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  1. #1
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    Default Flathead stuck valve

    Went for a ride the other day on my UL, I did about 150 miles with a coffee stop in the middle.
    Engine worked great.
    But suddently I lost power and the engine was on 1 cylinder.

    It looks like I have a stuck valve (exhaust rear cylinder)
    I didn't open the top end yet, just noticed that valve doesn't go down as it should.

    Any idea why this happens?
    What are my options at this point?
    Doing a complete valve job (and top end?) is mandatory or there are alternative ways to "unstuck" that valve?

    Click image for larger version. 

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  2. #2
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    excess carbon binding, valve stem galling, or too little clearance when installed. once you have the head off put some penetrating oil on the valve stem and wait a bit. if you can get the valve out you'll find out what happened. mite have to put a thick feeler gage on the tappet to push it up a wee bit to get the oil working.

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    Or somebody using guides other than high silicone cast iron. Never dealt wit a Hardly flatty but an Indian that is parade ridden needs a tiny hole drilled in the breather disk so that there is enough oil mist left in the engine for the guides n stems at extended near idle use. or any air leak between the crank case and the valve. Oil mist is really hard to get up an exhaust stem with the exhaust gas pushing down.
    Is it staying open (stuck valves stay open) your pic looks like the stem is close to the pushrod. If it isn't moving up and down as much as the other exhaust and has normal clearance when closed you need to look in the cam chest. If it's hard stuck the valve will stay wide open, if partially stuck it will go up and hang and then return slowly or snap down. If it's stuck pulling the top and doing it right would be the better option. They have gotten too valuable to Band-Aid.
    Dusty

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    I guess opening the top end is next, to find out more...
    If I don't see anything weird then outside from the stuck valve, I'm tempted to attempt of making it move again.
    Doesn't mean I wont do a valve job next, but just out of curiosity, if it was enough?
    I don't have "penetrating oil" on my shelf, would WD40 be stupid?
    I can sure order some oil no doubt, but if WD40 is fine...

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    WD40 = Water Displacer not the same as a good penetrating oil.

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    Following with interest..

    What causes this?

    Tolerances too tight and galling? Or clearances too loose and burned carbon fouling the guide area?

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    Quote Originally Posted by confab View Post
    Following with interest..

    What causes this?

    Tolerances too tight and galling? Or clearances too loose and burned carbon fouling the guide area?
    Almost always a vacuum leak causing the motor to run a little lean and overheat the exhaust valves. Hot exhaust valve galls the stem and guide, and stuck.

    Jim

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    Bingo .. ^^

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    ^^^^

    Seen a few?

    ^^^^^

    Jim

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    Quote Originally Posted by DoomBuggy View Post
    WD40 = Water Displacer not the same as a good penetrating oil.
    Got that! will get the appropriate.
    Is there any difference between penetrating oil and penetrating grease ?

    Found this:
    (Think it will do the job but just want to make sure)

    Click image for larger version. 

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    To be honest I have never heard of penetrating grease before.

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    Something we use for polishing deep passages in valve bodies is a wire hone.. It is basically a piece of coat hanger bent over flat at the end, with a few wraps of 1200 grit sandpaper around it. Chuck it up in an electric drill.

    You run it wet with mineral spirits, or brake cleaner or whatever.

    If you're just absolutely gonna run this, wouldn't removing the valve and polishing out the guide a little be the way to go?

    If you had a way to chuck the valve up and work on it too, that couldn't hurt..

    Be a pretty quick thing to do. Probably even re-use copper head gaskets?

    ???

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    Quote Originally Posted by JBinNC View Post
    Almost always a vacuum leak causing the motor to run a little lean and overheat the exhaust valves. Hot exhaust valve galls the stem and guide, and stuck.

    Jim
    I have the feeling I didn't have any intake leak, mounted new Peek seals recently. But also I changed the carb not long ago for a Dell'Orto and I have to admit I wasn't as rich as I wanted, I believe it was ok but a little too lean...

    Could that be the reason?

    Also it was the first time I did a 150 miles ride with this carb, but I did a 45mn stop in the middle so I assume the engine wasn't hot like if I did 150 in a row. Did several 50 to 75 miles ride before with that carb

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    what was wrong with the linkert?

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    Quote Originally Posted by Hubbard View Post
    what was wrong with the linkert?
    not sure what was wrong with it, tried to tune it for a long time but the bike never ran great with it, maybe it was too worn out (?) suddenly when I put the dell'orto all went way better

    Linkerts seems very simple to tune, I read a bit about them but it seems I'm not lucky with them, not sure why.

  16. #16

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    We are going from a possible valve prob to a possible carb issue. I had a WLA for awhile, the ULs little brother, and it was quite possibly the easiest motor to work on in the harley line, at least for me: I typically dont do bottom end work, but that motor was so easy, I did that work myself

    WD 40 to me is a bad lubricant. I dont even use them on guns, as it does have allot of water in the solvent to begin with. I use Marvel mystery oil for issues like you have, (I have always hated the name as it comes off like, "Snake Oil"), in order to possible "break loose" such probs.
    Aviators who own OHV engines in thier AC use and swear by it, as do I for stuff like this, at least to possible break loose a prob and see if it runs. My Ole man, a pilot who had a small airplane and a Avaiation mechanic he used, used it all the time in thier AC mandatory rebuilds.

    Have you done a basic compression check? If its poor you have localized that the issue is a ring, valve, or possibly a cam lobe issue

    If you do have a possible intake leak, to fix it, you are darn close to removing the head anyway.....

    I had very silmliar issue on my WLA. I was riding back from a warbird fly in, and one lung started to give up. About a mile from the house it died

    So I get it home, check the electricals, pushrods, etc. To that point that 45 had been practically a one kicker that I could almost hand start with the kicker arm. It would really blow people away how easy it started when a crowd would gather around hen I was ready to leave. This 45 was like the US Army issue, OD, Tommy gun, the whole works

    Now it took about 30 kicks till it would start and that one lung just wouldnt fire right

    It was a rear head gasket leak: Head bolts had worked loose (and it doesnt take much to cause a bad comp leak)

    My father was with me at the time, and when I finally could start it he said, "whats that glow under the tank"

    I could see the rear jug actually firing in the head to jug gap, so no need for a comp check at that point

    Took the head off, had a machine guy square the head surface back away, and thats it: Like $40 in machine work
    Heck, I even did a hand lap job on the heads valves myself before putting the head back on (the guides were in spec) for the valve seat to valve contact just to be sure

    Fired right up and ran great

    Regardless, do a comp check and it will help localize the prob

    But I cant over emphasize the basics. Check ALL your electrics as well. Sporadic power feed and ground mimics engine fuel delivery issues, and Vice Versa

    Good luck, keep us in the know!

    Dont know about the big flatties, but 45 engine and head parts are pretty cheap. Once i ordered set of bearings and pistons from V Twin. I got set of REAL, Military issue 45 parts, with NSN numbers on the boxes, and inside one was a service bulletin dated 1944 . Still have the boxes and bulletins. Supposedly HD made about 30,000 WLAs, and enough spare parts to build 90,000 more!

    Hell, I got a COMPLETE 45 tranny for that resto from a guy in Western NC that had three conexes full of 45 military surplus parts. Got the air box, horn, rims front/rear black out lights and WLA specific ign switch from a guy in Spring Valley NY that had complete 45's on crates for display and about a jillion parts for them

  17. #17

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    chuck up valve in electric drill or drill press and polish the stem. Also on youtube a guy polishes his valves with a cordless drill/ water/ and various sandpaper. Thing looks like chrome!

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