ANYONE in south Florida rebuild a g1

[sick1166]

love to do the top only ,is that all I need
found this today, guess this would cause no compression and no start, can I get away with just the top end rebuild, does the motor have to come out for that?

[TheGDFP]

Nope. You're almost there. Remove intake bolts and exhaust, pull jug up.
Maybe blow air around the base of the jug to keep crud from falling in.
You can check out the condition of the rod bearings once the top is out of the way.

[ferdabutt]

Looks like you might need a new cylinder or bore out... how do the cylinder walls look?

[sick1166]

I will look in the morning got dark here, im looking for scratches or gouges right?
the pieces of piston missing are they down in the main case do I need to take that apart or just do the top and go from there.
when I spin the crank it spins freely
what else do I need to look for
thanks for all you guys help....

[TheGDFP]

I highly doubt you'll be able to get all of the aluminum out of the bottom end, and it could cause additional damage. It really should come apart for a thorough cleaning and at least new seals. It's one of the simpler engines to tear down.

Bore doesn't look terrible, but a wipe down and accurate measurement would tell for sure. Adding $60 or so for a bore job, would ensure a round and straight hole, with correct clearance for the new piston. Skirt breakage is usually from piston and/or bore worn to the point the skirt snags the intake port.

[TheGDFP]

And, do you have a set of calipers? I'm interested in a couple measurements, if so.
Height of cylinder, top gasket surface to base gasket surface, and hold down hole centers.

TIA

[Tonka329]

Yup. I would do a full rebuild seeing those pics. Strip it, wash it and install new. You'll be golden after that

[sick1166]

Thegdfp, hope I understand you right, from the top gasket to bottom gasket 111.64mm
is this what you are talking about where the carb and exhaust hook up

[slonomo]

I have to wonder where the chunk from the top of the piston went? There's no way for it to fall down unless it is bounced around in there. I'd be looking really hard at the cylinder. It's likely that you'll see divots, dings, and gouges.

If it were me, I'd replace the cylinder, no guesswork then. New jug, piston, rings, reeds, and gaskets and seals. Check the play in the crank bearings. There should be no play up and down if you grab the end of the crank.

You might be able to do an overbore, but you'll need to measure it first to see where it is. Then you'll need to find an oversized piston and take that to the machine shop with the jug so they can match it.

Sometimes you get what you pay for with a rebuild. Spend the money on Yamaha brand parts, much better quality than the off brand China stuff.

Splitting the cases is tricky if you've never done it before.

[sick1166]

Where do I find Yamaha parts it seems everyone I talk to from company's say they are not oem and will be hard to find! Any leads will be appreciated