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Old 12-23-2010, 12:17 PM   #46
Beemerguru
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What about the rocker arms?!?!?!

Do you hav another set? The needle bearings are probably toast to you need 8 to replace and the plastic spacers.

Are the shafts scoured? Need to be replaced or still good?

Personally, I'd start bottom up...remove and clean the oil strainer..use red loctite on the 2 bolts.

Check for pitting on the cam followers - should be smooth. Pitted means the coating is going and once it starts...bad news for the cam. Replace if necessary

Replace the rod bearings and rod bolts. Already there.

You can probably use the same rings if the cylinder bores were NOT gouged or the Nikasil is ALL intact.

New gaskets and O rings all around

Clean the gunk out of the head or use Sea Foam for a couple tanks to burn it out.

Use a good straight edge across the heads in an X pattern and at 90 degree angles to check for warpage.

Fix the rocker arms.

Clean all the junk off the engine block top and cap the little pipe.

The engine stud should NOT have loctite. You chase the case threads with a tap hand turn the stud most of the way in till the length exposed is the same as the other studs.

Assemble with care and then take back your brother's Christmas presents to pay for the parts...around $250 or so.
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Old 12-23-2010, 12:19 PM   #47
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I think this thread will be a good testimony of how tough these motors are.
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Old 12-23-2010, 12:38 PM   #48
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Quote:
Originally Posted by Jasper ST4 View Post
I think this thread will be a good testimony of how tough these motors are.
+1 on that. I'm still a bit queasy from seeing the oil that seems to have turned into carpet fibres and yet each component seems to keep coming out relatively unscathed.
My fingers are crossed for a quick and relatively inexpensive return to the road.
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Old 12-23-2010, 01:12 PM   #49
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He started the bike and let it run in a stationary position until it started to smoke and eventually died. The choke was on and he explains that it was fast idling at about 4,000 rpm for about 45 minutes standing still before it died.

How anyone can get an airhead to idle for 45 mins with the choke on is beyond my realm's of wisdom. Mine's struggling after 45 second's.
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Old 12-31-2010, 06:41 AM   #50
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Old 12-31-2010, 07:54 AM   #51
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Any updates? New pics? Audience is back with popcorn and drinks
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Old 01-01-2011, 10:01 AM   #52
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Pure stupid what your brother did. I wouldn't loan him a stainless steel bowling ball. He might figure a way to destroy that too.
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Old 01-01-2011, 10:02 AM   #53
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Quote:
Originally Posted by outfit View Post
He started the bike and let it run in a stationary position until it started to smoke and eventually died. The choke was on and he explains that it was fast idling at about 4,000 rpm for about 45 minutes standing still before it died.

How anyone can get an airhead to idle for 45 mins with the choke on is beyond my realm's of wisdom. Mine's struggling after 45 second's.

Good point. They will not run on full choke for long. Half choke? Not sure.
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Old 01-01-2011, 09:39 PM   #54
jimbee OP
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I've been enjoying the festive season (), and having some non-motorbike related fun, but I do have an update...

I left off heading for Shail's with the heads, pistons, cylinders, and a shopping list.

Shail removed both valves on one of the heads and said that the head looked fine and so the other head was likely fine as well! I was busy at the counter filling a box of parts and forgot to ask if he put a straight edge accross the head, so I still need to go get one and confirm that there is no warpage, but so far, the heads look okay! There was oil dripping from both cylinders, but after cleaning it up and then letting it sit, my best guess is that the oil was leaking from the valve cover gasket, not the head gasket or cylinder base, but I won't really know until I get it running again.

Next he looked at the cylinder and comented that even though there was no visible scoring, the top and bottom of the piston travel was still clearly visable on the cyliner walls and he very strongly recomended having the cylinders honed with a special diamond coated nicasil hone, and he recommended a place about an hour away that could do it. He said that it would burn oil if the cylinders weren't polished so. Any one else have any other thoughts on honing the cylinders

As for the pistons and rings, he said that if the ring gaps still look good, to just reuse the very recent (1,000 miles) rings, but if the gap is off, to replace them. One piston had a small amount of damage where a connecting rod pin c-clip had somehow spun with some force to cut a groove in the underside of the piston, but Shail felt it wasn't worth worrying about and to reuse the piston.

