1920 Harley Model F

[TechNoir]

Thanks Steve, I had suspected that 5/16" was the factory number as its in the 1918 manual which seems to be the book to refer to for the J motors.

Thanks for reminding me about which cylinder gets the most oil. That confirms my theory.

I am back at work tomorrow but will do what I can over the course of the week and see where it leads.


John

[Steve Swan]

John i'm glad i can be of some help, i admire the leagues ahead of me you are in the machine work you turn out, i just don't have the equipment and more importantly, the room if i were to get equipment like a bigger lathe or a mill.

[TechNoir]

Steve, space is always an issue with me too.


Since my last installment I haven't been idle.

One small task that was niggling me was the rear cylinder leaks oil very slightly around spark plug. Taking a closer look the surface is rough and the spark plug washer is not sealing. I stuffed the hole with rag and used a wide file to carefully make a flat spot.









I have also ordered some copper sheet to make a copper washer rather than the standard spark plug crush washer. Hopefully that will fix it.



The 2" brass bar arrived and I started making the brass gas cap. I realised that I don't ave any fine straight knurling wheels so I did as much as I could and will finish it when they arrive.





John

[TechNoir]

The thing I have done the most of is to try to get the motor running properly.

I have moved the timing several times now (and as anyone who has adjusted the timing on these bikes that is no quick task). The biggest improvement in timing was moving from 3/8" BTDC to 7/16" BTDC. I have also tried 8/16" BTDC and also 9/16" BTDC (which is where it is now). I have a hunch that 9/16" is a bit too much but I need to ascertain the best setting logically and the bike is running so badly overall, irrespective of timing position, that its impossible to make proper informed decisions about the timing. I have spend ages messing about with the bike running terribly but with no success.

I am not one of those engine whisperers that seem to have an instinct as to what the issue is with an engine so I mulled the problem over whilst lying in bed a couple of days ago and came up with a plan.

When trouble shooting any problem you need to deal with one variable at a time or else end up going in circle. So my biggest issue is that I am not certain that either the timing is right AND the fueling is right so I need to eliminate one of them so I can deal with the other. Then I can go back and deal with the first variable.

I figured I can eliminate the fueling variable by substituting the Schebler for a carburetor known to be good. I had a hunt and found a couple of candidates but then realised that a slide type carburetor needs more height than I have under the tanks. I need to make an adapter anyway so rather than flip the existing manifold by 180 degrees and risk leaks at the nipples I figured I could just make a longer adapter.


So with my plan in mind I went on a hunt for materials. One item that I struggled with was some tube of the right size, 1" bore. I struggled to find anything but then found a couple of scrap camshafts which were the only candidates even close. These particular shafts are made of a hollow tube of about 1.2" OD and about 0.850" ID with cams and bearing journals pressed onto them. So I pressed the cams and journals off one of them and bored a piece out to 1" ID. This stuff is like extra hard chrome-moly. It needs a deep cut, high speed, fast feed and a new insert. Because I was doing relatively shallow depth of cut @ 0.100" it had a high birds-nesting factor made worse by the fact that I was boring an internal diameter.





Anyway I eventually ended up with this.








I screwed the parts together. I did think about welding but wasn't sure how the cam shaft material would weld and I don't profess to be the best welder in the world so didn't want to risk chasing leaks.

Next, with Cottons posts ringing in my head, I did a bubble test. All was well.





I wasn't too surprised as I had used this stuff on assembly of both my "new" manifold and also the original manifold and nipples.









The two candidates for a temporary carb were a 1" bore Amal 276 that looks OK but I have never used it before and a brand new Mikuni VM30 that I had bought for another project that is currently paused. I have an Amal type manifold adapter for the Mikuni. Because the Amal was an unknown at this point and the Mikuni was brand new I went for the Mikuni. Also, with the Mikuni I don't need a choke cable as it has a carb mounted lever.






Hooking up the fuel wasn't too hard but what about the throttle? The original arrangement for the 20F was out of the question but I have a cable and twistgrip destined for the other project but how to mount it? This prompted another search for materials that might trigger an idea as to how to mount the temporary twistgrip. After about 10 minutes I spotted an old broom handle which gave the an idea.






Here is a shot of the whole thing.



The bike first started after about 4 or 5 kicks and after that it started first time.


