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thomasj234

2007 WR450F - Won't Run After Modifications

23 posts in this topic

I got the AIS removal kit and did the following mods. Gray wire disconnect, small muffler baffle removed, throttle stop screw replaced, air intake snorkels removed, punched hole to access fuel screw and re-jetted with the jets that came with the AIS kit. the fuel screw has two turns per the instructions.

After it was all back together it would not fire up. I let it sit all night and tried it in the morning. It fired up but wouldn't run at idle and seemed to want to quit due possibly to lack of fuel. I opened the fuel screw a little more and it ran again but only if I held the hot start lever open even though it was not hot. Now I'm thinking that maybe it is getting too much fuel. I have no experience tuning the carb like this and was hoping for a little insight.

Thanks in advance.

Thomas

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By any chance did you remove the fuel screw at any time? Oring, washer and spring still in there? If the oring falls out it can cause problems with the idle mixture. It's tiny so you might not notice.

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By any chance did you remove the fuel screw at any time? Oring, washer and spring still in there? If the oring falls out it can cause problems with the idle mixture. It's tiny so you might not notice.

+1

Adding hot start means leaning the mixture. You are getting too much fuel in the pilot circuit I believe.

Check the fuel screw for o-ring.

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I think you are to rich, the jets that come with the kit might work at sea level in winter not in Utah in the summer. Sound like you are pretty much stock I'd put a 165 main and 45 or 48 pilot depending on how its running. Like the other guys said check the spring, washer, oring on the fuel screw.

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I really appreciate the help. I had taken out the fuel screw so I cracked open the carb again to have a look and sure enough the o-ring was missing. I hooked myself up with one of those flex fuel screws so that i could make adjustments on the fly. It was worth every penny. The bike fired right up and is running well. It is great to be able to reach down and adjust the fuel screw while riding.

Thanks again!

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Fuel screw is for idle only. Bike should be at a standstill, idling when adjustments are made.

Any adjustments needed off of idle are either the needle or main jet.

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I've been riding around for a few days now after having done all of the modifications (listed in the first post) to my 2007 WR450F. I wasn't sure exactly what the fuel screw does, but apparently only effects the idling. I've stopped tinkering with it, but the bike is still running crappy. I haven't really noticed any improvement in performance or power. When I'm cruising the ignition is missing every 8-12 cycles which causes a momentary bogging. There also is bogging on the low end of the power band. I don't know if I can resolve this myself or if I should just take it to the dealer and have them tune it up. Anyon have any ideas?

Thanks - Thomas

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As I said before you are to rich if you used the jets that come with the Yamaha ais kit. I think it is a 170 and it might work in the winter but not in the summer.

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Did the bike run good before the AIS removal?

what do you have in it for jets (I do not know what comes in the AIS kit...)

For a comparison, I have a 04 Canadian bike, no AIS, grey wire cut, air box cut outs, Hot cam's, and a FMF Ti powerCore , and JD Jetting , and am running a 170 main and I'm in Atlantic Canada at sea level, and cool conditions

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The bike ran well before installing the jets from the AIS removal kit. I pulled the spark plug last night and it looked like there was some carbon build up on the first two threads and on the rim. The elements (the prong and nipple) were clean but dark gray. I will post the original jet sizes and the replacement jet sizes next post as I am at work and do not have the numbers. I am riding at between 4,000 and 5,000 feet most of the time although I am occasionally as high up as 10,000 feet. It has been getting up to 95 degrees lately so it seems that I am dealing with both elevation and hot temps.

I'll post again when I have my jetting info. Hopefully all I'll have to do is reinstall the old jets or something simple like that.

Thanks - Thomas

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I guarantee you, the cost of a JD Jet kit for your bike will be WELL worth it, and follow the instructions from the kit to the letter.....you will not regret it.

Do not think your losing out from the AIS removal kit, or that you got it for nothing. You need the AIS kit to get rid of the AIS, and the included jets are needed. But a JD Jet kit is what you need to sort out your jetting issues for temp and altitude (That is my opinion anyway).

To me, it does sound like you have jetting issues, and if so, the JD Kit will fix them, and his tech support is top notch and personal if you do have any little bugs to work out.

