Any idea why I can’t get my V50 to tick over once the engine is hot? It is fine when cold but once hot it dies on closing the throttle. Sometimes instantly and other times it slows down first. I can then get it to tick over again by starting it (sometimes has to be several times) and then it’s fine.
I have checked the idle jets are clear. I have adjusted the idle screw/throttle stop as per book and tried richening and weakening it from there. I have checked the seal of the rubber boot inlet. I have increased the valve clearances in case they were not seating when hot. I could check the float height. Is there anyway of doing that without removing the carbs? I can’t think what else to check?
Re Chokes. There should be a clear imprint of the Jet onto which the Choke Plungers are held under spring pressure when the Choke is off… no prizes for guessing how I learnt that one.
Worst case scenario: the tiny round rubbers in the choke plungers have worn to the point that they don’t seal properly (had it happen on a couple of my Guzzis and seen it on others). The solution is to cut a piece of 3mm rubber to the correct size/shape and glue it on to the existing rubber.
Thanks for the replies. I know the springs are good and cables are moving freely with slack in both cables, but I could try the rubber extensions idea just in case. One more possibility to eliminate.
Each carburettor type has a specific float height setting (which is generally independent of the application/bike it’s used on, unlike jet and needle sizes).
The H tool is a special H-shaped tool that you use to set the float heights: with the carburettor inverted, the “H” straddles the float bowl mating surface on the carb body. The horizontal bar of the H has a notch at the centre to clear the main jet: the arms are used to set each float at the correct height, usually adjusted by bending either the tang that the needle valve hangs from, or each arm of the float arm assembly.
This means that when the float bowl is re-fitted, and the carb re-oriented the correct way up on the bike, the petrol pool level remains correct under all conditions of fuel draw from the main (and other) jets or accelerator pump.
If the spindle of the float arm assembly sticks, or the float level is too low, the idle and main jets will be uncovered (depending on load/draw) and you’ll have a starvation, usually resulting in a stall.
I’m no longer sure where they are available (also, I think they’re called float height gauges), as I bought the one for my LeMan2 back when I bought the bike in the mid-80s. I was racing LC 250s in those days, and as I’m sure you’ll appreciate, 2-strokes do not like mixture changes or fuel starvation, especially at high throttle… I learned the hard way.
It is worth seeking out, and getting the correct one for your carb model. I did have one for a V50 I was servicing for a friend a LONG time ago, but although I would offer it, I have absolutely no idea where it is now.
I have finally fitted the new correct 9.5 gm float, and although weighing the old and new, there is barely 1 gm difference in total weight, the change has indeed cured the hot engine shut down and I am getting a good hot engine tick over on shutting the throttle at last. Thanks for everyone’s help.
