replacing cylinders on 305

2 years ago I rebuilt the top end of my 305 but since oversized cylinders are unobtainium I couldn't do a rebore. The right cylinder was scored so I replaced that piston with a new one, but honing did not quite smooth out the bore so the rebuild was not entirely successful. It ran but smoked and blew oil on that side and lacked power.  I rode it up and down my street 15 total miles that summer, never getting above 45, and it hasn't been started since.

So after years of searching I finally found used cylinders that look good, but I won't know for sure until they arrive and get them measured. Assuming they are good to use with standard 61 mm pistons, do I need to do anything other than install it with new gaskets? Can I go with the present rings, which only have 15 miles on them?

 

Are these the rings that where fitted when it melted a piston ? If not I would think you will be ok but if they are, for the price I would replace (especially given the problems finding barrels)

Wookie58 wrote:

Are these the rings that where fitted when it melted a piston ? If not I would think you will be ok but if they are, for the price I would replace (especially given the problems finding barrels)

 

No that was a more recent thread from a different poster. My right skirt was scored along with the right cylinder, but I had the bores honed and replaced the bad right piston (kept the left one) and installed new rings on it. So all of the rings, and the right side piston, only have 15 miles on them. The left piston looked fine so I kept it and it has new rings with only 15 miles.

 

You should be fine as long as the pistons and rings have no sharp edges or burrs.


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My used cylinders arrived and they look great. I still need to get them measured and looked at by a pro but other than not seeing cross hatching I see no wear at all and they certainly haven't been overbored. Should I get them honed? I suppose with the rings being new-to-the-cylinders that I should, huh? Hate to take any metal off but guessing I need that hone

Yes, they should be honed.

Got my new-to-me block measured (its good!) and honed. Started the disassembly by photographing everything with a real camera, of which I have about 7 or 8.
Took the carbs out but not before discovering I hadn't drained the bowls last time I ran it, argghhh. Add "clean carbs, again" to the to-do list despite having cleaned them less than 15 miles ago. Got the exhaust off and plugged the orifices because I may be taking off for a month or so before I can get any deeper. Need to decide if I should just use the felpro gaskets that are left over from my rebuild 2 years ago, or bite the bullet and get Kawasaki.

I have used felpro gaskets in car applications without issue

A shame I didn't do that last time, then I'd have OEM gaskets ready to go.

I tore it down again and got the block off. Being my first time last time I expected some surprises, and along the way found this: Shavings in the ignition department. There's only one thing that could be (right?), and that's camshaft oil seal. Strangely though I looked at the seal under microscope and it looks fine, but maybe it just happened that way. I don't remember what I used for grease on it, or if I greased it at all, so what should I be using? New one is on the way...



Also, the head gasket was in fine shape but the base gasket is pretty stuck in spots so it will need cleanup. Its a lot easier to keep junk from falling in with the pistons off because you can really stuff it full with a rag, but I had a devil of a time with those circlips last time and would love to leave them on. Its a lot harder to seal it completely with rags when the pistons are on, and I don't NEED to take the pistons off to replace the block. But should I anyway? Will small fragments of base gasket really cause a problem, if any were to fall in?  Second time newbee wants to know.