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criswr400

my beloved wr400

12 posts in this topic

hello,my name,s cris i have a yamaha wr400 99 /00 model which i use quite often across the plains and tracks the bike performs really well untill you stall it! starting the thing back up is a nightmare i am used to the starting drills that ive read from diferent threads but it dosnt help much the bike has always been dificult to start since i got it even first starting it from cold but when it is hot it is vertually impossible the bike has a full white bros exhaust system tailpipe and ive changed the plug to a race plug but this has made no diference. ive cleaned the carb which made it run a bit better but it did not affect the starting .ive had bikes all my life and love riding them but my bikes starting is taking all the fun out of it !!!!! could anybody help me out with any ideas ,modifications,improvements to help with the starting also the general running or performance of my bike thanks CRIS

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How long have you had the bike? Is this issue recent?

Most likely the valve clearances are tightening up. Did you check your valves?

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You didn't say so I'll start simple. Adjust the pilot screw correctly according to the sticky in the jetting forum. Especially with an aftermarket pipe jetting is crucial to getting it to start well.

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And you don't mention if you have ever worked with the jetting. A properly jetted bike should be easier to start unless there are different issues, like the valves as JSanfilippo suggested.

Check out the jetting sticky at the top.

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Also make sure your hot start plunger isn't clogged. Another thing is the coil may be going bad, when they go bad they tend to put out a weak spark when hot and eventually fail completely.

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with out a description of what happens when you try to start it I would begin start checking things in this order (in order of easiest because I am lazy)

Check Coil - simple test with multi meter

Jetting and carb settings - the JD jet kit really makes a differance with this bike, use the jetting sticky at the top of the forum to fine tune the carb for your area.

Valves - this in combonation with the jetting is IMO where you are gonna find your fix. My 400 did the same thing when the valves tightened up (2000 WR400 lots of use and took 6 years for the valves to go out of spec) check them or get them checked.

I put the jetting before the valves because it really is amazing how proper jetting can wake up your bike

Also inspect the intake boot between the carb and the intake manifold, a six year old piece of rubber can dry up and cause air leaks which can cause all sorts of running and starting issues

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I have been having a strange issue with my bike, where if I ride wide open for a bit it will stall like it ran out of gas. I starts right up with no issue, so I am thinking I emptied the bowl by riding wide open like that. I didn't think that was possible to be using that much fuel on a wide open haul. Anybody have a similar issue?

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I have been having a strange issue with my bike, where if I ride wide open for a bit it will stall like it ran out of gas. I starts right up with no issue, so I am thinking I emptied the bowl by riding wide open like that. I didn't think that was possible to be using that much fuel on a wide open haul. Anybody have a similar issue?

You could be bouncing off the rev limiter - quite normal and is there to protect the engine from over-revving.

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I have been having a strange issue with my bike, where if I ride wide open for a bit it will stall like it ran out of gas. I starts right up with no issue, so I am thinking I emptied the bowl by riding wide open like that. I didn't think that was possible to be using that much fuel on a wide open haul. Anybody have a similar issue?

If you have a fuel filter it could be clogging.

Make sure gas pours out of the line after the filter.

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I have been having a strange issue with my bike, where if I ride wide open for a bit it will stall like it ran out of gas. I starts right up with no issue, so I am thinking I emptied the bowl by riding wide open like that. I didn't think that was possible to be using that much fuel on a wide open haul. Anybody have a similar issue?

Yeah, been through that. I had some glop in my fuel tank ,pet-cock screen, and then finally it worked into my carb. I removed the pet-cock screen and put in an inline fuel filter (easy to monitor and change) and just cut the screens off the pet-cock altogether. Also thoroughly cleaned carb, incl. AP. I had what sound like identical symptoms to yours and these steps really cleared them up. Still feel like the carb is a work-in-progress, but she runs pretty well now.

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