Top End Noob

Here are some pics of the No 3 Piston. Those small dings on the edge are pretty damn sharp, though it's hard to tell from the picture.

Take a very small file and gently smooth out the sharp spots.
Finish by hand sanding.

Daniel

Some ongoing questions:

Valve Crud The valve faces are pretty crudded up but look clean on the stem side. Any good chemicals to get the crap off?

New Valves? A couple of guides suggest swapping in new valves. Is that overkill? If that's worthwhile, better to get that done now while it's all torn down.

Lapping Seats Either way on the valves, I need to lap the seats. This frightens me. Clymers and the Service Manual are pretty thin on guidance here. Do I need to go to a machinist for this? Are there any good how-to guides for this? The valve replacement guide on BCliff's site requires some funky video player that I lack and won't/can't download at the office.

New Rings At 18,000 miles, do I need new piston rings? The current rings look OK, I think.

Flex Hone When I do the brush hone, what size do I use? The Flex-Hone comes in 64mm and 67mm. Stock width is 65mm, but my measurements so far come in about 0.3 - 0.5 below that (i.e., 64.70 - 64.50 mm). The mfc claims that the brushes are slightly oversized, so if you are honing out a 3" bore, the 3" brush will work because it is a little larger. It also suggests that if your size is not listed, go the next largest size. Will a 67mm brush be too large though for just a de-glazing?

Sorry for all the questions, but I want to place an order for the parts I need, and don't want to leave something out.

Thanks for continuing with this drama.

I removed the valves with a 6" c-clamp and a notched out deep socket.

Those valve stem seals are a real bear to pull out. Will replace.

The valves themselves have a healthy layer of carbon crud on them, but don't appear bent/burned.

The mileage on the bike is about 18,000 IIRC.

[Nessism]

The piston in that photo doesn't look bad at all. Those nicks are nothing and the skirt scuffing is minimal.

I'd go with valve stem seals too.

Give the barrels a clean up, replace those pistons and rings and get the head sorted out with new seals and valves/seats checked, rebuild and then enjoy.

[Nessism]

Since the rings look pretty clean, I am bewildered. I'll check the clearances. If they check out, wtf is fooling that plug??

Valve stem seals?

So how about some more information about how many miles this engine had on it and how you tested compression. For example, was the engine hot when you tested and did you hold the throttle wide open? If the engine was cold, those 110 psi compression numbers are not too bad. Also, if the engine has less than say 50k miles, the cylinder/pistons can be reused without worry.

My suggestion:

- pull the valves out of the head and inspect. Assuming everything looks good, lap valves into seat and replace valve stem seals.

- Remove rings and check piston to cylinder wall clearance as detailed already using a feeler gauge. Or get a proper bore gauge and check that way. Assuming these check out have the cylinder bottle brush honed and slam in new rings.

- If you are using an aftermarket gasket set supplement with OE rubber seals on the cylinder base, and get an OE base gasket if you are using an Athena gasket kit.

Good luck and hope this helps.

Since the rings look pretty clean, I am bewildered. I'll check the clearances. If they check out, wtf is fooling that plug??

[Nessism]

You can do a somewhat lame, but better than nothing, piston to cylinder wall check by first removing the rings and then sticking the piston down into the bore, usually up side down, and then cutting in a feeler gauge between the piston and the cylinder to see how much clearance there is. Check at the very top of the cylinder and very bottom, measuring perpendicular to the pin, since the piston doesn't travel in these area, thus the wear will be very light or nothing there. Next check this same clearance in the middle of the cylinder, and up near the top. The point of maximum cylinder wear is near the top. At any rate, a good cylinder/piston will take a .002" feelergauge but if you can cut in a .004" feeler there is a lot of wear.

Good luck and hope this helps.

For checking the bore, where can I get the right tool? I have calipers but nothing for the jug measuring.

Odd question, but do your pistons have pop.y stamped on one side?

Thanks.

Here are some pics of the No 3 Piston. Those small dings on the edge are pretty damn sharp, though it's hard to tell from the picture.

[Nessism]

Nicks on the piston can't cause oil burning, but it may indicate something else that happened which could. I'd inspect the pistons carefully, looking in particular at the ring lands, and then reuse them assuming the fit into the cylinder is still good.

There are tons of places that sell OE parts like gaskets and rings. Part Shark is one of the cheapest.

OK - Cylinder is off. HUZZAH. PB BLaster and a new mallet and prybars did the trick (with a healthy dose of swearing and rage).

I will post some photos, but the rings look OK I think. The pistons for Nos. 2 and especially 3, however, have dings on their top edge that create a couple of pretty sharp burrs. The jug walls don't look to be scraped or gouged, and you can still see the honing marks. Could these edge burrs be the cause of that oil fouling on No. 3?

Otherwise, can these burrs be filed off to salvage the pistons, od must I replace them? If so, do I need to swap all four pistons, as Clymer suggests?

Finally, where can I get new snap rings for re-installing the pistons?

TIA

[Nessism]

Try wood and some tapping back and forth against the cylinder walls tops. If the torque can just get you a little break in front or in back the rest will follow.

This seems like a good suggestion to me.

You've just got to get that first little gasket break and it will all go from there. Then you'll be rewarded with an hour or two of gasket scraping I know you don't want to break the fins. Try wood and some tapping back and forth against the cylinder walls tops. If the torque can just get you a little break in front or in back the rest will follow. See if you can get a friend to join in on the other side.

This is why mechanics don't usually work on bikes this old. You have the advantage of time and patience. Going back to the jack idea - jack that cylinder front up so the front wheel is just off the ground. Spray-spray-spray down the studs and the gasket surface, tap-tap-tap on the studs. Make sure the wheel stays just off the ground. Time and pressure. Walk away for an hour and do it again.