Yamaha 225 DX won't start, PLEASE Help

[71satellite]

Hi again guys,


I checked compression this morning (my compression tester doesn't have an adapter for the spark plug hole, so I just "held 'er in there real good" to get a reasonable idea of compression numbers). It hit 130 lbs, without proper sealing, so I think compression is fine.

This starter bypass issue.....interesting. I will check into it for sure. However, just out of curiosity's sake, what if I was using the pull starter (which unfortunately I am not as the spring thingy inside is shot)?

A few days ago I rigged up an adapter so I could spin the starter pulley with a speed wrench/impact gun, but I wasn't getting any fire then either.

I will write Unclediezel and get the haynes manual pages I need, and take it from there.

Thanks again everyone! The next update will come soon (hopefully)

Chris

[71satellite]

Hey guys,

Well, here's what happened. It was recommended that I:

1- Check the starting circuit to see why the starter button wasn't working.

I checked the sky-blue neutral wire with a test light, and eveything was OK.
Then I bridged the red and brown wires in the Main Switch harness, and located the starter cut-off relay. Applying the starter button does NOT cause the relay to click. Sooooo, I think I found the problem (i.e. the relay). I was wondering how to bypass the relay (there's only 3 wires, sky-blue, red, and red/white). But anyways, this is the minor part of the issue.

I was told that you needed to press the Start Button to Establish a Base Point for the CDI. Well, I tried just pressing the button (even though the relay isn't clicking over), but that didn't help.

So is a relay the only electrical problem here? And can I just bypass it for testing purposes?


2- Check valve timing

I popped the timing window, pulled the two valve covers, and turned everything over.
Pretty simple, intake opens as piston sucks down, intake closes and piston travels up. At the top of that stroke is "TDC" when the ignition should be firing (after which, piston travels down, then exhaust opens as piston travels up.
I watched it over and over, trying to make sure I had it right.
WELL.....my crank "T" and "F" marks (which are very close to each other on the crank) were 90 degrees OUT from the valve timing (i.e. both valves closed). So I figured I had found the problem. The piston was at the bottom of the bore when the spark plug was sparking, not at the top!

So, I carefully pulled the upper timing gear bolt, rotated the motor to TDC, then realigned the timing chain and reattached the upper timing gear.

3- Check valve lash.

Both intake and exhaust were pretty tight, so I use a 0.004" feeler gauge and set them.


The moment of truth...it all had to work now right?

Wrong. Not only did it not fire, but after 20-30 seconds (intermittent) of rolling the engine over with the starter, I heard a "PING", and discovered that the exhaust valve rocker arm had snapped.



Crazy.....I didn't think these were interference motors, but what else could have caused the exhaust rocker to break like that? Then again, I'm surprised just the starter motor could generate enough force to snap it.


Well, what did I do wrong? Obviously now I'm going to have to take the motor apart...but I still don't understand why it isn't firing?

Does anyone have suggestions? Should I just try to find an exhaust rocker arm somewhere and cobble it back together? Was I right to change the timing gear? What is the problem with this motor?


Thanks again for your help, looking forward to your suggestions,

Chris

[slothminx]

The rocker broke because when you "fixed" the timing you actually put it out of time. thus when you went to turn it over piston met valve and the rocker gave way.

I would count on a bent valve aswell.

Starter motors can power me on a KLT in gear up a steep hill there that powerfull(although not recommended).

Now this may sound slighty dumb but you sure your turning it over the right way?. If i were you instead of using the starter i would have put it in 4th gear and pushed it to bump start

At the relay there will be two BIG wires coming in from the battery and going to the starter. A way to test these would be to get a screwdriver and short the two terminals.

On the vavle clearences i would think you set them about right maybe too tight but that wouldnt screw the rocker.

Will

EDIT: another thing i do WHENEVER ive had an engine apart is spin it over 2 or 3 times by hand to check nothing is hitting and it spins freely

[71satellite]

Hey everyone,

Well, after pulling the top end of the motor apart to get at the broken rocker (thankfully the valve didn't bend), I decided to check the flywheel, and wouldn't you know - the Woodruff key had sheared.

So, I wasn't on crack when I thought that the valve timing was off from the crank position, the flywheel had rotated on the crank causing everything to "look wrong".

Fortunately, the local Yamaha dealer can get a new rocker arm and Key, so in a couple of days I'll bolt it all back together and see if this will actually run when everything is lined up right.