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MattF

'99 WR400 cam questions

9 posts in this topic

Went in this weekend to check valves and change to yz timing...

Manual states that at tdc, the punch marks on the cam should line up with the cylinder head (before yz timing mod). The intake cam on my bike is positioned one tooth clockwise. There were still 13 pins (timing chain) between punch marks.

Now, after the timing change, both of my cams are rotated one tooth clockwise. There are now 12 pins between the punch marks. Bike runs strong.

I remember reading a similar post on this same subject a while back. The responses seemed to say disregard the position of the punch marks as long as the cam lobes face away from each other and there are the proper # of pins between the punch marks.

I got spooked this weekend when the manual said to make sure the punch marks do line up with the cylinder head or else serious engine damage could occur. :thumbsup:

Anyone have any input on this? Any advice is much appreciated.

On a side note: How much resistance should there be when sliding the feeler guage under the cam lobes to check valves? I can fit a wide range of feeler guages in so surely the amount of resistance is important. Thanks again for any help.

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mattf i'm not sure but i thought only one was moved 1 tooth.

here is this anyway, but if you do a search under the title 13 pins you should get about 9 pages of info.

good luck.

http://www.thumpertalk.com/forum/showthread.php?t=244118&highlight=pins

http://www.off-road.com/dirtbike/jun99/hobbs/

Yeah, that's why I'm confused... the number of pins is correct but the intake cam looks like it has been rotated 1 tooth clockwise (the punch marks don't line up with the head). It was that way before I did any mods to it.

Thanks for the input.

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Sound like you had the same thing happen to you that happen to me. If they are one tooth off from eachother, someone has beaten you to the mod and done it already on your bike... If one is advanced a tooth from the other and they arent exactly in the same upright position at tdc then the mod has been done already. Anyone please correct me if im wrong.

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I messed with mine for ages when fitting a new chain!! The way I understood it, the inlet cam would have it's rear mark level with the head and the exhaust cam would move one tooth clockwise giving 12 pins between the top marks. However, if your chain is worn like the one on mine was, timing it with 12 pins was still giving WR timing because of the amount of stretch! You'll never get it dead accurate when you have fixed wheels on the camshafts so you have to go for a happy medium.

I kept removing the exhaust cam because I was convinced I had it wrong but then it would end up with the marks lower than the head!! When I fitted the new chain I kept the timing standard in the end. Fast enough for me where I ride!!

When checking the clearances, the feeler guage needs to be a nice sliding fit (slight pressure needed to insert and pull it back out (oo er missus)). That's just a case of getting used to it.

Obviously, if cam timing was out a long way, serious damgae would occur because the valves could come in contact with the piston. When you check and adjust the timing, always turn it over by hand (socket on crank) several times to check there is no resistance.

Good luck.

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Sound like you had the same thing happen to you that happen to me. If they are one tooth off from eachother, someone has beaten you to the mod and done it already on your bike... If one is advanced a tooth from the other and they arent exactly in the same upright position at tdc then the mod has been done already. Anyone please correct me if im wrong.

When I first went in, my exhaust cam still had the punch marks lined up with the cylinder head and there were 13 pins between the 12 o'clock punch marks (wr timed). However, the intake cam was clockwise one tooth (or at least the cam sprocket was) because the punch marks did not line up with the cylinder head.

After rotating the exhaust cam 1 tooth, I now have 12 pins between the marks (yz timed). The bike runs great, I was just bothered by the punch marks on the intake cam not lining up.

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Thanks for the replies fellas. Being that she's running well, I think I'm just gonna' ride 'er :thumbsup: . I'll let you know if something blows up! :thumbsup:

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