Valve timing problem

[grizld1]

Forget it? Hell no, give yourself some credit! Everybody who can remember doing this job for the first time is going to find something to relate to in your thread, and for others, it brought out a lot of details that usually get skipped in how-to articles. Good stuff!

 

[Gordon]

No way Pablo, this is gonna haunt you FOREVER! Just kiddin'. Hey, I know I've done some thing's that, once I got it, felt lower than whale shit. Like the carb's on mine. Could not understand how the damn diaphram's opened for the life of me. Then, once I got it, boy ,was I 'blind'.

 

[Sundie]

In the same vein... (thought of making a new thread, but might as well keep all the dumb questions in one thread)

According to the colouring book (Haynes Manual):
Inlet opens 36 btdc
Inlet closes 68 abdc (112 btdc)
Exhaust opens 68 bbdc (112 atdc)
Exhaust closes 36 atdc

A: the numbers in brackets i've calculated - anyone care to confirm?

2: i saw earlier in the thread "intake opens 47 BTDC" thrown out as a number... Is the colouring book wrong?

Pi: i'm not concerned with total accuracy - all i want to make sure is that i have my cam set right. So, what i've done is set the valves at *almost* zero lash, and basically wiggle it until i can feel pressure starting on it - is this a good/bad method? As i said, i'm not concerned with bang on blueprinting - just a general "that's as good as it came from the factory" thing.

D: i'm using this wheel i found online, artistically glued to cardboard
http://www.thegsresources.com/files/degree_wheel.pdf
Is there a better one out there anyone knows of?

 

[inxs]

- numbers are accurate
- 47° BTDC is for early models XS1-2 intake valve-open
- wheel is ok

 

[Sundie]

http://www.thegsresources.com/files/degree_wheel.pdf

Gah. I just realized that wheel is for turning clockwise. Confusion abounded. Don't use it, or ignore the "intake/exhaust opens/closes" notices.

 

[inxs]

- no, i think its alright

 

[inxs]

- rotor turns anticlockwise, so ABDC is on the rhs as is BTDC...ATDC is on the lhs, as is BBDC...which is what that wheel shows

 

[Sundie]

Er, no. (oddly, i got an email notification that you had posted exactly how i had edited the wheel, but i don't see it here now?) The wheel is from the link is designed for turning clockwise. it's for a v-8 whatchamacallit.

Anyway - the wheel moves counterclockwise, ATDC is RHS of TDC for an XS650.

(concession: if the wheel was static, and there was a dial moving around it, it would be correct)

 

[inxs]

- yes, youre right ... ive just checked the yamaha XS1 manual, p30 gives the right diagram, pity my scanner has sucked a kumara

If you can't understand it, it is intuitively obvious.

 

[Sundie]

Like So....

 

[inxs]

-

 

[Sundie]

For those who don't have QR readers....

 

[Travis]

What's the point of putting a QR code on something like that?

Just found an app for my android phone to read it though called barcode scanner! pretty cool...

 

[Kingwj]

Forget what? I just used the marks to set my cam, is that not good enough? And how do you change the timing without an adjustable sprocket on the cam?

 

[angus67]

the cam chain tensioner fine tunes the timing after the cam is installed correctly. Right, Guys??

 

[Sundie]

QR Code: no point. It's actually counter productive. That's why it's art hanging on my wall now. I used the plaintext one for actual timing.

The point of a timing wheel: well... self evident. You can check to make sure everything is correct. While it's not so critical in these engines, cams *do* wear, and you *could* be out. Or if you get a performance cam (especially regrinds) there's potential for it to be just plain wrong. Had that happen before.

Cam chain tensioner: nope, it doesn't fine tune anything - all it does is make sure that the feed is straight, and adjust for wear.

 

[jay760]

Is there any differance in the later cams (the standard and special) and if there is how do you know which is which?

 

[xsjohn]

Not sure at all about the early engines.........but after moving cams for people I have leaned some things.....When raising the head on mine to get it right for 8-1 I had 3 cams here........2 were marked 447 and all degreed the same....one a 79 and one an 80......the third degreed the same and the lobes looked identical but has no 447 marking on it...came from my spare engine which I think is a 76 or early 447...not sure of the year because there is no vin numbers on the cases....got the engine from a Yamaha mechanic and I think he bought the cases new....?........form all of this I assumed that all the 447 engines used the same cams.....if anyone knows different I would be interested in knowing........ I just move the cams per how much the customer is changing the deck height........

xsjohn

 

[angus67]

well, if the cam chain tensioner doesnt change the timming, then what do you tweak to adj. the timing, other that John's methods? Sorry if I dont get it, I just dont see another way to do it, and, no, I havent actually done it using the tensioner. This is my first real engine.(motorcycle)And I have yet to start it, although close.

 

[xsjohn]

The chain is tight across the front and this keeps the cam in time with the crank......a worn (stretched out) chain would retard the cam timing a bit.......I supose Yamaha set the cam timing specs with a new chain.......can open the valve adjusters to retard the timing if you can stand the racket .......closing them below factory specs to advance it will pit the valve tips from lack of lubrication........the later .0025 intake setting will take out the valve tips as I found...........lack of oil in the rear is a problem anyway.........that's the reason they tick at .004....mine is dead quiet with the added oilers I put on 40K ago........the dam on the cam tunnel prevents oil going back also...could be notched for more oil back there....never tried that myself...most of the oil is slung forward from the oil coming down from the top of the cam anyway.......the hole for the oilers I re-adjusted to .022 thou....directing oil from a slot in the dam with a small bill welded to direct the oil slinging toward the tip may do the same thing.....sorry for the rant........xsjohn