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-   -   YS70 (http://www.rcuniverse.com/forum/rc-pattern-flying-101/10711031-ys70.html)

MAVROS 09-11-2011 12:03 AM

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


Nathan King 09-11-2011 08:23 AM

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. </p>

MAVROS 09-11-2011 06:21 PM

RE: YS70
 
Thanks Nathan,

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

many thanks


regards

Mavros
:D

Nathan King 09-12-2011 06:14 AM

RE: YS70
 
http://tech.flygsw.org/ys_basic9.jpg

hou_zhenyu 09-28-2011 10:12 PM

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.

MAVROS 09-29-2011 08:27 PM

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
:D


bjr_93tz 09-30-2011 01:47 AM

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.....

MAVROS 09-30-2011 08:20 PM

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

:D

tande 10-01-2011 01:00 PM

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.....

MAVROS 10-01-2011 03:03 PM

RE: YS70
 
Hi tandee,

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

many thanks

MAVROS
;)

tande 10-01-2011 03:28 PM

RE: YS70
 


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....

bjr_93tz 10-03-2011 02:52 PM

RE: YS70
 


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...;)

Jon Wold 10-03-2011 11:43 PM

RE: YS70
 
1 Attachment(s)
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.

MAVROS 10-04-2011 01:36 AM

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:D

tande 10-04-2011 09:54 AM

RE: YS70
 


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:D
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....

bjr_93tz 10-04-2011 02:28 PM

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.


tande 10-04-2011 03:44 PM

RE: YS70
 


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 ;)

MAVROS 10-07-2011 02:01 AM

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 :D:D

regards

MANY THANKS

MAVROS


tande 10-07-2011 04:44 AM

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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