Hi all!

I recently picked up a 1969 Evinrude Lightwin 4 outboard for pretty cheap as it has a couple of problems. The main one being it doesn't really run! I have had it started (will only start at full throttle after a lot of attempts) and it runs very lumpy and cuts out when the throttle is turned down to the start position.

I have taken off the carb thinking it is a fueling issue and this is all nice and clean and fuel is getting through it no problem. I removed the spark plugs the checked them and only 1 had fuel on it so I think one cylinder is not getting any fuel at all. I am trying to get the bit the plugs screw into off (I think that's the cylinder head?) and am experiencing a few problem bolts. Once it's off what is it I am looking for? Never taken an engine apart before so any advice would be great as to what could be stopping fuel from getting into the cylinder.

I have also read that a blocked exhaust port could prevent fuel from getting in? Not sure how that could be possible though .....

Thanks very much for any help you can offer!

Mark

Could be the Crank seals, they often get tired on old 2 strokes, and instead of the cylinders sucking the fuel from the carb into the crank case, they just draw air in around the ends of the crankshaft, which is often why you can only get them started with loads of throttle and they die out as soon as you shut it off.
It's because they are running really weak due to the amount of unwanted air being drawn in.
This issue can also be exacerbated by worn main bearings allowing the crank to run eccentrically, and opening the annulus between the crank and lip seal even further.

That said, it's only one thing it might be, there are loads of others.

Good luck

Welcome, is it the model below (europe only) or the one with the plastic cowl? Only advice I can offer is to buy / download the factory manual for the model and follow the troubleshooting sequence before pulling the cylinder head off (which will likely break bolts and then create more issues).

Plenty around of this type 3/4hp around, so unless you got it cheap and it's in nice condition with a spark on both cylinders and decent compression tested (they have small pistons and do get coked up and worn out), don't spend a lot of money on it. If you need parts contact Mike at South Coast Marine in Christchurch - he'll have most bits for it on the shelf.

pspeed wrote:Could be the Crank seals, they often get tired on old 2 strokes, and instead of the cylinders sucking the fuel from the carb into the crank case, they just draw air in around the ends of the crankshaft, which is often why you can only get them started with loads of throttle and they die out as soon as you shut it off.
It's because they are running really weak due to the amount of unwanted air being drawn in.
This issue can also be exacerbated by worn main bearings allowing the crank to run eccentrically, and opening the annulus between the crank and lip seal even further.

That said, it's only one thing it might be, there are loads of others.

Good luck

Thanks for the reply I am not very good with mechanical things but trying to learn. Where would I find these crank seals? Might be obvious but working on an engine is all a bit new to me haha

Rapier wrote:Welcome, is it the model below (europe only) or the one with the plastic cowl? Only advice I can offer is to buy / download the factory manual for the model and follow the troubleshooting sequence before pulling the cylinder head off (which will likely break bolts and then create more issues).

Plenty around of this type 3/4hp around, so unless you got it cheap and it's in nice condition with a spark on both cylinders and decent compression tested (they have small pistons and do get coked up and worn out), don't spend a lot of money on it. If you need parts contact Mike at South Coast Marine in Christchurch - he'll have most bits for it on the shelf.

Thanks to you for your reply I paid 40 quid for it which I think is reasonable? It is the one with the plastic cowling like the top photo. Handy to know about South Coast Marine so thanks for that