So many questions, so little time

I need help bad! Not for me but for one of my friends. He has a '10 WR450.

His bikes run horribly. I have been searching like crazy to find the answers, but I'm on a short time table. I have to order parts tomorrow morning so they can make it to my friend who is coming down to Nicaragua.

Now here's the problem with the bike:

He has a procircuit t4 exhaust and pipe on it. He doesn't know if it was rejetted. As far as I know no free mods were done to it, but I really am not experience with these bikes. :smirk:

It's a bear to start cold, and when it runs it pops and back fires like crazy, and has no throttle response. To me it sounds like a pilot jet/fuel screw adjustment. Also to make matters worse the fuel screw broke and he's got some sort of plug? glued/siliconed in.

I'm trying to help him, he was last years top endure rider in Nicaragua, unfortunately the only mechanic he has near him is horrible. And being in Nicaragua he can't get parts.

So what do you recommend. I want to make it run like it should. JD jetting kit? What size jets? Any suggestions for a fuel mixture screw? Free mods? He was worried that the free mods cause engine damage. Any validity to that? Bestow upon me the wisdom and guidance, and really quickly too!

Thanks!

Edited by Kcizik
Stupid spell check, I hate you

He's running lean for sure. Can you get mains and pilots there? Needle can be dealt with by raising it using a small washer under the clip since the stock needle is nonadjustable. Something needs to be done about that fuel screw as well.

Free mods will cause no engine damage, in fact the engine will run better/ like it was supposed to. Yamaha fully expects you to derestrict them.

He's running lean for sure. Can you get mains and pilots there? Needle can be dealt with by raising it using a small washer under the clip since the stock needle is nonadjustable. Something needs to be done about that fuel screw as well.

Free mods will cause no engine damage, in fact the engine will run better/ like it was supposed to. Yamaha fully expects you to derestrict them.

I can't get those numbers off the pilots. He's quite a distance away from me, I was thinking of just ordering the JD jet kit and the JD fuel screw. That should have everything I would possible need right?

Also, If I do the free mods, what should my jetting be like?

I can't get those numbers off the pilots. He's quite a distance away from me, I was thinking of just ordering the JD jet kit and the JD fuel screw. That should have everything I would possible need right?

Also, If I do the free mods, what should my jetting be like?

The JD jet kit expects that you may or may not do the mods so they will tell you in the kit which jets to use for stock or modded. It gives you step by step instructions on how to jet the bike for which condition at which altitude. Heck my wife could do it with their instructions. You cant go wrong.

Also look up the free mods thread and do them all. Gray wire, air box, muffler insert. Your also going to want to order an AIS kit to remove the smog / emission stuff along with doing the throttle stop. After all of that you are going to love it.

I can't get those numbers off the pilots. He's quite a distance away from me, I was thinking of just ordering the JD jet kit and the JD fuel screw. That should have everything I would possible need right?

Also, If I do the free mods, what should my jetting be like?

Problem with the JD kit is price and I'm not sure how many mains you get.

Best bet would be a GYTR AIS kit if they still sell them in the states. This will get you your AIS blockoff, a good needle, YZ throttle stop, leak jet and a rich main and pilot, 175, 50.

I would buy a 168, 170, 172 main, bike comes with 165.

Pilot buy a 48. Bike comes with 45

My guess is you would be if low elevation

48 pilot

GYTR needle 3rd, 4th clip

168-170 main

The JD jet kit expects that you may or may not do the mods so they will tell you in the kit which jets to use for stock or modded. It gives you step by step instructions on how to jet the bike for which condition at which altitude. Heck my wife could do it with their instructions. You cant go wrong.

Also look up the free mods thread and do them all. Gray wire, air box, muffler insert. Your also going to want to order an AIS kit to remove the smog / emission stuff along with doing the throttle stop. After all of that you are going to love it.

You're right, JD's instructions are great.

I found the AIS kit http://www.powerpartsplus.com/pages/Catalog/Product/5618?categoryID=200&subCategoryID=400&catalogFilter1ID=1&catalogFilter2ID=4&catalogFilter3ID=49&catalogFilter4ID=94&catalogFilter5ID=0

He has a pro circuit exhaust, no need to modify the stock then.

Any comment on JD's fuel screw? Is there any good remote ones?

If you look at the JD website they will have a fuel screw recommendation right where you would find the jet kit for your bike.

I here the AIS is great as well but I have always gone with JD. Worked great the first time so why change from perfection.

You're right, JD's instructions are great.

I found the AIS kit http://www.powerpartsplus.com/pages/Catalog/Product/5618?categoryID=200&subCategoryID=400&catalogFilter1ID=1&catalogFilter2ID=4&catalogFilter3ID=49&catalogFilter4ID=94&catalogFilter5ID=0

He has a pro circuit exhaust, no need to modify the stock then.

Any comment on JD's fuel screw? Is there any good remote ones?

My recommendation is the R&D flexible fuel screw. Works so well you can do adjustments when riding :smirk:

One more question... I wish I had the FCR on my DRZ, then I could use that as reference.

One the fuel line coming into the carb, it has a small tee?. What come out of the outlet for that tee?

Or does anyone has a good profile shot of the left side of the FCR?

37daad23_vbattach7990-5.jpg

THis is what I was looking for: In the picture above the hose on the left has a tee. Where does that outlet go to? His is missing it. Any help is much appreciated!

