40 plus converted to 25:1 now only runs on half or full thr

[Burnham_Bob]

My 40 plus used to run fine on 10:1. I've put in the new needle and screwed flush with the top of the slide as instructed, but now the throttle needs to be half open at least or the revs die and it stops.

Seems to be plenty of power -although it sounds 'rougher' than it used to -when it is running but I'm not sure the throttle is opening fully.

From other posts it seems that to get the mixture right they've screwed the needle down further than flush.......but won't that make the needle shut off fuel even earlier?

Obviously I'll check the plug for signs of the wrong mixture, and i'll clean the carb, jet and float chanber properly, but in the meantime has anyone come across this before?

[Vic]

I assume we are talking Villiers carb.
It's worthwhile cleaning the float chamber and the jet. Be carefull that the float needle valve does not fall out and get lost once the jet is removed but make sure it is seating properly and shutting off the fuel flow.
Note that there is a fibre washer under the top shoulder of the jet which will probably come out with the jet. Dont clean the jet with anything that could scratch it like a steel wire and definitely no drills. A bristle of a stiff brush is often suggested but I use a soft copper wire when necessary.

Make sure that the jet retaining screw locates in the correct cut out in the shoulder not in the round hole! You can see the cut out from the top to check.

Check that the float is not punctured and causing flooding or at least a high fuel level

You can easily see that the throttle is opening correctly and fully by simply looking into the air intake (with the choke open) As soon as you start to operate the throttle lever you should see the piston start to rise and it should rise to completely clear the air way.

My question was prompted by the statement in the website FAQs that the needle adjustment screw should be flush with the top of the piston or up to a maximum of one turn down. Mine will run with it flush but 4 stroke. That's a symptom of an over rich mixture. So lowering the needle weakens it. It took 2.5 turns before it stopped four stroking under all conditions and now runs as sweet as a nut! I was concerned that I may now have reduced the lubrication to a dangerously low level but I've been using it like this for years.
It'll be interesting if you eventually find that you have to screw the adjustment down much further like I have done.

[Burnham_Bob]

I'm not sure what symptom to look out for. I checked my plug and it was a light tan - so if anything it was running weak. Tried richening the mixture and it seemed to be okay for a while but trying to achioeve the optimum I've now got an engine that runs raggedly and without power and seems to 'hunt' over a long cycle.

Will try tank running to get the best and then run it for a while in the dinghy to see if I can get a plug 'reading'.

My bin with the water in overflows if i try to rev too hard to get it warmed up!

[Burnham_Bob]

After Vic's advice I went back to basics and started all over again as I had at the beginning of the season. It was a new-ish plug but I replaced it.

I checked the points gap and cleaned them. Although I had set them they had opened up a bit. I found when I first got tyhe seagull that ragged and rough running was cured by cleaning and setting the points, so I got them right.

Then as to the new needle, set it flat as instructed. Mind you it's a dome head screw so is that with the top of the dome flat or the underside flat against the slide? Well mine's about half way.

Back in the dustbin full of water, full choke full throttle and she went first pull. Sounds a lot better. Still stops when the throttle is closed but I can get used to that, or maybe it'll idle when its warm.

As to 4 stroking, I think the noise it was making earlier was a rasp as oposed to a hum (if seagulls caan ever really be said to hum). Does sound much better now so it's back to sea tests on the dinghy this weekend but it doesn't sound as if there's much wrong.

[charlesp]

Stopping on idle sounds like a simple adjustment of the throttle - the adjuster's on the top of the carb. The slide probably closes a little too far. Not unusual I suspect after a needle change.

[John@sos]

Hello Bob,

the Villiers throttle like all the others, is supposed to shut the motor off when closed. The only exceptions are the few motors that have a kill switch, (stop button), they have tickover adjusters on their Amal 400 carbs.

All Seagull should 4 stroke at tickover and not till you open the throttle slightly will the note change to the irregular ting, t, ting of the 2 stroke.
Quite normal.

Happy Seagulling,
John

[CatiGull]

Thanks for that last post John - if a Gull doesnt 'four stoke' at low idle does this mean the mixture is probably a bit lean then??

Ill email you on some parts I need...hope you are well and enjoying summer.

[CatiGull]

When you are tank testing its a simple procedure to remove the propellor per the FAQs - you can also take that time to lightly grease the prop shaft to prevent seizing as well as carefully inspect your drive spring, washer, and cotter pin for wear and replacement as necessary.

When I go to Falmouth on Cape Cod and run my tender motor in salt water, I always come back home and run it in fresh for 30 minutes to keep it clean. Falmouth is so pretty you guys in the UK named a place in the South after it....