With this carb the bike runs OK with literally no adjustment (yet). By the time I had got to this point I needed to pack in for the day but I can say with certainty that I will now be able to ascertain the best timing setting. Assuming that it is currently too far advanced I should be able to retard it to the point where its at its best and then mark that point on the mag (I reckon two strips of tape and a pencil line). I can then measure the optimum timing and set it properly(again).

Then, once I have made sure the timing is right, I can get back to the Schebler.

With the Schebler It wont idle at all. It stalls at anything less than a quarter throttle and above a quarter the engine races. The idle screw is wound right out and the butterfly does close all the way and is a good fit.

I must be missing something.

One step at a time but I am glad that it now seems that I can move nearer to fixing this.

John

[painterdale]

Go, John! This is freakin' GREAT!

Dale

[Steve Swan]

John, i love how you have gone about narrowing down the variables and now can find the ignition timing sweet spot for full advance/full retard on your twist grip. Most definitely trouble shooting requires adjusting/changing one thing at a time or it all becomes chasing down rabbit holes. I admire your tremendous amount of patience, persistence and perseverance as well as skill with machine operations. You will figure out that "H" model Schebler. i wonder what part(s) of the carb control or affect the area between stalling and racing. i also wonder if what is causing stalling and racing are caused by the same issue; it seems perhaps the carb is allowing too much air.... i realize you were not able to ride the bike enough to check plugs look before you put on the Mikuni, or if you were able to check them, i do not recall....

[TechNoir]

Thanks painterdale for the comment.

Steve, I didn't manage to ride the bike because it was un-ridable with the engine running as it is/was. As I said, one step at at a time so once I get the timing nailed down I will at least know that I only have to think about one variable. It is tempting to make a more robust temporary twistgrip mount (cable ties are a but sketchy even with the bikes lack of braking force) and take it out.

However at the moment we are still on COVID-19 restrictions so I am reluctant to break the rules right now. The best I can do is a couple of hundred yards but that will be enough to make a rough assessment.

The good thing is that I now feel that I can take steps in the right direction rather than chasing my tail as I felt I was doing for the last couple of weeks.

I will investigate the Schebler in more detail and see if I can find the issue and report back.

The next job however is to tidy the workshop which looks like a disaster area at the moment.

John

[T. Cotten]

That's a sparkplug hole, right, John?

(Never touched anything but carbs and manifolds for these models, forgive me...)

Hand-filing the sealing surface perfectly square to the plug would be miraculous.

Even a piloted counterbore cutter (crude 14mm attached) only gets them close, and 'chatter' can still be a problem, even when turned by hand. But please consider it.

...Cotten
PS: I can send you PEEK scrap to cut seals if you wish (only $.25 a gram!)

[chuckthebeatertruck]

Go, John! This is freakin' GREAT!

Dale

+1 ^^^^^^^^^^^^^^^^

[TechNoir]

Hi Cotton, I agree I am no miracle worker. I have mostly just taken the nickel plate off and its no worse now than it was before. I really haven't taken much off. I could order a cutter to make a guided tool which I might do if all else fails.

The copper sheet turned up today so I will make some seals and anneal them.

I hadn't considered PEEK. I do have some that I got when I made the new air valve so I could try that if the copper doesn't work out.

Thanks for your input once again.



Thanks for the encouragement chuckthebeatertruck.



Today. after work, I managed to make a big dent in tidying up the workshop. I will get it finished tomorrow and then turn attention back to the bike.

John

[T. Cotten]

Shouldn't the fresh copper already be quite soft, John?

Best not to interject any more variables than necessary..

(PEEK would too, of course!)

....Cotten

[TechNoir]

Shouldn't the fresh copper already be quite soft, John?

Best not to interject any more variables than necessary..

(PEEK would too, of course!)

....Cotten

You are of course correct, fresh copper should be soft although I am not certain how much work hardening will be introduced by the machining process.

John

[T. Cotten]

You are of course correct, fresh copper should be soft although I am not certain how much work hardening will be introduced by the machining process.

John

Spare the hammer, John!

....Cotten

[TechNoir]

Cotton, how did you know what the inside of my workshop looks like?

[T. Cotten]

Cotton, how did you know what the inside of my workshop looks like?

I don't, John,...

The pic captured us outside.

Stone tools are timeless...

....Cotten