Hitchcocks Forum

Hi Guys,


I went for the first start of the year on my 500 K/S classic 4700kms on the clock, After many priming kicks it had a big kickback then after more kicking it subsequently fired up for 2-3 secs and died.


Now the compression is about 60% reduced. i have removed the rocker covers nothing obvious the pushrods spin ok at tdc. Valves open and close ok. Shall I go for a start and see if it sorts itself out.


Any ideas would be greatly appreciated.


Roy of Sussex

I'd go for a start and see what happens.


If the engine hasn't been run for some time there won't be much oil on the bore and the rings could be sticking a bit as well. You could try a squirt of oil down the plug and see if this restores compression.


Did you drain the carb when you layed it up? If not the fuel will be stale in the carb which won't help.

Plus one on Petes advice, whilst waiting for oil to soak just check decompressor hasnt stuck. Little oil on spring and cable, just work a few times. check battery is topped up and charged. Fresh petrol and try again. Or bump start.

Maybe all that priming and few seconds of very rich running has washed the last of the oil off the bore...... put a teaspoon full down plug hole and turn it over a few times and hopefully all will be well!


After the big kickback it wouldn't hurt to check for oil circulation at quill whilst spinning over at the same time as the plug is out....... just in case.

Thanks for all your help Gents.


I drained all the fuel out of the tank, put a couple of squirts of oil down the plug hole as recommended.


After a few coughs and farts it fired up, I ran it for about 10mins now the compression is fine again.


I now have to repair a stripped thread on one of the rocker cover studs that I discovered, obviously bodged on the engine production line. New stud required, hopefully the damaged one will come ouy ok!


Thanks again.


Roy of Sussex

Roy,


That's what mole grips are for


The torque on those rocker box caps is pretty low -  8 ftlbs if I recall.