His 74 if stock has two throttle cables. The dead cylinder method does both air mix screw adjustment as well as sync of the carbs.
Try it with the throttle cables unhooked. With out the cables hooked then it can't be cable ajustments.
With one plug off and grounded you set the idle speed screw on the otherside for the lowest idle speed without stalling. Adjust the mix screw to highest idle. Now turn the mix screw intil you get a stumble, back out 1/8 turn.
Now hook the plug back on, unhook the other plug. Do the same for other carb. Now both the idle mix is set on both carbs as well as carb sync.
Now with both plug hooked up start the engine. It should idle a bit high. Now adjust both idle speed scews the same amount to maintain the sync as you adjust to 1200 rpm idle.
Now with the engine off hook the cables back to the carbs. Loosen both cables to get a bout 1/8 inch free play on the right cable. Now as you slowly open the throttle watch the right side with your finger tips on the left carb. This way you see the right carb start to move and feel the left side move.
Adjust the left cable so the throttle starts to open at the same time as the right. also don't let it run out of free play on either side.
When they are even you have the carbs synced and the throttles cables set right.
Now with it idling turn the bars full left and right. If the engine revs up you need more free play in the cables, Back off the adjusters the same amount to get enough freeplay so it won't rev when turning.
Now with the bike warmed up give the throttle a quick turn, does it rev quickly with no hesitation, then your mix is ok, if it hesitates open the mix screws 1/8 turn on both carbs. Try the quick throttle again. Adjust the mix to get a smooth roll on with no hesitation. It may bog down on the quick throttle twist if it does turn the mix screw in 1/8 turn.
Now get out on the road and do a few rollons from idle up to about 1/4 to 1/2 throttle looking for smooth acceleration with no bogging or hesitation. This also gets you into the idle to mid range transition. Once you get that set you need a few top end runs, Get it up to around 35 to 40 in say 4th gear rollon from 1/2 to wide open. you should get a smooth transition from the midrange to WOT.
If find that ok then you need to find a long run where in 3rd or 4th you can do a WOT test. hold it wide open for a few seconds to make sure your fully on the mains. Back pf 1/8 turn on the throttle. Does it just back off smoothly or does it have a power surge or bog down.
The power saurge means you should try a bigger main, if it bogs go smaller.
Now test the midrange run from 1/4 to 3/4 throttle does is rev smoothly no hesitation or bogging. If so the bogging means you can drop the needle one step. Hesitation raise it one.
Now retest the idle to mid range and WOT again, the changes to the others may effect the ones already done. Adjust as needed. With a little testing you will get it right.
If you want to do a few plug chops you can. With todays fuel plug reading is getting tougher. They don't tan up like real gas did. You have to look at the smoke ring on the insulator way down deep in side. A 2 mm smoke ring is what I like. Smaller it's lean, bigger it's rich.
Leo
