Carb settings

My rule of thumb before setting carb adjustment is to do an old fashioned tune up, what used to be called "plugs and points". The object is to get spark as good as can be, timing set spot on, tappets set, air filter cleaned, etc. etc. Carb setting should be the last thing to set, never the first. This was the message from my fellow workshop mechanics when I was learning the trade and there turned out to be a lot of truth to it. Wise words indeed. Being young and brash I resisted of course..

I set the idle mixture with timing retarded and engine fully warmed after a 10 minute+ ride. Stop and immediately tune the idle mixture. Effectively find the midpoint between rich and lean. The main jet needs to be set by performance on the road. The engine should pull without misfiring from being too rich or lean.

Once I'm happy I've got these two settings close, I mark the positions of the two needles as in the pic.

Marks allow fine tuning, perhaps a click or two either way to see if there's any slight improvement. Marks also allow the original setting to be re-established (with accuracy) if need be. In addition this is handy if someone messes with your settings as some kind of sick practical joke.

Gas cap refurbishment

My 741 has a very nice original oil cap with a perfect seal. One gas cap was missing, other was partially loose in its' center. I had a pair of good fitting gas caps, not quite original but well usable. The seals were like cardboard and were quite ineffective. I hand cut new seals from thin rubberized cork sheet. Fit is good.

Update: These seals failed because they ripped. Studying a Chemical Resistant Rubber Chart it suggests Nitrile or Viton. Will visit a rubber supply shop on my next trip to town.

I found the right place and they cut seals on the spot from 1.5mm Viton. I put grease to help them slide nicely. As grease will simply wash away with petrol/gasoline I want to experiment with silicone or Teflon grease. Already I tried CPU heatsink grease and Wurth silicone spray grease. Both seemed to dissolve too easily.
8Dec update: These Viton seals worked a treat so far with part tanks of fuel.. Not a single drop of fuel leaked. I filled the tanks and I can say this is the best the caps have ever been,

I want to uncrimp the original gas cap, remove the worn/loose center then attempt to recenter it with parts from a donor cap. It will be the first time I've done this so we'll see. The cap is not usable otherwise.

3Dec2018 Update: I gutted out the original cap. Firstly I tried to roll the crimp back but cap was difficult to hold. I made a tool for the lathe toolpost which utilized a hardened steel roller. I had some but limited success. Eventually I elected to machine away the internal part till it was wafer thin. Then it crumbled away leaving the outer case perfect.

DIY Lathe tool with crimp roller.

 Original gas cap dismantled

Another view 

Updates to come..

Throttle & Advance/Retard Controls

The control twistgrips had a lot of slack in the working so push/pull movements weren't very well defined. I dismantled the twistgrips to study workings. It was discovered there was an important piece missing from cable mechanisms inside both handlebars. Schematic parts list diagram, part #14

I propose to make these bits then solder new bowden outer cable to them. The plan is to get nylon lined bowden outer and single strand inner from a local mower supply shop. About 2 years ago I made a similar cable for my Panhead so am hoping to replicate the task.

The twistgrips had a significant amount of endfloat so I added a suitable shim to each. Pic of RH advance/retard dismantled with shim in place.

8Dec2018 I haven't been able to find local stocks of this cable. It's bigger than typical lawnmower. I may elect to import from a dealer in Canada but currently a postal strike disrupts.

LED's, 6v considerations, Daytime riding light..

I'm studying 6v LED's so I can run the bike with some sort of lighting during the day and increase the distance I can travel at night without draining the battery. Currently the generator charge rate is set to trickle charge the battery.

These are what I fitted to the speedo... 6v BA9S, very cheap from Aliexpress.

1Dec2018
The tail light, stoplight and blackout lights take BA15S bulbs. I have 2 lots coming from Aliexpress to test.

Ideally I want the little front blackout to light full time when ignition is on. I want it bright, much like the brightness of some of the cyclist lights but not blinding for oncoming traffic.I'm considering this a safety issue. Hoping to achieve this with generator on trickle charge as it is now.

Tail light, I want more light for less amps. Pondering over whether I go red or white LED's.

Stop light, I think at least 50% brighter than the tail bulb.

That's my wish list so we'll see what's achievable in coming days when bulbs arrive.

4Dec2018 update: My "warm white" 6v LEDs turned up from China this morning. Took 13 days from time of order. Well packed...

I spray painted the inside of the stop/tail lamp and the little front backout light with bright silver-chrome paint. Pic is after masking/prepping ready for spray painting. The object is to make the inside more reflective and generate more light.

+

With several thin coats of chrome paint.

 I fitted the new LED bulbs and tested in total darkness. Seems OK but I should have taken a photo beforehand to compare. I was aiming to get slightly more light than before with significantly less tax on the electrics. Will ask a fellow motorcyclist to follow and observe before making final conclusion.

I believe it will be brighter than pic shows with the motor running..

Front little blackout light.. am hoping this proves bright enough to be seen. I've connected it so it's always on when ignition is on. These LED's are 1.5w therefore draw 0.25A at 6v. Pic taken with the inside painted with bright chrome.

8Dec update: This LED burnt out within an hour of use. Studying the issue closely, am wondering if the standard unregulated generator increases the voltage to limits above that at which the LED can handle? The generator current is set to just a couple of amps when running but volts could easily be a different story. Plan is to put a simple LCD voltmeter on the bike so I can monitor what the realtime voltage upper limit is.

 9Dec2108 In testing using a simple LCD voltmeter monitoring system running voltage I found readings as follows:

6.0 ~ 9.4v

I contacted the seller who confirmed my upper peak voltage was above what the LED was happy with. Perhaps I should have realized considering 741's have no voltage regulator. So, anyway I learnt something. Ideal would seem to be something that works between 6v and 12v

Stay tuned...

The 6v BA15s LED bulbs arrived for the stoplight....and yes they're nice and bright. These are a red light not white. Early indications are good

17Jan2019
I bought 2 x 5v -24v Ba15S LED bulbs. One is now fitted to the front blackout light. It was tight fit and I had to manipulate the bulb holder orientation slightly to get clearance. It's bright, now for some testing on road.

Armistice

Armistice weekend was 10th- 11th Nov 2018 Karapiro, Cambridge, NZ.

There was a number of tanks, half tracks, jeeps etc.

It was popular with a market and lots of activities.

 My 741 was right at home attracting many comments.

Visit to RSA

I visited a local RSA (NZ Returned Services Association) in nearby Morrinsville. I parked alongside a large gun for photograph. The cold beer was good too..

On road costs

Firstly I had to get a Warrant-of-Fitness (WOF) so I road the bike to local bike shop of Trevor Hall.
Trev has his own 741 Indian in the showroom so I was able to study it closely.
My bike passed inspection with a fee of $40. I then registered it after it being "on hold" for 25 years. I did this part on-line which cost $44 for a years rego. The label will be mailed out.