Old Suzuki engine fired into life

[Johng]

Well my first ever outboard, an unknown 400cc Suzuki twin, fired up yesterday

I had removed the powerhead to get at and free off the gearchange..

The block got hot and there was no water running out of the 'tell tale hole' for a few mins, but sure enough, the thermostat opened and out came the water, the engine was then running very cool... suprisingly so.

but.. I have noticed a few things..

there is smoke coming from the water outlet, and also, water getting into the main exhaust casing.. there are two gaskets between engine and casing, so I am buying some thicker material to try to fix this problem..

One spark is weak, causing the engine to run on one most of the time.. I have traced this back to either the Cdi or the pulse coil[s] but have done no more.. I am hopeful a bike Cdi from the 70's may get me through, if that turns out to be the problem.

The engine died, after about 5 mins of running, twice .. I get the feeling there was a last push of steam and then it stopped..it wasn't hot/seized.. I assume the gasket problem is causing this, but cant quite work out how, or why it happens after a few mins and not straight away.. any theories on this, I would be grateful.. Basically, I am wondering how/if water can get into the cylinders, via the exhaust.. does some exhaust gas get sucked back into a two stroke cylinder?.. that would explain the steam and the loss of power after a few mins...

despite all that, very happy, the engine was vitrually given to me (boat, engine, and trailer for £100) and to hear it running and see coolant coming out, having fixed the gears, was worthy of a beer comp checked revealed both pistons within a couple of psi of each other, about 130-140

John

[Johng]

well after a few weeks I have got the engine back together with some thicker cork gaskets..start and runs and idles... also found a few things..

there is a small transfer hole from the water outlet, upstream of the impeller, back into the exhaust casing. This may explain why there is some water present in the exhaust casing..

also, there is a larger hole from the exhaust casing linking it with the tell-tale outlet, this explains why i get some smoke from the tell tale I think.

the water I was getting into the lower cylinder seems to have stopped, with the thicker gaskets..

the engine smokes quite a bit, definatley caused by the weak cylinder firing into life and back off again. Engine almost runs better with that cylinder disconnected.. certainly smooth and smoke free.. to be expected.. anyway, have PEI/CDI box off, but my CD manual doesn't cover the test procedure for it.

I will swap the feeds into the cdi box from the two pulse coils, to see if I can get a good spark on the bad cyclinder.. if I do, then the pulse coil is to blame, if not then it must be the cdi .

John

[Johng]

well.. i did another 10 mins on this last night, and measured resistance of the two pick up coils, and both were the same.. so I guess it's the CDi..

no way I will get an original one, so will need to substitute a bike one I think.. could be fun

[Howstar]

You could have weak fuel pump, try squezing ball thing after few minutes still if keeps running , i had this few times, a weak diagphan

[Johng]

thanks Howstar..

no it's definately a weak spark on the lower cylinder

CDi is now the only suspect... they cant be taken apart (I tried once) so I have a new one offered at £100, which is more than the boat, engine and trailer!

or, the option of digging around at a local bike breakers and bringing home a selection of single cylinder Cdi's and using as a pair...or finding something from a 70's jap 2stroke twin... the breakers is doable in a lunch time, so will go one day this week...