Saving Old Seagulls

hi all just rebuilt my Forty Featherweight , blocked head...now cleaned, and looking like new..I managed to break a piston ring, so replaced both rings, engine will only run from cold, with first pull...then cuts out after a few minutes ? seems like its getting flooded? ..I cleaned all the carb, i cannot see what the trouble is, also got new plug and plug cap, getting a very good spark,even when it cuts out...
thanks mark...

Villiers carb??

If its flooding you will most likely see fuel leaking from the air intake or the vent holes in the bowl (If its a plastic bowl) if you turn the fuel on a just wait.

If it runs for a few minutes then dies perhaps more likely a fuel flow ( lack of) problem. Tank vent? tank outlet filter? carb inlet filter? float/ float valve ?

thanks for quick reply ,yes. it sounds like its getting starved of fuel..but seems flooded when i remove the plug? also i see a a spray of fuel now and again coming out of air intake?....but how do you reduce the fuel feed...after a few minutes of being left alone, it fires ok again...should there be a air filter? checked all the filters & they seem to be ok...going to try my mates carb on it tommorow ,to see if it is the problem..thanks mark.

When you say a spray of fuel from the intake. Do you mean it sneezes. If that is what its doing it indicates a weak mixture which could be carb incorrectly adjusted, dirt in carb, or lack of fuel.

Its the float and the float valve that control the fuel flow.... to maintain the correct level in the bowl. Is the carb correctly adjusted and do you have the correct needle fuel mix combination?

No there is no air filter but the intake compensator restricts the air to some extent

Have you read all the relevant info on the website and studied the carb diagram http://www.saving-old-seagulls.co.uk/fa ... s_carb.htm

how should the carb be adjusted?.. yes it sneezes, but not all the time...carb was cleaned and all jets blown with air...
i'm using a 25-1 mix fuel and outboard oil mix, cannot tell if the needle is for this or 50-1...
cannot see any numbers on needle or in carb...thanks mark.

There are are no 50:1 needles for this motor.

So 10:1 or 25:1, IIRC the 25:1 needle is either blank or has a 2.5 on it, probably need a magnifying glass to see it. The 10:1 has a 3 on it, I think, someone please correct me if I'm wrong.

The preliminary setting is with the needle adjuster screw top flush with the top of the throttle body piston it is in. Adjust from there. With 10:1 needle max. 3 turns in from flush according to Seagull literature, should give good results with 15:1 to 16:1 mix. Much less adjustment with 25:1 seems wise,perhaps one turn in max.

This info for Villiers carb. Bing carb is already set at 25:1

yes the crankcase is sealed....mark.

right...tried mates carb, still does the same, starts ok, runs for few minutes the revs die, then cuts out... i'm using a mixing bottle for mixture..25-1
any idea's? mark.

coming back to the crankcase question, how would that affect the performance...mark

Is the stator plate in the correct place? Timing screw in the dimple.

A head leaking gasket maybe?

I believe that it's something wrong with the timing. Points gap and spark plug gap 0.5mm.

Are you getting good fuel flow from tank? Disconnect fuel line from carb, turn on fuel tap and allow fuel to run into suitable container. Is flow good and steady?

When engines dies, is there fuel in the carb?

When engine dies do you still have good spark? Perhaps coil is on way out and fails when warm.

mark.
as you've already mentioned that you've rebuilt the motor. what exactly did you do to it whilst it was apart.
when you put the motor back together, did you use a little smear of rtv (silicone) on the head end of the cylinder and just a little bit on the gasket where it sits around the cylinder?
re crankcases, sealing them is quite CRITICAL. if the cases are leaking, they can also suck in air and so weaken the mixture. quick way to check this when you have the engine running, arm yourself with a spray bottle and some washing up liquid, and spray over the seam between the case halves. you'll see if its leaking because there will bubbles.but it may also cut out or run funny or suddenly stop!
if so, engine apart again, this time no need to remove the head.
carbs really do need to be absolutely spotless as well as the little filters in the banjo fitting.
as already mentioned check again the needle to see if you're running the correct mixture.
also make sure your carb is the right one for your motor. should be 1/2 inch bore i think (venturi size) if its the smaller one then its for fv or fvp, but unlikely that you've got the wrong carb? but worth a check all the same.
give your ignition the once over as well, points gap plug gap etc. new ht lead? they can sometimes break down inside.

jon

when it was stripped down ,I made sure that the both faces were cleaned up on the head, wet & dry sandpaper on a flat surface..blew it all clean with air , then used a silicone like you said, I was thinking of spraying with leak detecting spray (i use this for plumbing)got some in workshop...thanks for the help..mark

I will make a list for you as I understand that it may be confusing searching on the post what to check.

1. crankcase seal
2. head leaking gasket
3. undo the timing screw and check whether you see the dimple or not.
4. clean points and check gaps of spark plug and points


3 and 4 are something that I believe that may lead to sneezing or a condenser that fails. But in case you haven't touched the ignition system then 3 and 4 is likely to reveal nothing unusual.

In addition, when the engine runs, does it retain a tempo or it fires in an uneven way?
Could you also upload some pictures? Is it a villiers of a wipac ignition?