compression test questions

[Richard Thompson]

I have a comp test kit just turned up in the post all well and good and I understand that I will need to seal the exhaust and carb sides of the cylinder. So my question is what do you use for the temporary seals? ,

I have some tyre inner tube that I can cut for gaskets but do you place a profiled blank (steel, rigid plastic or alu ) over or just place the carb back on and screwed down tight?

I'd like to see as much as possible and reduce the amount of clutter so I can see any possible leaks.

 

I'm not really enthusiastic about grinding dozens of gaskets/plates for every two stroke engine I see if not needed

[Pbtaylor2014]

Hi mate inner tubes a bit thin if you can get you hands on a convaer belt or thick rubber will work better

[TimberCutterDartmoor]

Compression test doesn't need any of this... Leakdown test might but I don't know about all that... Crankcase air leaks etc

[spudulike]

Compression test doesn't need any of this... Leakdown test might but I don't know about all that... Crankcase air leaks etc

 

What he said! Are you testing primary or secondary compression and are you looking to test for leaks?

[TimberCutterDartmoor]

Yeah, cylinder compression is between the piston rings and combustion chamber, via the spark plug hole. There will be differences between hot and cold compression but not as marked a difference as with a 4 stroke engine. Should be hot to test against specs.

[Richard Thompson]

Thanks for the replies,

i'll be testing crank seals and oil seals

[adw]

As said inner tube is too thin, mud flap or such like if good, you will need an entry point for the tester, Stihl you can use the impulse hose, Husqvarna not so easy ( unless 372 ) modified piston stop does the trick.

[spudulike]

Leakdown test (Pressure/Vacuum) then. Just make up squares of rubber to suit and fit between the muffler/carb and cylinder.

[Richard Thompson]

Thanks again for the replies

I've got some thicker rubber enough for a couple of plugs but I'll get some mud flaps for the older tilly carbs for the 051 and 041's a I have

[woody paul]

Why is inner tube to thin if sandwiched with carb and exhaust.