1990 pg3 compression and valve adjustment

[dan161]

I have a 1990 marathon with a 2 stroke pg3 motor in it. Compression cold is 120 and hot is 110. What is the compression supposed to be in this motor?

Also does anybody know how to adjust the valves for this motor? Supposedly the top end was just rebuilt before I bought it, but I'm not so sure thats the case. The governor has been adjusted so it might not hurt to adjust the valves if possible. I'm just not exactly sure how to on this motor.

Thanks in advance for any help or suggestions regarding this.

[racin161]

Welcome Dan No valves to adjust 2 cycle engine. As for the governor most of us disable it or just remove it. What about fuel or you mixing or do you still have the oil pump. Again most of us remove the pump and pre-mix the gas at a ratio of 128:1 or 1oz per gallon. If the pump fails so does the engine and you won't have any warning.


LOU

[dan161]

Lou, the oil injection system has been removed and I just mix it. I was mixing it at 85:1 ratio as that is what i was told to use. I won't worry about the valves then obviously. So you know what the compression should be for this motor? There is oil residue in a couple different places around the motor, but when carb cleaner to these areas while its running it doesn't change or make any difference. Thanks for your help.

[Dave Box]

85:1 is a tad rich but in the big scheme of things it isn't going to hurt you. The great deal about using the "right" ratio is that it makes your life easy as 128:1 is one ounce of oil to one gallon of gasoline. On that subject you should not just pour the gas and oil into the fuel tank as they will not mix properly, in fact I will bet that if you drain your tank you will see a nasty oil residue in the bottom. You should put them both into a gas container and agitate to ensure a proper mix.

With regard to the compression it sounds about right, especially if the engine has just been rebuilt. As the engine cylinder beds in and you get a little carbon around the top ring you will hopefully see the compression creep up to 140 (ish) psi.

Just to go back to the oil issue for a moment. One of the disadvantages of too much oil is that a sludge tends to build up in the muffler and restricts the engine breathing. The solution is to remove the muffler and place it on a camp fire. After about 30 minutes the residue will ignite and flames will shoot out of either end, give it another 30 minutes and you are done. Simply tap all the ash out and reinstall.

Enjoy the cart.

Dave

[dan161]

Thanks for the reply Dave. I have no problem mixing the fuel with a 128:1 ratio if that is what they call for. I wasn't sure and so asked somebody and was told 85:1 should be sufficient. But for $900 for muffler I would like to keep it as clean as possible, and keep from having to barbeque it anymore then possible.

Again thanks for the tips.