View Full Version : hard start, valve adjustment
30th June 2005, 02:04
ive got a '62 ironhead with magneto and a mikuni carb. its really hard to start when cold. could it be that my valves need adjusted? the mag is on the timing mark and i have new plugs (ngk). the carb is fairly new. is adjusting the valves pretty straightforward?
30th June 2005, 02:17
Are the valves clicking? I would not think this would be the problem of hard starting. Sounds to me like fine tuning the carburetor may help.
30th June 2005, 03:12
Valve adjustment unlikely cause of hard starting.
62 has a fixed mag. Mag adjustment is a balance between retarded enough for easy (relatively) starting and advanced enough to not burn the valves when running. You must find this spot. Check point gap and condenser. Does it kick back badly (ignition too advanced)? Mag must be turned to adjust. The mikuni does not have an accelerator pump so kinda hard getting enough fuel into motor when cold starting. Choking should help. S&S E has an enricher and helps with starting. The starting routine with mine is: Two twists of throttle, kick through twice with ignition off, turn on ignition and give it all ya got scotty. Do not be timid kicking with ignition on as this will result in a mean response (read as nasty kick back). If bike fails to start, run through the routine again.
30th June 2005, 03:39
Yes, check your point gap and adjust and file the point contacts as needed. This was always the cause for hard starting on my 68 XLCH. In fact if they haven't been changed in awhile, install new points and condensor.
Also If you flood the bike and get the plugs wet, you may not be able to get the bike started until you remove the plugs and dry them out or throw in your new spare set, which I know every XLCH kickstart owner keeps in their pocket. Lacking an electric start motor, your leg is all you have to spin that engine. You need to have your electrics and timing dead on if you want to save your leg!
I don't care what others might say but in my opinion Mikuni carbs belong on Jap bikes only!! I shitcanned the Mikuni that the previous owner installed on my 68 XLCH Kickstart Magneto engine. I never liked that carb on the bike. At the time I installed a 'Lectron' carb with the clear fuel bowl. Once you set it up, that carb never failed to start my bike!! They still make'em. A great carb in my opinion. Also the S&S 'E' Shorty Carb should work well (I have one on my 74 XLCH kickstart) and the bike fires up first time everytime!! (unless I screw up).
If your magneto is old, consider sending it off to Joe Hunt for rebuilding with their stronger rare earth magnets. This will give you a much hotter spark when kicking over. I think they can modify it with their auto-advance set-up also. :smoke
30th June 2005, 03:53
thank you all for your advice
To answer your valve adjustment ? yes it is pretty straightforward.
They are solid lifters and the procedure is well covered in the service manual.
If you dont own one you should get one.
The XLCH is a great classic Harley but requires a tad more maintainence than a more modern bike and knowing how to do basic stuff like valve adjustment and ignition tuning is a must if want to ride one of those old kick start beasties on a regular basis lol.
30th June 2005, 05:23
so i retarted the mag a little, i moved the mag off the mark about between an 8th and a 16th of an inch. it started easy. under load it started making a clacking, and seemed to have lost some power, so i assume i retarted too far. does that seem about right to you guys?
as far as the mikuni goes.. i dont know if it has an accelerator pump or not, although i think it does. when i twist the throttle with the bike off, fuel shoots into the venturi. wouldnt that be an accelerator pump?
30th June 2005, 05:25
also i have never been able to start it witrh the choke on maybe i have too much fuel and not enough air in the mix?
30th June 2005, 05:37
Yes, Yes, and yes!
1st July 2005, 18:35
Dabronco says you have an accelerator pump, I stand corrected, good news for you as it takes pretty much gas to get the thing to fire. I am using the S&S E and it works great. Back the mag up just a bit, what you want is as far advanced as you can get and still be able to start it without busting your knee. By trial and error you should be able to find the sweet spot. The timing mark is a reference but you gotta fiddle with it. Sounds like you are getting warm.
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