426 hard starting


21 replies to this topic
  • 2001YZF426Rider

Posted March 24, 2008 - 11:36 AM

#1

Ok, last week i went out to start my bike and it took forever to start, i just went out today to start it and it wont.. It sometimes fires then dies, alot of the time it wont do anything.. It eventually floods itself out but i tip it over and drain the gas out of it, and in the past that always used to work, i would do that and it would fire right up.. It is pretty cold here still mid 30 degrees..

I dont know why, but i still have the decomp lever, and it never gave me problems, i can start it very easily.. Twist the throttle 3/4 times, pull choke lever and it would start. Now when i do the decomp lever, like i used to, i kick and the kick lever stops like half to two thirds of the way down every now and again, and when i kick it fully it isnt nice and smooth like it used to be.. I messed with the cable but it still does it.. It doesnt do it every time but a lot of the time it does..

My buddy has the decomp cam i can have for 75$, should that solve my problems? And is there a sticky thread on installing it?

  • DirtMongrel

Posted March 24, 2008 - 04:38 PM

#2

if you still have the manual decomp lever and can manage to kick fully through the stroke then it sounds like your valves need adjustment or maybe replacement... when was the last time they were checked/replaced?

  • 1rkcooper

Posted March 24, 2008 - 06:21 PM

#3

Here is a ton of info for you and yes the instructions for the decompression mod are in there near the top op the thread.

As already stated it sounds like the valves need checking/adjusting. This would be done at the same time as the decompression mod if you choose to do it.

  • 2001YZF426Rider

Posted March 24, 2008 - 06:37 PM

#4

I havent checked the valves since ive had it which is like four or five years! But i didnt because it always ran and started great!!

  • jmckinney

Posted March 24, 2008 - 07:48 PM

#5

I know when my 2000 YZ426 was getting hard to start i adjusted the valves and that did not work, eventhough they were out of tolerance. I ended up taking the carb apart and found some dirt and that was the problem.

  • Dustin_Mabro

Posted March 25, 2008 - 06:18 AM

#6

If you've got the money you might as well swap out the exhaust cams. I love my swap and it was a piece of cake. You're doing all the work of getting in there...might as well kill 2 birds with one stone






(I do not condone the killing of birds)

  • Dirtbiker05

Posted March 25, 2008 - 08:19 AM

#7

http://www.thumperta...078#post3706078
http://motoman393.th...ech/valves.html

you can read about the valve checking and adjustment and the cam mod here before you get into the motor so you know what your getting into. hope this helps. good luck!

  • 2001YZF426Rider

Posted March 25, 2008 - 08:34 AM

#8

Thanks guys, i have been doing some reading on the cams.. Im buying one at the end of the week. My buddy has one from an 03 so im going to put that in, im going to change the cam chain too, sounds like a good idea to do while im there... Ive been looking in the TT store, and i cant find the decomp plug, where is it located under?

Im also going to put in a new plug to see if that helps..

Anyone run seafoam in the gas tank?

  • grayracer513

Posted March 25, 2008 - 09:02 AM

#9

Ive been looking in the TT store, and i cant find the decomp plug, where is it located under?

The TT store no longer sells the decomp plug. There are some being sold on eBay, though. You can also use an 18mm brass or steel cup plug (freeze plug, expansion plug) from an auto parts store, but these can be a little difficult to install.

Another alternative that isn't as pretty is to cut the lever off of the outside end of the decomp shaft, AND the half round extension off of the inner end, and use that as a plug.

Just don't use the cheap POS from Yamaha.

  • 2001YZF426Rider

Posted March 25, 2008 - 07:48 PM

#10

Well i want to go with something that is clean, and a nice easy install, do you know which ones on ebay are just that?

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Dustin_Mabro

Posted March 26, 2008 - 05:46 AM

#11

Anyone run seafoam in the gas tank?


