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Discussion Starter #1
I've read 2 references to tdc. First between the 2 lines with the dash between (on the crank). Second is the 3rd line. After putting a screwdriver in the plug hole I've found the third to be true. But do I put my cam mark at tdc the same as the 3rd mark on my crank?
 

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You can also take down the camshaft sprocket cover and align the mark on the sprocket... I find it easier.
 

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Discussion Starter #4
thanx. but what im trying to ask is while my crank is at tdc (3rd line). should my cam sprocket also be tdc.
 

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thanx. but what im trying to ask is while my crank is at tdc (3rd line). should my cam sprocket also be tdc.


Yes, crank at TDC (3rd line), the cam sprocket has a line that should point to a cast in pointer on the head, it's just a little triangle, looks a bit like an arrow head.
 

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Yes, crank at TDC (3rd line), the cam sprocket has a line that should point to a cast in pointer on the head, it's just a little triangle, looks a bit like an arrow head.




uktw125,



I've not had to tear my engine down, nor do I hope I have to anytime soon, but as a bystander, I appreciate your assistance you give to other forum members with some of their technical questions.



Just wanted to say thanks.
 

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This is as good a place to put this as any, I guess.



On my '96, when the crank mark is where I think it should be:







The camshaft mark isn't:







When the cam mark is lined up properly:







The crank mark is past:







Any ideas?



Just came to me, I've got the head off, so it will be easy to see if TDC of the piston is the same as the crank mark.
 

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Either your cam timing is one tooth out or your timing chain is very worn. Did it run well without any bad rattling.
 

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Either your cam timing is one tooth out or your timing chain is very worn. Did it run well without any bad rattling.


Yeah, runs fine, no rattling, sprocket looks good. 1996 with 6500 km, so camchain shouldn't be worn out yet. Adjuster still had room to go:



 

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If you drill out the core of an old spark plug and insert a piece if steel rod with a smooth rounded bottom end that is a good fit in the drilled out hole it make a good TDC indicator.
Make sure the rod has a bigger end at the top to stop it dropping into the cylinder...
Running the T Dub with the cam chain a tooth out from the correct place on the top cam chain sprocket isn`t ideal, it might run mostly OK tho`.
A piece of wooden or plastic dowel straight into the spark plug hole works with care if nothing else is available, make sure irs too long to drop all the way in.
 

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If you loosened the cam chain adjustment screw all the way and turned the camshaft counter clockwise and/or the crank clockwise, would the marks line up?

When assembling the engine, how does the manual say to do it?

As long as the engine is running well I wouldn't worry about it.

And I would use the straight up mark on the cam sprocket to adjust the valves.

EDIT: I just noticed this thread is over 2 years old! Wonderful!
 

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I've changed lots of cam chains on a KLX and the marks do begin to vary as the chain wears. There is a 10 or 20 link spec on when the chain should be replaced. Usually about 10k on the KLX and probably about the same on the TW. High RPM's will wear the chain a littie faster.

But yeah, I usually figured if there was adjustment left, the chain was good to go.

I use a dial gauge to find TDC. Quite a bit more accurate. The dial gauge will rule over either of the marks.
 

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This is as good a place to put this as any, I guess.



On my '96, when the crank mark is where I think it should be:







The camshaft mark isn't:








Just came to me, I've got the head off, so it will be easy to see if TDC of the piston is the same as the crank mark.
Doing the cam chain myself on my '06 (theres an older style cylinder on it so it has the manual adjuster) and noticed the same thing.

TDC on crank:



camchain sprocket:



And obvious the reverse if I line up the camchain. I'm sure it didn't skip a tooth because its closest to the tooth its on (much like your pics). I'd be worried if when crank was on TDC the sprocket indicator was closer to another tooth.

my adjustment was about 5mm, I moved it right under flush with the bolt:



I was thinking about the 'stretched' chain thing though, wouldn't it go slack the other way if i rotated the crank slightly backwards (clockwise)? Just a degree or so on the crank, if its rotated, and the chain/sprocket is 'worn' wouldn't it go 'out of spec' the opposite way?

Basically i'm wondering if its just an acceptable tolerance.
 

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using a gauge/straw/wire/flashlight to determine actual tdc and also using the cam marks would be the most accurate.

the only thing that could be out then is the pulsar magnet and i assume that's keyed to the crank.

on my '90 with 14 000kms and undoubtedly the original chain, the cam mark is dead on at actual tdc.

maybe there are slight variences in connecting rod length, leading to the discrepency between crank and cam marks.....
wouldn't take much.

what? i'm half serious.

edit: actually, that wouldn't change the relationships between the marks; it wouldn't even change the relationship between any marks and actual tdc. it sure would change the compression ratio tho.

"fully engage brain before typing" i guess.

-
 

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I did my base gasket today on my 2004, the cam sprocket was dead on but the crank was a little before the mark/pointer. I put it back together the exact same way and it seems to be the same ..I can't tell any difference. So I guess one tooth out either way does not hurt these bike?
 

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I did my base gasket today on my 2004, the cam sprocket was dead on but the crank was a little before the mark/pointer. I put it back together the exact same way and it seems to be the same ..I can't tell any difference. So I guess one tooth out either way does not hurt these bike?
a tooth would be a lot. i'd say mine above was about a 1/4 tooth.
 
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