fleehillfarm

Both plugs are looking the same. Both cylinders are working as I pulled off the spark plug covers when it was running. Smoke still absolutely pouring out of the right hand cylinder exhaust. So it's definitely the one cylinder that's the problem. Going to have to take the cylinder head off. Thanks for all the advice.

The oil level is correct. If I take the breather off the back of the carb and block the hole up what does that achieve? Sorry but I'm not familiar with that . Thanks for the input.

Thanks for your thoughts spudulike. There's no water or diesel in the fuel and both cylinders were almost exactly the same in compression one was 120psi and the other was 125psi. In the leak down test both returned 20%ish leak which is quite good for an engine 20 years old. Yes all jets were checked when the carb was off. Choke isn't stuck moving freely. Quite a puzzle this one.

Sorry roys forgot to mention that I have adjusted the valve clearances on both cylinders. My first suspicion when the problem arose was obviously a blown head gasket but can an engine return a reading of 125psi with a blown head gasket? I'm reluctant to take the head off to find out but maybe it's the only thing left to do. The carburettor is the Nikki type with fixed idle mixture valves and limiters in the top so that doesn't help as you only have a very limited amount of adjustment and they come to a stop. Maybe they have moved. If I forced them beyond the limitation does anyone know whether I would break something? Also could a bad idle mixture cause the smoking? Many thanks.

Hi everyone, I have a problem that's driving me mad. I have a Cub Cadet ride-on mower powered by a Vanguard V twin 20hp Briggs and Stratton engine. It will only start with a squirt of easy start and then runs normally for about 1 minute and then starts to smoke quite badly. Bluish or white smoke. I have done a compression test and both cylinders have 120 - 125 psi. A leak down test shows only 20% loss. So all appears to be good. Carb has been stripped down and thoroughly cleaned. Both magnetos have been adjusted. Good spark at one plug. The other had no spark until I removed the kill switch wire. So it does have a short somewhere but that wouldn't cause the smoking or reluctance to start. I'm fairly good with the running of small engines but this one really has me beaten. Any advice or ideas would be much appreciated. Many thanks - Richard

adw when you say a leak down test is that a compression test on each cylinder? If so I think I can buy one that screws into the plug holes for about 25 quid. I removed the breather pipe completely and the plugs are still getting oily. I was wrong when I said black smoke coming from the exhaust it is actually grey smoke. I've just taken the carburettor off for the fourth time and will clean it again. while it's off I can have a look at the crankcase breather. Thanks for all the help.

It's definitely oil. The breather pipe that goes into the back of the air filter is badly deteriorated. I'm trying to get a new one online. Could that be an issue?

If it is just a massively rich mixture how do I remedy that? The carb has two mixture adjusters on the top that have limiter buttons fitted. One of these is intact so I put it in the middle, but the other is missing. Do I screw that one in until it seats and then back it of one and a half turns as is normally suggested?

I eventually removed the carburettor and dismantled it and cleaned out all the jets and cleaned it with carb cleaner. When I reassembled it to my honest astonishment it started first pull and ran beautifully. I drove it from my garage to a barn a distance of about 100 yds. By the time I got to the barn black smoke started pouring out of the exhaust. When I removed the plugs they were covered in oil. My question is have I done something wrong when reassembling the engine or has it coincidentally just blown a piston ring or head gasket. As it's a V twin and both plugs were oily it's a bit of a coincidence if both chambers had piston rings failing at the same time. Many thanks for any guidance.

Thank you very much pleasant for very good information .

Sorry guys just found the name on the front of the carb. It's a Nikki

Thank you so much for the replies. Looks like I have to take the carb apart. Would anyone know what model the carb is in case I have to buy any spares.

Could anyone please advise me. I have a ride on lawn mower that isn't working. The engine is a Briggs and Stratton Vanguard V twin 20hp. When I took off the air filter to access the carburettor i noticed there was two pipes coming from the top of the carb. The thicker one goes back to the fuel pump to provide the fuel supply. The thinner one is just hanging beneath the engine. My question is what is the purpose of the thinner pipe and should it be attached somewhere or is just some sort of breather. Many thanks in advance for any advice.

Could I ask another quick question please. When I recently layed some hedge some of the pleachers were hawthorn which were quite big probably 5 inches or so in diameter. when I laid them I left most of the top growth on as can be seen in earlier pictures. Is it the case that the tops should be cut back to help the pleachers survive? Is the small amount of bark left enough to allow sufficient sap to rise to cope with all that top growth? Many thanks.