26 JD starting issues

[MassHarley]

I am looking for some advise on how to get my 26 JD started. The motor is freshly rebuilt. I believe the distributor is timed correctly but I can't be sure. I time the distributor by bringing the front cylinder 9/32" before TDC then fit the compound gear while the small lobe on the distributor shaft was holding the points open slightly.

I am getting what I believe to be good spark at each plug. Points gap is set to .022". The motor seems to be getting fuel. I can see fuel slightly puddling in the carb body and the plugs are getting wet. I am also attempting to start the motor with the timing fully advanced as the riders manual states.

I can get the motor to pop and even got it to run for about 3 seconds. However, that all I can get.

Any ideas where/what I should check next? I would really like to here this project run.

Mike

[Steve Swan]

i can tell you my experience. i followed the instructions in the 27 Rider's Handbook for setting ignition timing and my engine started after complete rebuild for the very first time on the 2nd kick after the 2 initial prime kicks.

i did not bother finding tdc/btdc.
i lined up the marks on the pinion, rotary breather and cam gears.
i removed the compound gear.
then i set the ignition point gap at .024"
then i set the timer to full advance (forward.)
then i turned drive shaft in direction of engine rotation until the small heel of timer cam opened points to .015"
Then i fit the compound gear.
and that was it.
my engine, almost without fail, always starts on the 1st kick cold, after 2 prime kicks (ignition off.)

Please note: my points gap settings are very slightly different from the book, because i am using domed pistons.

initially, i was way overthinking setting ignition timing, made a protractor to fit on crankcase, a TDC finder, etc. The good people of this board and JD Yahoo straightened me out. One of them said, "The factory was very proud of that compound gear for a reason." aligning gear marks, setting correct points gaps and installing the compound gear is all there is to it.

all that being said, now i will ask the Tom Cotten important question.... "are you sure you have no manifold leaks?" no leaks where carb meets the manifold ? no leaks where the both inlet housings mate to each cylinder ?

what type packing are you using for the manifold nuts and nipples ? i went the PEEK route. i used a low pressure regulator and i used a smoke machine to locate any possible leaks. the only leak i had, was one between the carb and the manifold, a slightly thicker gasket gave a leak free seal.

[Steve Swan]

i will add, when engine is fully warm, turning the spark control from full retard to full advance, somewhere in between the two positions, you will find a "sweet spot," where the engine runs smoothest at it's most ideal advance position. this "sweet spot" is easy to notice when running at road speed.

[ChrisLewis]

Starting issue

Mike

May sound stupid but a friend of mine has a similar issue, we checked the timing and carb settings and all seemed in order, we then checked the valve clearance and this was to tight resulting in the ports not fully closing, quick adjustment and she ran like a dream.
Also he had not fully tightened the oiler's so was not getting full compression.
May be worth doing a compression test as the result will eliminate any valve seepage.
Only one of the hundreds of reasons why your bike is not running. worth a look !
Steve's suggestion is route 1, including carb leakage, then maybe the valves.
Chris

[T. Cotten]

....all that being said, now i will ask the Tom Cotten important question.... "are you sure you have no manifold leaks?" no leaks where carb meets the manifold ? no leaks where the both inlet housings mate to each cylinder ? what type packing are you using for the manifold nuts and nipples ? i went the PEEK route. i used a low pressure regulator and i used a smoke machine to locate any possible leaks. the only leak i had, was one between the carb and the manifold, a slightly thicker gasket gave a leak free seal.

Smoke machine, Steve?

Mike!

Bubbles are simple and easy to "read": http://virtualindian.org/11techleaktest.html
Even the tiniest leaks will display as little blisters of foam after a half-minute or so under a constant 15psi.

The carb-to-manifold seam cannot be bubble-tested, so both flanges should be arbitrarily dressed to 'flat'.
Fastener stress over the years invariably distorts them.

.....Cotten

[Steve Swan]

automotive people use smoke machines to locate vacuum leaks. home made ones are simple to make or inexpensive to purchase. can be found on You tube and ebay.

[T. Cotten]

automotive people use smoke machines to locate vacuum leaks. home made ones are simple to make or inexpensive to purchase. can be found on You tube and ebay.

Don't see no smoke in your utube video, Steve!

Bubbles seem a lot simpler to me, and they stay there while I put my glasses on....

