What to do with a G1??

[super99]

This will be kinda long, but I'll try to include everything I know about this cart. I bought it a couple of years ago, sometimes it runs great and the next time it misses and dies out. It has been converted by a PO to a electric fuel pump. It had carb issues and I read on here about a carb rebuild, so I took it apart and cleaned it up. The bushing on the throttle shaft was worn, maintenence guy at work made me a new bushing and put it in. The throttle shaft was wore, so I took it apart and put some solder on the shaft and filed down to fit. Helped it a lot for a while. I took the muffler off and cooked it to get the oil burned out. It seemed that the consensus on here was to disconnect the oil injector and mix oil in the gas, so I did that. I took it to a tractor show last fall, the first day it ran GREAT, slow, fast and anywhere in between, The 2nd day, it wouldn't run unless wide open and then missed badly. Changed the spark plug and it helped but didn't cure it. Got it home and it ran good again. I had trouble keeping the port on the block under the carb plugged, the hose I put on it would come off. Grandson was here at Thanksgiving, very cold out, and he wanted to drive it around. I choked it and got it running and he took off. It died on him and I couldn't get it started, so we pushed it into the shed and left it set all winter. Nice day today, got up to 70°, so I tried to start it, turns over, no start. I checked the fire with my spark plug tester and it has good fire. The spark plug was black, so I cleaned it up on the wire wheel and sprayed the electrode with brake cleaner and blew it off with the air hose. Had the plug out, so I ran a compression check on it cold. I got 100#'s compression, then I put some oil in the plug hole and tried it again, got 110#'s that time. I put the spark plug back in and tried it, started right up and ran good, so I took it off of the blocks and drove it around for a while, ran great! To me, the compression is low. I have read on here about replacing the crank seals, wondering about doing that to it. Undecided where to go from here. Any thoughts?? thanks, Chris

[slonomo]

A few of questions:

1. What kind of gasoline/oil mix ratio are you using?

2. What kind of 2 cycle oil?

3. New fuel or old fuel?

4. Is there any oil around the crank seal behind the clutch? Does it look like it's seeping?

5. Did you plug the oil injector off? Run dry?

I'll give you some standard responses.

I would ditch the electric pump, you just don't need that. These engines run great with the standard vacuum operated fuel pump, in fact, the fuel pump may be too much pressure, even if it's a low pressure pump. Too much fuel pressure can push too much fuel into the bowl, which may find it's way into the carb via vacuum, and make it run rich. The factory style Yamaha pump is the best one to use, however, I have used a small Briggs and Stratton pump for years, and they are only $17 at the tractor store. Ask for one that is for a Briggs engine of around 10-20 hp, not the larger engines. Ebay also has these cheap.

Mix ratio of the factory oil injector is 150:1 at max, and 300:1 at low speeds. I used 85:1 for a year, then used 100:1 for the next 2 years. That engine was disassembled at around 100 hrs to inspect, no wear at all. That engine is still in use today. No smoke except at start up. If you are using 50:1 that is way too much oil for these engines and it will run badly, smoke, and will accumulate in the exhaust. All the stories about the muffler being plugged up with oil gunk is from over oiling.

The crank seals will leak over time, but your compression reading sounds like it's good. Some G1's have low compression around 90 psi from the factory. The seals might need done, but that usually causes the cart to only run with the choke on, or run better with choke.

The carb shaft and bushing is normal. How you fixed it might work, but there could still be dirt or a piece of the old bushing stuck in the housing. It doesn't take much of a metal particle or dirt to plug up a passage and cause flow probs. A new carb might be in order. If the shaft was that worn out, I usually recommend replacement. You still have an "old carb" and it could still have other issues like a crack somewhere or other wear and damage.

[super99]

Thanks for the reply, I'll try to answer in order;
1. 7oz/5 gal of premium non ethanol gas, shooting for about 100/1
2. I have a quart of Quaker State 2 cycle oil
3. It has about 1/2 tank of last fall fuel with Stabil in it
4. I can't see any seepage around the crankshaft
5. I removed the tank and lines, I put a short hose with a plug in the end on the block.

The electric pump was on it when I got it. I can get a picture tomorrow and post, looks to me like they added a T in the line to feed extra fuel pressure back into the line before the pump.
Sometimes when it starts acting up, pulling the choke out helps for a little while, but doesn't cure the problem.
Sounds like I should start by replacing the carb.
Yesterday, I drove it around for 15 or 20 minutes, went over 1/2 mile, ran great. Today, it was colder, in the 40's, I started it to go to the mail box and it started cutting out as soon as I got out of the shed, choked it and it helped a little and then died. It didn't want to start, ended up pushing it back into the shed and quit for the day. Thanks again, Chris

[slonomo]

100:1 is good. Make sure that oil is "air cooled 2 cycle oil". There is a difference with some oils if it doesn't say "air cooled". Echo brand is good from Home Depot.

I'm thinking it's a fuel delivery problem, but that's just a guess. You already know the carb had some issues. I'd go that route. I'd also change the electric pump out and go back to stock vacuum pump. Once you're there we'll see what happens.

[super99]

I didn't know there was a difference in 2 cycle oils, I'll look for the correct oil. I'll search this site and try to find a new carb and start there. Thanks again, Chris

[slonomo]

All 2 cycle oils are not the same. Since this is an air cooled engine, it runs hotter than a liquid cooled engine and needs a different grade of oil. Marine 2 cycle oil is different all together too. I don't like the synthetics that "one mix fits all". They seem to be smoky, even though the bottles say "no smoke" lol.

I have had good luck with Echo brand. You can find it at Home Depot over by the weed trimmers and blowers. I get the biggest bottle, the one with the "squeeze to measure" feature. I don't bother with the mini bottles since they are made for 50:1 with 1 gallon.

Some on here also swear by the Yamahalube from the Yamaha dealer. I've never tried it, but I know it's pretty pricey comparatively.