Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Still trying to figure out what is happening in the UL motor

Still trying to figure out what is happening in the UL motor

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Post Sun Sep 10, 2006 5:57 pm
JIm

Posts: 801
Location: Planet Earth
Piston damage was front and back (thrust face). All indications point to heat and or oil but all seems OK. Going to see if I can measure the amount of expansion of a couple of sets of pistons I have here to see if they are expanding more than thought. The piston clearence was set to what has allways worked but this time didn't. So thinking that they may have expanded more than previous pistons I have used.

Jim

Post Tue Oct 10, 2006 6:03 pm

Posts: 530
Location: Ogden, Utah, USA
Jim: Just a note to let you know I still am interested in what you find. When I first got our ulh it was running nice and quiet. Smooth and nop oil leaks. I put on some easy break in miles and it was weak, but quiet and smooth. If pushed hard a little oil weeped at the valve covers. So I think, fine just another old HD with some charaacter flaws. Wrong. It got a bit hot on an easy ride up the local canyon. I started my personal journey thru the valley of intake leaks. Only cost a set of rings and a ton of work, but what a difference. Pulls hard and runs crisp. For about 25 to 30 HP. Nice lumpy idle and a great sound thru a stock muffler. But I can't get past the blue rings in that motor from the leaky intake. Now I worry as the motor sound change when it warms up and..... You get the picture. I don't want to have any motor trouble with this one. I have a riding partner for the first time since 1966 and she is important to me. And where am I gonna find some part in the back roads in UT? So I still care what you find and what others have learned. Don't forget to look at the odd chance that some crud from some other place was picked up in the oil and sent to the cyl as a reminder we all can miss what matters.
Steve H

Post Wed Oct 11, 2006 7:58 am
JIm

Posts: 801
Location: Planet Earth
SteveH,

I have been taking a break from the flathead for a bit. This Winter I will get back to it and will be checking more. I am going to test the heads, especially the rear for porosity and any leaks at the spark plug hole. Also going to see if I can test how well the copper head gasket seals. That might be a bit tricky to do hot. As far as piston rings, I don't use the ones that come with the replacement pistons. I have read a few threads about them and most have been negative. I will be testing the oil system to see how much volume it pushes and if I can get more out of it. Testing the skirt oiler circuit more than I already have. Initial results on the skirt oiler circuit are not what would be expected. I have to make a test block to do the testing.

It's going to be a busy Winter to say the least. Between the Flatty and everything else I have to do.
J

Post Wed Oct 11, 2006 4:46 pm

Posts: 530
Location: Ogden, Utah, USA
Jim: Good luck with the winter project. I would love to see what you have for oiling the piston skirts. I have read other posts about it but still a bit fuzzy in what and how. Our bike has no skirt oiler at this time and I would like to know if it is worth the effort. Ride happy when you can.
Steve H

Post Mon Oct 16, 2006 1:24 pm

Posts: 151
Location: Carver, MN

I'd also like more info on piston oilers for flatheads. Are you using them only on the thrust side of each piston, or is it reccomended to put one on the front and rear of each cylinder? Anyone have any pictures of an installation? Thanks in advance for any advice anyone can give.

Post Tue Oct 17, 2006 3:38 pm

Posts: 1671
Location: Interlaken, NY USA

Lee W, Here are some pics of how I've done it. I just copied the way H-D did it. On Frankie, it was easy, as the jugs are already setup for skirt oilers. On the BT 80, I made a template so that I could drill the holes in the mounting flange similarly, and then blocked off the hole to the cyl wall with #10-32 allens. The actual size of the hole through the cyl wall matches the one that H-D used on the K cylinders. Just copycat engineering.
The feed on the 80 is from the sending unit, on Frankie, it comes from a feed line on the BSA oil tank that originally was used for OHV valve gear.
On both, a banjo fitting is held in place with a longer case bolt as the pics show. Also, the right case is drilled larger, 3/8", I believe, up to a point where it will meet the drilling from the cyl mounting flange going down. It all really copies the K design, except that I had to run the oil via the banjo and ext oil line.
Sorry the machines are a little grubby, the closeup lens really shows all the warts!
Dr. Dick
Image
Image
Image

