YZ 125 Not starting - Please Help - Timing???

[theBIGnaud]

9 minutes ago, Cjj.243 said:

 

 

After trying everything I had no luck. But when I was trying to bumpstart it, it always backfired so maybe timing. So I pulled the flywheel cover off and the mark on the stator and the arrow line up exactly but at TDC my mark on my flywheel is not lined up with the stator mark does this mean anything? Is the flywheel mark suppose to line up at TDC?

I would take a look at a manual but the stator should line up somewhere at 10* Before TBC

[TommyCrown]

Yes. (It will be a fraction before TDC, but to the eye it will look like TDC)

[mlatour]

Recently rebuilt engine, if by chance you replaced the crankshaft, is it a stock OEM crank or aftermarket ?

(possibility of the Woodruff key timing being off on an aftermarket crank)

 

You didn't mention what model year YZ125 but as an example, the 2010 service manual specs

those timing marks should line up when the piston is 0.48mm (0.019") BEFORE reaching TDC.

Edited July 16, 2018 by mlatour

[Cjj.243]

6 minutes ago, TommyCrown said:

Should be if it is the correct flywheel. If you have all these lined up the end of the shiny metal strip on the outside of the flywheel should be very close to the round pickup coil. If it is not, then the flywheel is not right.

 

This is what everything looks like at TDC. 

[Cjj.243]

6 minutes ago, mlatour said:

Recently rebuilt engine, if by chance you replaced the crank shaft, is it a stock OEM crank or aftermarket ?

(possibility of the woodruff key timing being off on an aftermarket crank)

 

You didn't mention what model year YZ125 but by the 2010 service manual specs,

those timing marks line up when the piston is 0.48mm (0.019") BEFORE reaching TDC.

I have a wiseco crank and piston. Any way I can check this? If so how could I fix this. Bike is a 1999

Edited July 16, 2018 by Cjj.243

[mlatour]

Line up the timing marks, measure how far from TDC the piston sits, compare to OEM specs for your bike's specific model year.

Ideally with a dial indicator but a digital slide caliper will do.

 

From past posts I've read, it wouldn't be the first Wiseco crank to be off.

Edited July 16, 2018 by mlatour

[Cjj.243]

11 minutes ago, mlatour said:

Line up the timing marks, measure how far from TDC the piston sits, compare to OEM specs for your bike's specific model year.

Ideally with a dial indicator but a digital slide caliper will do.

 

From past posts I've read, it wouldn't be the first Wiseco crank to be off.

So line up my flywheel mark with my stator mark and measure how far from tdc the piston is? Right now at TDC my flywheel mark is 180 degrees from my stator mark. But I was also told the flywheel mark means nothing.

Edited July 16, 2018 by Cjj.243

[TommyCrown]

Download a manual for your year. You do need one.

Below is an example from a 2003.

 

[Cjj.243]

9 minutes ago, TommyCrown said:

Download a manual for your year. You do need one.

Below is an example from a 2003.

 

I tried to find a manual which would really help but I can not find one for a 1999 for free. 

[mlatour]

25 minutes ago, Cjj.243 said:

Right now at TDC my flywheel mark is 180 degrees from my stator mark

Pull the flywheel off and inspect it the key slipped out of place during installation.

[Cjj.243]

I just rebuilt my bike and now I am trying to figure out how to time it, my mark on my stator lines up with the arrow above it, but when I go to TDC the mark on my flywheel does not line up with the mark on my stator, it’s a full 180 degrees off. I was wondering how to change this so it’s lined up at TDC and is timed right. Photos are taken at TDC. Bike is a 1999, thanks. 

[GCannon]

•YZ250 Timing Thread: Covers timing setup for 99+ YZ250 engines

You have some reading to do!

Edited July 16, 2018 by GCannon

[Cjj.243]

5 hours ago, GCannon said:

•YZ250 Timing Thread: Covers timing setup for 99+ YZ250 engines

You have some reading to do!

My bike is a YZ 125, is it the same?

[mlatour]

The timing mark it isn't on the 'face' of the flywheel but rather a line and arrow on the cylindrical section as TommyCrown posted in your other thread:

 

As suggested, have you checked if the Woodruff key is still in place ?

Edited July 16, 2018 by mlatour

[Cjj.243]

3 minutes ago, mlatour said:

Your flywheel pic doesn't show the timing mark,

it isn't on the 'face' of the flywheel but rather a line on the cylindrical section.

 

 

I will take a look at this and post a picture, thanks. 

[Cjj.243]

7 minutes ago, mlatour said:

Your flywheel pic doesn't show the timing mark,

it isn't on the 'face' of the flywheel but rather a line on the cylindrical section.

 

 

I found the line on the cylindrical part, it was right by the arrow ingraved in it also. At right about TDC it is behind the stator piece I will post a picture. The mark is right behind that plastic piece by the arrow and does not line up with the stator plate marks, what does this mean? 

[mlatour]

11 minutes ago, mlatour said:

As suggested in the other post, have you checked if the Woodruff key is still in place ?

 

Edited July 16, 2018 by mlatour

[Cjj.243]

2 minutes ago, mlatour said:

 

I’m planning on picking up a flywheel puller today, the ones I used at first I borrowed from a friend. What is that timing mark suppose to line up with then?

Edited July 16, 2018 by Cjj.243

[mlatour]

Re-read your other thread, all was explained.

TommyCrown posted an image of a service manual showing timing marks and BTDC measurements,

perhaps not the exact model year of your YZ but the same principal applies to yours.

 

To avoid potential damage, I hope you are not using a 'universal' type puller (2-3 adjustable 'fingers' that grab from behind)

but rather the thread pitch specific type 'bolt type' that screws into the flywheel. 

 

Edited July 16, 2018 by mlatour

[mlatour]

Not related to your timing questions bust a thought, since you're having trouble starting the engine after a rebuild and, 

don't seem to have a service manual to refer to, did you make sure the piston was installed facing the right orientation?

 

Some model year engines have 'windowed' pistons, a quick peak up the exhaust port will confirm.

 

 

 

Edited July 16, 2018 by mlatour