Hi
I reassmble my YS-110FZ after replacing the bearings, and piston ring but the engine dosen't want to work...

i wasn't able to start it at all but then after many attempets i finally managed to start it but the engine was running at low r.p.m for few seconds ( no matter what was the throttle position ) and then it dies

i tried it severall times but it was the same oncwe the engine start it works for few seconds and then it die..

it looks to me that the engine is starving for fuel but after those few seconds of working there was perssure on the tank when i release the check valve

any ideas ?

Thanks

1 - TAPPET CLEARANCE ADJUSTMENT

2 - CAM GEAR TIMING ADJUSTMENT

Are both correct ?

1) Yes

2) I put the crankshaft dot at 6:00, and the camgear dot at 12
there is no reference dot on the crankcase so it's bit difficult to see if it's 100% aligned with the crankshaft dot
so i will remove the backplate, and reacheck it.

I'm confused. Is your engine dripping fuel from the carb or do you mean fuel starvation? Drom what you are describing I think you mean the engine is not geting enough fuel.

Double check your cam timing and also make sure nothing is obstructing the passages from the fuel nipples to the regulator.

it's very strange becuase it looks like it's driping fuel from the regulator screw.. it's like the fuel flow is blocked and when there is no other place to go it's starting to drip from there , but then after several attempts it started to drip fuel from the carburator..
i disconnected the fuel line that connects the left nipple to the HS needle body and i spin the engine by using starter, and i saw that the fuel is flowing ( although it's wasn't constant but more like in pulses )

selnekav,

The drive washer mark should point up at th 12 position not 6, mine does not have the mark on the drive washer, so I put it a TDC (Top Dead Center), the cam is good as you installed it at 12, and install the dot in the cam gear in a position close to 12 as it will not be exactly 12 but very close to it's left.

Regards

what do you mean "very close to it's left" ? like 11:55 ?

Yes.

I believe the CAM gear mark should be at the 12:05 position when the piston is at TDC. 11:55 is probably 1 tooth retarded.
Skids

Yes, that's correct, retarded will give better performance than advanced. Anyway, around 12, and try what works best if it does not actually fall exactly at 12. There is not such thing as one tooth retarded, is the fact that most YS never get at the perfect 12, so if it can not be at perfect 12, then you have to choose fwd or aft, I choose aft.

Thank you it will be easier to check it like that rather then remove the backplate

by the way is it possible that i fasten the disk valve screw to much ? is that can cause some issue ?

Yes, it should not be that tight, not loose either, as soon as it stops turning with my wrench(the bolt) I turn it 1/8 of a turn more, that's it. You should be able to turn the disk by hand easily, not freely, but it should need the same force to turn from start to stop, as long as you don't feel there's like an extra torque to start moving it and then it reduces the amount of force, if that happens then is too tight.

Well I set my motors up as they were set from the factory. As for what gives the best performance I can not speak to the effect of change by moving the cam gear off the factory setting. I can however speak as one who has owned many of these motors from .91-1.40. My motors have always performed perfectly at their factory settings.
Jimmy Skids

Just my two pence worth..

Check the tapet clearences are correct after you reassembled the engine.

Union

Union,
Great advice! I left that out.
Skids

Jimmy,

I think you got the wrong idea from my comment, I have owned almost all the YS four strokes versions, and in the manual says to have the cam gear at 12 o'clock, and in several models is mechanically impossible, that's the reason for the suggestions, so if that is the condition, then is when you install it as close to 12, but you will have to choose forward or aft of the 12 position.

Review the post again and you will see I say to do that if it does not fall exactly at 12.

Regards

Understood, basically I have looked at all my motors and when I look at the cam gear with the piston at TDC the cam gear is just past 12 o'clock on the motors from the factory. As such I just make sure to place it in the same position when I reassemble the motor. Either way as Union stated, it is very important to check the valve adjustment when ever you have the crank or cam gear out for servicing upon reassembly.
Skids

If you know that all other items are correct.
Step back and look at the fuel line setup.
It is very easy to get your lines routed wrong and to install the check valve in the wrong spot or even backwards.
Start at the beginning do a methodical check.
Good Luck.

Hi, just want to add my 2 cents worth because I had a similar thing with mine when I first went to put it back together after replacing the bearings.
When you remove the backplate , you will see that in the rotating disc there is a rectangulr hole which must line up with the end of the crank that sticks out slightly through the conrod, which is also the same shape as the hole in the rotating disc.
It can be assembled incorrectly and still give you some pressure in your tank, but it will not work as intended.
Just rotate the disc to line up with the end of the crank. Reinstall your backplate and away you go.
To check it is correct remove the carby plate as well and you can see if the disc is moving at exactly the same time as you turn the prop shaft.
Hope this helps.

If memory serves me correctly, when the dot on the crank is at 12:00, the piston is not quite at TDC. I seem to remember Richard telling me to line up the dots, and not use TDC. A call to him would solve it for sure.

775-267-9252

Blessings, Terry