New G1 owner - crank no start

[BreezyGreen1]

Hello, I just purchased an old G1 2 stroke. I have not ascertained the year yet but was told 1978. It ran when I got it, I drove it around the yard several times in 2 days and then it suddenly would only crank over and not start. I am an automotive professional but know nothing about 2 strokes!

[slonomo]

Principals are the same. Fuel, compression, spark. Check those and report back.

[BreezyGreen1]

Ok so I have spark, compression over 100 and I have fuel that is at least making it to the plug but still not fire. It does fire immediately with starting fluid.

[BreezyGreen1]

aLSO i GOT IT TO FIRE UP AND RUN ENOUGH TO DRIVE A FEW HUNDRED FEET . But I had to block off the carb with my hand to do that, ran once it fired up, But when doing that I also started seeing some mix coming out near the clutch, crank seal maybe?

[slonomo]

100 psi isn't high enough. You need more compression and on these engines it's usually leaking at the crank seals. That oil you see coming out behind the clutch is from those rubber seals around the crankshaft. Time to order parts.

There are a few threads on here that will walk you through the process of changing the seals. It's not that bad, you do have to remove a lot of parts around the engine. I found it easier to remove the whole engine and work the engine on a bench top (bad back). Once the engine is out it's a 45 minute job for me. Taking the engine out is fairly easy though, there's not much to disconnect....electricals, muffler, belt, intake, fuel lines, governor and throttle linkage. Make sure you take a pic of the throttle linkages (if you still have them), and be prepared to buy new plastic ends for them.

[slonomo]

The reason it runs when you put your hand over the carb is that it's running lean, not enough fuel. Covering the carb reduces the amount of air that can enter the carb, thus enriching the mix.

Also, with the G1 two stroke, it requires internal pressure to build in order to run properly. The air inside the engine flows in a pattern according to the cylinder porting shapes and locations. If there is a pressure loss somewhere, the fuel/air flow will be altered and it wills suck/expel air from the leaking area. This is why you were seeing oil/fuel around the crank.

There's no way around it bro, you need a rebuild. Don't just replace the crank seals either. I'd take the engine apart and look at the rings. Chances are the rings are worn out, or even cracked. If the engine was taken care of you might get lucky and have low wear. But with two strokes, people often use too much oil, not enough oil, or no oil.

I would also disconnect your oil pump supply line and premix the fuel at 100:1. The stock mix is 150:1 (according to the manual) at high usage and 300:1 at low usage. The oil pump supposedly takes care of the mix, however, they often run dry, get plugged, or fail.....then boom....bad engine. I ran mine at 100:1 with no smoke, almost no wear, for over a year. Prior to that I ran at 85:1 and it smoked a little. Also, use a really high quality "air cooled 2 stroke oil". I used Echo brand from Home Depot. Don't use the "one mix covers all" it's B.S.....it'll smoke.

[BreezyGreen1]

So low and behold I found that although I has spark I did not have good consistent spark. I found that one of the wires going to the coil where it had a push connection had broken except for 1 strand of wire just before the connector. The reason it fired while covering the carb is because that wire is where my hand was and I obviously hit it enough to make a contact. Since repairing that it has run flawlessly! What a great machine, 1979 and still going strong!

[cgtech]

Oil/gas coming from crank seal area is no good, you may be killing it. Any air allowed into a 2-stroke that didnt come through the carb leans out the air/fuel mixture, a lean 2-stroke often will run with good power, but its eating itself internally from lean burn causing too much heat (can literally melt the Piston, murder the spark plug, ect).