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YS70

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Old 09-11-2011, 12:03 AM
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MAVROS
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Default YS70

Hi all,

Just wondering if anyone can show how to set the timing on YS70 after reassembly of entire engine.

There is a mark on the back of the crankshaft but it doesnt line up with anyting.

Many thanks

Mavros

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Old 09-11-2011, 08:23 AM
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Nathan King
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Default RE: YS70



Insert the crankshaft at top dead center with the keyway and rod journal up. Then insert the cam with the timing mark directly over the bottom screw hole.

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Old 09-11-2011, 06:21 PM
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Default RE: YS70

Thanks Nathan,

Which bottom screw are you refering to...the one on crankcase ...can you draw diagram maybe

many thanks


regards

Mavros
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Old 09-12-2011, 06:14 AM
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Old 09-28-2011, 10:12 PM
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Default RE: YS70

However, in the manual of YSFZ70S, it said

"Then installing the came gear, the side with a point mark should be facing the opening of the gear box. Note that is should also be mounted with the point mark located towards the top of the engine just below the cam followers."

Which is oppisite to the picture. Which one is correct or both works?

In fact, recently i disassmbled a FZ115s, which has the same note in the manual. I followed what the manual said but found that the tappet clearance is huge after the reassembling. After adjustment, the clearance is go back to what's suggested but I'm still not fully confident I did it right.
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Old 09-29-2011, 08:27 PM
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Default RE: YS70

Hi There,
I have reassembled the YS70S as per the picture but cannot get it to fire up.
It spits a lot of fuel through the carby but will nt fire.......back to the work bench.....will not give up yet

regards

Mavros


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Old 09-30-2011, 01:47 AM
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Default RE: YS70

If you got the cam in 180deg out of wack and haven't bent a valve then quickly go out and buy a lotto ticket....

Even though I'm "sure" nothing moved when I changed the timing belts on my Goldwing, I still turned the motor over a couple of times by hand to make sure nothing clashed, and the marks still lined up before hitting the starter button.....
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Old 09-30-2011, 08:20 PM
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Default RE: YS70

Hi again,

Not sure about your goldwing but the YS70 will not start unless the timing is spot on eventhough the engine will turn nicesely....

regards

Mavros

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Old 10-01-2011, 01:00 PM
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Default RE: YS70

FWIW....You need to start over....TDC is NOT related to ANYTHING....The dot on the crank should point straight down at 6:00 ....This is NOT piston TDC....Now install cam with timing dot pointing straight up at 12:00.....
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Old 10-01-2011, 03:03 PM
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Default RE: YS70

Hi tandee,

This is opposite to the previous post but I will give it a go......

many thanks

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Old 10-01-2011, 03:28 PM
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ORIGINAL: MAVROS

Hi tandee,

This is opposite to the previous post but I will give it a go......

many thanks

MAVROS
The IMPORTANT point is the dot on the crank must be at 6:00.....Since the cam rotates at 1/2 crank speed it can be installed with the dot at 12:00 or 6:00....Makes no difference, if installed at 6:00 then one complete revolution of the crank & the cam dot will be at 12:00....
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Old 10-03-2011, 02:52 PM
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ORIGINAL: tande
The IMPORTANT point is the dot on the crank must be at 6:00.....Since the cam rotates at 1/2 crank speed it can be installed with the dot at 12:00 or 6:00....Makes no difference, if installed at 6:00 then one complete revolution of the crank & the cam dot will be at 12:00....
It's obvious now that you mention it.

I should wear my thinking cap more often instead of my tin-foil one...
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Old 10-03-2011, 11:43 PM
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Default RE: YS70

Cam timing mark: UP
Crankshaft timing mark: DOWN

When you assemble the parts this way, the piston is at TDC. Pictures shown are taken from a 170 DZ, but I assume the 70 is similar.
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Old 10-04-2011, 01:36 AM
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Default RE: YS70

Hi Jon,

You are correct ...the TDC occurs when the mark on the crankshaft is on the bottom and the mark on the cam at the top.
The YS70 will not start otherwise.


REGARDS AND MANY THANKS TO ALL FOR YOUR HELP..

MAVROS
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Old 10-04-2011, 09:54 AM
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ORIGINAL: MAVROS

Hi Jon,

You are correct ...the TDC occurs when the mark on the crankshaft is on the bottom and the mark on the cam at the top.
The YS70 will not start otherwise.


REGARDS AND MANY THANKS TO ALL FOR YOUR HELP..

MAVROS
Guys....I'm not trying to rain/on/your/parade...but, TDC & the crank punch/mark at 6:00 are NOT one & the same! ....I have no idea what method you're using to determine TRUE TDC, but IF you are setting the cam punch/mark at 12:00 along with TRUE TDC, then you may or may not have hit on the correct tooth engagement....Will the engine run with the cam timing off one tooth?...ABSOLUTELY ...Will it run like "Yamada" intended? ....ABSOLUTELY NOT....
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Old 10-04-2011, 02:28 PM
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Default RE: YS70

Yeah, it's pretty clear (in the YZ170 at least) that the crankshaft dot lined up with the seam in the bottom of the case isn't top dead center.

It's really really close but it's not.

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Old 10-04-2011, 03:44 PM
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ORIGINAL: bjr_93tz

Yeah, it's pretty clear (in the YZ170 at least) that the crankshaft dot lined up with the seam in the bottom of the case isn't top dead center.

It's really really close but it's not.

Good Eye!.....Thank You
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Old 10-07-2011, 02:01 AM
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Default RE: YS70

Hi again,

Just to justify my curiosity I pulled the YS apart again and Tandee is 100% correct the piston is not quite at TDC when the mark on the crank is at 6 oclck and cam at 12 oclock.

Prety close but not quite.......however It does work and engine runs nicely.

Maybe we should leave the TDC alone and talk about the marks instead

regards

MANY THANKS

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Old 10-07-2011, 04:44 AM
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Default RE: YS70

Maybe we should leave the TDC alone and talk about the marks instead
You/Got/It! ....(but only if you want to be sure your cam is timed correctly; the difference is worth approx. one tooth engagement )
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