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Here is my jetting. Hopefully this will help. The original pilot jet was a 45 and the kit jet is a 50. My original main jet was a 162 and the kit jet is a 175. The original leak jet was a 60 and I don't know the number for the kit jet. There wasn't a main air jet before and the kit came with a 110. I installed all the kit jets. From the plug description someone told me they thought I was running lean and suggested reducing the size of my main air jet. Can someone steer me in the right direction? I'm sick of looking at my bike half torn apart in the garage. I want to go ride!

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Listen to what zukrider and others said. You are too rich for your mods and riding conditions. The AIS jets are too fat for riding in most places in Utah, especially with these high temps and a stock bike. I have a Full DRD exhaust , twin-air air filter with the snorkles removed and I'm running 165 main, 45pilot jet and 4th clip from top on the red needle in the JD jet kit. If you don't want to buy the correct jets then I suggest putting the stock jets back in. It will be closer to where you need to be. I ride from 4000 feet to 11,000+ here in Utah and find the bike to run great.

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Oh yeah, you can leave the GYTR needle in, just put the clip on 3rd or 2nd from the top. I would try third first and see how your mid range is. Ideally you want to richen the bike until it starts sputtering then start backing down on the jets, or needle clip position till it doesn't sputter and its real clean and crisp. But since you're already rich, throw that 45 pilot jet back in (1 1/2 to 2 turns out on the fuel screw), put the needle on third from top, drop the main down to 162 or 165 and check it out.

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The original pilot jet was a 45 and the kit jet is a 50. My original main jet was a 162 and the kit jet is a 175. The original leak jet was a 60 and I don't know the number for the kit jet. There wasn't a main air jet before and the kit came with a 110. I installed all the kit jets. From the plug description someone told me they thought I was running lean and suggested reducing the size of my main air jet. Can someone steer me in the right direction? I'm sick of looking at my bike half torn apart in the garage. I want to go ride!

Wow, way too rich. Follow the advice above. I would go back to the 45 pilot and start working on that circuit. Search this forum or the jetting forum for "pilot circuit". Get that dialed in a little better. Then maybe try a 165 main. Not sure what the main air jet should be as I've never touched that one.

And I don't think looking at the plug is as reliable a source of info unless you are doing the plug/chop test.

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'Reading' a plug is useless with pump fuels.

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.

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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Hey Thomas, I hope you are listening to the advice you got here.

It's good advice. You owe a couple of guys some good gas for their time. :banana:

...... bahhh :worthy:

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Yup, way to rich.....

You need to decide how much your time is worth now.

Time is what your going to invest in dialing in your jetting so it is where it should be to match your area.

I still humbly suggest you consider the JD Jet kit for your bike, as it pretty much takes the guess work out. I'm not saying you can't get it dialed in on your own, but it will take considerable investment in time.

For me, the cost of the jet kit more then offset the time investment I would have had to make. JD's instructions are spot on from my experience, and from what I hear from MOST others (Can't please everyone all the time), and his customer service/support can't be beat.

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I really appreciate everyone's help here. I had the bike out last night and it was running better, but the air temperature was also a lot cooler and I had put in a new plug. I pulled the plug after the ride and I could already see carbon build up way beyond what I thought it should be. I'll get to work following the advice posted here and report back. Thanks again everyone and especially William1 for taking that much time and thought to help me out. Hopefully my next post will be to report that the bike is running like the animal that it should be.

Thank you

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Just got back into town so I'm just getting back to working on my bike. Since my last post I took William1's advice and started with the fuel screw. I could turn it all the way in and the bike would still idle fine. I took out the #50 pilot jet that came with the mod kit and put the stock #45 pilot jet back in. This got rid of a lot of the hesitation/missing when at constant speed. The engine still misses a tiny bit, but way better. It has now started to backfire a little bit. Also, I don't know if I'm getting the power out of the bike that I should be. I still have a #175 main jet in and my needle at the 4th position. Could my pilot jet still be too big? Is my main jet too big? Can running too rich cause the bike to loose power? I would bet my new plug is already pretty dirty.

Thanks in advance.

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