backfire screen


22 replies to this topic
  • sausage boy

Posted December 01, 2008 - 08:14 PM

#1

thinking of removing the backfire screen from my airfilter cage to allow my bike to breathe better, i have a twin air filter not stock, whats the risk of it setting on fire? or is it time to shoot the lock off and buy the twin air power flow kit?

  • aussieklx

Posted December 01, 2008 - 09:38 PM

#2

been covered before but the general opinion seems to be removing the screen will make SFA diff to your bike performance, the chance of the bike burning the ground far outweighs the performance (if any) gain. Twin air is a good filter and works well, bikes breathing should not be an issue, have you removed the airbox lid and hacked the sides out fo the box?

  • sausage boy

Posted December 02, 2008 - 05:28 AM

#3

been covered before but the general opinion seems to be removing the screen will make SFA diff to your bike performance, the chance of the bike burning the ground far outweighs the performance (if any) gain. Twin air is a good filter and works well, bikes breathing should not be an issue, have you removed the airbox lid and hacked the sides out fo the box?


yes mate i have, the problem i have with the bike breathing is that i live in Aspen 8000 ft (2800m) so its already (just like) me struggling for air, now winter is here i have put an Ad boivin explorer snowbike kit on it. the temp is down to -0c so i have to lean the mixture right off, so to offset the amount i have to lean it off i have bought an FMF powerbomb header then i was thinking of removing the bickfire screen. i'm down to a 158 main jet and the next size down is a 155 i was hoping not to go too lean. a friend of mine who is a bike machanic told me it will breathe better if i buy the twin air power flow, but it's expencive for what looks like a stock cage with the screen cut out?

  • bfogelma

Posted December 02, 2008 - 05:52 AM

#4

your not paying for the cage, your paying for the fireproof dual layer foam. but ya, it is kinda expensive.

  • ckroto

Posted December 02, 2008 - 06:31 AM

#5

I have not used a backfire screen on any on my bikes. Never burned one to the ground yet. Removed from my 07 for almost 2 years now.That being said, its probably more of a mental performance gain than anything else. Its not a lie if you believe it.:bonk:

  • KJ790

Posted December 02, 2008 - 06:37 AM

#6

Removing the screen will not make one bit of difference in the way the bike runs. The screen simple does not restrict the flow. The only advantage to removing it (and I have removed it from all of my bikes for 9 years) is that is makes it easier to put the cage in the filter. I just buy two stroke cages since they are the same as the four stroke one without the screen.

  • grayracer513

Posted December 02, 2008 - 09:09 AM

#7

As KJ says, the screen is not significantly restrictive. While it is obvious that it offers resistance to air flow in an absolute sense, it is less restrictive than the air filter itself is, and is therefore not the bottleneck in the intake tract.

  • WR_Dave

Posted December 02, 2008 - 10:46 AM

#8

yes mate i have, the problem i have with the bike breathing is that i live in Aspen 8000 ft (2800m) so its already (just like) me struggling for air, now winter is here i have put an Ad boivin explorer snowbike kit on it. the temp is down to -0c so i have to lean the mixture right off, so to offset the amount i have to lean it off i have bought an FMF powerbomb header then i was thinking of removing the bickfire screen. i'm down to a 158 main jet and the next size down is a 155 i was hoping not to go too lean. a friend of mine who is a bike machanic told me it will breathe better if i buy the twin air power flow, but it's expencive for what looks like a stock cage with the screen cut out?

If it's getting colder and your adding more load to the engine via the snow travel additions I don't think you would want to be leaning the bike out at all. I would go quite a bit richer in the jetting IMHO. The backfire screen is only for the psycological benefit. WR Dave

  • grayracer513

Posted December 02, 2008 - 11:13 AM

#9

If it's getting colder and your adding more load to the engine via the snow travel additions I don't think you would want to be leaning the bike out at all. I would go quite a bit richer in the jetting IMHO. The backfire screen is only for the psycological benefit. WR Dave

You are correct. Colder temperatures require richer jetting, not leaner.

  • Charles De Mar

Posted December 02, 2008 - 12:44 PM

#10

Unless you don't want to ride very long:excuseme:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • aussieklx

Posted December 02, 2008 - 12:52 PM

#11

yes correct dave cold air = more denser air = more mass of air = need more fuel but he says he is riding at high alltitude so we can expect a reduction in air density also. I would put money on that, in this case, the alltitude is going to have more effect on air density than the air temperature.

