Plug Reads and Mixture, also ping when very hot

[Anonymous]

Ok, hate to beat a dead horse here but something strange is happening to me -

I understand the proper plug color is toast/tan, and the place to read plugs is the porcelain surrounding the electrode.

So: My #1 cylinder had a plug that looked almost new - clean white. The other plugs were tan. Here's the thing though: I moved this plug from #1 to #4, and have ridden for a while. The plug reads the same - white. The plug from #4 that is now in #1 is the same as it was, too: tan. Anyone have any ideas here?

I think its running lean overall. The engine has stock airbox and filters, has not been jetted, and has replacement pipes. (stock HD pipes) The new pipes, despite being ridden 150 miles, have no carbon anywhere in sight near the outlets. This may be normal, but I'd rather run a little rich than lean.



Oh, one more question: When I get stuck in traffic, and the engine gets nice and toasty warm, if I load the engine down at all (accelerate hard under 3k rpm) it would ping hard. It does NOT do that when at a normal temp. I run 89 octane plus gas.. I could use 92, but I thought these engines were supposed to run properly on 87?

[Anonymous]

On both of my GSs, and most others, the stock fuel setting is a touch low due likely to emissions. Pull the carbs, clean them and raise your floats 1mm. The difference is night and day.
You could just have number 1 with some junk in a passage too. Before I pulled the carbs, I'd pull the bowl off #1, pull the pilot jet out and clean it.
That will take care of the low speed fuel but it sounds like you'll need a deeper cleaning as the rest from 1/4 throttle to WOT is needle jet related.
Good luck

[Anonymous]

Carbs have been thourougly cleaned, twice. I'm not sure if the problem IS number 1 - like the original post says, if I move the 'white' plug from one to 4, the problem is now #4 .. Oh, and its a relatively new plug too.

[chuckycheese]

Plug

Before I'd do anything drastic, I'd replace the white plug with a brand new one and see what happens. The fact that the plugs' conditions didn't change when you changed their positions is very telling!

[Anonymous]

It could be just this plug I suppose. When you cleaned the carbs, did you reset the float level? Or at least make sure that they are all the same where they were? Does this cylinder (with this plug in it) heat up slower than other cylinders when you first start it? Bob

[Anonymous]

Haven't checked the actual float measurements. I did confirm they were all equal when I disassembled the carbs before, though. I'll pick up some new plugs and see what happens there...

How fast should new plugs show their indicating color after installation?

[Anonymous]

Ok, a question about plug reads:

I installed new plugs last night, and rode 50 miles today (commuting) and after pulling the plugs, they still look almost like they came out of the box. The porcelain is perfectly clean. The ground electrode is tan on the end, though.

Any advice?

[earlfor]

Pretty simple. Changing to a HD pipe has changed your backpressures. Same thing happens for example when you change to a Vance and Hines 4 into 1. There is nothing wrong with your carbs. Your main jet size is now too small because of the HD pipe. You probably need to go to about 105 mains.

Earl

Ok, a question about plug reads:

I installed new plugs last night, and rode 50 miles today (commuting) and after pulling the plugs, they still look almost like they came out of the box. The porcelain is perfectly clean. The ground electrode is tan on the end, though.

Any advice?

[Anonymous]

Thanks, Earl.

So, will changing the mains affect the whole range?

Can I possibly get by with just raising the float level?


Yeah, I'm a cheapskate. I don't mind spending the cash on jets, but I don't think I can get it by the 'boss' right now.

