Backfire issue with Mastiff

[KROGOTH]

HI,
Just insatalled a second DM spiral air intake and the bike runs fine on idel when I start it and runs great when speeding. Only problem is when I decelerate and come to a stop the bike either sputters off or once backfired. What do I need to adjust? I have a big air carb. Never had these issues before. Please help!:bang:

 

[bruce]

need more info, do you have S&S carb. if so may just need to adjust the idle air screw. but there are several things, main jet, inter. jet, all pretty easy to change or adjust. were do you live a lot of members on here, you may live near someone who can show you how. also you can print instruction off the S&S website on how to do these things. also a lot in the (how to) section of this site

 

[Raywood]

Pull the bowl vent as recommended by S&S

 

[KROGOTH]

Hi all..thanks for the reply..The carb is a Big Air CArb PSI..Its should be easy to adjust as per follows.. Just wanted your opinions anyway to see if it is lean or rich.. http://www.psicarbs.com/PSISeries3TuningSheet.pdf

 

[lee]

what do you mean by "sputters off or once backfired"? Can you give some more detail? Just for info, a lot of people haven't got on well with those intakes but have had better luck if they turn them upright

 

[Justintime]

If it is coughing/backfiring through the carb. it is most likely too lean.

 

[woodbutcher]

what's the gas like there in Malta?????????????????? may just be crap gas.

 

[KROGOTH]

Gasoline in Malta is fine..they have to follow the Eu standards so the octane is at least 95. You are also right about the spiral air intakes..Did not have any problems with one ( that is when they ususally complain about). So when I installed the second one the backfire happens after an acceleration happens and when suddenly I come to a stop. It happened twice and it backfired thru the carb/air filter with smoke coming out. So if you say it is too lean, you mean I have too much air and therfore should increase the pilot fuel to aricher setting? Please help and thanks!

 

[2004BC]

Gasoline in Malta is fine..they have to follow the Eu standards so the octane is at least 95. You are also right about the spiral air intakes..Did not have any problems with one ( that is when they ususally complain about). So when I installed the second one the backfire happens after an acceleration happens and when suddenly I come to a stop. It happened twice and it backfired thru the carb/air filter with smoke coming out. So if you say it is too lean, you mean I have too much air and therfore should increase the pilot fuel to aricher setting? Please help and thanks!

Well, usually too lean sputters, pops, or backfires out the carb on heavy acceleration. You're describing deceleration backfiring which, if concentrating on the carb, could be a little rich and loading up. Try turning in your air fuel mixture screw a 1/4 turn at a time and do a hard acceleration and then let off to observe the results. A little trial and error with the mixture screw is the easiest first step to address your symptoms. Also, as a tech tip, if you find that it helps and your happy with the results put a dab of clear silicone caulk on the threads of the air/fuel mixture screw so that it can't move from vibration over time. Good luck!

 

[KROGOTH]

thanks for the reply..so by installing the second air intake it is causing the air to be too rich then? Is that it? I will do as advised, but would like to know
if the second additional air intake is causing the air to bee too rich and at the same time the gas to be lean? Is that possible? Thanks

 

[silver09]

Do simple test first like check your plugs to see if it's rich or lean and did it start having this problem right when you changed filters if so what's different.Don't make it complicated this should be a easy fix and a good learning experience.

 

[KROGOTH]

Yes it started right after I added the second air intake. So what do I look for at the plugs when I take it out?

what is differnt is that when i decelerate after running up hard,
and I bring the bike to a sudden stop it stops or backfires. Before that all was fine. When I am cruising all is fine. So I need to know do I adjust the air to lean or rich or the fuel to lean or rich. The big air carb has these options.

 

[KROGOTH]

ok enriched the adjustment on the carb. Now I get a sharp pop when I am idling. Its like the engine wants to shut down and pop. PLEASE need advise and thanks