1965 XLH timing and spark problem

[cajun1957a]

We had some nice weather yesterday so I thought i would take the bike out for a short run just to get the cobwebs of winter out of it.  It started fine and idled good.  I got about a half mile down the road and the rear cylinder started to backfire with a bit of flame coming out of  the pipe.  I nursed it home and found that it was missing pretty bad.  I changed the plugs and it seems fine after that, but the plugs in it were new.  I was using a set of "splitfire" plugs in the fall and they worked great untill i put in the new Mallory distrib. that i had to have rebuilt.  The rear cylinder would backfire and spit flame.  I swapped out the plug and the front did the same.  Logic dictates i had a bad plug.  Makes sence.  Now yesterday with the new plugs ( stock plugs) i put in a month ago. the same rear cylinder plug stops working.  Is my timing off?  Could the coil be messing up on the rear cylinder?  I have the valves set proper so I know its not that. 

Also does anyone know what the timing should be set at in degrees.  This distributor i have always set by ear, and i know that is not the best way.  I bought a real fancy electronic light and now i will finally set the timing to that.  I just dont know what the advance should be.  Mallory suggest the timing be set when the bike is warm at a minimum of 2000 rpm. 

The motor is new from the ground up and has 220 miles on it.

randy

[saltcaveminer]

are the plugs fouling with oil?check compression.are the coil and wires compatible with the mallory?Salty

[Pynzo]

Timing marks on a '65 flywheel were for automatic advance breakers so you shouldn't have any trouble using your timing light. There are 2 different marks on your flywheel, a single line for full advance 45 degrees BTDC, and a double line 15 degrees BTDC for retard position. What kind of carb are you using? My bike fouls up plugs in colder weather because I leave the enrichener on too long and take rides too short to heat up the engine enough to burn off the plugs. I pull them after short rides and flash them with an Oxy Aceteline torch, cleans off the insulators instantly.

[cajun1957a]

The plug was fouled with carbon only on the rear plug.  That failed both times with the splitfire plugs and the stock ones.  Compression is 150 in both holes.  I do have a tendancy to start the bike up and not run it long enough to get hot at times and short short runs, so i guess it is real possible that that is the cause, however after cleaning and regapping, neither plug from the rear cylinder will run again.  Could be a strange coincedence but those plugs no longer work at all. 

As for the timing, The mallory reccomended the coil and wires and I went with what they said.  The timing in degrees I was interested about, is that the new timing light i have is digital.  If i understand this correctly, i should bring the  rpms up to around 2000 or better, according to Mallory then set a light to it.  I spoke to them a while back and they said their electronic ignition is at full advance at that rpm.  This light however is digital and i need to set the advance in degrees in it.  I think how it works is that when I see the timing mark "single line" in the site glass center, I will mean that the timing is correct.  I must assume that this light has to have the set amount in degrees set as to zero it.  Not sure but Mallory said 28 deg.  That number sticks in my head for some reason. The light has up/down buttons to program in the advance in degrees.  The way I have it now is that after one primer kick it starts usually hot and twice cold.  When I set the timing by ear, I brought up the motor to around 2000 and slowly turned the distributor left and to the right and tried to find the best spot where it smothed out and had the best rpms.  Oh yes, the carb is S&S Super E...brand new.

Anyway, Hope you guys can make sence out of all this.

thanks again

randy

[Pynzo]

How's your carb jetting going? Your best bet with that S&S is to turn the accelerator pump screw all the way in until you get your intermediate jet set right. Any pump action will totally throw off your jetting trials and foul up plugs, especially the rear, till you get that idle to intermediate set. With your bike I wouldn't go over a .028 jet to start. What I have to do with my bike is as soon as it fires, turn off the enrichener and crack the throttle open till it warms up- any enrichener and back plug will foul. If plug does foul sometimes you can pull rear plug wire off the plug a little, and the double gap will help the plug heat up quicker and clean itself up. As far as timing goes, I have a light similar to yours, and it was setup that way for timing old V8 cars, where sometimes the timing marks past 5 degrees BTDC were hard to see. You'ld set the light to your timing spec, say 10 degrees BTDC, and timing marks would then line up at 0 mark, dead center of scale. I'd set your light at 0 degrees advance, set rpms at 2000, and look for the single line mark dead center in timing hole. Any Dyno testers in your area? If you continue to have trouble, and alternating between timing problems and carb jetting can be a serious headache, defer your problems to the Dyno- it just might be worth the loot.

[LONE WOLF]

After 30+ years of wrenching on my 1960 XLCH (bored + .070, torque notched pistons, pb cams, ported, big valves dual plugs, Joe Hunt mag and drag pipes with baffels) and trying to get it to start easier and foul the plugs less - this is what I have learned.