I use it in all my trucks, and have put a little in my bike...can't really say I noticed a difference....do a search on this I know it's been discussed before

  • 2001YZF426Rider

Posted March 27, 2008 - 04:02 PM

#12

Ok i have a cam from an 03, do i have to remove the flywheel to install it? I plan on changing the timing chain while im there. I also have to put in a lighting stator, so i have to remove the flywheel anyway.. Will this flywheel puller work?
http://cgi.ebay.com/...sspagenameZWD1V

And also, will this decompression plug fit?
http://cgi.ebay.com/...sspagenameZWDVW

  • grayracer513

Posted March 27, 2008 - 05:07 PM

#13

The answer looks like yes to both. Use you original seal with the decomp plug.

  • 2001YZF426Rider

Posted March 28, 2008 - 05:48 AM

#14

Thanks grayracer!!!

  • 2001YZF426Rider

Posted March 29, 2008 - 02:28 PM

#15

I put a new plug in and she fired right up! So that is a good thing, now i just need to order the decomp plug, flywheel puller, and install the new cam and chain..

  • angrybob

Posted March 29, 2008 - 06:49 PM

#16

Ok, last week i went out to start my bike and it took forever to start, i just went out today to start it and it wont.. It sometimes fires then dies, alot of the time it wont do anything.. It eventually floods itself out but i tip it over and drain the gas out of it, and in the past that always used to work, i would do that and it would fire right up.. It is pretty cold here still mid 30 degrees..

I dont know why, but i still have the decomp lever, and it never gave me problems, i can start it very easily.. Twist the throttle 3/4 times, pull choke lever and it would start. Now when i do the decomp lever, like i used to, i kick and the kick lever stops like half to two thirds of the way down every now and again, and when i kick it fully it isnt nice and smooth like it used to be.. I messed with the cable but it still does it.. It doesnt do it every time but a lot of the time it does..

My buddy has the decomp cam i can have for 75$, should that solve my problems? And is there a sticky thread on installing it?


I have a '00 426 that I have had since Jan '02. The bike was stock everything and was a total SOB to start. Sound a lot like your situation. I had some time off of riding due to a broken ankle and decided to either sell the bike or tune it. I HATED it.

I did three things that were popular TT mods at the time.

#1 was the A/P set screw mod
#2 was the JamesNOW mod
#3 was the blue wire mod (this one seems to have some controversy after I did it)

The bike was transformed completely, had good hit & low end, never bogged and I kept it.

What I learned from that trial and error was to not twist the throttle at all prior to starting...regardless if the fuel petcock was on or off between rides. Seriously, I put my right hand on the m/c so as to ensure no fuel is added.

My bike under any circumstance is a first kick start even after months of storage now. You might want to try that before you throw $$$ at a cam. I know that there seems to be an issue with the decomp, but its free and easy to install. :prof:

My $0.02 worth.

  • 2001YZF426Rider

Posted March 29, 2008 - 07:56 PM

#17

Well i just supermotoed my bike, and there is no place for the decomp lever, unless i want it on the throttle side, so i got a cam from a buddy for a good deal so i said i may as well!!

I dont have a bog in the bike at all.. And ususally it starts up within a few kicks after sitting, but i always shut the gas off when im done riding, and i forgot to so it sat like that for a month or so..

  • 2001YZF426Rider

Posted April 03, 2008 - 04:37 PM

#18

Ok, grayracer, the decomp plug i posted above i didnt end up getting a chance to bid on, so can you tell me if this one will work? It says it will.. http://cgi.ebay.com/...sid=p2759.l1259

And also, does it go where the decomp cable connects to the lever that goes into the motor? Im not quite sure where exactly it goes, or how to get it in there.

  • grayracer513

Posted April 03, 2008 - 06:11 PM

#19

If it says it will, that's all I know about it. You'll have to remove the original shaft seal to use that one.

These plugs replace the decompression shaft (the part the lever is attached to). Remove the shaft, install the plug in it's place.

  • 2001YZF426Rider

Posted April 04, 2008 - 04:55 AM

#20

Sweet thanks again!!!





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