G8 motor not firing up

CajunLoneWolf

OK at the advise of one of the Yamaha gurus I am starting a separate thread for this problem so that I can get ideas from other members. I have a 1992 Yamaha G8 that will not fire up after tearing it down to do some maintenance work. Here is what has been done:

1: Motor was running when pulled out of the cart but needed both seals and the crankcase gasket changed. Done.
2: When I pulled the motor out I also changed or cleaned all of the electrical fittings on the cart and the motor.
3: I also removed the carb and took it apart to clean and soak it.
4: The fuel line to the carb was left connected to the pump and the line to the motor was left on the motor as not to switch them up when reinstalling.
5: I also removed the valve cover and readjusted the valves at TDC on the compression stroke to .004 and checked it five times after locking them down and replaced the gasket.
6: While the motor was out I also changed the brushes in the starter.
7: I reinstalled the motor and hooked everything up just the same as it was taken out.

The motor will turn over but will not fire up so here is what I have done so far to troubleshoot it.
1: Rechecked the valves to make sure they are set right.
2: Removed the carb and cleaned it now going on three times. (float might be sticking)
3: Checked to make sure I have spark at the plug.
4: Did every step in the So your Yami wont turn over thread.
5: Removed the fuel line to the carb from the pump and spun the motor over (fuel pulses out of the line)
6: Rechecked all of the wiring to make sure something was not crossed.
7: Replaced plug with the NGK 2ES style
8: Replaced the fuel filter
9: Shot ether in carb to try and hear a pop from it trying to fire. (It seems like its spitting the ether back out)

The next step is going to be to replace the float or maybe the whole carb. It does seem like it's a ignition or a fuel problem but I am starting to run out of ideas here. I am sure I have done other things that I have forgotten to mention but hopefully someone can throw me some new ones.
Thanks, Brandon

BGW

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crash12888

Post the compression reading please.
Put in neutral, hold throttle full open, run at least 4 compression strokes.

CajunLoneWolf

Just ran a compression test. I'm getting 175psi so I'm in the money

Universal_Mechanic

You said you had the crankcase cover off. Any chance the cam timing got changed a tooth or two by accident? Seems weird how it won't even start with ether. I found that non-chlorinated brake cleaner works better than ether on these little engines, and also its much less potentially harmful than ether.

To me, your problem sounds like a timing or valve issue if you definitely have spark.

CajunLoneWolf

No the gears didnt move. I used a paint pen to mark the gears to make sure just incase I pulled the cam. Although I didn't need to. Good to know about the brake cleaner

CajunLoneWolf

OK me and my father in law just messed with the valves and motor again. Here is what he sees and now I'm all screwed up. When you crank the motor over with the starter it blows pressure out of the carb and has a vaccum on the exaust pipe. The dang thing is backwards. WTH did I do.

smallblock450sl

Sounds like its time to pull the motor and check the timeing marks again? I can think of no other reason you would have "backwards" intake/exhaust pressure. With the cam's big alighnment hole lined up with the crank mark, valves should be closed.

Attached Images

P9290298.jpg (129.5 KB, 10 views)

CajunLoneWolf

What would have caused the cam to move. I didn't pull it all I did was change the seals.
I know this may sound stupid but which way does the motor rotate clockwise or counterclockwise?

smallblock450sl

Counterclockwise do you have the battery hooked up backwards????

CajunLoneWolf

It's running clockwise lmao but when you turn it counterclockwise it does right