1920 Harley Model F

[TechNoir]

Cotton, thanks for the reminder about the butane. Before I do that I think I will first make a new, slightly thicker, gasket and use some "Wellseal" to ensure its gas tight.

Steve, thanks for the email. I had seen the JD Group files but not the service bulletin, thanks. BTW, didnt all of the Yahoo files move to the new "Group"?


From the various sources the timing is stated as:

Owners Manual: "When a motor must be retimed it is best to refer it to the nearest dealer because absolute accuracy is essential."

1923 Military "Repairer" manual: "until the piston has dropped five-sixteenths inch from top dead center."

1918 Motor Repair Manual for the Guidance of the Motorcycle Repair Man: "until the front piston is between 1/4 inch and 5/16 inch before top center on the compression stroke"

1926 Mechanics Bulletin (courtesy of Steve Swan): " "L" Model Motor Ignition Timing - 13/32" to 7/16". " (I am not sure what the "L" motor is?)

JD Group files. They seem to infer that its 3/8" but on reflection they don't state if this is for the "J" or "JD" motor.


If the 1926 service bulletin is correct then my motor is timed a bit too late but looking at the earlier references then its a bit too early. I guess I will try to rule out the other issues and then, if required, I will play with the various timing possibilities.

Regarding the timing stick. All manuals give a timing procedure with the motor on the bench and the timing on the front cylinder. That fine if the motor on a bench but as we know, with the motor in the frame the front cylinder is off limits with regard to establishing piston position. However the rear cylinder is accessible with the tanks off.

I made the timing stick initially with a 1" diameter cap on it but that isn't wide enough to clear the frame tube. It would be OK with graduations marked on the shaft but to do that I wanted to use an indicator to establish TDC. So I made a 2" cap but then realised that a part of it clashed with the rear cylinder steady mount hence why it has a "D" shape. Then I decided that the indicator was better than markings on the stick so didn't bother with marks. Until I establish the best figure there is no point anyway. If I were doing another one I would maybe have made the flat on the cap a bit smaller but its fine as it is. The shaft is just some 1/4" cold rolled steel with the bottom end rounded slightly. I had imagined making a clamp for the clock but quickly realised that two cable ties were perfect when using my 2" travel instrument. If I were using a 1" gauge I am sure I could have used a Noga type clamp.

Using this tool the timing is straightforward with the motor in the frame. I also use a timing light. I have a Fluke meter that I could also use but I tend to find that the light is more convenient.

John

[Steve Swan]

John, you are doing a wonderful job with your thread documenting what you are doing. i really like the tool you made up to use a dial indicator with the engine in the frame. That is something i am going to borrow should the time come when i may need to readjust ignition timing. fwiw, i made up a protractor (attached) that mounts on to the 2 studs that hold the primary cover and i marked the drive sprocket in 3 places so i can at least have an approximate setting in the future. wish i could suggest BTDC measurement for the 61" engine, i have no experience with them. Wondering if you have what the Factory discussed about ignition timing in the Mechanics Bulletin, dated June 10, 1926? (i'll scan and email to you). The Bulletin states, "Exact timing specifications from 1915 to date are..." "..."L" model motor... ignition timing is 13/32" to 7/16" fwiw, back in the day when JD Yahoo groups was there, there was a fellow who converted inches BTDC to degrees. fwiw, i will attach his documentation including his protractor fixture to this post. In trying to upload his calculations, since they are MS Word, they will not upload, i will email them to you. i realize what i am writing is at least somewhat off topic, but it may be of use to you.

20200222_234657.jpgTimingFixture.jpg

[T. Cotten]

That's one interface that cannot be bubble-tested, John,..

(So we arbitrarily dress them..)

The best test I know of upon a running machine is an un-lit propane torch.

...Cotten

[TechNoir]

Well, John,..

Your shaft fixture is nothing like mine, but I'm sure the cat still skinned out OK..

(The setscrew airvalve snubber ball-cap replacement and domed knob are certainly 'signature', so nobody better steal them, or we can track them down!)

Aside from any leaks at the nuts and nipples, did you grind the manifold flange to flat? It doesn't appear you lathe-dressed the carb's flange.

....Cotten

Hi Cotton, no I didn't dress the flange, I will have a look at it tomorrow. An air leak at the gasket is an obvious place to start. I will report back.

