Misfire

[NickT]

I've had a few runs out this year and on the first one the engine had a misfire at low speed.

I thought this was just as a result of the winter and eventually the mis fire disappeared.

Then it came back so I changed the plugs. Everything was OK again.

I have been out today and the mis fire is back.

I have had a hunt around various forums to see what the problem could be.

On the first trip out there was some surging so I presumed this was some water in the tank that was stirred up and was sucked through into the fuel line.
(it was quite rough).

Someone has mentioned that even a little bit of water in the carb bowl will block the idle jets - this seems a reasonable theory.

Anyone have any ideas please? My gut feel is that it is a fuel not ignition problem..

[Ianfs]

Hi Nick

One of the easiest but expensive ways to check fuel issues would be to drain your tank into jerry cans. This would at least eliminate the fuel.

I would be surprised however if one season of non use would cause a misfire, but its worth a try before you think of things like valves etc.

[shibbs]

I had this last year, and after chasing down all sorts of electrical possibilities, it was finally narrowed down to fuel.
This led to a carb strip, clean and re-build, problem solved..
Maybe worth a try?

[NickT]

Thanks for the tips so far..

Fuel is now fresh and I have done over 25 miles in the last few trips. The prospect of emptying the tank to clean out any sludge in the bottom doesn't fill me with joy.. Anna swapped her tanks over on her Fletcher but I can't see how I can get to a drain point if there is one.

I am pretty sure the issue is fuel related and a carb strip and clean is probably overdue. However, I am nervous of messing up all the balancing on 4 carbs without proper equipment.

Some people have used a fuel conditioner to solve minor problems although its a long shot.

If I could find the carb drain screws without dismantling the whole assembly I could drain off any water sitting in the bowls (and bowls!).

On a different note, I popped into Brixham last week to sus out the slipway.

Its quite narrow to turn into but the slipway itself is firm concrete. I have taken a few pics and I will post them when I can.