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In general is there a loss in power using a spark arrestor equipped silencer versus a non spark arrestor silencer?

If so, how much of a loss in power?

Yes.... I would say maybe 10% fully verified seat of the pants dyno.

Kill? I vote no.
Change? Yes.

I agree with Mojo. Change it a tad. The ~loss is negligible. My FMF Q really quieted it down - which I don't mind.

Mojo is probably right. I run without the Spark arrestor when I go to the dunes. I have to run one fatter on my jet and the thing just feels like it rips everywhere a little harder. For off road which I ride 99% of the time I am arrested and it still has plenty of power but if I run the same jetting as I would with the SA it is blubbery.

Maybe Roosty will chime in, I'm sure he has dyno'd this stuff.

In general is there a loss in power using a spark arrestor equipped silencer versus a non spark arrestor silencer?

i dont think its much difference, i do think it runs crisper/cleaner without it, but i dont think theres much power difference

No
Air filter screens don't either.
Anyone that claims you'll "lose like 2 HP" with them is an idiot

Man for shits and giggles I rode my newly built sand bike without spark arrester and then hopped onto the daily grinder with a spark arrestor. Both have pretty fresh vertex's, the daily grinder is fresher pretty much same everything, both on stock pipes. I swear without the spark arrestor feels faster, seems to pull longer, runs super crisp. I'm going back to my first statement. I'll say 10% or about 2hp.

Rhino89523 wrote:Man for shits and giggles I rode my newly built sand bike without spark arrester and then hopped onto the daily grinder with a spark arrestor. Both have pretty fresh vertex's, the daily grinder is fresher pretty much same everything, both on stock pipes. I swear without the spark arrestor feels faster, seems to pull longer, runs super crisp. I'm going back to my first statement. I'll say 10% or about 2hp.

1. That's 2 different bikes. Useless comparison.
2. By change, I mean move. It may run out better without, but it will pull better down low with it.

MojoScojo wrote:...but it will pull better down low with it.

I did notice that.

Thx.

I have the turbine spark arrestor and thought it would semi choke the motor.

It was actually same motor in 2 different bikes, only difference was the SA. Then similar motors, same heads, pipes, reeds, ignitions and carbs in two different bikes....both ways it felt better without the SA, probably in my head.

assume it was the same sprocket ratio?

Yeah rode bike in AZ, came home and washed it. Rode it up and down the street. Pulled the motor to put it back in the very pretty 1990 it came from, I always felt a little guilty for pulling it out of there. Put it into the 1990 with no SA and took it for the same rip. Man this thing feels faster. Put the 1992 motor I have into my daily grinder. Top end on this motor is fresh so is the other, vertex piston, stock reeds, R head, stock pipe, stock PJ same jetting, everything the same as the other motor, similar hours, same gearing, same close ratio trans, only difference between two motors is nothing, only difference between two bikes is one is all deserted out, other is bone stock cream puff to be purely a duner. Rode both bikes back to back and the non SA seems faster, seems to pull longer, neither bike on the street I can just pin or I'm looping it so torque felt the same. I don't know maybe its all in my head but I prefer the non SA given the choice.

Get Roosty on here to tell me I'm nuts and it's all in my head....you guys are probably right. I know seat of the pants dyno's are BS. Both are running FMF silencers, one Non SA other is a turbine core or whatever they call it, not the Q.

Rhino89523 wrote:Yeah rode bike in AZ, came home and washed it. Rode it up and down the street. Pulled the motor to put it back in the very pretty 1990 it came from, I always felt a little guilty for pulling it out of there. Put it into the 1990 with no SA and took it for the same rip. Man this thing feels faster. Put the 1992 motor I have into my daily grinder. Top end on this motor is fresh so is the other, vertex piston, stock reeds, R head, stock pipe, stock PJ same jetting, everything the same as the other motor, similar hours, same gearing, same close ratio trans, only difference between two motors is nothing, only difference between two bikes is one is all deserted out, other is bone stock cream puff to be purely a duner. Rode both bikes back to back and the non SA seems faster, seems to pull longer, neither bike on the street I can just pin or I'm looping it so torque felt the same. I don't know maybe its all in my head but I prefer the non SA given the choice.

Get Roosty on here to tell me I'm nuts and it's all in my head....you guys are probably right. I know seat of the pants dyno's are BS. Both are running FMF silencers, one Non SA other is a turbine core or whatever they call it, not the Q.

You're willing to do that, but not pull the SA off of one and put it on the other?

I'm not saying you're nuts. I agree.

Again, I don't doubt that no SA = more run out and top end pull. But kill it? No. Hell, length of the silencer makes almost as big a difference, SA or not.

As for preferences, it depends on what you're going to do with it. No?

Duning or SM or flat tracking etc.: No SA.

Rock crawling, singletracking: SA.

Motocrossing... well that depends on the rider and the track. If you ride it like you oughta, a gear high, you want the SA or at least a longer silencer.
Remember the stock silencer that came on these things?!?!

Doppler wrote:No
Air filter screens don't either.
Anyone that claims you'll "lose like 2 HP" with them is an idiot

what do you mean by air filter screens not making a difference my af wouldnt run worth a shit with the screen in

I was changing motors anyway. I ran it after I washed it just because thats what I always do. I ran it after I switched motors to make sure it ran. I ran it after putting motor in other bike to make sure that ran as well. I don't really care the bikes have too much power for me either way, just seemed to have a little more without the SA. It was not at all a scientific test, it was just a guy putting a really pretty motor back into the really pretty bike where it belongs and noticing....man this thing hauls ass.

didnt rss396 dyno his liger with and without a spark arrestor, i think the diffrence was 2hp and thats 600cc+ at 7000rpm+

i like the cleaner running at low throttle without the SA

This is a funny discussion, if you have to ask then you probably need one any way. next time you go for a ride on a fire road or what ever, try it with and without and decide for your self.