WR426 hard to start when hot


12 replies to this topic
  • glasseye

Posted July 02, 2005 - 01:36 PM

#1

The WR is very difficult to get started when hot. When cold, first start of the day, it will start on the first or second kick. But when the engine is warmed, I need to give it several twists of the throttle and on average, about 20-30 kicks. Once started it runs great.

It is not the spark plug. I assume it is carb related. Anyone know where the problem likely is? Is it something that I can fix without removing the carb?

  • jamieyz426f01

Posted July 02, 2005 - 01:41 PM

#2

try not turning the throttle when you star your bike. you are flooding it when you do and it takes about 20-30 kicks to clear the engine afterwoods.

  • byggd

Posted July 02, 2005 - 01:53 PM

#3

try not turning the throttle when you start your bike



This is true......you should never give it gas when starting it. Try turning your idle knob up about a 1/2 a turn and make sure to pull the hot start plunger out too.

  • glasseye

Posted July 02, 2005 - 01:54 PM

#4

Read my first post... I HAVE TO twist the throttle to get it started. I realize that normally you will flood the bike but something is wrong with the carb. Start circuit?????

  • glasseye

Posted July 02, 2005 - 02:01 PM

#5

Oh, an by the way, I've had the bike since new, 2,800 miles on it now. This is a new problem and I know the normal drill (I now have auto-decomp cams for the last 1200 miles).

It's a wierd problem, that's why I ask.

  • ToooFaarOutt

Posted July 02, 2005 - 03:44 PM

#6

Make sure your air cleaner is clean. If it cant get enough air it wont fire real easy. I just cleaned mine for the first time and it was hard starting when hot always had to use the hot start. Now when its hot I do not even have to use the hot start. All the hot start does is let in more air by passing the aircleaner.

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  • byggd

Posted July 02, 2005 - 06:44 PM

#7

Oh, an by the way, I've had the bike since new, 2,800 miles on it now. This is a new problem and I know the normal drill (I now have auto-decomp cams for the last 1200 miles).



Oh. so sorry. You didn't say that in the first place. Just letting you know what works on my 02 426 :)

Sorry guys, just has to stir the pot. it's in my nature :)

  • Dan_Lorenze

Posted July 03, 2005 - 06:39 AM

#8

When valves become out of spec you'll notice the bike is harder to start and after the bike's warm you'll notice that using the hot start circit is the only way to get it to start. There's a good possibility that your valves need adjusting.. Since you mentioned you wouldn't want to tear the crab apart I'm sure you'd feel the same about adjusting the valves. Nothing wrong with having a factory trained Yamaha mechanic take care of it for you..

Dan

  • glasseye

Posted July 03, 2005 - 11:52 AM

#9

Hey Dan, thanks for the reply. Valves are in spec and I don't mind doing any work myself. To date, Ive replaced the cylinder, piston 2 times, Had EDCO rebuild the head after a valve broke, replaced the crank, replaced all my own tires, bearings, brake pads, chains/sprockets, and all PM in-between rides. In fact, I've maintained all of my bikes myself for the past 35 years. And to tell the truth, the factory trained guys tend to overcharge and fail to identify the root of the problem way too often!

This is a real unique problem and I've never seen it myself before. Of course, none of my past bikes have had as sophisticated carb as this. All I'm looking for is if anyone has expierenced this problem before. Again, when the bike is hot, I need to pump fuel into the engine via twisting on the throttle a few times to get it started. Pulling out the choke aslo helps a bit. There must be something plugged in the carb and if I don't need to pull the carb to clear it, that would make me very happy :D .

I've dissasembled and rebuilt many carbs in my riding career, basically I don't want to do more than necessary. As it stands, I spend as much time working on the bike (counting normal maintainence as well as engine failures) as riding it. Kind of reminds me of '70s vintage snomobiles. For us guys that can't afford new bikes every year, these new breed, high performance thumpers really suck. :D Too much time and $$$. I hope they get the 4 strokes figured out before the greenies outlaw sales of new 2-strokes. -- OK, DONE RANTING NOW!!--

I'll be out of town and return with 1 day to fix the problem before a 3 day ride. My son will be on the GasGas so that's not an option for me. As it stands now, looks like I'll be spending 1/2 of that day removing and cleaning the carb. Or maybe I should just eat the loss and trade it in on another GasGAs before the event :). Damn, that would take 1/2 a day also :D (but the future would be much brighter). :)

Anyway, thanks for all the input. and if anyone KNOWS where the problem resides, I appreciate your input very much.

To all of you TT'ers, have a wonderfull 4th, and happy riding to all!

  • 1rkcooper

Posted July 03, 2005 - 07:00 PM

#10

If you are going to pull the carb I would have a look at the float. I don't know, just a guess. Good luck.

  • Hamish

Posted July 04, 2005 - 12:31 AM

#11

if it needs fuel (choke or squirt) to start when it's hot, chances are you have an air leak between the head and the slide. Get it running, and gently spray fuel around the manifold rubbers, clamps and carby. When it stalls or starts running like a hairy goat, you've found your leak.

  • glasseye

Posted July 06, 2005 - 03:47 PM

#12

Hamish, That's a good possibility to look for. I'll check for air leaks before removing the carb. Got back too late to mess with it today, so I'll be working on it at the trailhead tomorrow morning.

Thanks for the input everyone and have a good weekend of riding!

  • tp3dxf

Posted July 07, 2005 - 04:25 PM

#13

My 01 WR 426 was getting hard to start as well.

I pulled the carb for the first time after 3,400 miles and installed my JD jet kit. The first thing I found was that both my throttle cables were frayed badly. I think this contributed to my hard starting and irratic idle. I think the throttle was hanging up just a bit.

Also the carb in general was very dirty. I am glad I took the time to pull it apart and clean it. I couldn't believe all the fine dirt that came out of that thing. I am surprised it ran as well as it did.

After all the work was done she started on the first kick and starts within three kicks when hot with no hot start needed. The bike runs great.

I learned a lot about the carb it was a good lesson for me.




 
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