1920 Harley Model F

[Steve Swan]

I don't have the btdc settings at my immediate disposal, but they can be readily found under "Files" at jd yahoo groups. Once you are in "Files," you will see "Timing."

[TechNoir]

Re: 1920 "F" Project

Well John,

You can take a chance on paying for a modern one-size-fitz-none needle,...
Or you can just stone-dress what you have.

....Cotten
PS: I charge five minutes, but only with a complete overhaul.

Thanks Cotten, the answer now seems obvious, I need to stone dress my original.

John.

PS. Does anyone else have any advice on points gap and timing setting?

[T. Cotten]

Well John,

You can take a chance on paying for a modern one-size-fitz-none needle,...
Or you can just stone-dress what you have.

....Cotten
PS: I charge five minutes, but only with a complete overhaul.

[TechNoir]

Re: 1920 "F" Project

Back to Basics.

When I rebuilt my Triumph motor a couple of weeks ago I was reminded that I have been meaning to get a Magneto Timing Light so i ordered one which didnrt come in time to time my Triumph but now that I have it I figured I could use it to check the timing on the ZEV mag on the HD.

I have a couple of questions. First question is what points gap is recommended? The manual says 0.020" and I have also read on here that 0.015" is the gap to go for. Which one is it or does it matter? I have always erred on the high side with points gap so my instinct says 0.020". They were set at 0.015" when I got the bike which I left them at. What does the collective wisdom on here think?

Second question is am I right with the timing at 3/8" BTDC fully advanced?



Also I had a look at the build report from 1989. The carb rebuild did not mention the needle so I pulled the needle and had a look.

There are a couple of ridges on the tip. You can feel them better than see them but I have tried to show them in the picture below. I guess it is best to replace it. Where is the best source of these needles? Also I have read somewhere that different lengths are available, is this correct?






John

[TechNoir]

Re: 1920 "F" Project

I'll be following your progress, John. Some people love a mystery; me, I hate a mystery when it comes to motorcycle engines

Ha ha, that made me smile Eric. I agree, I would rather not have a mystery when it comes to engines.

The air valve has made a massive difference to starting it so thats one thing sorted out. I will set it up as per Tommo's and Cotten's advice to get the right spring tension although at the moment I suspect that it is close enough.

Before I wound the "Intermediate adjustment" knurl right down it was running exactly like a later carburettor (with removable jets) would run with a way too big main jet in it.

The popping on the overrun could be a few things, timing, mixture, exhaust leaks (I have a poor seal on the rear cylinder exhaust fitting so that might be it). Now that it goes I can run it and see where it leads but I am not expecting it to be too hard to sort out. (Lets hope that by saying that I haven’t jinxed it!)

Its pouring with rain now (08:00 in the UK) but its forecast to be fine later on so it looks like an afternoon job for today.

John

[exeric]

I'll be following your progress, John. Some people love a mystery; me, I hate a mystery when it comes to motorcycle engines

[TechNoir]

Re: 1920 "F" Project

After doing some essential chores this morning I turned my attention to the H-D and made a new air valve.








After that I had intended to go through the bike and check the points, timing etc but I couldn’t resist having a go at starting it after finishing th air valve. On the second kick it fired and it started on the third kick so I didn’t bother checking the timing etc.


I took it for a 3 mile run to warm it up and it was running rough. It would only run on more than half throttle, anything less and it bogged down. When adjusting the needle valve adjusting knurl the bike runs best with it screwed down tight when the needle valve lift lever rests at the position where the cam strip is supported on its supporting casting.

With the knurl screwed down tight it runs better but the bike pops on the overrun.

The high speed adjustment is set in the middle.

Also the bike seems to start best with the air valve in the lowest position i.e. in the normal running position. There is minimal tension on the spring, I haven’t measured it yet but I have it adjusted so the the spring is just tight enough to keep the valve closed. If I loosen it any more the valve would be loose and would not be fully closed.

I didnt have time to do too much more today because I had other stuff to do with my family but I will have some more time tomorrow to try to get it running better.

On the plus side at least I can start it now.

John

[TechNoir]

Re: 1920 "F" Project

Hi folks. I leak tested my inlet manifold and found no leaks.

Then I tried starting the bike and continued to do so for the best part of an hour but with no luck.

I have a good spark.

The timing is right.

When I first got the bike complete it would start after 4 or 5 kicks but didn’t run very well once started.

Since then the only thing I have changed is the carburation so at the moment my money is on fuelling.

The 3 things I have adjusted (when the bike was running about 3 weeks ago) are:

1. Float height which is as per the manual.
2. Idle adjustment. The bike wouldn’t idle at all on a closed throttle the first few times I ran it and I found that the "low speed adjustment" screw was screwed right in. I wound it out 3 turns.
3. After warming the bike up I also adjusted the "Intermediate adjustment" to get it running better.

It started after about 10 kicks last night but today I have nothing after about 100 kicks. (I am knackered)

What are the recommended base settings? I have read somewhere that a starting point for the needle is 3 turns out. I have also determined a starting point for the needle on my carb by sucking on the bowl stem (following advice from Cotten on this forum).

I am off out on my Triumph now to have a think and once I get back I guess I need to go back to basics.

On the bright side my new float seems to be working OK.

John

[TechNoir]

Re: 1920 "F" Project

John!

14.7 is equal to absolute vacuum at sealevel at standard temperature and pressure, so if a cheap regulator reads 15, y'er there.

...Cotten

Doh! Of course its obvious to go for 1 Bar.

Thanks.

John

[T. Cotten]

John!

14.7 is equal to absolute vacuum at sealevel at standard temperature and pressure, so if a cheap regulator reads 15, y'er there.

...Cotten

[TechNoir]

A quick question, what pressure is recommended for testing the manifold?

John

[TechNoir]

Cotten, thats a good point and one that had slipped my mind this evening in my haste to compare your new float with my old new float.

Before I do anything else I will bubble test the manifold.

John

[T. Cotten]

John!

There are always other worms in the can.

Since its been such a long discussion, I must ask, again perhaps,...

Did you bubble-test your manifold assembly?

Carbs are forgiving. Manifolds are not.

....Cotten

[TechNoir]

A new float arrived from Cotten and after work tonight I had a bit of time so had a look at things. As promised it is less than half the weight of the knock-off at 3 grams vs 7 grams.



The fuel level is much lower down the float than the knock-off.



I put the bike back together and after a few tries got the bike started and no leaky carb.

The bike is still tricky to start but that might be down to the spring tension on the air valve. I need to look at that but before I do I am going to see how it goes with the adjuster backed right off. It was starting to get dark by the time the bike was back together so with no lights I wasn’t going to take it out.

At the first opportunity I will spend some time dialing it in and report back.

John

[TechNoir]

Golly John,

I could have saved you a whole lot of trouble, and trial-and-error to find the sweet spot level for a heavier, 'sealed' float, and its extra expense for the sealer, if you would only let me.

Postage for my float is only $13.50, but if you are having fun, go for it!

....Cotten

Tom, I have sent you a pm.

When I saw 1st pics your sunk float, I thought, "better get Tom's."

On another note, John, I want your lathe.......

Steve, I love my lathe. It is an early version of a Harrison lathe. Harrisons were sold in the USA under the "Clearing" name. Mine is about 60 years old which is fine for cutting inch threads but I could do with a later model with the dual metric and inch capability at the flick of a lever rather than messing about with a 127 tooth change wheel.

It is built like a tank and despite its 60 odd years is accurate enough for my needs. I could never be without a lathe.

JOhn