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Have always had a problem since new of starting my Briggs and Stratton 24HP engine on my Simplicity Regent Ride-on Mower.

I first thought it was either an air-lock or drain back of fuel in the fuel lines (the twin carb is higher than the fuel tank). By blowing into the fuel line at the fuel filter it will always start first time. If I don't do this it takes about 3 x 10-seconds turns of the starter before it fires.

However since then I have discovered my choke has no effect, the mechanism is in place and appears to be turning the butter-fly valve in the carburetor when I put the lever full on (the swivel turns at the end of the wire) I have not taken off the carb. I first discovered the choke has no effect when the engine was ticking over and putting the choke full on/off there was no difference to the tick-over.

Any other time I start the engine when it is warm it fires up immediately but not when cold unless I do the above.

Anyone any ideas on this? I have considered putting in a primer bulb in-line at the fuel filter. Or should I be taking the carb off to see if there is a problem there?

I would make sure the choke is actually closing all the way. If you have the type of control where the throttle and choke are combined, sometimes the cable will shift and not allow the choke to close properly.

I have a briggs 35 hp here at the choke attached to a stump grinder, that can from the factory with a boat like squeeze bulb in the fuel line to refill the carb after it sets for a few weeks and can be hard to start.

After checking and adjusting the choke more times than I cared to on my 22 hp briggs I devised a primer for easy starting for a couple of bucks. Usually starts on first piston up on compression even in cold weather. Needed were the parts pictured. 1) eye dropper 1) valve stem minus dust cap 1) 1/2" length of 1/4" diameter wooden dowel.

Thanks for the info. It is a separate choke lever and you may be right about it not having full movement (it however looks as if it does). I have seen another thread where even a minor adjustment to the cable was the solution. I will try that.

Thanks for the pics of the primer, I am leaning towards an in-line primer bulb similar to that on out-board motors or smaller. I could position that next to the fuel filter without breaking into the line.
I have also read in these types of vacuum pumps on these engines that there is a one-way valve that restricts fuel syphoning back from the fuel line into the tank. Can't see one on mine but I feel that is one of my problems, hence having to prime it.

Will get back to you.

Well I've tried to adjust the choke cable but it was originally set correctly, it is moving the swivel that is attached to the carb/choke shaft the full 90 degrees and shutting on/off OK. No difference, still have to blow into the fuel line towards the carb and it starts immediately when cold that way. Tickover of the idling engine remains the same when the choke lever is put full on, so the choke does not have any effect on the engine. If I had not bought it new and knew that the engine has not been touched I would have sworn that there was no butterfly valve inside the carb. So why the choke doesn't work has me stumped. As I can start the engine by 'priming' it I won't bother to take off the carb.

I have ordered a compact primer bulb (from a marine supplier) on-line and just waiting for delivery. Will report back how that works.

Have you removed the air filter and looked into the carb to see if the choke plate is there? Maybe it got left out during assembly. :confused2:

I've had the air-cleaner off but it's not possible to see inside the carb due to its position. I have felt inside the carb with my finger but can't feel anything there. I will now try with a small mirror.

Thanks

Removed the grill and the top of the engine housing, still can't see inside the carb but I was able to feel the butterfly valve inside and it moves with the choke lever so I haven't been short-changed on that. Still no reason why it doesn't work.

Whilst the housing is off I'll take the opportunity to clean up the rotor area.

I have bought a mini inspection camera and can now see the butterfly valve in the carb. It works perfectly. I have a video in both .wimp and .avi format showing it working but this site does not accept either.

So it beats me that putting the choke full on or in any lever position when the engine is idling that it does not alter the engine tickover. To me that means the choke isn't working but I can see mechanically it is.

Just waiting for the primer bulb to arrive and will live with having to prime it on cold starts.

Start up the engine and flood all of the areas where the carb has a hole or bolts onto the manifold and where the manifold bolts onto the engine with WD40 or similar from a trigger pack, not a spray can.
IF the engine changes speed or starts blowing white smoke you have an air leak.
Poke you camera down a bit further and see if the inlet has an obstruction somewhere.
I have found engines with gasket material almost totally blocking off the inlet.
The customer had been using it like this for 2 years and thought it seemed a bit under powered !

OK you got it, it's an air leak on the right-hand side of the carb manifold. Engine starts staggering on tick over when manifold flooded with CRC.

Was leaning towards an air leak this morning when reading another thread and have done the same with my motorcycle carb manifolds previously but for some reason I never thought to apply the same to my lawnmower. Thanks a lot. Cleared up a mystery.

BA24HP said:

OK you got it, it's an air leak on the right-hand side of the carb manifold. Engine starts staggering on tick over when manifold flooded with CRC.

Was leaning towards an air leak this morning when reading another thread and have done the same with my motorcycle carb manifolds previously but for some reason I never thought to apply the same to my lawnmower. Thanks a lot. Cleared up a mystery.

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Glad that it is sorted.
Very important for you to monitor the exhaust valve lash for the next season as you have been running lean and may hove softened a head.

Thanks will keep an eye on it.