1920 Harley Model F

[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]

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]

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]

...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]

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

[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

[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]

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]

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

[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

[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

[T. Cotten]

A couple of notes on the gasket, John,..

The fatter the gasket, the more the flanges can distort. If machined flat, then thin ones (such used on the carb side of the 1109-41 'extention', or Indian models) should do, and reduce distortion. Please do not torque 5/16" fasteners beyond 10 to 13 ft/lbs max, 1/4" fasteners beyond 7 ft/lbs.

(Over-torquing a conventional "tube" carburetor, such as DLXs and Linkerts, actually distorts the bore at the throttledisc.)

And beware that modern quality gaskets (such as from JAMES) are already impregnated with a fine adhesive, and adding anything would defeat it.

....Cotten
PS: Beware also of modern 1 1/4" repops with enormous bolt holes (attached).

[Steve Swan]

Hi John, i realize i am not of much help. the factory information is vague. Referring back to my notes back when i was asking questions for setting up BTDC for restored '27 JD, the one gentleman (Joe Drociuk of JD Yahoo) who always gave me solid information said, and i quote, "since you modified a stock 27 JD engine to dome top pistons, you have a raised compression and I be thinking give it more more advance like 3/8 or 7/16 be required and throw the spec book under the bench with 5/16th BTDC."

[TechNoir]

Thanks for the advice Cotton. The gasket isn't that thick, just a bit thicker than the previous one which could be described as thin. I made the gasket myself out of standard gasket paper so it wasn't already impregnated with something. The carb is held by the original slot head screws and isn't tightened too tight. Over tightening is an issue with most flange mounted carbs.

Steve, I think that you are right with regard to the timing. After the below I might even go back and advance it a shade more but we shall see.


After making a new gasket I tried it again but it ran the same so I figured that I should time it at 7/16" BTDC on the theory that I can retard it using the left grip if needed.

As an aside, as I was taking the tanks off I was reminded of something that is on my to do list. My bike has (an apparently uncommon) Johns Manville speedo which is mounted on the tank because it is an accessory. It is mounted too far back, to look at it you have to look down almost at your crotch. I am pretty sure its mounted there because on the J model the toolbox is mounted further foreward on the tank so the speedo wouldn't fit there on a J. however that isn't an issue on an F so at some time in the future I plan to get a longer speedo cable made and make a different mounting bracket and fix it. This would also fix a major annoyance every time I take the tanks off.









Anyway, back to the task in hand. I re-timed the engine to 7/16" and after the showers passed over I took it outside and fired the bike up. It ran less badly but still not great and I still cant get it to tickover. When I open the air valve to the mid position and advance the ignition, the revs rise and the engine races until I close the throttle. Anything less than a quarter throttle the engine dies. Above a quarter it races. I have tried weakening the mixture and making it richer but to no avail. The idle screw is about 4 turns out at the moment.

At some point when adjusting the mixture and restarting the bike I got a backfire through the exhaust. The next time I started the bike to play with the settings I realised that one of the cylinders was un-silenced. So I took it back into the workshop to cool down so I can deal with the exhaust as un-slenced the noise would really tick the neighbours off.





What do folks on here do to stick the exhaust together. I would use silicone sealer but I was wondering what people on here use?


While the bike was cooling down I did some tinkering in the garage and dug out my compression tester. It is a cheap import unit (I used to have a better one but it was stolen a few years ago). I am not sure how accurate the readings are, I suspect not very, but I use is to compare cylinders, i.e. in a multi cylinder situation its fine for diagnosing one cylinder which is low. I got 40psi on the front cylinder and 45 on the rear. I am not surprised that they are not the same. Both cylinders are on new bores and pistons so wont be bedded in yet. However I suspect the valves are probably OK as the variance between the two is not so far off and it would be unlikely (but not impossible) for both to have similar valve issues.

Also, I observed that the front plug was black and sooty and the rear black and oily. The colour is as expected as the bike hasn't been run properly yet at temperature so has mostly been run in the starting condition. I forget, is it the rear cylinder that gets more oil than the front? If so then the oily plug probably isn't so surprising too. The oil might also be why the rear cylinder had a higher compression reading.


Finally, how do people get to the locking screw for the idle screw? It is almost impossible to get at with the tanks on, how do other people get at it?





To recap, any ideas on the exhaust, idle screw and of course setting the engine up are all gratefully appreciated.

John

[Steve Swan]

John, looking through more of my notes.

From George Hood, 5/16" btdc is factory.

Re: oiling, the front cylinder gets less oil, the flywheel rims throw more oil directly into the rear cylinder. Per George, front cylinder runs 400' to 450' the rear 300" to 350' which is consistent with when i put the heat gun to cylinders of my restored '27.