yamaha troubles

[sfl]

Can somebody tell me how a motor can jump timming when compressing water and how you fix it

 

[TwoFish]

Re: yamaha troubles

I'm new to Yamaha motors. Previously had Mercury outboards.

One possibility is the engine stopped so fast it sheared the key on the flywheel. If this is the case you will need to pull the flywheel and replace the key.

Not sure how the timing advance works on Yamaha but on Mercury there is a linkage system connected to the throttle linkages. Check to see of these are damaged or working correctly.

I'll look online later to see if can find an exploded diagram of you engine.

How far out is the timing?

 

[sfl]

Re: yamaha troubles

I am not a gear head so here is my explanation. when the piston is all the way to the head and both valves are closed the magnets on the fly wheel are directly across from the coil. i believe that is tdc and the flywheel position is off. I need to get a fly wheel pulle. I tried with what i had and it wont budge.

 

[Capt Ken]

Re: yamaha troubles

Lack of information will get no usable information. Telling us what engine would greatly help. Magnet position is not how you check timing. Try using the timing marks.

 

[sfl]

Re: yamaha troubles

It is a brand new yamaha 4 hp 4 stroke short shaft.. Would have to get a look at the paper work for the model number. I see the timming marks on the fly wheel but where do you line them up too. Could not find any marks on the crnk case housing

 

[Capt Ken]

Re: yamaha troubles

There is a mark on the crankcase that the flywheel aligns with. If its brand new then its under warranty and if you go digging into it you will void it.

 

[sfl]

Re: yamaha troubles

I was told the warranty was void because I sunk the motor while running. So the sky is the limit

 

[TwoFish]

Re: yamaha troubles

sfl,

Can you post a couple of photos of the top of the motor? This could help find the marks you are looking for. Id expect the mark you are looking for will be towards the front of the motor possibly slightly on the Ports side.

You could also try removing the sparkplug and inserting something relatively soft (pencil or plastic rod) into the sparkplug hole. Rotate the flywheel until the rod is push out of the hole to the highest point. This will be top dead centre. If the flywheel is still in the correct spot 0 Degrees on the flywheel will line up with the mark on the motor. Hope this makes sense.

The other option would be to take it to an outboard mechanic to have them check it over. They should make short work of diagnosing the problem. Compression, spark and timing checks, are quick to perform.

 

[99yam40]

Re: yamaha troubles

I was told the warranty was void because I sunk the motor while running. So the sky is the limit

Never seen a outboard motor that sank that ended up as a reliable motor.

If motor was running when it sank and ingested water then it more that likely had hydro-lock in the cylinders , so could not compress the water and ended up bending rods and maybe even other damage like they said sheared key as flywheel was still trying to go forward but pistons said no you don't

 

[Capt Ken]

Re: yamaha troubles

Actually the timing mark is on the aft side of the flywheel. That engine uses a plastic cam and timing gear.

 

[sfl]

Re: yamaha troubles

As of last night i got the flywheel off and the key was sheared placing the flywheel almost 180 degrees off. Getting a key today and hope it starts now. Thank you all for your help.

 

[TwoFish]

Re: yamaha troubles

That?s good to hear. Hope that is all you need to get it going. Fingers crossed.

 

[sfl]

Re: yamaha troubles

It started right up runs great. using it today

 

[TwoFish]

Re: yamaha troubles

That is good news. You have been extremely lucky.

Hope all goes well on your day out.

 

[sfl]

Re: yamaha troubles

Yes i was. The motor ran great all day. thanks again for your help