Post deleted by Steve_Claus

Thanks guys!

I had a 'challenging' day at work today. I came home, logged onto TT, read this forum thread and have been laughing my ass off ever since.

Not to be an instigator, but...

Quite frankly, me thinks some of you have too much time on yer hands. I could see worrying about the effects of that silly little screen if you were Pastrano or McGrath. But, come on...


Well Let that be a lesson to Ya

This is a toughie, kinda like choice of oil.

On the one hand a lot of folks have used no screen in these bikes since they first came out i.e. YZErnie. On the other hand, I have personally seen a Yamaha street bike burn to the ground and almost burn down a garage in the process from a backfire catching the air filter on fire. I know it's not directly apples-to-apples but, not pun intended, it burnt a lasting impression in my puny mind.


I'm not sure what to think about this.

In regards to the "Swirl" effect, many of the new high performance Big Air Kits for Cruisers have a mechanism in them to "CREATE" a swirl effect because it flows in MORE air.

Now that said it might not apply to the 426.

I do know that I have seen a few 426's backfire and blow the carb away from the boot.

I'm not sure taking my screen off would give me a difference that I could notice.

I will see Brian Kenny soon and ask him what he thinks/uses.


Us guys from New Jersey know EVERYTHING that is worth knowing. Any of you Cali wiseguys give us a problem we send over Tony Soprano. I used to build race engines but most of them blew up. Bye for now, liquor store closes in 10 minutes. :)

Ego- You crack me up, man! That was pretty funny! :) I can just imagine the look on my wife's face if I did that! Actually, the look on my face would be funnier after she slapped the crap out of me.

Rat-Good luck making the main in MI. What number are you so I can watch for ya?

Looking forward to hearing what BK has to say about this screen biz. Please let us know.

I got to put in my $.02.

Take the screen out and it back fires and catches on fire, two senarios.

1 bike didn't die flame is snuffed from the pull of the air going into the carb. (Seen this many times on cars and snowmobiles)

2 Bike died flame is snuffed by kicking the bike over, your 12.5 to 1 piston sucks the flame out ounce more. (also seen this on cars and snowmobiles)

Turn the starter or pull the rope and the flame is sucked out. I have done this and seen others do this. I'm not saying it is 100 percent fool proof but odds are it'll work. And the reason the air filters were off was for repair work on carbration.

The air flow is better is there is less turbulance. Why else would you want more air flow? More air means there is less restriction and the air flows smoother. Ask a guy that races drag cars. When you have a v-8 pulling 8000 rpm you definitly don't want restriction. I think this would aply to a single cylinder bike.

Maybe I'm talking out me arse. Cris

THUMPIN' ROCK HUCKER If the thumper pulls in a little piece of foam it won't hurt anything. Can't bend a valve the valves are closed when the piston is up, it would have to be something bigger and harder. Like a choke butterfly.

If you suck a huge chunk of air filter maybe. But why are you running a worn out and crusty filter for in the first place?

And if a rod would bend that easy we wouldn't own these bikes would we? I am not sure if you realize that only the screen part is cut not the whole support structure.

Not trying to be an ass but I don't think it would cause damage and no I haven't cut my screens, but I just may to see if it makes a difference. I guess the saying "each to their own" would apply here. And yes throwing a rod would such.

Everyone should take what they want from all of these coments and decide on their own what to do. I'll listen to any advice, doesn't mean I'll follow it.

Keep kicken rocks TRH. Cris

When I got my first YZF in 98 I wondered about the flow of the stock air filter versus a Twin Air, and whether or not the cage and the screen presented a flow restriction or caused any problems. About 15 hours of flowbench time later I found the following:

- The stock air filter flows within 1 cfm of the TwinAir on my flowbench but doesn't seem to be as rugged so the TwinAir IS a worthwhile investment from a durability standpoint.

- The screen presents no measurable flow restriction.

- Measured flow through complete airbox path (carb (WOT) with the complete airbox assembly in place) flows the same whether the cage is removed or not.

- The complete airbox and filter path only represents about a -2% flow restriction versus an open carb. It's a VERY good airbox.

People who are removing the screen in an effort to increase power are fooling themselves, but like my mentor always told me "never let the facts stand in the way of a good half-assed theory" :)

Rich Rohrich

Applied Fluid Dynamics

[ April 08, 2002: Message edited by: Rich Rohrich ]

Hey Chris!!

Maybe you should tell them the real reason your air filter will never catch fire?! I think it has more to do with the fact that your filter is usually full of muddy creek water. Screen or no screen, I think your pretty safe from a fire. I'm leaving the screen in my 450.


Hate to bring this one up again but .........RAT>>>>>>>

check this out from the CRF side>>>>moto614

ThumperTalk Member

Member # 3352

posted April 25, 2002 11:48 AM


all you CRF owners see your dealer about the potential FIRE HAZARD,it appears honda didn't believe the air filter could ignite when the bike backfires and is now retro-fitting all crf450s with a backfire screen kit. you all should be recieving a letter shortly.

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