[KEITH KRAUSE]

The main jet regulates fuel flow from 3/4 throttle to full open.
If you were riding fairly slow, say 40-45 mph and less, then you are on the pilot circuit with a small overlap from the jet needle. If you were going faster, say 60-70 mph, then you are still on the pilot circuit, but there is more overlap from the needle. If your exhaust flows better than the stocker, then you should try going up a full size on the mains. I doubt the plug reads you got after your 50 mile ride involved the mains, unless you were at 3/4 throttle +.
Pinging as you described is caused by pre-ignition. A lean mixture can cause pinging, so can too much advance on your ignition timing. Lower octane fuel makes it worse.
Before playing with the jetting, the ignition timing MUST be correct first.
Then you should adjust the mixture screws for the highest rpm and synch the carbs. If the mixture screws still have their "tamper" caps on, do not adjust them at all. You still need to synch the carbs. You also should set the floats to the factory spec'. Don't just eye-ball them.
Except for allowing a larger main jet for the exhaust, I think your lean/pinging problem is just a matter of maintenance. I know you want to save money and may not want to buy a synch tool even though a poor synch is a common cause of your problem. So are incorrectly set mixture screws. At least check/adjust the timing and check the floats.

[Anonymous]

Re: Plug Reads and Mixture, also ping when very hot

So: My #1 cylinder had a plug that looked almost new - clean white. The other plugs were tan. Here's the thing though: I moved this plug from #1 to #4, and have ridden for a while. The plug reads the same - white. The plug from #4 that is now in #1 is the same as it was, too: tan. Anyone have any ideas here?

Are they the exact same plug make and number? If the white plug is hotter it will be whiter. I think D8ES is spec and D7ES is the next hotter. Can't quite remember... anyway, check that you have apples and apples.

Michael

[Anonymous]

Thanks for the replies all.

I'm running NGK B8ES plugs.

The carbs still have the anti-tamper caps on the adjustment needles, so I can safely say no one has changed them. (OK, its possible, but who puts new caps back on?)

I have not synced the carbs yet. When I removed them for cleaning, I did not break the rack, therefore assumed that the carbs would not require syncing.

As for performance, it really hits about 3 - 4k RPM, and throttle response seems a little, eh, touchy in the 40 - 60% throttle range. There is no stumble at all anywhere in the powerband. 70% - WOT is a little disappointing - doesn't seem to be much better than 50% throttle.

Idle is about 1200 RPM, and not perfectly smooth.

The new pipes might breathe just a LITTLE better than stock, but not appreciably so.


So, do you really think that just a good sync might cure my ills?

[KEITH KRAUSE]

The carbs need to be synched to work well and deliver the same mixture and amount of mixture to each cylinder. They may have not been synched in years. The ignition timing needs to be correct too.

[Anonymous]

Ok, so I'm not sure yet, but I think I found the problem with the lean-ness.. The intake O-rings. When removed, they stay flat. That, and bend them 60 degrees and they crack and break. Fortunately, I found new ones at the Suzi dealership in Seattle.

Checked the float levels - all 22mm. I'll leave that as is.

At the recommendation of the dealership, I shimmed the needles up 1/2 mm.

Mainjets are 115 Mikunis - So someone had changed those out, I think. According to my svc manual, the bike used 107.5 mains factory.


I'll get the rack back on tomorrow and see how she runs.

[KEITH KRAUSE]

For a stock motor with your pipe, I would go up 1 full size on the mains. But your 115's are only a 1/2 size larger and may work.
I don't think the needles would need to be raised, only an adjustment of maybe 1 full turn or less at your mixture screws.(I would try 1/2 turn out from where they are now.) My previous post said to leave them alone if they were still capped but if your pipe does flow better than stock then I would richen the screws a little. I would also verify the pilot jet size and make sure they are stock and not actually too small.
The manifold o-rings will flatten out somewhat when torqued down. It's always a good idea to change them but yours sound like they were OK as they sat. To help them last, apply a coat of hi-temp' bearing grease and torque them to 6 ft/lb. A leaking o-ring(s) will case a higher than normal idle once warmed up. A rise of 200 rpm or so is expected, but leaking o-rings can raise the rpm much more.
Is the 22mm float height what the manual calls for?
The ignition timing needs to be checked/adjusted. Too much advance will cause pinging. Good luck and let us know how it goes.