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tdubliture

Wr450 only runs with choke. Ran fine minutes before.

14 posts in this topic

Ok so I am a newbie to the dirt bike realm and this forum. I have spent the last two weeks trying to familiarize myself with the bike. Here's what I know: it's fairly stock with about 1300 miles on it. It has the yz throttle stop but not the gray wire mod. No air box mod either. I first bought the bike about a month ago and it ran awesome up until two weeks ago when I let a friend test drive it. This was halfway through my second tank, 91 ethonol(couldn't find any without). He rode it up the street and back and it died before he got back. Couldn't get it to start without the choke on. With choke on it runs fine. As soon as you push it in it starts to die and within about 30 sec will die. If you give it any throttle it spits and dies immediately.

I searched a bunch of threads that said it most likely is the pilot jet clogged. They also mentioned to check the hot start. The nut on the hot start happened to be stripped and the PO gorilla glued it in but it had come out. For how long I don't know.

I ordered the tokyomods carb set with the fuel screw hot start nut and sump nut and installed it. The fuel screw was set at 1.25 turns so I put the new one at that. I pulled the pilot jet and main jet and cleaned them good (very clean already).

Anything else I should check? Should I pull the whole carb and go through it? I'm stumped.

Thanks in advance

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You can't clean a pilot jet unless you have a sonic cleaner.

Put in a new one.

 

You need to service the carb.

All sections must work properly to get good results.

 

You should also clean out the gas tank and petcock filter, as it is probably passing the small dirt.

 

Rerouting the carb vent hoses is essential to reduce dirt into the carb. Reroute under the gas tank and add filter to each/all hoses.

 

These are common issues.

Read the FAQ section at the top of the forum

Use the search function.

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Ya I read the faq section and searched all the threads. My prob seemed different because all other issues seemed to stem from letting the bike sit

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Used the search function (FAQ W450) NOT FOUND) and I haven't heard of the issues with the carb vent tubes.  Can you post a link to that?   Thanks!!

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Used the search function (FAQ W450) NOT FOUND) and I haven't heard of the issues with the carb vent tubes.  Can you post a link to that?   Thanks!!

 

No such thing a a W450

 

You search for 'carb vent tube re routing'

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Ok first of all I want to say thanks for the time and suggestions.

Today I pulled the carb and cleaned all the passageways with brake cleaner and blew it out with air.

Replaced the pilot jet with a new one. 45. As I was cleaning I noticed that someone has broken off the corners where it goes in so the baffle has more wiggle room. Do I need to worry about this?ImageUploadedByThumper Talk1459477267.416171.jpg

I didn't get a chance to get it back on the bike yet as I found the fuel screw o ring was cracked in half and I couldnt track one down at autozone or ace hardware. Will go to the Yamaha shop tomorrow. Anything else I need to check while I've got it out?

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That broken piece will not affect you.

Do the oring mod while you are in there , and change your leak jet to a 50 or 55, and if your are able, change the apump diaphargm to the short river version (Honda crf450r 2007/8)

Make sure the pump system is squirting at least a few feet for 1 second

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Ok not to sound like a noob but I don't know what the oring mod is and I searched for a few min and just found people talking about it. Is there a sticky on this. The leak jet is the one mounted in the carb bowl right?

Also thinking I should check the slide o ring?

Edited by tdubliture

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Just pulled out the leak jet and it is a 60. What will the difference between the 55 and 50 get me. I live at 4700 ft and go riding up to 6000 and down to 3000 if that matters

Edit:

Understand the leak jet now. I didn't feel like it bogged that bad so I will purchase a 55 and the ap plunger and put it all together tomorrow. Thanks for all the help kran

Edited by tdubliture

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Just got done putting it back together. After looking at charts and reading posts I decided to go with the following.

168 main

48 pilot

55 leak

Parts guy didn't have the newer ap stuff so I can do that later.

Also cut the gray wire

All I can say is wow. What a difference. It runs great now. My only concern now is that when I tried to adjust the fuel screw I tightened it all the way in and it still idles. Does this mean the main is too big? I'm not sure what notch the needle was at. Do I need to check that

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Just got done putting it back together. After looking at charts and reading posts I decided to go with the following.

168 main

48 pilot

55 leak

Parts guy didn't have the newer ap stuff so I can do that later.

Also cut the gray wire

All I can say is wow. What a difference. It runs great now. My only concern now is that when I tried to adjust the fuel screw I tightened it all the way in and it still idles. Does this mean the main is too big? I'm not sure what notch the needle was at. Do I need to check that

 

Right, cause you need a 45 pilot jet.

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Ok swapped the pilot with the factory 45. Now turning the screw in all the way kills it but it will idle with .5 turns. Leave it or go smaller?

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Ok swapped the pilot with the factory 45. Now turning the screw in all the way kills it but it will idle with .5 turns. Leave it or go smaller?

 

 

You need to follow the proper fuel screw tuning procedure.

 

Start with 1 turn out, and the lowest possible idle with a HOT motor. Never adjust cold.

 

Turn the screw out SLOWLY and listen for a SUBTLE rise in rpm.  VERY SUBTLE. 

Blip the throttle now and then and re-check, screwing a bit in and out.

You are seeking the highest and smoothest idle you can acheive.

 

This is your 'base tuning' spot.

For further fine tuning, blip the throttle and listen to the rpms drop. 

1/16-1/8 turns may improve this, and this is your 'sweet' spot.

 

You will find that this spot is approximately 1.25-1.75 turns out, assuming your carb has no worn components whatsoever.

 

If you find the spot, and the idle is too high, lower it with the idle screw, and check it again.

 

https://www.google.com/search?q=r%26d+fuel+scrwe&rlz=1C1CHMO_enUS529US530&oq=r%26d+fuel+scrwe&aqs=chrome..69i57.3919j0j7&sourceid=chrome&ie=UTF-8

Edited by KRANNIE

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