I'm sure George is a better judge of this than I, but if the will "bounce" on compression, your probably OK
I believe I read that George made a compression tester for one of his builds recently....maybe it's the radial...I'll look
No I don't believe a full size compression tester would be useful here as the internal volume of it would be very large....you would need a much smaller unit to really be useful with small cylinder I would think.
PS Didn't find it in the radial build.....Can't really remember where I saw it but it's around .....
What Dave said is how I judge compression. When the engine is turned over if a definite resistance is felt when the piston is nearing top dead center then there's usually enough compression to start the engine. If it feels like what I call 'soft' when it gets to TDC then a person should start checking for the problem. I would say 90% of the time it's leaky valves. Over the past many years on this forum it seems the primary reason for 'soft' compression is from valve leakage as opposed to piston blow-by.
At one time I had made a miniature compression tester but with the very small displacements I don't know how accurate it was. There are some commercially made compression testers that won't even work on small engines, the lawnmower, weedeater type. The reason for this is because they don't have the check valve, that holds the compression, right at the tip of the adapter so when the engine is checked the amount of area in the hose has to be added to the volume of the cylinder thus reducing the compression pressure.
The saga is not over yet ;D
Bez and Aus came over today and we got a couple of short runs out of her, but we all agreed there are carby problems.
As yet I'm flying blind here, but for the lack of anything better to do, I turned up a brass bush and pressed it in the throttle body taking the the venturi from .250 down to .190.
While I was at it I lengthend the cross slots which were not allowing full throttle.
Another weak area that came up was the throttle lever which kept slipping, so maybe ill pin it or something.
All in all, my take on the situation is this.
The Cam and Valves are good but the carby not so much. :big:
With any luck, ill try again in a day or so.
Looks like I was off the track a bit with the venturi bush, but I think I have it now. scratch.gif I had noticed that the wallaby would only fire when the mixture needle was basically falling out and today this led me to the discovery that I could only blow through the draw bar once the needle was almost taken out so after a bit of a rummage in the wife's sewing box I found a needle with a very blunt point and after soldering it in, I can now blow a little air threw it just cracked open.
Before tyring to start her again I want to remake the starting spigot out of silver steel and harden it but I think she will run now.
I pulled her down the other day chasing a very bad oil leak and after a full days work getting her back together found i'd mistimed the valve gear again, dame it. Which as im sure you will find out soon takes a good bit of time to take apart and put it back correctly.
And to make things worse it still leaks :big:
just at the moment it all seems like hard work ;D
not so much beer time as Tax time at the moment
yup got the one way breather, I'm using some thin shim metal as the diaphragm at the momant but may go to rubber later if I need to.
I'm not sure whats leaking yet but it may be the banjo seal is not up to the task.
( A little plumbers tape on the fittings easily fixed the leaks )
One day Tel, I want to come down for the race over the Mountain and we will see then, what you keep in your fridge :big: