Need advice from the Guru's. My set up is 06 Silverdo, with Cobra Speedster Slashdowns, Barons BAK, Needle on the 4th groove, 170 main, stock pilot, PMS about 2 turns out, Barond Ported manifold. I posted a couple of months back that I was getting pinging on highway roll ons. To be more specific, I am in top gear at 70 -75 mph and go from 1/4 throttle to perhaps half or a little more and the bike accelerates nicely but I hear a high pitched sound that I believe is pinging or slight detonation. Sure does not sound like my old RoadRunner 383 Magnum when it got bad gas, but I believe pinging. At the time of my last post I had not put the manifold on yet, so had hoped that the slightly richer mix would make a difference. Well I did the WOT test Saturday and while she runs really strong and I did not hear any pinging, until I did a turn around and began running into about a 15- 20 mph head wind. Then when I rolled on the pinging began. Good news is that since I changed the manifold there is no gas smell when I park it in the garage.
For those with some miles on your scooters, I have a little over 30,000 the rubber inside the stock manifold was badly cracked for the first 1/2 to 3/4 inch from the flange in. It looked burned. There were no cracks through, but there were pieces that had come out and no doubt had been sucked into the engine. I know we need a flexible manifold for expansion, but this is not a durable solution for long term. I replaced the plugs at the same time, had hoped to put in Iridiums, but could not find any anywhere. I am auto parts challenged here I just got blank stares when I asked for Iridium plugs and even had the part numbers for the NGK or the Autolite...so plain 4164's went in. Plugs front and rear looked excellent, light deposits on the strap, cone and electrode, with a little black around the interior of the threads.
All that said to ask how to I address pinging. I am trying a tank of middle grade gas just to see if the pinging goes away. If it does why is the next question. Why does my scoot now need higher octane fuel? I am mechanically inclined just do not know what to adjust to resolve the issue. Got to imagine that I am lean on the main or needle, but not sure from how the plugs look.
Thanks for the help.

Gas very's soooo much from pump to pump, it's almost impossible to measure. If you want to check the fuel before you buy, get a clear mason jar, pump about 1/3 full into the jar, put the lid on and swirl it like a tornado, look for water droplets in the gas, they will look like little bubbles on the bottom of the vortex.

I'm presuming that you always get your gas from the same place? What is the Ethanol %? That's probably more important than the octane.

If you don't want to do the mason jar at the pump, get a 1 gallon can and pump it into the can, take it home and try it at home. If there is no water, use it, if there is, try another gas station or use a "Fuel additive" to DRY the fuel.

Did you get your jetting hardware from a kit..?? I have the same setup as you but i have the kit's pilot jet in and i am told its all made to work together.Your main jet could even be too small at 170..i would go up to a 175 and try it..i have a 180 in mine,and the same exhaust as you do..just an idea..

If memory serves me right, you posted your dyno and AFR chart a number of months back, and if correct, your AFR was close to 14 across the board? Fine and dandy for a cruise ratio, but not for WOT, wot would be better between 12.5 to 12.8, to help keeping heads cool and to help alleviate detonation as well. Also, to achieve max Tq, requires a ration of 13.5. I found this article to be extremely useful to determining my set-up, Though with the 42hsr, tuning each ckt can be done independently of each other, and also a few more options in tuning compared to stock carb. To me, tuning the stock carb was more of a balancing act between the 3 ckts when I compare it to the 42

http://www.daytona-sensors.com/tech_tuning.html

don't mind that the article is geared for HD, but the air/fuel applies to any engine. I just did a 200 mile ride Sat. mostly 50 to 65mph (90%?) 50mpg. even though my WOT afr is approx 12.3, cruise throttle position is far away from 3/4 throttle where I'm at 12.3afr.

Thanks guys, left out that I have the Dyna 3000 set at 34a too.

My jet kit is the Baron's kit with the Barons needle and Mikuni jets. I have run the 170 main here in Florida for 3 years with mid to low 40's gas mileage, plugs read good, and the pinging started quite a while ago, and was only noticeable when I was bucking a head wind. Now it happens nearly every time I roll on from highway speeds of around 70 mph. I have tried gas from several sources, including most locally available major brands and find little or no difference in the behavior. The gas contians up to 10% ethanol.
Erbman, sorry I think you have me confused with some one else, but I am looking for a good dyno to tune my scoot. I will review what you have provided and see if I can make some changes that improve the pinging.
Honeslty concerned that somehow the carbon has built up and is causing an increase in compression!! Don't know how the bike has been set up on the ragged edge of lean for at least the last 3 1/2 years and 26,000 miles.
I guess if the mid grade addresses the issue I know it is detonation. If not I will have to get someone else to ride it and tell me what I am hearing.
By the way the ported manifold really seems to let her breathe as it was really easy to get it up to an indicated 110 and still pulling hard. She pulls strong through the gears, runs strong, just makes a pinging sound in a roll on. Love this scooter and just want her to run her best.
Thanks

Wasn't sure, well, a roll-on from 70, you certainly are getting on the main jet ckt and diminishing off the pilot and needle, probably will need to have a larger main, 1 or 2 sizes up. when doing the roll-on from 70mph are you in 5th or 4th gear?

I hear it in 4th or in 5th, but it is much worse in 5th as the engine struggles to overcome the ratio. I might try putting the 172.5 in and see what happens. I do not want to get too rich as that invites problems I do not want to have.

Bob , while you're in there fiddling with the carb , find an auto parts store that has a competent employee , and order yourself some Iridiums for the old girl. I got mine and a buddy got his from O'riley's. I think you need DPR7EIX-9 for yours. Cleared up my bud's R* from pinging. BB

+-1 on what BB said. If you want to order your own BikeBandit has them. Auto-zone should be able to get them also. I have them in mine and did a 1,448 mile trip last week and they seemed to do better at higher temps.

Hey Bob, where did your jetting end up and what about the ping?