OEM Yamaha Exhaust Camshaft retro

12 replies to this topic
  • Todd98YZ400F

Posted December 07, 2004 - 07:04 PM


Gives your '98 through '02 models automatic decompression just like the '03-'04 models. Includes OEM plug for decomp. cable. Nothing else required for installation. (valves must be adjusted on 400 and 426.)

Has anybody done this exhaust cam mod on their 98-02 YZ400/426/450F?

Is it worth it? I seem to have no problem pulling in the decompression lever then releasing half way thru the kick to start my bike. Is that the right way to start it? Thanks.

This is my first dirtbike for almost 15 years. I use to own a '81 RM125 and a 84 XR200R. I bought a '02 Yamaha Raptor 660 a few months ago as well. So I guess I missed dirt riding and now I'm coming back with a vegence...hehe :cry:

  • grayracer513

Posted December 07, 2004 - 07:08 PM


Well, yes....



  • Todd98YZ400F

Posted December 07, 2004 - 07:29 PM


Thanks Gray. It looks like I should not worry about that. I can start up my bike usually on the first kick anyway. Hey, BTW. I seem to have no problem pulling the decompression lever in then releasing it half way thru the kick to start my bike. Is that the right way to start it?


Posted December 07, 2004 - 07:52 PM


NOOOO!!!, Push the kickstarter down untill it gets really hard to push then pull in the decompression lever and push the kickstarter down an inch or so, this puts the motor at TDC, then kick.

  • myoung

Posted December 07, 2004 - 07:52 PM


If it works it is. :cry:

Sounds better than the normal drill if you have perfect timing every single time you kick it. For me, I'll stick to my mindless auto decompress cam. :cry:

  • Todd98YZ400F

Posted December 07, 2004 - 08:07 PM


Yeah, I seem to be able to do it almost every time. I pull the lever all the way in then begin the kick and release it about half way during the kick and the bike starts up. No problem. Is this bad for the bike?

I use to push the kick starter down lighlty until it clicked (TDC) then kicked it over. It just seems faster and easier to use the decompression lever. Is this bad NAFLASH?

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  • myoung

Posted December 07, 2004 - 09:07 PM


The only problem I can see with your method is the possibility of you holding the lever in at just the wrong moment and the piston hits the exhaust valve. The way the lever works is by cracking open the exhaust valve a small ammount to let the compressed air bleed off making it possible to rotate the crank with minimal effort. This is also what the auto decompress cam does, except it is timed so there is no chance of the piston hitting the valve. You are esentially doing what the auto decompress cam does, with the small exception that you don't actually know where the piston is in it's travel while you have the lever pulled in. Pretty risky move, but I have seen other guys that can do this. I prefer the safety of a timed cam, but that's just me.

  • myoung

Posted December 07, 2004 - 10:41 PM


Wait a minute, I just remembered, if you flood these bad boys you pull in the lever and kick away to clear it. That means there's no way you're going to hit the piston on the valve. That means if your method works and you're happy with then go with it. Sorry, it's been so long since I had the lever I just plain forgot you could hold it open and kick through. DUH! :cry:

  • Todd98YZ400F

Posted December 07, 2004 - 11:40 PM


Yeah, actually once you get the timing down it's pretty easy to kick these bikes over. I pull the decompression lever all the way in then I start to kick down, let off the lever at about mid kick and the bike fires right up. It seems to work like a charm. I just want to make sure I don't ruin my bike using this method. I understand the concept of kicking from TDC since the piston travels down with a full stroke. These bikes seem to start up fine at half stroke or less, especially after warmed up. So far I love this bike, it's pretty cool.

I have the upgraded clutch that's easier to pull. It's not hydraulic, it has a longer arm where the cable hooks up (at the engine) to to give it more leverage, it pulls in easy. I have the large tank, brush guards (no hand whacks), IMS shifter, BBR kick start, upgraded suspension by Moto Pro (high quality) set for my weight (200 or so lbs), newer tires, fork guards and after market graphics. I got a good deal from a very nice and cool guy.

  • YZFan

Posted December 08, 2004 - 02:37 AM


I got my cam cheaper at the local Yamaha dealer it was $100 bucks out the door. Good luck.


Posted December 14, 2004 - 06:33 PM


My buddy stripped the kick starter shaft on his 250f doing it the way Todd98YZ400F does it. I admit i did it this way for the first month i had my bike but im pretty sure your supposed to get the motor just past TDC then kick it. But hey if you havent had any probs than all the power to you, start anyway you want to.

  • Todd98YZ400F

Posted December 18, 2004 - 10:05 PM


Why would it strip due to this method? I believe you, I just want to know why. Is it because of the back compression putting too much pressure on the shaft threading where the kick starter clamps onto or the threading inside of the kick starter itself? Could you ask him please? I can see that being a problem if you release the decompression lever too early. The previous owner of my bike installed a BBR aftermarket kick starter. I don't want to strip it so I am interested in your advice. Thanks a lot.

  • Todd98YZ400F

Posted December 18, 2004 - 11:04 PM


How many hours are involved for a professional bike mechanic to install the cam mod?

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