Do you ride a 426? Please read this.

[YAMABEN]

I can't believe it was this easy, but it works. I just installed the auto compression release YZ 450 exhaust cam in my 2000 426, and it is really cool! It starts easy, like a 450, and it seems to run great. I have a noticable improvement in midrange power, but that is kinda skewed because the engine was so worn out before I took it apart. The power seems less twitchy though. On my first test ride, I rode the best wheelie I have ever ridden on that bike, because it seemed a little more mello in the mid range (maybe it was just me being totally excited).

I don't have any dyno results yet, but I will as soon as I can.

You can retain the stock compression release too, which I always liked for clearing a flooded engine.

I have plans with another member for posting pictures, and instructions.

I like talking tech, so ask me any questions that you might have, and I'll try to answer them.

Otherwise, look for more on the subject soon. ?

[StreetMoto]

How about a break down on the parts needed and the cost?

Looking forward to seeing those pics.

[yamaha.dude]

I know this is exciting, and I am going to be working with Yamaben to get a good write up done on the mod... I will be looking to produce a PDF file, with clear instructions and pictures, as well as part numbers and tips to get the mod done.

At the moment we want you to know this is in early testing, and is something you will do at your own risk. Once we get more feedback and a larger sample of people who have successfully done the mod, and have some miles on it, then we can more confidently recommend the mod... But for us tech freaks and early adopters, it looks promising... stay tuned for more...

Form a queue behind me at the parts counter... LOL

Thanks,

David

[Wyatt]

YAMABEN can be our official exhaust cam dealer ? Boy, if this works, you better get plenty of cams in stock!!!

[John_Lorenz]

Whats the Warranty Like ?

Just had to do a poke

Good luck wil be waiting....

[jmiakaike]

Awesome! i read over on the 250 side that it worked as well, i look forward to the pics and info!!!! thanks again for having the cajones to try it out Yamaben!!!! ? :D

[YAMABEN]

Wyatt-you sound as excited as I was, when I fired that thing up this afternoon. It definitely works, but I need to dyno it to make sure it still makes as much power.

Durability remains to be seen too, but I bet I'll have fun trying to break it. ?

[Hick]

That doesn't totally surprise me, but still, with a totally new head and all I thought the 450 cam would have smaller bearings, shorter distance between lobes etc.

Ultimately, it would be good to know if the timing and profile are the same and if not how they differ...

[YAMABEN]

The only part needed (for my mod) for 01/02 426 bikes is the exhaust cam. The cam retails for about $150.

I also replaced the steel exhaust valves in my 2000 with the titanium valves from a 2002. I felt it was a good idea, because the titanium valves probably use a steeper lobe angle for faster opening and closing of the valve. I was afraid the heavier steel valve would be subject to valve float at high RPM.

I talked with the Hot Cams research guy today though, and he said they use the same cam in 00-02 426s. So it looks like I may have wasted my money on the titanium valves.

I also ordered in a 450 intake cam, because cams are really designed to work together. I was going to use the 450 in cam if I wasn't pleased with the way it ran with the 426 in cam. So far I couldn't be happier with the way it runs, so I might just return the new intake cam and keep the money.

Who knows, maybe I'll try it anyway to see if it makes more power than the 426 cam.

I want to post all the specifics in one place so people can find the info easier. That is why I want to work with Dude to make a thorough post with a simple subject line that people can find easily.

[YAMABEN]

The cam profiles differ for sure. The 450 cam has a smaller base circle, and the overall dimensions are different too. The sprocket is somehow a smaller diameter, but with the same number of teeth (don't ask me how). This does slightly affect cam timing ( it ends up retarding the overall timing a little). The cam lobes are narrower than the 426 cam lobes, which I suspect might cause undue stress somewhere in the exhasut cam or journals.

There can be now way to tell how well this mod will hold up over time, except for some of you to try it and provide feedback.

I promise you though, I am not kind to my bikes. If it's going to break, I'll break it.

[FFRacing79]

Yamaben, you will be able to use lighter valve springs with the Ti valves...possibly the 450 springs?

[Rando400]

Will this mod work for a 99 wr400?

[Wyatt]

Rando400,

It is too soon to know if it will "work" at all. Stay tuned, I am sure that YAMABEN will keep us posted on his progress and results with this project.

[yamaha.dude]

Well, I have the write up done... go to the link below to get the PDF file (approx 78KB) or right click and choose "Save As..."

PDF with 450 Cam Fitting Procedure

This is a work in progress, and remember, it is early days yet... this is a more serious mod to your bike than cutting a grey wire or removing an airbox lid... proceed with caution...

David

[MXOldtimer]

Your BS'n me right! I put a 03 Ecam in my 250F and can't believe the difference in starting, it's just great. If what you are saying is true, I'll be down to my dealer ASAP. This just to good to be true WooooooooooHooooooooooo!!!!!!!!!!

[Penton]

Now is someone could only come up with a diet for the

large world plastic of the 426... ?

[fog527]

SWEET!...you da man ...if it's affordable.The thing is I like the hit of the 426,I don't want to lose that!!!What valves did you use ,the stock 426? The exhaust cam only?...the dyno will tell the story, if you have a good baseline to compare with.I am very interested my friend.

[YAMABEN]

I currently have the 2000 springs, 02 valves, and 450 cam on the exhaust side only. I think I will swap the 00 springs to 02 springs (to match the 02 valves). I wanted to install the ti valve springs (2002), but I ordered them later than the cam and valves, and I just couldn't wait.

If you are asking me are the lighter springs the best thing to use, I would answer I don't know. My reasoning for trying a lighter spring is that a lighter valve might benefit more from a lighter spring. Also the ti valves might actually need a lighter spring to reduce wear on the valve face.

I have talked with 2 different reputable engine builders that have stated they feel that swapping the 2000 head to ti valves would be unnecessary for installing the 450 cam. I was worried that the heavier steel valves would float at higher RPM, but apparently that is not a big problem.

I wish I would have used my steel valves after talking to those engine builders, but I probably will not take the head back off to try it.

[idahusker]

I am very excited and hoping the details and spec's come as quick as possible. Thanks for all the work 'ben and 'dude

[YAMABEN]

I don't have a 400 to try it on, but rest assured that someone will. Do companies like HotCams, or Web cams show the same cam fitting in 400s and 426s? If they do, it stands to reason that the same cam that fits in my 426, would fit in your 400.

I typed in Hot cams in Yahoo and it listed about 7,000 porn sites. ?