compression reading

[coolguy147]

wellll i have a 1962 qd-23 10 hp motor and i was talking about a compression reading. sooooo i got a compression mainly for my atv but it used a 10mm spark plug hole in whcih i didnt have so i decided to test the boat motor before it took it back ,anyways i got about 70 psi on the top cylinder but im sorry i couldnt get to the bottom one because i didnt have enogu room the dumb tester wasnt small enough even though it was hte hose kind. well i told my buddy and he asked his boss about it and said it should be liek 75-80 but he said its ok so im guessing its ok but lol when i did the test i saw the plugs were fouled with black gunk lol pure black and is 70 psi good? this is in top cylinder

 

[JB]

Re: compression reading

Psi doesn't mean much in a 2 stroke, particularly a rope start 2 stroke. What matters is the degree of match between the cylinders.

Does the engine run well? Might be running a bit rich.

 

[coolguy147]

Re: compression reading

well ya once i get it started ya its runs well i cant keep it at idle cause carbs r all gummed up and i guess cause of spark but at a little faster idle its a beast plus im running it in kinda old gass so ya i know my bad i need to fix those things but other then that it runes good so im guessing its ok any things to say?

 

[tashasdaddy]

Re: compression reading

get the carbs cleaned, get rid of the old gas. dirty carbs do not deliver the proper fuel and OIL, to the cylinders. you can destroy the motor with dirty carbs.

 

[kenmyfam]

Re: compression reading

Dont understand why you would run it with gummed up carbs and old gas ????
You are asking for problems in my opinion.

 

[coolguy147]

Re: compression reading

dang man dont got to get mad ok but seriuosly whats whats the proper compression for my motor and sheesh im 13 god give me a break its was my grandfathers motor and i got another one that has been sitting for 10 years a 1962 merc500 and a atv from my grandfather he passes away in 2003 so god i got a lot of thign espcially since school is 2moro

 

[tashasdaddy]

Re: compression reading

no one is mad, just emphatic. we see too many people ruin motors, doing stupid things. just educating you. as you should know we more than welcome the teenage members and have quite a few. the main thing with compression is that the numbers are close to equal, within 10%. compression guages read differently, that is one reason, the manufacturers, do not publish what compression readings should be.

 

[coolguy147]

Re: compression reading

ya my bad but sorry man about the compression the compression meter had a rubber hose on it yet it didnt bend enough for me the get to the bottom cylinder not enough room any ideas on how to get to it and ill get to the carb cleaning look at it i think its pretty simple but another problem came up when i was starting it cause the flywheel cover screws wont come off and i dont wanna strip the screws

 

[coolguy147]

Re: compression reading

please help my find out how to check the bottom cylinder

 

[tashasdaddy]

Re: compression reading

i use the rubber hose, and bend it, and just work with it until i can get the threads to bite. twist the complete hose. i don't know if you can drop that lower pan or not.