  • flyer05

Posted December 02, 2008 - 01:03 PM

#12

1 degree warmer than standard is the same as 120 feet in altitude increase. 1 degree colder is 120 lower in altitude. You can calculate from there and see what altitude you are at. Good luck

edited temp in Celcius.

  • grayracer513

Posted December 02, 2008 - 02:05 PM

#13

yes correct dave cold air = more denser air = more mass of air = need more fuel but he says he is riding at high alltitude so we can expect a reduction in air density also. I would put money on that, in this case, the alltitude is going to have more effect on air density than the air temperature.

Since we have that he has been in Aspen for some time already, and the condition he is complaining of has arrived with the whether, altitude has nothing to do with the equation. It's a simple temp adjustment. Additionally, as temperatures dip below 40 (5C), it becomes much harder to cold start the bikes, as getting the fuel to vaporize to a viable extent when the internal metal parts are that cold is a major challenge. Extra priming is usually required.

  • sausage boy

Posted December 02, 2008 - 06:50 PM

#14

If it's getting colder and your adding more load to the engine via the snow travel additions I don't think you would want to be leaning the bike out at all. I would go quite a bit richer in the jetting IMHO. The backfire screen is only for the psycological benefit. WR Dave


its showing really rich on the plug, (infact its now black) the snow bike kit dose add more load so the rich jetting is making it bog down on full throttle. also i understand the theory of jetting but its dosn't seem to be working that way. the jetting for the summer was JD jet kit 160 main 40 leak, 45 pilot, 68 starter, red needle #4, the bike ran great, the plug was only slightly sooty, its definatly running rich, maybe its time to check the shims.

  • WR_Dave

Posted December 02, 2008 - 08:09 PM

#15

Not to argue cause I regularly ride in the 4500-8000 range myself, I am running 165 main, 42 pilot stock leak, YZ needle on the 3d clip down. Thanks Grayracer, by the way, as I assumed his jetting was OK in the summer months and didn't change by more than 15 feet higher due to snow loads ( I live in Canada and have heard of snow ) Last year while winter riding my filter got fairly plugged due to snow getting in the airbox. I am wondering if you are running rich due to the track kit throwing more snow up into the airbox area. I'm not trying to be a smart a$$, just throwing some thoughts out there. Try a hotter plug and maybe check that the engine isn't runing too cold in the snowy conditions. Try and get hold of Frostbite on what he does for the cold weather. His thread last winter was a classic. WR Dave

  • aussieklx

Posted December 02, 2008 - 09:08 PM

#16

cool didn;t realise it was running good in summer

  • sausage boy

Posted December 03, 2008 - 05:28 AM

#17

Not to argue cause I regularly ride in the 4500-8000 range myself, I am running 165 main, 42 pilot stock leak, YZ needle on the 3d clip down. Thanks Grayracer, by the way, as I assumed his jetting was OK in the summer months and didn't change by more than 15 feet higher due to snow loads ( I live in Canada and have heard of snow ) Last year while winter riding my filter got fairly plugged due to snow getting in the airbox. I am wondering if you are running rich due to the track kit throwing more snow up into the airbox area. I'm not trying to be a smart a$$, just throwing some thoughts out there. Try a hotter plug and maybe check that the engine isn't runing too cold in the snowy conditions. Try and get hold of Frostbite on what he does for the cold weather. His thread last winter was a classic. WR Dave


when it started bogging and coughing the airfilter was the first thing i checked, it was very cold -8c and snowing hard the last time i rode it, i was thinking maybe it could have been ice forming in the carb? the bike started fine, idle was fine it was when i was riding full throttle, i will try a hotter plug and check the jetting again. :bonk:

  • Charles De Mar

Posted December 03, 2008 - 07:51 AM

#18

I hate to sound like a broken record, but get that JD needle out and put a YZ needle in it. I think you will have a better result. do it for piece of mind you can always return that yzneedle if it doesn't ease the pain.:bonk: look at the yz450 manual to figure out what you need. you can search my threads to read about my dealings with the jd kit and the needles. YZneedle4me should be my screen name now.:bonk:

  • aussieklx

Posted December 03, 2008 - 02:37 PM

#19

anyone know whats the part number and neddle name for a YZ neddle to suit an 05 wr450f?

  • Charles De Mar

Posted December 03, 2008 - 06:20 PM

#20

anyone know whats the part number and neddle name for a YZ neddle to suit an 05 wr450f?


look at an 05 yz450 parts diagram.




 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.