Yamaha G1 Won't Run

[cuttingedgedesigns]

First off so far this forum has been a great help getting me out of jams but I cant seem to get my newest g1 running. This will be my second G1 my first g1 ran great and the basics filters and carb cleaning helped it a lot but my newest addition is making me want to set it on fire. So far I have cleaned the carb, bbq'd the muffler, changed the fuel filter, changed the air filter, disconnected the oil injection system and premixed, changed the spark plug, ran a jumper to the ground on the coil which made the spark noticeably stronger but didn't fix the issue. my plans for the next evening is to spray carb cleaner around the crank seals and check them. I was just wanting to see if I have missed something obvious. I have the basics spark gas and air but no run. any help is appreciated thanks in advance.

[cuttingedgedesigns]

this is my first g1

[cuttingedgedesigns]

Anyone have any suggestions?


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[sho305]

Spark/fuel/compression! If you have spark squirt fuel in there. Check the compression. Bad crank seals make them hard to start choke it hard it might.

[cuttingedgedesigns]

Looks like reeds lots of space and gas blow back crank seals seem to be good


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[slonomo]

What is your compression reading? That's the first step. Once you know compression you can move forward with your diagnosis.

Hopefully the compression is good. If so, try to squirt mixed fuel in the carb manually to see if it will start. If no start. Look to ignition. If you have spark now it should be good. These engine rarely skip time.

These G1's are known for needing top end rebuilds if they are high mileage and haven't been maintained. Also the crank seals go hand and hand with the top end rebuild. They are easy to do once the engine is out. Make sure you have a puller tool for the flywheel and a clutch puller tool for the clutch. These tools are invaluable when rebuilding these engines. If you have the tools and a place to work, the rebuild will be pretty easy. Taking the engine out makes it a lot easier. There are a few wires to disconnect, but they are cannon plugs so they go back together real easy, the throttle cable, drive belt, starter gen belt, and 4 bolts under the engine and the engine will come out. It weighs about 50 lbs or so, have a buddy help you lift it out for safety.

When you buy parts, get the Yamaha brand only. I have not had any luck with the chinese parts. They are much cheaper, but they are not made with the same metal and quality as the Yamaha parts. Get the jug measured and order an oversize piston and rings, have the jug bored to match the new piston. Get new engine gaskets and seals. It will run like new.

[sho305]

Reeds should be closed at rest or they are no good, but I have seen them run with reeds that were not all the way closed however they moved easy and would close on compression.