Hi. I’ll be honest with you. In the past and frankly, even now…I tend to think too much into things around fault finding with engines like this and further developed, in terms of era. It’s just what I’m guilty of, with being a strictly educated marine engineer, taught by old school guys that are now long gone. Most of the things they taught me are undoubtedly to be adhered to and certainly installed a likely excellent culture in my chain of thought.
But just every once in a while (far too often), I’m very guilty of thinking far too deeply into fault finding on very simple engines like this and similar. Especially when I don’t have these wee engines on or in their natural operating environment.
Long story short, what I’d advise a fella in your situation (but admittedly likely not what I’d be thinking if it was my own situation, rather unwisely), is to make sure you have a good spark plug, make sure your carb is clean and definitely getting fuel…and perhaps even (since you seem like a fella of a more than capable understanding of such things) have a meter across each end of that HT spark plug lead to make sure it had good continuity across the length of it, then give her a go.
Someone on here will certainly offer you a more technical and better explained version than this. But I certainly know that these wee things and the lovely 2 strokes of similar size that followed them shortly after (which I am guilty of having far too many off, unused in the garage), have their own wee ways of starting. Despite any instruction manual there ever was.
So here are some absolute truths about every one of the old Yamaha 2 stroke I have now (and even the 78’ 8hp I used to).
Without fail this is true for my 92’ 8hp, my 99’8hp, my 93’ 3hp Malta and any other decent quality old school Yamaha and even similar era merc I’ve had.
Despite me going far too deep into wondering if they will actually work or not, by pulling them over (after acquiring in an unknown state of condition) and watching for a spark with the plug out and earthed against the block or similar…then wondering if there was one or not ???
Basically, I just simply became aware of how ridiculously good these old things actually were. Especially the Yamaha.
So. Long story short. Outwith major failure and ridiculous neglect…if you know you have compression, a clean carb, good plug and fresh fuel…99% of the time, these things are going to start after the 3rd pull, worst case.
I’m definitely going on a bit here, and had a few beers…but I know for certain, that if I go out to the garage right now…grab the older of the 8hp Yamahas (that’s not been ran for years)…sit her in water, pump some fuel into it with carb drain open to flush, close carb drain…choke full on and throttle full open, pull her over once or twice at maximum…she will then kick…choke off and half, to 3/4 throttle…try again..:she will start. Bet my life on it.
Anyway..
oint is…new plug, fresh fuel through her and she will likely fire up. If she definitely doesn’t after ages trying…then thing about coils and all that. But they are easily tested, if need be.
Just one final beer fuelled thought, before I finish boring you…I think your compression gauge is very optimistic. No big deal though. Right. Let me know how you go. Don’t hesitate to contact or keep me updated. I love these old things and keenly interested in their affairs. Good luck. Wee video of one of mine firing up after years and years of lay up. Added a wee tell tale water outlet mode to this too. Sporting a much newer hood than she actually should have
