Low compression

[Mrileyrealtor]

My 1982 Marathon has 40 compression. What should the compression be. I bought it used for my son it was running and we did a tune up and put on a new belt now it just wont run. It is getting fuel and has spark.

[1lane66]

not sure what yours is suppose to be but after all that Iv'e done to mine and found I only had 90psi it was time for me to get up off the hip. Have ordered a new top end kit that I should be getting any day now. Piston, rings, cylinder all shot on my 88 marathon, has a 2pg 2cycle robin engine. So I'm almost sure you should have alot more than 40psi. good luck and welcome to the forum. If your looking for help and advise these guys on here are the pro's. They've helped me alot.

[skimaniac6]

I just rebuilt my top end on a 91 2-stroke and was getting about 120 lbs when I finished. I found the 2 strokes really need to be sealed good to run properly. If you rebuild the top make sure you do the seals while you have the motor out of the cart. That was the advise I got from my postings so I will pass that on to you.

[racin161]

Min. 90 lbs it's time to do a top end kit and also crank seals plenty of info on here and easy done. Should be able to get a kit for around $200.00 seals at $7.00 each. After rebuild if it still has the oil injector remove it and mix your fuel. Mix will be 40:1 first tank then 128:1 there after. First tank 3oz.per gallon after that 1oz.per gallon. Any questions just shout out alot of help on here and we'll get it going.

[Dave Box]

Your options will depend on your mechanical abilities and your enthusiasm to get this engine running. Then you will have to decide how much you want to spend. You can rebuilt the entire engine for less than $400 and you will end up with the original crankcase halves and the original head but everything important will be new. The disadvantage of this plan is the cost.
You could also just replace the top end for less than $200, this will cure your compression issue. The disadvantage of this plan is that if the bottom end is on its way out then the increase in compression may speed up its demise.
In either case it is most important that when the engine is out you replace the crankshaft seals.

Now it may be that you are not a nut and bolt kind of guy well as racin161 said there are a lot of guys who get their kicks out of helping a fellow carter so if you have the inclination we have the knowledge.

Finally having made you read all this why don't you wrench on the 5 head bolts to see it the head is still on tight, but remember these are metric bolts.

Dave

[1lane66]

With all I've been through with mine I tend to listen to all these fellows. Haven't been steered wrong yet. Got my new top end today and yes I'm replacing the seals also. Plan on getting them at work tomorrow. I did a good check of the bottom end and found nothing wrong there,,all seems to be tight and no end play or slop in the components. Hope to have it back together this weekend and finally get to cruise down the street and make the Tenn. fans a little P-Oed. Also going to install the Bama fight song horn to play.