Post Tue Oct 17, 2006 4:35 pm

Posts: 151
Location: Carver, MN

Dr. Dick,
Thanks for the quick reply! I really apreciate you taking the time to include pictures.
Lee

Post Tue Oct 17, 2006 4:52 pm

Posts: 530
Location: Ogden, Utah, USA
Dr. Dick: Warts = RIDER. Thanks for the pics. A lot clearer. A simple set up with benifits. Cool. Thanks again.
Steve H

Post Tue Oct 17, 2006 7:23 pm

Posts: 1671
Location: Interlaken, NY USA

You're welcome Lee, no prob. Knuck, yeah, she does get ridden. 8) I first did the 80 back in '75, after I burned her up in Montana passing a motorhome! Back then, you didn't get repop pistons anywhere. Anyhow, brought her home in a'60 Falcon and did the skirt oiler next rebuild. I think it's helped, but I think this may be the year it gets a sporty pump.
Dr. Dick

Post Wed Oct 18, 2006 11:40 am
JIm

Posts: 801
Location: Planet Earth
Dick,

You got mail

Jim

Post Wed Oct 18, 2006 5:47 pm

Posts: 1671
Location: Interlaken, NY USA

Say fellas, the question's come up as to what size metering jet hole I drilled in the cylinder wall. The fact is I can't remember. I tried to copy the hole that H-D used on the K's. So,,, do any of you guys with stashes have a cyl you can check out and tell us what size the hole is HD drilled?
Thanks,
Forgetful Dr. Dick

Post Thu Oct 19, 2006 2:42 pm

Posts: 1671
Location: Interlaken, NY USA

Well, this has nothing to do with skirt oilers, except that the motor didn't have any and the front piston burned up 3 days later. Just happened across the pic this afternoon.
We're in Yellowstone, 2200 miles from home, in 1974.
Just packed a few essential things for the trip.....
Image
Dr. Dick

Post Thu Oct 19, 2006 9:24 pm

Posts: 640
Location: Wisconsin, USA
Hey Dick, When you say "we're" in Yellowstone, I hope you are speaking of you and the bike, cuz if you had a passenger and all that gear you were packing a little heavy. Any more to the story? More pics? Thanks, Kyle

Post Sat Oct 21, 2006 10:14 am

Posts: 530
Location: Ogden, Utah, USA
Hey a blast from the past. I remember that sign and bits of 1974. That was a good ride and you had to go farther than I did. First long ride on the Knuck and I was supposed to be at work. That was the ride that set me apart from the Honda I had before and kept me on the Knuck until now. Good times. :)
Steve H

Post Sun Oct 22, 2006 4:02 am

Posts: 1671
Location: Interlaken, NY USA

Knuck, Yeah, you gotta wonder how many bikes got their picture taken next to that sign over the years... I came back 5 years later on the '62 pan/49frame, best running bike I ever had. made the round trip on less than a quart of oil, 4k plus mi.
Kyle, "we" was just the bike and me. I traveled lighter that time. The pan had to haul all that plus the lady du jour and her baggage,(mental and otherwise) :lol: I'd love to come out on the Knuck for the Knuck reunion sometime, but I don't think the butt can pull those kind of rides anymore... even then 700 miles was a big day. I must have some more pics somewhere, but, who knows where. That trip in '74, the plan was to ride out to California right up to the studios of Easyriders and have'em take some pics. You know, a young man's dreams.. and Easyriders was a much different magazine then. They might actually have appreciated a journey like that back then. Well,,, it was July and hotter than stink, and I kept going further north to try to get some cooler weather. That's how I ended up in Missoula Montana when the Piston burned up. Actually, it was crossing Illinois and Iowa on a 100+day that probably started cooking the engine, started sounding a little funny after that. (the weather never did get cooler).
Dr. Dick

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