Thanks,

John

[T. Cotten]

Well, John,..

Your shaft fixture is little like mine, but I'm sure the cat still skinned out OK..

(The setscrew airvalve snubber ball-cap replacement and domed knob are certainly 'signature', so nobody better steal your machine, or we can track them down!)

Aside from any leaks at the nuts and nipples, did you grind the manifold flange to flat? It doesn't appear you lathe-dressed the carb's flange.

....Cotten
PS: Did you inspect/set-up the needle by sucking upon the bowlstem nozzle? There's little other way to guess an initial setting, and if the cam actually increases the flow.

[TechNoir]

I ordered the slitting saws from a supplier who normally gets things to me in 1 to 2 days, however they took two weeks to arrive due to the lockdown. In the end I made 3 fixtures for the shaft. I wasn't happy with the first one because the groove was a few thou off at one end so I made another one a bit like Cottons but then changed it after trying it out.




I also ended up making three shafts and three discs until I was happy with them.





I usually pride myself on neat soldering but I struggled getting enough heat into the parts with my small torch inside the bore of the carb. I got there in the end and even though its not so neat the solder eventually flowed including through to the other side of the disc (through the holes that are used to hold it to the lathe fixture). I could have heated the parts a bit more and wiped off the excess solder but I didn't because I had the disc exactly right and I didn't want to risk moving it.








I took some time to do a couple of other jobs that I have been meaning to do for a while. One was to make a new locking screw for the air valve. The old one wouldn't tighten up because it was stripped (not my work) so I took it to the next size and made a new screw.





Also, I have had some concerns about the right hand gas tank cap. The original cap only holds on by about one thread and I don't want to risk losing it. It screws in fine on the other three tanks that I have but not this one so its not the cap at fault. The threads looked OK on the tank but were apparently oversize so I made an oversize cap. I only had aluminium so I made a temporary one to make sure that an oversize one would work, which it does, so I ordered some 2 inch brass bar and will make a proper replacement when it arrives. The aluminium cap screws all the way down on all threads.







This afternoon I took the bike outside to see if it would run. .





At first it started for about half a second and then refused to re-start. After much checking I tried again for ages but nothing. Then I realised that I had knocked the high speed air valve open so I closed that and it started again after several kicks but wouldn't run for more than a couple of seconds.

I checked the plugs and they were very wet so I cleaned them and screwed the needle down a bit. After a lot of messing about I have now got the bike to start first kick every time but I cant get it to run right.

Once it starts I drop the air valve back to the intermediate position and the revs go up as you would expect. I then advance the ignition and close the throttle to stop the engine racing but at lower revs (but still much higher than tickover speed) the engine spits back through the carb. It wont idle either.

I have the needle about 2.25 turns out at the moment and the idle screw about 2 turns out.

Spitting back through the carb can be a few things, I think.

Timing. I have read three different timings for these engines. 1/4" BTDC, 5/16" BTDC and 3/8" BTDC. I set mine at 3/8" but now I am not so sure about this figure. I am confident that the timing is 3/8" because I used this setup. (I had been meaning to make one of these for a while so I made one while waiting for the saws) What distance BTDC do people on here recommend for timing of the 61" motor?










Air leak. I bubble tested the manifold when I first assembled it so whilst its not impossible that the manifold is leaking its not my primary suspect. I made a new carb gasket when I fitted the carb but I suppose it could be that even though its new.

Leaky inlet valve. I am hoping its not this. I could maybe do a compression test to check.

Carb setup?

Anything else?

I didn't do too much today after I got it the point of starting first kick every time because it started to rain so I tidied up the disaster area of my garage.

I will get back to it tomorrow, hopefully its nothing too tricky.

Any suggestions or comment gratefully received.

John

[TechNoir]

I figured that you meant with more conventional tools.

I had ordered a small block of aluminium with the intention of boring it out to fit the spindle and make clamps using grub screws. Turns out that it would have been not too dissimilar to your arrangement. The only difference was that i would have gripped it in a mill vice on the horizontal mill.

Like you say, a horologist would have used a hand tool.

John

[T. Cotten]

...I am always reluctant to declare anything impossible, although a lot of things are not cost effective. I am pretty sure EDM could cut a slot in difficult parts but the equipment would make them very expensive.

