Engineers Emporium Economy H&M Engine

[brozier]

John,

Are you continuously spraying the easyStart into the air intake? With throttle wide open, ignition on etc?

If it is not firing with the above setup I'd suggest either the ether isn't getting to the cylinder or your ignition isn't working correctly. Are you sure you are getting a spark? Have you played with the timing?

Is the spark plug gap right? Too small it will short circuit with any unburnt fuel, too large it won't jump under compression....

Dumb question #2 are you spinning it the right way?

Cheers
Bryan

[John Wood]

Still can't get it to cough.

Went to the Bristol show yesterday and had a close look at the demo model, I found their compression was far greater than mine which would certainly explain my problems. Have checked it all out again (valves, head gasket, port sealing plugs, spark plug etc) but can find no fault except that I have inadvertantly gapped the piston rings to about 10 thou instead of the recommended four. I will order a new set of rings and see if that makes a difference.

I guess their demo model is well run-in but I have run mine from the lathe for four or five hours so wouldn't have thought it would make that much difference - or would it? The boss wasn't there on Sunday so couldn't really get any advice,

Onwards and upwards

John

[John Wood]

Hi Bryan.

I have used the Easy Start method and reckon it tries a bit but not properly. I am using a trembler ignition which is working fine. I have checked the timing that many times and varied it at all points from way before TDC to a bit after. The plug gap from new was around 20thou but have now widened it to nearer 25 and I have made sure it's sparking in the bore because I took the head off to check! Can't actually check under pressure though so perhaps I'd better return it to 20.

A perfectly reasonable question "am I turning it the right way?" I asked that of myself and looked in the construction book just to check, I have also gone through the 4-stroke sequence very carefully to make sure the timing and ignition is right.

Having now proved low compression it's reasonable to suppose that that is the real culprit, something I couldn't find out until I looked at a working engine (see previous reply).

Many thanks, John

[John Wood]

Have found out from a past Westbury article that trembler coil ignition takes place on make, rather than break contacts therefore the timing needs to be adjusted accordingly.

I have had a look at the demo engine at the Bristol show recently, it has certainly got a lot more compression than mine. I have replaced the piston rings and gapped them carefully this time and have run the engine from the lathe for about twelve hours. I think the compression is better than it was but still not like the original. I havn't had time to try starting it yet but am hopeful.

John

[brozier]

Hi John,

You could check if it's the rings/bore causing low compression by putting a small quantity of engine oil into the cylinder (above the piston) this works best if the cylinder is vertical.

If this improves compression it's the rings. If not you need to look elsewhere.

Have you tried starting it whilst it is assisted by the lathe? Turning a leaky engine over at high speed will tend to reduce the effects of low compression as it takes a finite amount of time to leak away.

Speaking of leak down tests that reminds me of the "pro" way of testing rings/valves - pressurize the cylinder via compressed air through an adaptor in the spark plug hole, watch dial to see if pressure is lost - you could to this with a foot pump or similar. You my be able to track down the source of any leaks easier that way....

Good luck!
Bryan