Not pleased (compression)

[BigMike]

But I'll live with it. was having trouble starting the relic, checked the compression, front: 130; rear: <70, wet or dry. I didn't want to tear it down this year, but I have no choice. by the wear on the piston of rear, and the scoring locations, I'd think that the jug was bored and honed to size without a torque plate. also, same hole's exhaust valve may be burned a bit.
Anybody ever use Wiseco 9:1 pistons? Maybe an AB grind cam and dual exhaust or drag pipes will squeeze a little more out of the old beast.

[Cotten]

BigMike!

Torqueplates are usually not critical until you get to .060" overbore. How big was the cylinder?
If there was a wear pattern into the spigot below the ring travel, then that would be "the smoking gun",...but that shouldn't burn an exhaust valve.

But frankly, since only one cylinder destructed, I would look elsewhere for a source of heat. It took combustion heat to burn the valve; friction from the skirts rubbing the cylinder wouldn't ordinarily do that.

You should still have been able to start the bike easily with 70 psi on one cylinder. Something else was amiss.

It sounds more like the Evil Manifold Leak strikes again.

Since you can't test it now that it's apart, you can only hope the cause comes out in the wash of a rebuild. but to insure your investment, please pressure test your next manifold installation with soapsuds.
Wisco pistons are quality of course, but pricey overkill unless you are competitive. And the weight of forged pistons might demand some thought about balancing. And consider also that gasoline with octane to sustain 9to1 compression is getting scarce. You will run very warm on pump gas.
And (by my experience) Andrews doesn't make a practical Pan cam, unless it is a stock FLH replacement. And dragpipes rob you of low and midrange, all for a tad more top end. How often do you run over 80mph?

[BigMike]

no detectable manifold leak, at least in the last few months. (new S&S with new O rings and clamps) stock CR for the FLH was 8.5:1 anyway, is 9:0 gonna do that much anyway? as far as cams, I was hoping to get a little more lift and more duration on the exhaust side, in hopes of it breathing better and perhaps running cooler. I don't want to flog the old girl that hard, but I live in Florida, there are many opportunities to run at 70+ for extended periods. I'd rather change sprockets and keep the RPM lower. I would assume duals with a crossover would be better than drags, but running stock heads, there doesn't seem to be much available. the stock 2:1 with squish pipe is OK, but can't be the best option, even for bottom end. gonna finish the teardown tonight and see what I find in the front hole. with 130 psi it should be OK.
the existing slugs are +.010, .020 should clean em up if they are round. I'll think it over a bunch before I order anything. I'm still puzzled about the scoring, it's worst above the top ring, and on the skirt opposite that. There is wear below ring travel rear side of jug. loose fit or twist in rod? seems odd to me, I'll take my time and do it right. Thanks Cotten, I'll take all measurements carefully, and check the valves. I've built hotrods before, but this one is too sweet to get stupid with.

[Cotten]

Mike!
Unfortunately, many destructive manifold leaks aren't 'detect'able by any other means than the pressure test. (barnyard gimmicks like spraying WD around it only show big leaks).

And yes, a half-a-point of compression is significant. Ask any racer!

You have to look at the piston scoring and decide for yourself if was heat, spigot scuffing, or just gouged by chunks o' sumpthin.
You can't go wrong by going conservative. Unless you crave speed so much that nothing else matters. Don't forget that Pans are by design a torque motor, not a horsepower mill.
Still, even a pooch Pan should cruise at 80 all day. My wife's has done it for many years,... with a hack attached.

[BigMike]

more studying of the piston, and orientation of it .... It appears as if what ever caused the scoring was the infamous mystery gunk, the bike sat for 2 years before I got it, maybe dirt, dust, gunk or something got sucked in on initial start-up after sitting. There is virtually no damage to the cylinder, whatever it was was tough on the piston and easy on the barrel or the rings polished it out. I'll go with the forged slugs, but run the stock profile cam. Clean up the heads and just lightly lap the valves. If there appears to be damage or burning in the rear head, I'll cross that when I get to it. Also will dress up the intake spigots and intake manifold before assembling it (new O-rings and clamps again). This is 12 month riding country and I really don't want the scoot down any longer than necessary. (don't want to rush the work and f- it up either) the radical difference in compression merits attention even if a top-end job is a little overkill. I'd rather have it on the lift awhile now than in the trailer to get it home later. gonna look into sprocket changes to keep the rpm down at higher speed. The way it is now, 50-60 seems to be the sweet spot, I'd like that to be up to 60-70 for highway use. I'll keep the board posted.
btw, thanks cotten, you are a calming influence, a buddy and I got carried away a few years ago and ended up with a tintop so radical that it was unrideable, except for showing off for short periods and surprising ricers light to light. I'm really trying to avoid changing this 64 away from stock, there will never be any more of them.

