Re: Lark V BigTwin Help...
Check compression. With the spark plugs removed, check spark. Take pictures and make notes of the carburetor, linkages, etc, then remove, clean, and rebuild the carburetor.
Be sure to manually clean the fixed high speed jet that's located in the bottom center portion of the float chamber. Use a piece of single strand steel wire.
The carburetor will no doubt be fouled, clogged, gummed. Running the engine without being sure that it is perfectly clean may result in having the engine running lean..... piston damage etc.
Flywheel key aligned with fiber rubbing portion of points... set points so that a .020 gauge passes thru but a .022 will not. Use either Champion J4C or J6C plugs gapped at .030.
Lower unit if electric shift, use ONLY Premium Blend, also know as Type C, available only at your local dealership. If standard mechanic shift, use HiVis 80/90w available at Wal*Mart, K-Mart, etc... also at your dealership at a somewhat higher price.
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.
Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.
When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
(Carburetor Float Setting)
(J. Reeves)
With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
Oh, important torque spec here. If you have that flywheel off, be sure to torque that flywheel nut to exactly 105 foot pounds. Anything less results in a sheared key, damaged tapers to the flywheel and crankshaft.... a real mess.
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