1920 Harley Model F

[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]

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

[chuckthebeatertruck]

Go, John! This is freakin' GREAT!

Dale

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

[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!)

[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

[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....

[painterdale]

Go, John! This is freakin' GREAT!

Dale

[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

[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

[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]

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, 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.

[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]

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."

[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).