Stalling after flooding the engine with Petrol - 550K 1978

[Phteix]

So last day after changing my handle bar I managed flooding the engine with Petrol  very amateur, I know.

But after that the bike would start and after starting would run very "heavy" as expected, I noticed the smell of petrol in the oil, so decided to replace the oil for a new oil, Valvoline 15w-40  and new spark plugs.The bike is starting okay, but after running a few miles, it starts losing power and stalling.

I don't think it is the carburetor, I have managed to keep it clean and synchronised. The bike was running perfect before.

Any idea what's going on?
Is this a good oil to use on my 1978?

Thank you in advance

[Johnwebley]

This may be a daft question.

Were do you live?.

If you live in the UK.at present it's cold with a high moisture content.

You may be getting carb icing.

I think it will be more frequent with  the E5 biofuel

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[Phteix]

Not at all!
It's around 7 degrees Celsius at the moment. Is that possible? 😕

[Johnwebley]

Not at all!
It's around 7 degrees at the moment. Is that possible?

It happened to me last week. Went for a brisk ride. Coming back. And stuck in traffic. Just ticking over and the bike stopped. Wouldn't start immediately. But was rolling down a slope. After about 30 seconds it started. No probs.

I THINK the slow running caused ice to form in the venturi.

When it stops. The engine heat can warm the carb and melt the ice.

In aviation. Small Cesnas and Pipers have carb heat levers to stop this happening.

Cars tend to use hot water ducted  through the inlet manifold to curb it.

Just an idea.

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[taysidedragon]

Could be carb icing as suggested. In the right ( or wrong!) conditions it can happen even on quite warm days. Some later bikes have electric heaters on the carbs to prevent it.
The recommended oil is 10w-40 but you're not far off, shouldn't make much difference.

[McCabe-Thiele (Ted)]

Icing up was common on old cars with SU's

[flatfour]

Carburettor icing, as suggested, will most often occur between 0 - 7c on damp days and when engine speeds (i.e. airflow through the venturi) are low. It does not readily occur when air temperature is below 0c and is infrequent above 7c, although can happen.

I seem to remember Kawasaki retrofitting some of their bikes with a small "Water Jacket" around the carburettors and intake manifold a few years ago as they were suffering quite severely from the problem.

Perhaps, given recent weather conditions it is the cause of the problem mentioned?

[JezzaPeach]

Just a thought. Maybe try running a shorter distance (before it cuts out) then stop and idle for a few minutes and then carry on the same distance, and do the same again. That might keep it warm and show if it’s more likely to be icing. Or maybe fuel starvation.

[Phteix]

True, could be that. I live by the sea, was very misty and cold when I tried. I found someone talking about Silkolene Pro FST on a Kawasaki forum. I just bought some online, I will try to run a few miles with that and see how it goes. Definitely not the best time of the year for a ride 😑

Thank you for all the help.

[JezzaPeach]

I use Sta-Bil which seems to help keep the carbs clear.
Back in the ‘70s my 500/4 never iced up even in snow in the Alps, but if fuel has been left for a while and absorbed water as we are told, then maybe that increases the risk of icing.

[sye]

True, could be that. I live by the sea, was very misty and cold when I tried. I found someone talking about Silkolene Pro FST on a Kawasaki forum. I just bought some online, I will try to run a few miles with that and see how it goes. Definitely not the best time of the year for a ride 😑

Thank you for all the help.

Pro FST works well. I had to use it every winter in a CBX750 that was my only form of transport. The carbs iced up every winter and FST stopped it happening at all.