I learned a lot from "automotive people", honest. But most often it was from their mistakes.

....Cotten

[MassHarley]

Well folks I got her running! I swapped out my coil just for laughs and it fired right up. I think my other coil might have just been producing a weak spark. I'm hoping to have the coil rebuilt. It was great to hear it running after this many years.

It did seem to run a bit rough though. I could hear one cylinder popping now and then as if it wasn't firing. I was thinking of going back and retiming the machine like Steve described by lining up all timing marks and setting the points approx half open. I'm hoping that will smooth it out a bit.

Also turns out my throttle shaft bushings are pretty heavily worn. Fuel was actually exiting the carb through the throttle shaft. Would this excessive clearance effect how the machine starts?

Mike

[Steve Swan]

Tom is the carburetor expert.

all i will say is that worn monel bushing and perhaps worn shaft also, will permit drawing excessive air.

[MassHarley]

Just a little update. I took the timing chest back apart and lined up all the timing marks like it shows in the book. With all the marks lined up the front cylinder is past TDC which doesn't seem right. The only timing mark that is slightly off is the breather. It looks as though it is one tooth past the "A" stamp on the case. Would this have an effect on starting the bike?

Mike

[Steve Swan]

given my engine is a 27 with a 27 timer, i fear perhaps i have given misinformation for setting ignition timing on a 1926 distributor model. my sincere apology for any confusion i have caused. more experienced minds need prevail.

[Steve Swan]

the below in reply to harleytoprock and Mike, since i can't figure out how to load pics on caimag forum, the following i posted elsewhere, but also includes this pic.........

Thanks, Harleytoprock, i appreciate your comments. attached is a picture of the tools i made early on, a tdc tool in place of the 17-25 front cyl.plug, a protractor attached to LH crankcase and a buzz box to indicate the opening of the points. looks like i better set timing using these tools before i set engine in frame, before i begin my final assembly of restoration.... ! (i "wondered" about that sweet spot.... thinking it would be nice to have full advance be when spark control is fully turned to advance position.)

The factory Mechanics Bulletin, June 10, 1926,states ignition timing is set at 13/32" - 7/16" BTDC. this being said, i wonder what btdc position i should use with domed pistons.....?

sorry Mike, i feel like i am hijacking your thread, but i think what we learn may benefit us both.......!

20160306_104154.jpg

[Steve Swan]

seems i can't attach a microsoft document, the following is from JD yahoo groups, it may be helpful

Degree Conversion Table

Inch BTDC/ATDC - Degrees (Rounded to nearest tenth)

1/16" - 12.9'

1/8" - 18.2'

3/16" - 22.4'

1/4" - 26'

5/16" - 29.1'

3/8" - 32'

7/16" - 34.7'

[Steve Swan]

below is scanned from the June 10, 1926 factory Mechanic's Bulletin.

ign.timing 1 001.jpgign.timing 2 001.jpgign.timing 3 001.jpg

[Steve Swan]

i just finished using a dial indicator and a buzz box to set the ignition timing at 7/16" btdc. (points gap set at .022") rotating the engine several times, the buzz box goes off/points open at exactly 7/16" btdc full advance. when i very lightly touch the timer lever in the retard direction, the buzz box immediately shuts off. i am thinking the ignition timing should be dead nuts on. once the bike's back together, when i turn the spark control full advance, the contact points should just open at 7/16" btdc. that should be the "sweet spot" for road speeds.

before making the above adjustments, using the dial indicator/buzz box, i checked the settings i previously made using the gear marks/compound gear visual method. points gap set at .024" i had aligned the gear marks as precisely as my 20/20 vision at 3 inches would allow and had positioned small heel of cam to be in the process of opening the points gap to .015" at full advance.

using the dial indicator, i located 7/16" btdc. the small heel of cam had opened points gap to .013" at 7/16" btdc, moving timer lever to full retard, the cam position indicated the points were not far from breaking contact. at full advance, the points were open to .022" this would explain why i was finding the "sweet spot" when turning the spark control to approximately 2/3 of the way to the full advance position. turning the spark control to full advance the engine began running poorly, ignition timing was too far advanced. and the timing probably could not be fully retarded either.

thanks harleytoprock for giving me a kick in the pants and i hope this helps Mike.

20170101_181839.jpg