2002 WR426 very hard to start


10 replies to this topic
  • noosphere

Posted April 23, 2012 - 04:15 PM

#1

Bought an '02 in pretty good shape. It is very hard to start. I've been spoiled w/ an '03WR250 w/ electric start. This 426 is a beast to kick over...
I've ordered a Hot Cams Exhaust cam, new cam chain, and a metal plug to replace the decompressor gizmo.

Thought it might be a dirty carb, so installed a JD jetting kit (had great luck with those in the past), a flexiJet fuel screw, and a Boyesen Quickshot3. Gave the carb a thorough cleaning, replaced most o-rings, and did the AP o-ring mod.

It runs fine once it is started, but dang is it hard to start. Last weekend kicked it for an hour before finally getting it started. It did sound a little lean to me (no bog at all (before installing the QuickShot) and some minor popping on decel. Cleaned the carb in the past few days and put on the JD kit, FlexiJet and Boyesen. Kicked it over so many times yesterday and never got it started. So many time that I actual tore up the bottom of my Alpinestars boot :banghead:

Here's what in the carb:
Currently at 6600 feet, but will ride it mostly at 8500-11,000 feet.
Fuel screw out 1 1/4 turns.
JD Red needle - 4 notches from the top.
Main jet - 160 (from the JD kit).
Starter - 65
Pilot air jet - 75
Main air - 200
Pilot jet = 42 (from the Jd kit).
The Quickshot is about 1 turn out, maybe 1 1/8th.
Air filter is clean.
While I was cleaning the carb the squirting seemed good. I was amused how many times it squirted with the fuel line removed.


The jets I reused seemed clean and I soaked them in carb cleaner and dried with air compressor.

Things I haven't done yet:
- try starting with choke off.
- try starting with Hot Start on, even though it's a cold engine.
- pulling the plug and checking spark.
- checking valve adjustment (was supposedly done regularly, I'll have to do this with Hot cam anyway).

Anything else you can think of?
Thanks.
- Checking timing chain.

Edited by noosphere, April 23, 2012 - 04:16 PM.


  • GCannon

Posted April 23, 2012 - 08:41 PM

#2

you may be lean (at least at start up), Try give it one big throttle twist and then kick it if it helps then you know which direction to go.
I use the iridium Spark plug The fine wire plugs seem to be easier starting (CR8EIX)
I left the Decomp lever on I find it is great for clearing the cylinder after a crash, hold it open and kick it a few times then start normally.
Check your valve clearance if they are good then go for the carb. Get the idle misture perfect that is a big help.

  • MANIAC998

Posted April 24, 2012 - 04:45 AM

#3

I would definately start by checking your valve clearances. This is almost always one of the major factors on a hard starting bike. After that, a fresh plug, fresh fuel, clean air filter, and it should fire right up as long as your jetting is good. Like GCannon said, twist the throttle a couple of times before trying to start the bike for the first time. This will help considerably! Maniac

  • jcbikes

Posted April 24, 2012 - 05:32 AM

#4

I ride my 2002 wr426 at the same elevations that you do most of the time. Here are my jets and the bike starts first kick all most all of the time at any elevation. This jetting was tuned for the Rampart range elevation around 8,000 ft but works good at all elevations. I live in the Denver area. If the bike is cold, and the temperatures are below 70 degrees, I always pump the throttle about 4 times before kicking it to start it. Never when the bike is warmed up, do not touch the throttle then.

Main jet - 152
Starter - 65
Pilot jet = 40

Edited by jcbikes, April 24, 2012 - 05:36 AM.


  • noosphere

Posted April 24, 2012 - 08:35 AM

#5

Thanks for the replies. Now I just need to figure out what is the right flywheel puller to buy...

I live in the Denver area also! Don't go to Rampart that often as I usually ride on weekends and its so crowded. Sure is a nice area though.

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  • Stealth13

Posted April 24, 2012 - 09:00 AM

#6

you may be lean (at least at start up), Try give it one big throttle twist and then kick it if it helps then you know which direction to go.
I use the iridium Spark plug The fine wire plugs seem to be easier starting (CR8EIX)
I left the Decomp lever on I find it is great for clearing the cylinder after a crash, hold it open and kick it a few times then start normally.
Check your valve clearance if they are good then go for the carb. Get the idle misture perfect that is a big help.

not to thread jack but mine always needs a couple throttle pulls then a nice kick and it fires right up, does that mean the idle jet is too lean?

  • Pooley

Posted April 24, 2012 - 11:01 AM

#7

Exhaust valves would be my first thoughts.

  • dustdogg

Posted April 24, 2012 - 12:12 PM

#8

I had a similar issue with my 426. Everything was great and then all off the sudden it wouldn't start. I had recently checked the valves so I knew that probably wasn't the issue. I pulled the plug and it was fouled so I changed and it started on the first kick. I was expecting the worst, but I started with the easiest task and luckily it was easy.
I would think your problem is either electrical or tight valves. You need to correct the real problem before you start throwing a bunch of parts at it because then you may never know what really caused it. There is no reason a correctly jetted and operational bike shouldn't start within a few kicks. Read the manual, ask more questions and trace down the real problem, then add new cams etc. etc.

  • noosphere

Posted April 25, 2012 - 06:26 AM

#9

Well, checked valve clearance. Exhaust = 22 and 21. Intake = .11, .10., and .9.

So, I guess that's not too bad.

Interestingly, my Cylmer manual says exhaust should be .25-.30, and the intake should be .15-.20. The online Australian and European Yamaha manuals state exhaust should be .20-.25 and intake should be .10-.15. I'm assuming the Clymer manual is wrong.

Spark was good.

  • Pooley

Posted April 25, 2012 - 01:13 PM

#10

If you leave the gas on, without running the bike, do you eventually get a puddle of gas on the floor, or at least dripping? I'm thinking that if the valves don't need shimming, carb is clean, timing is proper, and spark is good, the o-ring around the float valve assembly might have hardened up, leaking gas into the bowl and overflowing. This would make it very difficult to start, but if it were slow enough you might not notice while riding only affecting the first start of the day.

  • noosphere

Posted April 25, 2012 - 03:36 PM

#11

Thanks Pooley. I'll give that a try once I get it all back together. I'm going to go back through the carb tonight. I'll take a double look at that o-ring too.




 
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