Yamaha 2B woes.............

[MINESAPINT2]

Very old engine but perfect for my needs - well it would be if it worked!!!!!

The story so far

For 7 years it has never missed a beat then a few weeks ago it started OK and ran OK for 200 yards then started running rough but got me to my destination. Once turned off would not re start.

I then discovered the plug was all gunged up and it restarted once a fresh plug fitted.

Had a look at the carb which looked OK. but as a new one was available from ebay for £20 I bought a new one.

Fitted new carb but made no difference - still running for a few minutes but then running awful.

I then got it into my head the head gasket might be the problem. (Water entering the cylinder from the water channels surrounding the cylinder).

New set of gaskets fitted, engine reassembled and now I am unable to get it started at all. Completely dead. As if the stop button is permanently depressed.

Looking for ideas what to try next

Thanks

Mike

 

[LiftyK]

Are you in the habit of using fuel stabiliser? My identical engine behaved similarly when left for a while. Adding stabiliser cured this. E.g. Sta-bil or Briggs and Stratton stabiliser.

 

[MADRIGAL]

Are you in the habit of using fuel stabiliser? My identical engine behaved similarly when left for a while. Adding stabiliser cured this. E.g. Sta-bil or Briggs and Stratton stabiliser.

Or Seafoam, widely available.

 

[MINESAPINT2]

Thank you, I have never heard of these additives although I do not think there is an issue with the fuel. I sail regularly and buy 5 litres fresh petrol +/- every 3 weeks. I also have 2 other outboards (Mariner 3.2 hp and Tohatsu 2.5 hp) running very happily on the same stuff.

I was hoping the collective genius on this forum would put their finger on the problem.

To summarise original post

Yamaha 2B 2hp Starting but running rough. Eventually diagnosed (rightly or wrongly) head gasket issue.

Fitted full set of 3 gaskets using high temperature silicone gasket sealant.

Reassembled and now engine will not start at all.

I have 2 carbs (one new) and have tried both.

I have a good spark when the plug is held against the exterior of the engine.

Completely baffled.

Is it possible to fit new gaskets incorrectly and cause this issue??

Thanks

Mike

 

[B27]

I once bought a non-running motorbike, I was expecting to break it for spares.
Turned out, the vendor had put the air filter together wrong, so no airflow through the engine.

Point is, you have to go right back to basics, trust nothing.
There's a spark. Is it at the right time?
Do you have air, fuel and compression when the spark happens?

I've also known engines not start because the exhaust is completely blocked.

It's a reed valve engine, it should pump air? Does it?

 

[Steve65]

DId you remove the stator plate.....have you tried spraying a small amount of easy start in the inlet...just to see if it will momentarily run.
Check the Woodruff key in the crank has not sheared

 

[Porthandbuoy]

Do check the stop button. I had a similar problem and it turned out the stop button did not go completely open circuit when released. Sometimes the resistance was high enough to let the engine start and run, at others it would start, falter and die. I replaced the switch with a kill-cord.