plug readings and cleaning preference?

[Forden]

So I've embarked on tuning my newly rebuilt carbs for the first time--I think I have the principles straight, still battling rich conditions overall--simple (hopefully not stupid question):

What method for cleaning plugs do people prefer between readings? I've got three sets of new plugs I'm using to tune. With trying to get good reads for different throttle positions, I'd like to clean them (rather than have umpteen brand new ones). I tried gas and a toothbrush, and that worked pretty well (for rich deposits) but didn't really get the porcelain white again. Brake cleaner, perhaps? I know they make pneumatic cleaner but hoping to use something I've got already.

Also, when trying for a read on a specific throttle position (let's say half), will a run of a few miles eliminate any traces of previous plug condition (say if it was rich from choke/idling)?

Thanks.

[Guest]

What method for cleaning plugs do people prefer between readings?

I just let the engine clean itself. It does not take very long to change the color. The wider the trottle is open, the quicker it happens. Full throttle can be done with a single blast. Remember that the critical part is throttle opening, not engine speed, so you can get into fourth gear at 20 mph, open the throttle fully, the by the time you get to 70+, pull the clutch, hit the kill switch and coast to a safe place to stop and read your plugs. Repeat at half throttle, but it might take 30-45 seconds, so find a hill where you can hold half throttle, then pull the clutch, hit the kill switch, coast to a stop. 1/4 throttle will also require a hill, higher gearsand maybe a full minute. Idle to 1/8 throttle is easy enough to do just riding through town. Give that at least a minute.

[Forden]

Thanks, good to know. I'll still happily accept recs on cleaning plugs, since a clean set can't hurt, right? I thought it worth reposting this excellent explanation of chop tests too (which I just found) to complement what you've said, in case it helps anyone else who might see this and need the same help I do.

That is what is important with the plug chop test. To save some research, here is the basic concept.

Mark your throttle. Put some tape on the housing and the throttle grip. Make matching marks at idle. Move the throttle to full open, make a mark on the housing there. Measure between idle and full, make a 1/2 mark, repeat for a 1/4 mark.



Warm up the bike so you don't need to use the "choke". Install a fresh set of brand-new plugs. Start the bike, let it idle for a couple of minutes, turn it off. Read the plugs. Pictures at this time are great for documentation.

With the plugs back in, find a place where you can ride and hold the throttle very steady at 1/8. It does not matter much whether you are in second gear or fifth, the important part is 1/8 throttle. Hold it there as long as possible, a full minute would be great. Pull the clutch, hit the kill switch, coast to a stop where you can safely remove the plugs. Take a picture of the plugs, continue on your ride.

You may have to find a small hill, but repeat on 1/4 and 1/2 throttle settings. Using a higher gear will allow you to hold 1/2 throttle longer, 30 seconds will be a decent opportunity for coloring the plugs.

Finally, find somewhere where you can safely get up to higher speed and also has a pull-out area where you can read the plugs. Get into fifth gear by about 30-35 MPH, then hold the throttle wide open. It should only take 10-15 seconds to get a good reading, but you will proably be doing well over 70 by that time. Again, read the plugs.

Each of the throttle settings will determine which jets are in use, and they all overlap a bit, so we need to see them all. For example, with your one picture, if that was at idle, I would guess that everything might be pretty close, but your petcock diaphragm was leaking, allowing extra fuel. If that was after a run down the drag strip, your main jets would be entirely wrong, but mostly in just one carb. That is why it's important to know what was happening just before those plugs were pulled.

.

[alke46]

But the question remains-------what or how do you clean the plugs?

Or, is Steve's advice all that matters? Doing successive plug chops cleans the previous finding??????

[Guest]

Doing successive plug chops cleans the previous finding??????

It has worked well for me for many years and many bikes.

[Burque73]

Someone, maybe Grimly, said they use a torch to heat the electrode till it glows to clean them. A quick google search shows lots of posts about using a torch to clean plugs.

[mustangflyr]

Someone, maybe Grimly, said they use a torch to heat the electrode till it glows to clean them. A quick google search shows lots of posts about using a torch to clean plugs.

I follow the advice of Allen Millyard and use a torch, works quite well.

[Rich82GS750TZ]

I follow the advice of Allen Millyard and use a torch, works quite well.

That guy?! What a hack. Just kidding, man's a freaking genius. I would watch a 3 hr. video of him making toast. And then wait patiently for the follow up of him spreading jam on the toast.

[mustangflyr]

That guy?! What a hack. Just kidding, man's a freaking genius. I would watch a 3 hr. video of him making toast. And then wait patiently for the follow up of him spreading jam on the toast.

You and me both, some people know how to pick a hobby.