Hitchcocks Forum

The 612 rebuild is just about complete save for fitting some slightly higher bars which I will do in the next couple of weeks or so prior to using it in anger. Anyway, after carefully re assembling the engine I thought it felt low on compression - how could this be I thought valves have been ground in, new head gasket, valves properly adjusted. What gave it away was the odd sort of hissing sound comming from the exhaust on the compression stroke - that unmistakable sound that comes from an open de compressor. De comp adjustment appeared to be right so I pulled it apart - seat was pretty black looking so ground it with fne compound, the stem was also pretty black and even had some carbon on it - must have been leaking when the PO had it. Anyway, re assembled, compression re stored !! Just have ot fill her up with 20/50 then I can fire her up. Never had an issue with a De Cmp before.

Had this on a Redditch 500, a faulty inner crush waher on the decomp stopped it from starting. No hissing, nothing. Took ages to suss it out! REgards, Mark