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eduardo426

Installed the cams...something weird is happening.

11 posts in this topic

My 426 used to ride like a champ, but due to my insaciable quest for performance that i dont even use, i installed a Wiseco high compression forged piston, a set of HotCams and an YZ426 cdi. I timed the cams as i had them before, YZ timing, and now i have a serious problem to solve (or maybe not). I havent tested the bike in the woods yet, i only took an half an hour spin on the road because the guys at HotCams said that i needed to break-in the cams at midlle rpm`s and not to let the engine idle. So i did. The bottom and midle range is stronger without a doubt, even a woman could notice the changes, probably due to the raise of the compression ratio from 12.5/1 to 13.5/1.

You can even notice the extra strenght you need to do on the kick starter.

Back to my problem...when i am riding with 1/4 throtlle opened the engine is not smooth, in other words, the engine goes .....pof.......pof..pof.......pof.......pof..pof.....pof.....

This type of failure only disapears at 1/2 to full throtlle. I have to consider the spark plug wear too. I never changed it before. Its still the factory one.

Can some of you give some ideas on how to make that "failure" go away??? Is there any good jeting mod for my case???

Thanks.

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You cam timing is off.

Do the hot cams have adjustable cam gears?

If so I'd recheck the timing.

The cams should look something like this when they are timed right.

fb3f0bf6.jpg

NOT LIKE THIS

fb3f0bd9.jpg

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Sounds like quite a project! You are braver than I.

Definitely sounds like you will need to make some jetting adjustments though, but I would think that would be expected with all the other changes you made! I am sure someone here will be able to help you, but I would suggest posting your question in the jetting forum.

Good luck, I am sure your bike is gonna rip!

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Assuming the bike is timed properly, I would address jetting. Post your jetting specs. I just went through this on the WR426 I recently acquired.

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I would think that if you were going to go threw

all that work you would put a 450 cam in that bike

with the auto decomp . I put one in my 426 and I

have run 30 gal of gas in that bike with NO problems

. good luck with your project . :):D

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Eduardo426

How are the paint marks lined up on the cams in relation to the head?

Well, from what i understood, the adjustable cam gears are pre-set from factory. I havent touched this adjustment. The cams went fine with the WR timing adjustment, as i have in my manual. All the cam marks seem to be in place with the crank mark. But i changed the exhaust timing one teeth clockwise, as you would do to get Yz timing. I dont know if they work better with Wr timing...i didnt tried it, since these cams fit Wr and Yz.

The bike still starts great and easely and idles with no problem. Today i will get a new spark plug just to test. Sunday is off-road morning for me and friends and i dont want to experience anything unusual while we are alone in the woods, a long way from the nearest road.

As for my jetting, its stock except for the main jet wich is the larger one that comes on the Wr kit.

REMEMBER- my bike is that one with the welded tip, when i saw the post about the free mods some months ago when i registred, i started looking for that grey wire and throtlle stop but they werent there. :) I believe you guys have this bike as a Canadian version. The stock jetting is different from US specs from what i`ve seen in the manual, but any help would be much apreciated :D

PS- Just a curiosity...i spend money on performance mods but i admit that some of them i dont even use because i`m not a professional rider nor Arnold Schwarzenegger but i have the "missfortune" to ride with another 8 local friends (the rest of the people here all have quads :D...almost everybody sold the two wheels for those) and these guys ride a few Cr500r, a 93 Wr500 2 stroke (weird and rare bike) and the only thumpers are me and a KTM 620sc guy. As you would expect, my Wr has to use every bolts and bits to not let the others go away :D

Eduardo :D

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The Hot Cams are not timed by YZ, or WR specs. They are timmed where we got the most usable power, and should be installed striaght up, with the center paint mark on the cam in the very center at the top. If a person wanted to change their timing then they should use a degree wheel. By retarding the exhaust cam one tooth, you get into very dangerous territory, when it comes to piston to valve clearance. Also do you know what your valve lash is set to?

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The Hot Cams are not timed by YZ, or WR specs. They are timmed where we got the most usable power, and should be installed striaght up, with the center paint mark on the cam in the very center at the top. If a person wanted to change their timing then they should use a degree wheel. By retarding the exhaust cam one tooth, you get into very dangerous territory, when it comes to piston to valve clearance. Also do you know what your valve lash is set to?

Ooopss...i thought they could be advance or retarded like the OEM ones...

I`ll try for the factory marks and see if it works better.

Strange, because the bike still runs great and starts great, even with the modifed exhaust timing, except for that low end of course.

I`ll give it a try. As for the degree wheel, a friend of mine who helped with the install (owned an Yz400 98`and now is the 620sc guy) did that adjustment and cheked the valve clearence but thats one thing i cant discuss about, since that technical stuff is not my territory. :D

I`ll let you know the details further ahed when we got the timing straight (maybe tomorrow morning.) :)

Thanks for all the help.

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