Real World Tune

[Deejay]

For the last few months, my Evo has had a "clacking" sound when running at 3/4 to WOThrottle. Thoughts of predetonation, possible collapsed lifter, bent rod, etc. always flooded through my head. For the Colorado Doofapalooza, I bought a case of Amsoil octane booster and added half a bottle per tank. It helped but never totally got rid of the "clack" especially when first starting the bike in the morning. Well, riding home yesterday in 90 degree heat, the "clack" was getting worse and the gas tank was nearing empty. I filled up with super (92 octane) and was out of octane booster, so of course it got even worse. I decided enough was enough. I pulled off the 43 timing cover to find that the two screws that hold the timing plate were loose which caused it to be way too far advanced. I retarded the timing until I could blip the throttle and not hear the "clack". I then retarded it about 4 degrees more and tightened the screws and put back the 43 cover. I went for a 30 minute ride pulling hills at 3/4 and WOT (still 90 F). No more "clack". I continued to advance the timing a degree at a time until a faint "clack" returned. Backed the timing off a single degree and tightened both screws down. After another 1/2 hour ride and all types of terrain, I no longer had the "clack". I did have a small mid rpm flat spot when accelerating, so I changed the ignition curve from curve 4 to curve 3. 1/2 hour ride and flat spot is now gone, but the slight "clack" returned. Retarded the timing one more degree and tightened both timing plate screws down tight. Put my 43 cover back on and another 1/2 hour ride..... No flat spot and no "clack"

Took the timing cover off and with a blade, I marked across the timing plate and timing housing for future reference should those screws ever loosen up again. Great throttle response, no flat spot, no "clack", and best of all NO MORE OCTANE BOOSTER!!! I love my old Evo....

Moral: Sometimes that "sound" is not normal. Don't mask it. Do something about it.

[dynageno]

Great job Deejay, you figured out the problem and fixed it! The best part is that you didn't need help from the Garage. Think I'll close up shop and go for a ride. Them old bikes just keep going and going.................