As far as spark plugs go I do not use the Harley recommended HC8, HC10 or HC11 - too short a reach and too cold. I have tried just about every imaginable plug that would fit in an effort to reduce "fouling" and have settled on Champion J12YC. As my bike is magneto ignition and kick only it is very important to use only non-resistor plugs. I have found that all plugs are not equal and by that I mean that out of the box some plugs (of the same brand) will not show continuity from electrode to end (where plug wire is attached) when checked with an ohm meter - this is the first thing I check with new plugs. If I cannot see full contimuity with a plug I will take it back to the store along with my meter and show them. I take a good plug along to show the difference - people working at auto stores nowdays don't have a clue, but they will normally let you check a few plugs to get good ones. BTW if using resistor plugs you will get some type of a ohm reading, but not full continuity.
Note: I have also tried Splitfire plugs and find them worthless. BTW I no longer use the second set of spark plugs - didn't make that much difference and too expensive to keep changing 4 plugs several times a season.

As for fuel delivery:

I was (about two years ago) running a Bendix carb easier to start because of the choke plate, but constandly leaked - now running a new S&S Super "E" which I find very difficult to get tuned exactly right, but doesn't leak and bike does run great. I have tried many different combinations of jets and am presently running a #29 intermediate and #58 main jet - this seems to work about the best, starting and running with minimum fouling.

Note: for kick start bikes anything smaller than a #29 intermediate jet is too hard to start - might not be a problem for electric start? Also, for kick start bikes you CAN NOT USE THE ENRICHER too rich - will never start, but kick start owners probably know this.

As others have said in preveious posts the accelerator pump must be disabled after starting (screw all the way in) and until warmed up - then 1 to 1-1/2 turnes out - no more. In fact you can run fine with no pump action at all. Taking a hard run with no pump action will tell you what your plugs are really doing, however, I do believe for normal around town bar hopping you can expect to change plugs at least 2 X per riding season, and they should be checked before each ride, and always carry an extra set - just in case. Consider it an accomplishment if you can get your plugs to look a medium gray (on the insulator) after a test run. Plugs like this should last 5000 miles.

Note: While on a ride if bike sits for 1-2 hours and is hard to start (cools down), back out the accelerator pump screw 2-3 more turns so you can squirt some raw gas into the manifold and have a buddy hold their hand in front of the carb opening to act like a choke - it works! Just don't choke it off completely.

Other old timer Sportster riders have told me that by fabricating a "restrictor" plate to mount on the fromt of the carb it increases velocity (better throttle response) and makes starting easier (acts as a partial choke) - I have not tried this yet, but thinking about it. Also, as far as the fiber plate between the manifold and the carb - I have tried tried them, but could not get it to start or run right - mixture too cold. By mounting the carb straight to the manifold it gets the needed heat to atomize the fuel better. Maybe on a long hot run theough the desert it would work, but here in northeast Ohio it doesn't.

As far as why the rear cylinder always seeming to foul plugs more than the front, I have this theory that the force of acceleration pushes more fuel to the rear cylinder - just a theory. If that is the case a dual plane manifold would surely help - surprised no one has come out with this.

One last thing about "Super Coils":
Actually I found this out on a car; a buddy of mine put one on a early Firebird and started having starting problems - turns out there is a downside to the way these "Super" coils are wound - yes they will provide a hotter spark at higher RPM. but will also provide less spark at cranking speed - it's a give and take situation. He re-installed his old (stock) coil and the problem went away. Acutally he never had a "problem" to begin with, but like a lot of guys he thought "Super" would be better.

Happy wrenching,

Wolf

[cajun1957a]

I tried finding Champion J12YC plugs and up where I am they are no longer available.  Can someone suggest a better plug than the stock HC8's

randy

[LONE WOLF]

You can also try Autolite 4265 (an early shovelhead plug but will work), also AC Delco 44S or 45S.

Note: many of the older (non resistor) plugs can be purchased on the internet.

[wreck74]

harley davidson spark plug #3 is a J12YC. any HD dealer should have them. champion spark plugs went to pot. try this link.

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

[cajun1957a]

Well Im still having issues.  I changed spark plug wires and still the rear cylinder will fire intermitently.  If the wire is almost off the plug fires.  I have an inline wire tester that lights up and the spark looks good on both.  I ve changed plugs as well.   Whats with the fire here?  If I hold the wire almost off completely it will spark.

randy

[olpigiron]

     
                 "worked great untill i put in the new Mallory distrib. that i had to have rebuilt."

         U Might Want To Look @ The Distributor, Maybe Try a Different One And See What Happens!!!

[cajun1957a]

I keep a spare mallory because i had issues.  The one that is in is not the factory rebuild but brand new.  Could it be the coil?  Is there a way of testing the coil?

randy

[olpigiron]

         

                                          Have U Tried A Different Condenser???  Try A New One There Cheap!!!!
                    Do U Have Access To A Different Coil,???  Make Sure It Is For The Right Application, Try It, If It Works, Keep It Bolted On!!!!
                                             
                                           

[LONE WOLF]

Check the coil with an ohm meter should read 3.0 ohms across leads for stock coil. BTW the reason it fires when you pull the wire away from the plug is that you are adding resistance to the circuit causing the spark to jump the gap. Check that rear wire with an ohm meter - should be low 1-2 ohms max. - better yet use solid copper wire "0" ohms.