Two Stroke Motocross
Two Stroke Motocross Forum => Technical => Topic started by: kent-o-matic on March 02, 2011, 05:56:32 PM
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As the title states I a trying to figure out which silencer is better for MX.
I understand the point for the shorty is arena cross/supercross or tight woods,
because the shorter silencer makes more bottom and mid range power.
But does it actually sacrafice that much top end?
I have seen alot of people still use this silencer for outdoors MX.
Thoughts and comments appreciated.
Thanks,
KP
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I use a shorty in all conditions. I just like how the bike barks off the bottom better with it. It definitely does not pull as long on top though. That is a sacrifice I am willing to make.
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get a quiet one
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I use a muffler(s), with 600mmm of perforated core alone, on my bike.
So I can ride virtually anywhere, and people don't hear me.
I've got probably 8 mufflers hanging up in my workshop, for my bike, and just use the 2 looooong ones I made - one is a big size , fairly thick walled , oval canister, to take the abuse in amongst all our rocks, the other, a small outer dia., thin walled one. Both are as quiet as can be.
The thing is, the bike is a 500, and I don't notice Any power loss at all............ it actually smooths out the bottom end / mid range hit. But when I put on my short PC 11, I don't notice much extra power at all, just a hell of a lot of extra noise, that would bring the local authorities down hard on me, as they do with all the drongos with their Loud 4ts. The first thing the 4t riders seem to do, is throw on the loudest pipe they can find, and then they wonder why the locals bitch to the Police, and they get harassed. The local cops know me and my bike, and I get waved on by them, going into , through, and out the trails, quite often, as they are booking gooses on their loud (inevitably) 4t bikes.
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Personally I would stick to the regular length if the engine is to remain as standard. Just bear in mind that while changing the "feel" of power, any change could actually be reducing maximum power :(
Obviously for a critical racing application this is a concern.
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I just bought my nephew an RM125 and it has a Bill's shorty on it. I can't say if it improved power because I didn't ride it before, but I know it is too loud for my tastes.
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I just recently had to take the shorty silencer off of my cr125, because it was falling apart. I decided to buy a powercore 2 rather than a shorty again because I hate loud bikes, and also because i like to rev my bike, not bog it. I can not wait to hear my bike with the new silencer
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in my experience, a shorter silencer makes for a sharper, narrower power band. I had a standard pipe on my old kx85 (going back a few years) and 3 silencers, all standard, one normal length, one cut 2 inch shorter and one about 3.5 inches shorter, the shorter ones were better on hard pack/ tacky grippy ground, the longest was best in deep sand/ mud, hope this helps
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I just bought my nephew an RM125 and it has a Bill's shorty on it. I can't say if it improved power because I didn't ride it before, but I know it is too loud for my tastes.
In my experience the shorty's are a bit louder. Of course maybe you should check the exhaust packing, as it may be saturated and ready to be replaced.
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In my experience the shorty's are a bit louder. Of course maybe you should check the exhaust packing, as it may be saturated and ready to be replaced.
Once I get the other parts in (wheel bearings, brake pads, etc) I figured I would spend an afternoon and really go over the bike and change the oil, clean/oil the filer, repack the silencer, etc.
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get a quiet one
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I am a big supporter of quiet bikes. It's why I am not changing the stock exhaust on my KDX. As soon as I can afford it I am getting a different silencer for the 125 too to try and quiet it down some.
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TurbineCore II here. Very quiet for one, the power is spread out more evenly. It's got a lot of low end (but I really only use that in the pit's and on trails) and the powerband doesn't have a huge hit, but it lasts a little longer.
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i have always been told that a shorty silencer was more of a 'top end' muffler, letting the motor rev out more, but sacrificing low end torque?
and that a longer muffler tends to have more low end pull, but because of the increased back pressure, they don't rev out as far?
is this incorrect? it sounds like everyone is saying the opposite? i do agree shorty's are a lot louder.
any guru's here that have a definite answer?
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In my experience a shorter silencer definately helps the motor come on the pipe quicker but you sacrifice top end.
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Yes DirtAddict, what you have been told before coming here is all BS.
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One question, do shortys actually give more bottom/mid and reduce top end or do they just allow the bike the rev out quicker making it FEEL like it changes the power? I have always thought it enabled the bike to rev out quicker resulting in the different feeling power curve
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Well I'll tell you this, the RM85 I bought for my daughter came with a FMF SST pipe and Shorty silencer, the ignition was also advanced to the max. The SST is a topend pipe the Shortly is a bottom end silencer, from open to 1/2 throttle the bike had nothing, then it would just scream with power to about 3/4 throttle and had nothing else. The jetting was also very rich, FMF recommends 48 pilot 125 main stock needle at second clip, this thing has 50 p, 128 m. I moved the clip up to the 4th groove, installed a Moose torque spacer between the Vforce 3 and intake tract set the air screw 2 turns out. Now the bike is like a tractor, until half throttle then it friggin rips, up to just about 3/4 throttle and falls flat.
I wish I had the stock silencer or a Powercore to test against the Shorty.
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in my experience, a shorter silencer makes for a sharper, narrower power band. I had a standard pipe on my old kx85 (going back a few years) and 3 silencers, all standard, one normal length, one cut 2 inch shorter and one about 3.5 inches shorter, the shorter ones were better on hard pack/ tacky grippy ground, the longest was best in deep sand/ mud, hope this helps
i wrote this a few days ago, and with standard front pipe a shorter silencer let the engine pick up sooner and go better in the right conditions, if your really serious about racing then its an idea to stock up on a few different lengths, but on my rm250 im not bothering changing lengths because with bigger bikes there is less emphasis on peak power as useable power gives better laps, so i have a full length silencer ont the 250