Cam Direction



14 replies to this topic
  • Guest_Guest_*

Posted January 22, 2001 - 09:28 AM

#1

Hello guys. I have a dumb question, that has been bothering me in the service manual. when doing the valve, the cams should be facing away from each other when the piston is at TDC on the compression stroke. What it does not say which is bothering me is if they should be exactly the oposite direction. right know mine are facing up slightly. Should the cam lobs be perpindicular to the lifters which are at a slight angle, Or should they be parallel to the cylinder head......any help would be grate.......

  • Guest_Guest_*

Posted January 22, 2001 - 10:02 PM

#2

I noticed that as well when I did my valves. When I lined the dots up parallel w/ the head the lobes were not parallel. Thats how I left it and it seems fine.

Nick

  • Sandracer_uk

Posted January 22, 2001 - 10:25 PM

#3

i believe this is due mainly to wear in cam chain etc, but they never line up exactly.
maybe the factory bikes do

  • Taffy

Posted January 22, 2001 - 12:33 PM

#4

the picture in 4-22 is correct. both cams should point away from each other & a face on each lobe will be parallel to the top of the cylinder head. the letters etc never line up, they are hell.

set the engine at tdc & draw literally like an artist the arrangment, take a photo even. if you only kew it, there is a big increase in power to be found in timing the cams correctly at a race tune shop.

Taffy

Taffy

  • Guest_Guest_*

Posted January 22, 2001 - 04:40 PM

#5

hey guys, right now I have one cam lob faceing up above the cyclinder head and I have the intake parallel to the head. a difference of about 2 teeth. is there anyway that the chain could slip over that many teeth? the bike runs like s*&^. The thing is that the darn punch marks are still lined up with the head.

  • Hick

Posted January 23, 2001 - 07:06 AM

#6

I don’t think the chain could skip teeth unless something was obviously wrong with the tensioning system, cam wheels or chain.

There are more than one set of marks on the cam wheels, are you verifying TDC by aligning the marks on the flywheel and ignition cover?

Maybe your cam wheel rotated on the cam somehow, I believe I read another post here where that happened. If so you can get a new camshaft or have a new gear pressed on.


[This message has been edited by Hick (edited 01-23-2001).]

  • Guest_Guest_*

Posted January 23, 2001 - 08:09 AM

#7

Hick,
I made sure that everything was lined up. the marks on the flywheel, ect. Is there any way to check to see if the cam gear is slipping. Thanks......

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  • Hick

Posted January 23, 2001 - 09:02 AM

#8

Originally posted by Spud:
Hick,
I made sure that everything was lined up. the marks on the flywheel, ect. Is there any way to check to see if the cam gear is slipping. Thanks......


If the motor is at TDC, the marks on the cam gears line up roughly with the head but the exhaust lobes are pointed skyward then I’d say your gear HAS slipped.

Taffy had aftermarket wheels pressed on his cams so he could degree them, I believe he used a dial indicator to do this. I think he said YZ exhaust timing was 101 DBTDC, I’m assuming that is at .000 of lift. (?)

That doesn’t seem right, that must have been 101 degrees @ max. lift.

I degreed the cam on my Chevy but I got an idiot-proof degreeing kit.

Taffy?


[This message has been edited by Hick (edited 01-23-2001).]

  • Taffy

Posted January 23, 2001 - 02:10 PM

#9

hick

i've read your threads & respect your views, so calm down with rumours. to repeat them is to enforce them.

spud, i went to falicon cranks, in clearwater florida & got a pair of camwheels that have a press fit inner hoop & an outer hoop that can be slid around & pinch tightened wherever you wish.

how about you posting, with a little help from a techno wizard, a picture of the engines top end at tdc for us?

if we did that first we could then definately say that the wheel has slid on your cam. nobody, as i'm aware of, has actually said, first hand, MY CAMWHEEL SLIPPED!!!

spud have you checked against your workshop manual & against the photo in our technical section.

Taffy

  • Guest_Guest_*

Posted January 23, 2001 - 03:08 PM

#10

Well guys, now I guess I can actually say that my cam wheel sliped. I went down to the yamaha dealer today and he had an extra set of cams in the service department. I held them up against the ones I had and you can tell that my intake cam gear has sliped. Just by looking at it I would say at least two teeth. Know I have the problem of what I want to do to fix it. A new cam goes for $205. I'm just a poor college student.
Taffy how much was that kit from Falcon.Any ideas would be grate......Thanks

  • Hick

Posted January 23, 2001 - 04:08 PM

#11

Originally posted by Spud:
Now I have the problem of what I want to do to fix it.


Spud,

I hate to depress you further, but that isn’t your only problem.

You need to figure out why this happened or it may happen again to your new $200 part. I would have the valves removed and checked for bends and binding in the guide and possible contact with the piston. Maybe you had an exhaust valve stick, maybe overly tight clearance caused it.

The point is that other parts (buckets, piston, valves) may have been damaged as a result of this (or the cause of this) in a much less obvious manner, waiting to fail and REALLY ruin your day.

Here’s Taffy’s Falicon cam wheels post from the WR side.

Taffy,

If some guy on the WR side says his cam wheel slipped I’ll believe him, unless there is an obvious reason not to. Why it happened is a different matter entirely, which I don’t claim to know with any certainty.

If I’ve misquoted the cam timing that you measured I apologize (and will chalk it up to the language barrier), I wrote it down from an earlier post of yours for future reference. I thought it might be useful information, and if I understood things properly it likely would :)

[This message has been edited by Hick (edited 01-23-2001).]

  • Guest_Guest_*

Posted January 23, 2001 - 04:58 PM

#12

Hick, the reason that yamaha could come up with, for the cam gear to slipp was that there most of been some type of ceasure on the cam. wich they might be right. I looked at my intake cam cap and you can see some pitting and scrapes on the cap wich would be from a lack of oil to the cap. So maybe one of my oil holes is pluged up. I have not checked it yet.

Now about the head and the vavle. I took the head down to a head shop. and had the guy look at it he said that there was a little leak on the valves, but nothing that would require a valve job. I hoping that sence the valve don't leak that nothing is bent or hurt to badly.....Any ideas

  • Taffy

Posted January 24, 2001 - 03:41 AM

#13

out the top of my head i recall that the cam timing was found as follows:

inlet maximum lift @113 deg ATDC
exhaust maximum lift @101 deg BTDC

these figures were changed to:

inlet retarded (4 deg) to 108 deg ATDC
exhaust advanced (7 deg) to 108 deg BTDC

when the head was torqued etc these figures may have moved one degree but they were the one's i was aiming for.

each of the teeth on the camwheel is worth 22 1/2 deg @ the crank. there are 32 teeth. 32 x 22 1/2 = 720 deg.

don't forget it takes two whole turns of the crank for the camwheels to do one whole turn.

you could have told if you had a problem two ways. with a compession tester or if the tappets had loosened.

i would be tempted to put a light weld from camwheel to falicon camwheel or KISS & go with the new cam c/w camwheels as i've previously mentioned.

Taffy

  • Guest_Guest_*

Posted January 24, 2001 - 04:25 PM

#14

Taffy,
When you had your Falicon Cam gears pressed on did you see any indexing marks on the cam. If not what did you do. I talk to the Falicon people today, my gears should be in on friday. I looked at your post on how to set it up, and it seems pretty simple so I will give it a try. Are you still using the cam gears from Falicon? Did you notice that big of a differnce just by being able to move the cams over afew degrees.

  • Guest_Guest_*

Posted January 25, 2001 - 04:45 PM

#15

Question. Are the 426 cams in roller bearings or are they riding in a bushing?





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