[panhandler]

Mike, I run wiseco's in my 63 and an Andrews J grind. I am NOT a racer and like to cruise around the 60 MPH mark. I was running a stock FL cam and when she wore out I replaced it with the Andrews. I was impressed with the power off the line and mid range and also have the upper range when passing. The wiseco's are fine but I may look at Keith Blacks next rebuild. Some say overkill, I say - "My Bike". I have only done 80 a couple of times in the 10 years plus that I have owned her and she just plain don't like that kind of speed for too long. Bring her back down to 60/65 and she putts happily. good luck!

[BigMike]

Update! .009" piston clearance on rear jug, .002" on front, poor sealing exhaust valves both jugs, rear intake valve marginal seal, front intake semi-decent. Time for the top-end job. With .010" pistons in it now, and .009 clearance, going .020 over may not clean up the cylinder walls. I guess it will be +.030" and a valve job. New valves, seats, guides, I guess it could have been a lot worse.

[BigMike]

update! definitely need a top end job. I disassembled the heads yesterday, valve guides are shot, so much clearance (actually beyond that... call it slop) in the exhaust side of rear, the top of the guide (inside the spring) is worn nearly to the edge. Almost a sharp knife edge on one side! With the valve held in the approx open position, valve head can wobble at least 1/8" fore and aft. Needless to say, seats are trash. possible cause: repair to rear exhaust spigot, looks like a piece of aluminium pipe welded in, without matching the inside , that is there is about a .250" step, coming from valve pocket to spigot. I'd be willing to bet that poor flow and turbulence there caused a high heat condition around that valve and trashed the guide. This repair is beyond my skills, may have to replace that one head. Going to have a couple of disinterested engine builders locally look at it.
I hate changing it, the casting date (3-63) is correct for my bike, and I assume it's the original. front head is (2-63) so it makes sense.

[Jack_Hester]

BigMike -

As far as the seats are concerned, you may want to send both heads to Don Sullivan, and have them repoured to a stock configuration. He can also put you new exhaust flanges on that will be hard to tell from stock casting (and aligned with the port). As part of the seat work, he will put in new guides, as he recuts the seats when finished, and must have guides installed to do so. The work ain't cheap, but the heads are some of the finest looking Pans that I have seen.

Jack

[BigMike]

Had to farm the heads out for new seats, minor crack repair, exhaust spigot clean-up, new guides, valves, springs, retainers and locks. Sent to a shop in Wisconsin via a retired HD Factory Racing Team rider. (the '50's) Same shop used by S&S, Zipper and a couple others for their one of a kind "special jobs" not cheap, but still reasonable. Certainly cheaper than a set of STD heads. Long lead time though.... gotta ride the Victory or the Sporty for a while.
By what I've found, I didn't specifically have one problem, I had a combination of several somewhat minor things which acting together, made for a rattling poor performing and hard starting sled. I know that does not have to be the case. I'm looking forward to making it right.

[suicideshovel65]

Hi Big Mike, Panhead,

These tantalizing references to top grade shops around the traps could be a great resource...maybe we could put together a "Panhead board approved" list of vendors and workshops to save others some ha$$le...?

Cheers,

S.

[BigMike]

I definitely will give these guys a plug when I get the heads back. The only problem is that these guys deal only with licensed repair shops, no work to the general public. Your local shop can send them for you, and cut themselves a little slice for their efforts.
Finished the barrels and pistons, and put them back on.
Used K-B 8.5 : 1 pistons with Hastings rings, .00075 - .0015" clearance and extra end gap on top ring as per KB instructions. This should work out well without getting stupid with compression and cam selection.