So, I left feeling pretty good and with a box of new gaskets, oil, o-rings, plugs, etc and few parts on order.

Got home and pulled the connecting rods, and inspected the shells. I've never pulled these before so don't know what to look for, but they don't look mangled to me. Maybe the fact that the shinny coating is vislbly worn slightly means it got hot? In any case, I will reassemble with new shells.




Thanks for the complete thought process Beemerguru. I too am worried about the rocker arm abuse, especially beacuse not only were the plastic spacer washers toast, but many of the mounting stud nuts also came loose during the torture and so the push rods and rocker arms were all rattling around loose and banging against one another in there as the engine ran.

Here is a picture of one of the shafts:



Again, I've never really pulled these apart to have a good look, so I don't know what normal is. It is visibly clear where the bearings and shaft are in contact, but so far I haven't felt any grooves, pitting, or otherwise. There are pieces of plastic (reminants from the black spacer washer) inside the rocker arms, which I am carefully removing with q-tips, but the needles are all still there. So not really sure how to tell if I need to replace all the 8 bearings (they aren't cheap and quite easy to get to if I need to later). What is a good way to test the rocker arm bearings?

Quote:
Originally Posted by outfit View Post
How anyone can get an airhead to idle for 45 mins with the choke on is beyond my realm's of wisdom. Mine's struggling after 45 second's.
It was in the half choke position on a cold and wet PNW day - does that make it easier to swallow?

Thanks everyone for your continued interest and help. As Jasper wrote, this is definatly a testimant to the durability of these motors. At this point, it looks like I am really looking at a best case scenario here! This could have been much worse, but still not getting too excited until its back and running without burning oil or sounding like a rattel can.

I'm nursing a hangover, but tomorrow I will tinker further. It has been suggested here that I dissasemble the oil strainer, clean, and reinstall with red locktite. I'm not sure how to do this (not in my Haines manual) but I'll see what happens. Also going to clean up the carbon on the pistons and heads, then it's time to put her back together....

Happy 2011!
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Old 01-01-2011, 11:42 PM   #55
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Wow. Those big end bearing shells look better than mine did at 68K. And my little brother never tested its suitability as a nuclear power plant.
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Old 01-02-2011, 06:49 PM   #56
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piston ring gap?

Cleaned the carbon off the heads and pistons today. I'm almost finished with all this cleaning crap.

Anyway, I also checked the piston ring gaps but was a bit confused!? The spec is approx. 0.3 - 0.5 mm for both rings, but all mine were over at about 0.55mm?

I had a new set of rings and so used a new ring to compare the ring gap and sure enough it also came back >0.5mm - so the brand new ring wasn't even within spec?

The measurments didn't change anywhere in the cylinders (even where the piston doesn't travel) so I don't think there is any real wear on the cylinder walls.

Am I missing something? Thx JB
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Old 01-02-2011, 08:05 PM   #57
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It may have quit running because the ignition pickup died from the heat.
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Old 01-02-2011, 08:24 PM   #58
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Quote:
Originally Posted by jimbee View Post

The measurements didn't change anywhere in the cylinders (even where the piston doesn't travel) so I don't think there is any real wear on the cylinder walls.

Am I missing something? Thx JB

Did you push the ring into the bore with a piston to keep it 90 degrees to the cylinder?
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Old 01-02-2011, 08:39 PM   #59
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I'm still concerned about your engine parts.

A visual inspection is useful, but I'd like to see a machinist pass a cylindrical dial guage over the barrels, and a hardness test performed on the heads. Due to the abnormally high heat your engine was subjected to, the big enemy is distortion so it's possible for your barrels to no longer be round, and for the heads to have gone soft. If the heads are soft, the valve guides could move and/or the valve seats could drop out.

When alloy gets overheated, weird stuff can happen.
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Old 01-03-2011, 07:25 AM   #60
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I haven't worked with Nikasil as much, so I can't comment on honing it. But with steel cylinders, you lightly hone to "break the glaze", and Nikasil is a completely different critter.

Agree with Max, my concern would be that the aluminum cylinders would be more prone to warping than steel lined-cylinders when overheated. Careful measurements to check that they are round and straight; if in specs, they'd be good to go. But go with what your local expert, Shail, says. He's at least seen the parts, we're commenting based on past experience. :)
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