just bought a YZ426F

30 replies to this topic
  • redneckfyrfytr

Posted August 12, 2008 - 11:35 AM


i doubt i'll be in texas anytime soon. i live in new york state. The redneck portion of it anyways. I've worked on cars and trucks and rebuild a bunch of auto engines but never touched a bike motor before. It shouldn't be to hard. Should I buy the intake and exhaust hot cams or just the exhaust cam? I noticed the other day in the woods, it was usually easy to start when it was hot. I barely even touched the hot start lever on the handle bar (after-market set-up). Anyone have any tips, tricks, or secrets to switchen out the cams?

  • curthall11

Posted August 12, 2008 - 01:28 PM


I just put the exhaust cam in my 2000 yz426f. It was relatively easy if you have automotive experience. Just don't forget to re-shim the valves. Mine kicks over very easy and starts on the first kick every time whether hot or cold. Then you can get rid of the decomp. lever and put a plug in it's place. You can get the plug off Ebay or maybe the TT store.

  • TommyBoyee

Posted August 12, 2008 - 06:50 PM


Not sure if it was mentioned but after starting it let it run awhile before giving it a shot of gas. If you twist the throttle to soon there is the chance of flooding the bike and fouling the plug. I spent all afternoon one time kicking my 426 over. Never thought a four stroke would fuel soak a plug so bad as to foul it but alas it happens. That was a very embarrasing learning experience for me.

  • cdelap

Posted August 13, 2008 - 03:34 AM


I just bought my 426 and changed the plug from a CR9E to a CR9EK. The new plug has 2 points instead of one and seemed to make starting alot easier. Still think I will look into the Hotcams or the Accelerator Pump Mod ... It still is to easy to flood the bike.

  • BASSic

Posted August 13, 2008 - 08:15 PM


The only time I ever had a problem starting my bike was when I cracked the spark plug at the top of the threads by using the wrong plug wrench.

They're not hard to start if you understand how everything works. I won't go into great detail explaining it now because others on TT have done such a better job than I could do, but once you understand exactly how the accelerator pump behaves and understand it's role, starting isn't a problem.

When the engine stalls after running, the hotstart knob may or may not be required. I know my bike enough that I can tell whether I need to hotstart knob or not. If I stall the bike while I was twisting the throttle, then there's more fuel in the intake ports or combustion chamber (because the AP squirted it in there when twisting) and the hotstart is required. If the bike stalls while the throttle was held steady or if I hit the kill switch, the hotstart isn't needed.

The manual compression release keeps my friends from riding my bike because they can't figure it out!

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  • redneckfyrfytr

Posted August 16, 2008 - 12:03 PM


when it comes to the spark plugs... i'm runnin CR9E but they foul almost everytime i'm on the bike, it doesn't really matter if i'm runnin it easy or hard. They still seem to foul out a lot. It's annoying as hell too. I've replace three in the last week. Any ideas of what I should do to fix this problem?

  • BASSic

Posted August 16, 2008 - 12:48 PM


when it comes to the spark plugs... i'm runnin CR9E but they foul almost everytime i'm on the bike, it doesn't really matter if i'm runnin it easy or hard. They still seem to foul out a lot. It's annoying as hell too. I've replace three in the last week. Any ideas of what I should do to fix this problem?

Is your bike jetted properly? Is your fuel screw set properly? I run the stock CR8E and have never fouled a plug.

  • redneckfyrfytr

Posted August 16, 2008 - 01:06 PM


I'm not sure if it'd jetted rite or not. the bike doesn't have more than 20hrs on it. The guy I got it from didn't have time to ride it after he bought it new and other than the occassional ride, it sat in his garage. The only fuel screw i'm familiar with on the bike is the idle screw and it idles ok, Not perfect but then again, i'm not a bike mechanic. I know trucks and old muscle cars.

What ideas do ya'll have for jetting and such?

  • 426ing-in-MD

Posted August 17, 2008 - 04:38 PM


I have had 2 426's the first one had the decomp lever and it was a pan to start and restart. I was getting ready to sell it then it got stolen. I replaced the bike with another that had the hotcam intake and exhaust cams and it was pure heaven!!!! The bike is a beast, power is EVERYWHERE !!!!! I'd advise you to get the hotcams and replace the spark plug frequently, when mine doesn't want start thats the first thing I do. I always give two short blips of the throttle when I start it cold to get fuel in there. Hope this helps, just rode all day today and I am on cloud nine !!!!!

And hey I met a guy once and he told me to go up a size on the main or the pilot jet to make it start even easier (I forget which one becuaseI didn't have to) GOOD LUCK brapppp brapppppppppppppppppppppppp

  • jeffer22

Posted October 12, 2008 - 04:15 PM


i also have a 2000 426...awsome bike. i agree with the above videos with exception to a couple things. 1.) i never "prime" with 1 or 2 throttle twists'!...this actually makes it harder to start (even after long periods of never starting the bike) instead, hold in the decomp lever ind give it 5-6 fast kicks. 2.) i have never had to use the "hot start" button!
after my first few rides i was looking up hot cams with auto decomp just like you...but once you get the hang of starting this machine it is easy as can be! mine literally starts on the first kick every time!

  • herm5877

Posted October 16, 2008 - 03:10 PM


Thanks a million for that video link!!! I have a 2000 YZ426F, I have only had it a short time and the guy I got it from sure told me wrong about starting this bike.I saw that clip and went out to the garage and did just like it said, WOW!! That made all the difference, my bike fired on the first kick!! I was so happy to have found that video link, I can't thank you enough!

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