your idle on the carb. Do a search for the correct procedure. William1 does a good post on this. This will get the pilot jet/fuel screw set-up properly. Next....have a read and understand what is going on - http://www.thumpertalk.com/forum/showthread.php?t=920989.

The leak jet is in the float bowl - try a 45#. Needle - NCVQ. JD does good needles in his kit also.

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First off....set up your idle on the carb. Do a search for the correct procedure. William1 does a good post on this. This will get the pilot jet/fuel screw set-up properly. Next....have a read and understand what is going on - http://www.thumpertalk.com/forum/showthread.php?t=920989.

The leak jet is in the float bowl - try a 45#. Needle - NCVQ. JD does good needles in his kit also.

Thanks for the specifics. I get on it this week.

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48 pilot, 168 main and two shims under needle and the oring mod. What size leak jet? Which needle? YZ adjustable? The oring and spring and washer are on the fuel screw. I can turn it all the way in and it does not effect idle. thanks

Then your pilot jet is too small.

YZ adjustable, same year.

50 leak jet.

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[/b]

Then your pilot jet is too small.

YZ adjustable, same year.

50 leak jet.

Krannie...If the OP has slowed his idle and is able to screw the fuel screw all the way in, with no perceived change, then he needs to go down on his pilot jet size.

To the OP....Here is a copy of a post by William1 which will explain the correct procedure.

To William!....I hope there are no 'copy rite' infringements. :smirk:

Do the pilot test/fuel screw adjustments

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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That stock needle has to go. You are going to be chasing your tail with that thing.

I'm not sure why you are fighting puchasing the JD kit, but just do it. The time and aggravation you save will more then make up for the cost.

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That stock needle has to go. You are going to be chasing your tail with that thing.

I'm not sure why you are fighting puchasing the JD kit, but just do it. The time and aggravation you save will more then make up for the cost.

That's what I said. All the work is done for you...just install and ride.

No respect I tell ya, no respect.

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That's what I said. All the work is done for you...just install and ride.

No respect I tell ya, no respect.

Yeah sounds like the jd kit is the way to go here and be done with it. I like to tinker with things and nothing was open this memorial day weekend so I started messing with it. Lot of good advice here; ended up taking off the rear sub frame to get the carb off and surprisingly it only took an hour to get it off and back on not bad for the first time. And never twist the throttle when the top of the carb is off. It unwound the AP cam and I like to never have figured that out. I am going to order a jd kit and should have it in by next weekend and ride then. thanks all of you. Anyone near Western KY?

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Main & pilot can be accessed thru' the nut on the bottom of the float bowl. Leak - just remove the bowl. Needle - just take the carb top off. No need to pull the carb....:smirk:

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Main & pilot can be accessed thru' the nut on the bottom of the float bowl. Leak - just remove the bowl. Needle - just take the carb top off. No need to pull the carb....:smirk:

Do you actually have any experience with an 07+ WR450? I'd like to see you get the bowl off and then back on the carb while it's still on the bike:bonk:

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Do you actually have any experience with an 07+ WR450? I'd like to see you get the bowl off and then back on the carb while it's still on the bike:bonk:

Yep...pretty much impossible from my experience.

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Yep...pretty much impossible from my experience.

Really.....? :smirk:

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