Topic: Detonation prevention questions -retard timing or higher grade fuel?

[hapsh]

I checked my plugs on my 550 after a 60 mile ride at 75-80 mph and found that the color is just where I think it should be, right at #14 on this chart http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html .   However even though I did not notice any pinging I found a small aluminum ball on two of the plugs near the center insulator.  I have read that that is common on motors that are jetted very close to max power, they will sometimes show subtle signs of detonation.  The bike runs great however, I don't hear any pinging at all (I don't know if I could hear it at 80 mph anyway).  But, should I be concerned?  The timing is spot on for static and advanced.  I am currently running 87 octane which was said to be OK for these bikes in the FAQ.  My question is; should I slightly retard timing so that it is not quite at the full advance marks to be on the safe side?  Or should I pony up for midgrade?  I am shooting for max fuel economy over performance on this bike so I have already been thinking of retarding the timing anyway.

[KeithB]

Try running higher octane fuel for a while.

[dusterdude]

you can try that,but you may be a tad lean too.

[Bob Wessner]

Is it a stock motor and set-up?

[hapsh]

I am very happy with its performance and it is quite a way off from being lean enough to be the cause of detonation.  I will try retarding the timing a few degrees and also try higher octane gas.  I have DE7 plugs in it now for the cold months, but will be putting back the DE8's in May.  The motor has 4-1 exhaust and Uni pods.  However I worked quite a bit to get the jetting adjusted to compensate for these changes. I've done plug chops and adjusted jetting until it ran its best.

[johnny_from_bel]

plugs nr 2 and 3 ?

[hapsh]

plugs nr 2 and 3 ?

[merc2dogs]

 Believe he's asking if they were plugs no 2 & 3 that you found the aluminum balls on. The outer cylenders run cooler than the inner two.

Ken.

[johnny_from_bel]

 Believe he's asking if they were plugs no 2 & 3 that you found the aluminum balls on. The outer cylenders run cooler than the inner two.

Ken.

Correct ! Did you find the aluminium balls on plus nr 2&3

[hapsh]

No, they were on plugs 1 and 4.  I checked timing again to see if 1-4 are slightly more advanced than 2-3 but it looks right on the mark at full advance.  I also thought about richening the mixture a bit to help keep the bike cooler this summer but my main goal is to maximize fuel economy.  That is why I am thinking of playing with timing retard.  I am going to the junk yard to pick up a used 550 timing advancer to modify today.  I am going to play with the spring tension and the full advance stops so I can keep the timing normal at idle but just a bit retarded at full advance.

[johnny_from_bel]

No, they were on plugs 1 and 4.  I checked timing again to see if 1-4 are slightly more advanced than 2-3 but it looks right on the mark at full advance.  I also thought about richening the mixture a bit to help keep the bike cooler this summer but my main goal is to maximize fuel economy.  That is why I am thinking of playing with timing retard.  I am going to the junk yard to pick up a used 550 timing advancer to modify today.  I am going to play with the spring tension and the full advance stops so I can keep the timing normal at idle but just a bit retarded at full advance.

Its a timing issue.
Running lean does not saves much on fuel. Better to run a bit rich and advance timing.