A65 Carburettor

[Kevin-G]

Hi Everyone.
I need some help please...S.O.S
1962 BSA A65 Star with monobloc carburettor.
I decided to strip and clean the carb in a sonic tank. I have replaced the gaskets / washers and put it back together (several times now), returning the Air and Throttle stop screws to their original positions having previously recorded the number of turn before removal. The bike is now dead, no glimmer of a start. It appears the plugs are dry, no fuel getting to them. I have not adjusted the position of the jet needle (not intentionally anyway). The Main jet and needle jet are clear, as is the pilot jet. The fuel chamber is full and fuel is getting to the main jet, nothing is getting to the plugs.
I have spark but the plugs are dry.
The Air valve and Jet block seem to be operating when I twist the throttle.
It was all running reasonably well before I took it apart 
Any suggestions gratefully received.

[DAVE BRADY]

Hi Kevin,

It may be worth giving the tiny primary drillings another clean.  They are easily blocked and if so will prevent starting.  Try carb cleaner and and air line to blast out any obstructions.

Dave.

[Kevin-G]

Hi Dave,

Thanks for the speedy reply, sorry to sound so ignorant....... but what would another term be for those...in Haynes manual speak!!

K

[DAVE BRADY]

Hi,

If you look at the carb. you will see some very small holes.  Not much bigger than a pin hole but they need to be clear.  If you spray carb. cleaner in the holes were the adjustment screws and pilot jet go it should come out of the small holes. Poking wire through is not really recommended as it can cause a bit damage.   Also, once the carb. is clean the original setting of the screws may not be correct.
There is tuning sequence in the Haynes manual so give it a go and see how you get on.

Dave.

[Kevin-G]

Thanks, will give it a whirl..... watch this space.

K.

[Mike Farmer]

 

My Favourite ploy. Splash a drop of petrol into carb intake. It should start. If it does it may well suck out anything small in one of the drillings. Probably worth a try.

If it doesn't you haven't lost any thing

Mike

[Nanonevol]

+1 to Mike.
I use a spray bottle with petrol hoping to get a bit of a mist into the carb intake.
Sometimes use ether starting spray but it's not good for the engine in excess and it costs $.

[chaz]

I tend to spray (with the aid of tube supplied) the carb cleaner into small holes and always check that it comes out of another hole. if it dosnt then it should or why was it drilled there in the first place.

[ChrisG]

Have you checked the fuel level in the float bowl? There is a pip on the float bowl cover under the Amal name. That is the correct level. You can make up a simple level gauge using an old main jet cover nut and old jet (size irrelevant) and a piece of clear pipe that will fit over the jet.
You need to drill and tap the underside of the cover nut to take the main jet (Its a 1/4"BSF thread) and contersink the hole on the underside face. Screw the jet in tight and clamp the pipe over with a pipe clip. Attach to the carb and hold the tube vertically against the float bowl. Turn on the fuel and the level in the chamber will be mirrored in the tube. If it's too low then fuel will not get to the mixing chamber so no combustion.
Worth a try.

[chaz]

is the float the right way around? they  can be put the wrong way permanently shutting off the flow

[Kevin-G]

Not having much luck this end. Have taken the carb apart again, thoroughly cleaned but she still doesn't want to go. Have put a new battery, coils and new plugs in to cover the bases (they were pretty old). Dave, how many primary drillings should i find when its all stripped down, i can only see 1 on the edge of the Jet Block.....and 1 in the carb body near the  ('0') ring grove (pilot jet). They are tiny, i missed them the first time around.
New plugs in, after a dozen kicks they have no fuel on them.
Fuel bowl is full, plenty of fuel about.
Tried fuel in the air intake... no joy.

Thansl for all your tips everyone....... keep'em coming.

[DAVE BRADY]

Hi Kevin,

I think that is it. So if fuel or carb cleaner can get through then it is clear.  Does the carb. flood when you hold the tickler down?  This ensures an abundance of fuel for starting.  Also, I suppose that it is possible for there to be an airlock in those small drillings.  Sometimes a bump start can help as the spinning engine creates more vacuum.  Once started to problem could well disappear. 

Dave.

[Kevin-G]

Goodness me this is driving me mad....

So carb cleaner goes through the holes, have looked in detail with a magnifying glass and all passage ways are clear.
When tickled fuel comes out the tickler and the 2 holes at the rear of the carb. by the air intake. Tried bumping no joy.
Plugs are still dry, have also raised the jet needle to see if this helps but no luck.
Any more thoughts?

I'm guessing the pilot jet should be screwed home? Not over tight, i have just nipped it up.

Does anyone know a carburettor magician in the Beaconsfield / High Wycombe area?

K.

[Nanonevol]

Be careful not to tighten that pilot jet to hard.  You don't want to deform the needle or jet.
If you are trying to start the bike with the pilot screw "nipped up", there's your problem.
From the gently closed position unscrew the pilot 1 1/2 turns.
Put the needle height back to the middle.

[Kevin-G]

will give it a go.