37daad23_vbattach7990-5.jpg

THis is what I was looking for: In the picture above the hose on the left has a tee. Where does that outlet go to? His is missing it. Any help is much appreciated!

Thats not a 2010 WR450.

Thats not a 2010 WR450.

I know its not. Its a picture of the FCR39 though. I'm trying to figure out what he's missing. Every time a mechanic here touches it, less parts make it back on.

I know its not. Its a picture of the FCR39 though. I'm trying to figure out what he's missing. Every time a mechanic here touches it, less parts make it back on.

OK cool, just making sure we're on the same page.

Are you talking about the breather tubes from the carb????

Really not seeing what you're talking about.

As far as i know all the clear hoses from the fcr just vent and trave to the swing arm area.

Did not know that Yamaha manufactured a WR450 in 2010. Anyway, I hope this helps.

From the symptoms you describe sounds like the bike is running lean.

You can't go wrong with the JD jet kit. It's virtually fool proof. Or you can go this link and find someone running in similar conditions with bike setup the same way and mimic their jetting. You can buy Yamaha parts (jet and needle) and get it really close. Saves alot of money too. http://www.thumpertalk.com/forum/showthread.php?t=411240

Definitely replace the fuel/air screw. If there is a problem with that screw you will NEVER be able to get the jetting right. It will NEVER run right. It will ALWAYS be hard to start. Also make sure it has the spring, washer and o-ring, in that order, bottom to top, when the carb is mounted on the bike.

Check this link for an exploded view of the carb. Fool around on this site. Look at the listing for YZ carb parts, the jets fit the WR and the YZ carb listing has a variety of jet sizes listed with the part numbers. Also a stock YZ needle is a good choice. It will be better than the WR needle and give you ability to adjust the clip up and down.

http://www.ronayers.com/Fiche/TypeID/26/Type/CARBURETOR/MakeID/4/Make/Yamaha/YearID/50/Year/2009/ModelID/8781/Model/WR450FY/GroupID/424313/Group/CARBURETOR

Here is a diagram from my Yamaha service manual

http://s1187.photobucket.com/albums/z397/poopieinthehole/?action=view&current=FCRdrawing.jpg

Edited by ur2silly
Did not know that Yamaha manufactured a WR450 in 2010. Anyway, I hope this helps.

From the symptoms you describe sounds like the bike is running lean.

You can't go wrong with the JD jet kit. It's virtually fool proof. Or you can go this link and find someone running in similar conditions with bike setup the same way and mimic their jetting. You can buy Yamaha parts (jet and needle) and get it really close. Saves alot of money too. http://www.thumpertalk.com/forum/showthread.php?t=411240

Definitely replace the fuel/air screw. If there is a problem with that screw you will NEVER be able to get the jetting right. It will NEVER run right. It will ALWAYS be hard to start. Also make sure it has the spring, washer and o-ring, in that order, bottom to top, when the carb is mounted on the bike.

Check this link for an exploded view of the carb. Fool around on this site. Look at the listing for YZ carb parts, the jets fit the WR and the YZ carb listing has a variety of jet sizes listed with the part numbers. Also a stock YZ needle is a good choice. It will be better than the WR needle and give you ability to adjust the clip up and down.

http://www.ronayers.com/Fiche/TypeID/26/Type/CARBURETOR/MakeID/4/Make/Yamaha/YearID/50/Year/2009/ModelID/8781/Model/WR450FY/GroupID/424313/Group/CARBURETOR

Here is a diagram from my Yamaha service manual

http://s1187.photobucket.com/albums/z397/poopieinthehole/?action=view&current=FCRdrawing.jpg

Thanks, that's what I needed. It was marked a 2010 here in Nicaragua. Who knows. It's hard to tell what's it missing when so many ppl have touched it and you don't know where to start. I should've thought the parts diagrams!

Thanks for all the help!

He has a procircuit t4 exhaust and pipe on it. He doesn't know if it was rejetted.

Did he install new exhaust gaskets when installing the new exhaust? A possible air leak in the exhaust system could be contributing to your symptoms as well. If he didn't bother to rejet after the exhaust swap then he may not have bothered to install new gaskets as well. Just one more thing to eliminate from the list of possibilities, along with what everyone else here has suggested.

Although the JD Jetting kit is a bit expensive, it should have everything you need to get the jetting right, and from what I've been told, it's pretty much idiot proof, with great instructions. Definately get that fuel screw fixed as well like ur2silly suggested, if you don't, you'll just be pulling your hair out and chasing your tail!

You can also go to the WR Jetting database thread in the stickies, and find what others have used for your bike setup, temps and elavation and use that as a starting reference if you want to buy your jets individually.

Did he install new exhaust gaskets when installing the new exhaust? A possible air leak in the exhaust system could be contributing to your symptoms as well. If he didn't bother to rejet after the exhaust swap then he may not have bothered to install new gaskets as well. Just one more thing to eliminate from the list of possibilities, along with what everyone else here

thanks, good thought. I'll check that out. I'll let you guys know what I find when I get a chance to look at it.

.... Also to make matters worse the fuel screw broke and he's got some sort of plug? glued/siliconed in....

Get that problem fixed! I just wont run anything near right with a 'half' fuel screw no matter way jets and needles you put in.

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