I meant with a conventional 'slitting saw', of course, John!

I 'spose it could even be chewed out the old fashioned way, if one has the time and patience of a watchmaker.

But I needed to do a quantity, with minimum set-up time, even in the future.

My fixture bolts to a toolpost block.

....Cotten

[TechNoir]

You have the luxury, John,...

Of only needing one kind of shaft.

....Cotten

Indeed, I will be surprised if I need to make another for a while. (at least I hope not)

Since the variety seems endless, I made shaft 'blanks', to which a variety of top "towers" could be pressed and pinned by the cam, salvaging the original when possible.
....Cotten

Thanks for the insight tom. If the shafts are all similar then your approach makes a lot of sense. My original is long gone (1988) so I don't need to salvage anything.

(And some shafts would be impossible to slot otherwise, such as the example in the second attachment.)
....Cotten

I am always reluctant to declare anything impossible, although a lot of things are not cost effective. I am pretty sure EDM could cut a slot in difficult parts but the equipment would make them very expensive.

I tried fixturing shafts similarly to yours, and it didn't work very well for me. But then I cut the slots with the lathe.
....Cotten

I am planning on cutting mine in a horizontal mill used as a stub mill which is actually very similar to doing it in a lathe.

Thanks again Cotten.

[T. Cotten]

You have the luxury, John,...

Of only needing one kind of shaft.

Since the variety seems endless, I made shaft 'blanks', to which a variety of top "towers" could be pressed and pinned by the cam, salvaging the original when possible.

(And some shafts would be impossible to slot otherwise, such as the example in the second attachment.)

I tried fixturing shafts similarly to yours, and it didn't work very well for me. But then I cut the slots with the lathe.

....Cotten

[TechNoir]

I'm probably stupid to be altruistic ...Cotten

Hi Cotten, I always think that we should treat others well and we will be better of for it in the end. Thanks very much for the picture of your setup for aligning the flap.

I made a fixture for making a disc.




At some point over the weekend I will turn a disc or two but I wont be able to finish one until I have cut the slot in the shaft.


I made a shaft. I made it with the small flange as a washer. The existing one looks like its a washer even though its stuck solid. With it as a washer it makes the holding fixture a bit easier.

The threads are a bit longer than required. I will adjust the length before I solder the disc into place.





As mentioned previously, current events have delayed deliveries of both slitting saws and also some aluminiun stock that that I had in mind for for the fixture to hold the shaft while I slit it. I had a look around and found a 3 foot length of 1" x 5/8" aluminium bar and used a piece of that to make the fixture. The only difference between what I have and what I planned is the clamping arrangement. I need to swap the screws for cap head ones once some arrive.




I will update on progress once I have got the saws.


John

[T. Cotten]

Thanks for the pictures Cotton. ..

Here's a couple more, Folks!

I'm probably stupid to be altruistic (it always bit me in the ass..), but I'm probably soon out of business anyway.

...Cotten

[TechNoir]

; It came back out for filing and inspection dozens of times.

Nobody in their right mind should attempt to do it "right". Lest you lose your 'right mind' as I did.

Thanks for the pictures Cotton. Patience is certainly a commodity that is required to work on these old carbs.

The saws that I ordered have not arrived yet. The supplier I used usually deliver in about 24 hours but this COVID crisis is slowing everything down so it looks like I will have to wait until after the Easter weekend to test my own patience.

John

[T. Cotten]

Uh... Steve,...

There's always just one more tool necessary.

And the disc in the pic has not yet been soldered; It came back out for filing and inspection dozens of times.

Nobody in their right mind should attempt to do it "right". Lest you lose your 'right mind' as I did.

....Cotten

[Steve Swan]

This pic, Folks,...

Shows much better how the idle notch is not easy.

(Please note that the friction disc must be perfect first.)

....Cotten

Wow. position, shape, angle of notch is critical. i can appreciate at least one of the challenges confronting restoring this carb to like-new function. Tom, you have to know what you are doing and have all the necessary tools and equipment to restore these carbs without test running them before returning them to your customers. gorgeous soldering job. following this conversation, i am somewhat more able to appreciate why the H model Schebler can be challenging to work on.