Compression Check

[teeoce]

I was wondering what compression should be at when the engine is cold and when it is warmed up. Everyone says 120psi, but how much below that is acceptable?

I have an Elite LX engine and it is only registering at 60psi. I'm not sure how tight I have to get the hose to get a good reading? I'm going to check the reeds next, if they are ok I guess it is time for a ring job.

[bradthreee]

I dont know the direct answer to your question but my engine had 80psi compression and it wouldnt run. It had one ring stuck...

[teeoce]

It wouldn't run at all? Mine has trouble starting but once I get it going it runs good. Just hard to start without dumping gas in the carb/cylinder.

[Wheelman-111]

Greetings:

The compression tester fitting has to be completely airtight in the plug hole. Any reading is useless without that.

[teeoce]

Thanks Wheelman, of WHAC. How do you get the fitting airtight? It is hard enough for me just to get the sparkplug out in that tight space (my hands have possibly grown since I was 15). I purchased the cheap compression tester from Harbor Freight. I disconnect the gauge and basically just twist it in as tight as I can using the tube. Any suggestions?

[wikked_spree57]

Strange as this sounds, but I used DW's gauge and I only got 45PSI on my Dio motor... and it runs perfect.

[evilone]

teeoce, tightening it like you did should be good. Maybe you could rent a tester from Autozone or other auto store (Possible better quality). Are you using electric start and wide open throttle when testing? If not, try that.

[teeoce]

My electric start doesn't work. I used kick start with WOT. How much does warming up the engine make a difference?

[burnt_toast]

My electric start doesn't work. I used kick start with WOT. How much does warming up the engine make a difference?

Do it and find out

Proper check should be done warm, 100-110psi warm is limit