Cobra Exhaust Proper Jetting

[Semi239]

I have a new to me Vmax1200 with the 4-4 Cobra Exhaust on it. I know...I know it sucks. I hate how it looks and sounds but it's what I got right now. Planning on a 4-1 full exhaust and an S7 or Muscle kit this winter.

For now, I have an idle problem. It backfires and lean pops on the rear two cylinder at idle and decel. Runs strong over 4000rpm. I pulled the carbs expecting to see ethanol gumming everything up. But that's not the case. The carbs are pretty clean in there.

I found the stock pilot and main jets 37.5 and 152.5. Should I up the pilot jet? Or change any other setting to help the idle/decel pop?

 

[sdt354_8Qi]

Sounds like the piolet jets are restricted and the cause of your idle and off idle issue. For Cobras I'd go 150 main, Mikuni's. Sync and float level are important. A shotgun might ave you a tear down, if crud isn't too hard.

 

[Semi239]

Thanks for the comment, after multiple tear-downs and an ultrasonic bath it ended up being one of the air circuits. The pilots were good but the air circuit was clogged up.

The little "sneeze" was corrected by switching from Cobras to the Supertrapp exhaust. Runs like a beast now!

 

[Fire-medic]

There are many who think the Cobras are 'bad to the bone' visually, and perhaps you can sell 'em on social media to one of those owners.

 

[Semi239]

Actually, I got lucky on Facebook. I was bitching about how I hated them on a post and somebody chimed in and said I'll trade ya! Well, I'll take that deal every day of the week! He got the Cobras and I got the Supertrapps. He has two sets of Cobras, and he's working on modifying them to perform better. An exercise in futility I believe.