Carb balance question

[MrRiden]

I may be splitting hairs here but...I've decided to have a go at the one plug lead grounded method of carb tuning. After reading several writings on the subject [including our own trolle] I was wondering, is it preferable to leave the plug in the cylinder that you are grounding or is it more better to remove the plug from the side you are grounding? I'm curious because removing a hot plug doesn't seem like a great idea but equally bad may be sucking gas into a cylinder with no spark. Maybe I'll just stick to the manometer but I've heard this grounding method is preferred.
rich

[nothing]

Sucking gas into a cylinder with no spark will not hurt anything, except your wallet these days. Leave the plug in, that way you can move from side to side quickly to check balance - which is the whole point, after all.   [smiley=beerchug.gif]

[beemer]

Iv'e heard a lot of talk on this method,some say it will kill your electronic ignition?i wouldn't risk it myself this is just MO of course. :-/

[larstorders]

I prefer the grounded spark plug method (with non firing plug left in cylinder) to set the balance at tickover . Because, My crankcase breather is piped into the right carb intake only.As a result the pressure in that carb is affected at tick over and produces uneven readings on manometers (carb tune etc). To the extent that if I balance the carbs for even running at 1000 rpm using a manometer alone, the compenstory adjustment to the right cylinder means that it won't tick over by itself at all. All is well if the crankcase breather is routed out from the carbs btw. Can't fiddle about with the breather pipe every time I want to check the balancing, though. However I do use the manometer to check that carb pressures rise together evenly when t'throttle is opened. So a bit of both really.

[not-so-fast-ed]

I heard it was a matter of if your bike was using points ignition, then no problem.  Electronic ignition would go TU if you tried it..  What year R65 are you trying it on Rich?    :-/

[nothing]

What kills electronic ignitions is pulling off a plug wire WITHOUT grounding it. Using grounding extensions/adapters and grounding the current with a screwdriver is the safe way for electronic ignition systems.

MrRiden: do you have plug shorting grounding adapters? Or are you just pulling plug wires and attaching them to ground? This balancing method works best (and safest for the electronic ignition) if you use a short bare extension on both plug connections (with plugs installed), then short that extension to ground with an insulated screwdriver. This way you can switch quickly from side to side to check balance, and the current always has a path to ground (protecting electronics). Snowbum has a good writeup on this method buried in his pages.

Sorry if you already have all this in place, it wasn't clear from your original post.

[not-so-fast-ed]

Way to go "Nothing"..  Now I remember where I heard it, and I think this is the link.  Thanks, Ed

http://www.airheads.org/content/view/216/98/

[MrRiden]

Thanks all!
On further reading I see that there are no less than three slightly differing methods for tuning. The first simply uses a manometer without any sort of ignition interruption.

The second calls for setting the mixture WHILE one cylinder has the spark interrupted either by grounding, plug removal, or disconnection of the plug wire [the latter is fatal to our post '81 black boxes] I've seen Triumphs tuned in this manner.

The third calls for the mixture setting to be carried out with both jugs firing and the spark is grounded only briefly as a means of comparing one side to the other.
 
I've also discovered that balancing by manometer alone will not necessarily produce the best idle. This is due to differences in each cylinder and carb [like "lastorders" pointed out] so the time I've spent getting the reading exactly the same on each bank was a waste of time. While blindly fiddling previously I hit a spot where the engine was smoother than I've ever heard it but the levels were not the same on the meter so I readjusted 'till the readings were exact, ruining the nice idle.

I'm going to try the third method, also outlined on the Air Heads site, [thanks for the link Ed] leaving both sides running and grounding the spark with an adapter only briefly for comparison purposes. I'll also leave the manometer connected just to see how different the readings will be when tuned by ear.

Off to the garage to make some adapters for my '82 LS [A la "nothings" suggestion] while repeating a mantra: idle balance->left mixture->idle balance->right mixture->repeat from beginning
rich

[nothing]

....leaving both sides running and grounding the spark with an adapter only briefly for comparison purposes. I'll also leave the manometer connected just to see how different the readings will be when tuned by ear.

You may have an issue when you do that, as all the the manometer juice may be sucked into one carb when you ground the other side. I've not tried this personally, so this is just theory (I've avoided trying it purposely due to said theory). If you do try it, be sure to report back, I'm curious.   [smiley=2vrolijk_08.gif]

Marvel Mystery Oil is the best manometer juice, by the way - it just smells so yummy.

[MrRiden]

Nothing & All,
I'll keep an eye on my poverty rider manometer, If someone hasn't seen one here is the how to: http://www.powerchutes.com/manometer.asp
As for the adapter, I had to run over to ACE to make it. Cost was $1.30. I had a couple of old spark plug screw caps, what I bought was a couple of 4 X 70 screws that are 60mm long. Thats metric, don't buy an SAE #4 screw it will be too small. Who knew that spark plug tops were metric? I also went all out and blew 13 cents on a couple of jam nuts, I'd get wing nuts net time to make installation on the plugs less fiddly. Screwed em into the caps part way, tightened the jam nut against the cap, clipped off the screw head and viola

[beemer]

Nothing & All,
I'll keep an eye on my poverty rider manometer, If someone hasn't seen one here is the how to: http://www.powerchutes.com/manometer.asp
As for the adapter, I had to run over to ACE to make it. Cost was $1.30. I had a couple of old spark plug screw caps, what I bought was a couple of 4 X 70 screws that are 60mm long. Thats metric, don't buy an SAE #4 screw it will be too small. Who knew that spark plug tops were metric? I also went all out and blew 13 cents on a couple of jam nuts, I'd get wing nuts net time to make installation on the plugs less fiddly. Screwed em into the caps part way, tightened the jam nut against the cap, clipped off the screw head and viola

Did you make just the one or two of them?leaning over shorting the plug while doing the adjustment seems a recipe for disaster if you loose the earth contact for a moment?great idea though  

[Semper Gumby]

I use the colortune plug.  No guess work when setting the idle mixture.  PLus you can see if the carb is working properly when you advance the throttle.  Also you can keep both plugs going.  No need to ground anything.  

[not-so-fast-ed]

Neat Rich!
Now you can make $10 kits, and retire wealthy...
Ed

[MrRiden]

Beemer,
I made a pair. As for earthing myself, If I've read correctly adjustment is made while both sides are running. only a brief grounding of each side is done for comparison. You don't actually adjust & ground at the same time.
Ed,
I was thinkin' of selling a kit on late night TV. The $5 tune up for only $19.95. Order now and Ill double your order. But wait theres more!
rich
Lookin' for RONCOs phone number

[beemer]

Beemer,
I made a pair. As for earthing myself, If I've read correctly adjustment is made while both sides are running. only a brief grounding of each side is done for comparison. You don't actually adjust & ground at the same time.
Ed,
I was thinkin' of selling a kit on late night TV. The $5 tune up for only $19.95. Order now and Ill double your order. But wait theres more!
rich
Lookin' for RONCOs phone number

I thought you grounded one plug while adjusting the other side carb say for 850rpm,then did the same on the other till both were at 850rpm,am i wrong here?