Problem with Yamaha 50

[cbs]

Ok Guys, I'm a little out of my depth here, so looing for some general guidance on this one.

I have a 2001 model 50Hp Yamaha 2-stroke with oil injection.

I recently had it serviced including a full carby clean out from the local yamaha dealer. This was about 2 months ago.

Now everything seems to be running fine since then except that after some time of low speed operation (10mins or more or restarting drifts etc) it starts to cough then run on 2 cylinders or less then won't restart easily.

I believe that my plugs are oiling up and causing the problem. I have pulled the plugs while on the water and cleaned them which seems to fix the problem for a while to get me home. The motor also seems to be using a far greater amount of oil than it did before the service.

So my question, Is there an adjustment on the oil injection that would have (could have) been changed during the service that would be causing this issue?

At the moment I am not all that keen to travel farther than I can swim if you get my drift.

Any help would be appreciated.

[bluefin59]

Me personaly if i have anything suspect happening to my motor its straght back to the shop to have it checked its just not worthwhile getting caught out mate I.M.O .....matt

[Timmy94]

Im with you on that matt theirs alot of water out their and the last thing you want is motor problems.

[cbs]

I appreciate that guys, but what I'm trying to do is simply arm myself with a little information before I take it back thats all. I don't intend to do any adjustments to the oil mix on my own....

[aido]

might pay you to have a look at it yourself first,
might be something obvious like the oil pump control
linkage has fallen off or not put back on after the service??

[cbs]

Alright, I just lifted the cowl off and can see a linkage arm on the port side of the engine from what appears to be an oil pump/manifold. ie Oil supply in, 3 out to each cylinder I'm guessing.

Since the linkage arm appears to be connected to the carby buterfly's (moves with throttle adjustment) I assuming that this would have been taken off for the carbies to be stripped down, cleaned and rebuilt. There also appears to be some adjustment/locking nut on the linkage rod which could* have not been put back exactly the same way.

please tell me if I'm not on the right track before I call these guys.

cbs

[mowerman]

Have a look at a post I put up a week or so ago "cdi unit"

If its like that then get back to me.

Have since discovered the problem could be low fuel level in the main tank and the engine is sucking air when it comes down off the fast idle start.

[cbs]

Mowerman, just took a quik look at your thread.

I'm pretty confident its an overoiling problem for the following reasons

1) Since the service, the amount of oil used is at least double. Last weekend, during a trip to Wavebreak from Biggera waters, (probably 5 min return trip) it used an amount equivilent to what I would have previously used for a much larger trip.
2) The last time it happened so that I couldn't restart I beached myself, pulled the plugs out, cleaned them and replaced. Resulted in start first pop then then drove home without problem.


cbs

[aido]

Alright, I just lifted the cowl off and can see a linkage arm on the port side of the engine from what appears to be an oil pump/manifold. ie Oil supply in, 3 out to each cylinder I'm guessing.

Since the linkage arm appears to be connected to the carby buterfly's (moves with throttle adjustment) I assuming that this would have been taken off for the carbies to be stripped down, cleaned and rebuilt. There also appears to be some adjustment/locking nut on the linkage rod which could* have not been put back exactly the same way.

please tell me if I'm not on the right track before I call these guys.

cbs

that would be the oil pump control rod from the sound of it.
o/k, it's fitted. thats about all i was thinking for you to check.
i doubt the mechanic would have adjusted it without telling/charging you.

it's pretty involved to check the oil pump output, you will need the maintenance
manual. goes something like this...
run the engine from a pre-mixed fuel/oil supply at a set rpm, like 1500rpm
have the oil lines disconnected from the carbies into a calibrated container and measure
the oil collected from each delivery hose after a set time, like 5 minutes.
with the control rod in the idle position it might be say 5mls and at the wot position 15mls.
just guessing the figures here to give an example.

it is in the realm of backyard maintenance if you are mechanically minded
but you will need the manual and some patience.

good luck with it.
aido.

[tigermullet]

This might be very wide of the mark but we had a similar problem a while ago with a 40hp 3cyl Tohatsu. It was over propped causing an alarming increase in oil usage. Adding to the problem were those mongrel resistor type spark plugs.

We chucked our the BR7HS10 plugs and replaced with B7HS10 and dropped the pitch on the propeller. Everything back to normal now.