Exhaust valve seat came out completely

[suicideshovel65]

To add to the recent spate o' troubles experienced by board members....

I was riding my pan on the first day of a very hot 4 day holiday over the long weekend here and had a gawd awful sound come from the motor.
I shut down quickly and with growing feelings of dread I looked around under the bike fearing to see a pool of oil and innards on the road. Nothing at all. Breathing somewhat of a sigh of relief I set about looking at the top end of the bike.
I noticed low compression and a slightly odd sound coming from the rear head when turning the bike over slowly by hand at the kerb. I organized a tow to a nearby shop (no easy task on the O-bon holiday weekend in Japan, and in 30+ degree heat), and they looked first at the pushrods. The rear exhaust rod had maybe 5-10mm worth of vertical play without even loosening the locknuts and adjusting. Hmmm...
Off with the rear head and voila, the exhaust valve seat had come out completely, gouging the top of the piston and also some of the combustion chamber. Judging by the carbon buildup *under* the seat (!) it had been working its way loose for some time - if not incorrectly installed to begin with. I also note that they were not bronze seats, but steel.
The shop took a look at the tappet blocks as well and noted excess wear in the bore, and also excess play in the rollers. I'm guessing that the .020 over cylinders/pistons could also do with a look, so it seems I'm facing a complete top end rebuild just before peak autumn riding season in Japan. Curses!
Now, my bike is a '49 engine in a '58-'64 casting swingarm frame marked "L6" on the RHS of the engine mount. Judging by repair costs here in Japan even for a top end, my guess is that it might be better to look for a complete, titled pan engine matching the frame year to get me back on the road and re-match years for the engine and frame in one hit. I can then work on the '49 as a project moving forward.

Does any one know of:

a) what year engine would be right for that frame (I have Palmer's book, but L6 on a swingarm frame? Surely it's not December '66 and hence a shovel frame? It has '58 casting codes in various places around the frame and seems to be a drop-arse frame).

b) of anyone wanting to sell one?

c) if I am barking up the wrong tree altogether, and should just fix the top end and get back on it?

Advice and sanity checks welcome,

S.

[2dogs]

There's a completely rebuilt '51 FL motor on ebay tonight with bidding up to $2247USD with 1 more day left. Will probably go for around $3500 and there is nothing mentioned about a title.

I've seen titled motors go for over $4000. I paid $3800 for a titled 1963FL motor and a pickup load of various, mismatched parts 2 years ago, and then paid another $2100 to have the motor rebuilt. So I basically paid $5900 to get a running, titled late model panhead motor.

I hope you can do way better than that. Would a top end rebuild cost that much in Japan?

Incidentally, trying to mount a 1963 motor in a frame with a first casting date of 1965 is a real pain in the ass.

[sleeper]

SS65, sorry to hear of your woe. Pan is the hardest motor to replace a seat & have it stay.. Best not to remove them, if possible.

For less than $5900. you could have had a BFN S&S
Pan clone. If Original & Correct is not an issue.

[suicideshovel65]

I hear that the quote for top end rebuild here will be $1500-$2500+ depending on what is done and what parts I can supply myself.

As I'm already running a '49 engine in a '58 pan, non-original is not new to me, however I want to stick to original matched HD cases rather than go down the STD / aftermarket route. The thing is though if I'm looking at major expenditure of this magnitude I'm almost tempted to match engine to frame by buying in a duoglide year engine, and start on a second bike using the '49 motor I have now - ie to start caring more about at least the core aspects of originality with regards matched engine and frame years.

For some reason I rarely see 58 / 59 engines only up for sale - it's always early 50s or 60s. Odd.

[Jack_Hester]

SS65 -

Contact Don Sullivan at Head Hog, Inc.. He will not touch a Panhead, to put steel seats in. However, he will repour to the old seats. And, said he was working on a process to repour with no original seat in place. Maybe he has his process perfected. His cost will include new guides and valves. Seats will be cut to correct angle, and ready to use. I'll be he would send you the assembled heads, so that all you would have to do is install the rocker arms and Pans. I don't have his email with me, but do a search for Head Hog, Inc.. He's in Ohio.

Jack

[ArizonaMike]

For Two Dogs:

What're the problems you've encountered in mounting a Pan in an early swingarm shovel frame? If I want to
mount the engine in a pre-70 (unnumbered) frame,
is there a range of years I should look for?

[King]

Dear Suicide

Sorry to hear of your problem. Valve seats falling out is what the Pan Gurus I consulted warned about when I wanted to repair my worn out Pan heads with new inserts. So I didn't go that route. I've heard good things about the technique Jack noted but, like he, I don't know if it can be applied to a totally missing seat or over steel seats to "seal" them.

I went with STD heads and have been happy ever since. They cost me $1600 installed using my existing rockers. So, even with new pistons and cylinders I think you would be ahead of the game to rebuild your present donk especially when you consider all the title and reg. hassles associated with even the "cleanest" used motor.

Good Luck

King

[2dogs]

Mike: My problems may be unique to my own level of ineptness, lack of decent shop area and the right tools but....

Two problems have been the primary cases and the exhaust system.

The 1965 frame seems to want the cast aluminum primary but the 1963 left motor case won't accept the shape of the 1965 style cast aluminum primary case. One or the other of them has to be machined and I don't care to do attempt that with a dremel tool. The cast primary also requires a different transmission case to hold up it's heavier back end.

The correct tin primary for the 1963 motor doesn't quite fit the later style frame. Other's may have solved this problem with ease but I had to take the dremel tool to the back end of the primary case. The inner primary fits now but I haven't yet tried to mount the outer primary.

The 1965 frame is supposed to use the one piece squish/Y-pipe. The 1963 motor and frame were designed to use the two-piece squish and Y-pipe. With my motor/frame mating neither combination works well. the front header just doesn't connect solidly with the one-piece Y/squish and the two-piece Y/squish is too short to connect to the frame mounting tab in front of the kicker.

I've been told "do whatever you have to do to make it fit up." Well, I've done what I can and the results are not great.

Living here in this vintage technology "black hole" does not help. If I had it to do over again I would sell this 1965 frame and buy a 1958-64 frame.