How much to shorten RM silencer?

[nzfred]

I have an '02 RM 125 and I want to shorten the silencer. However I dont know how much to take off, if anyone knows how much to shorten the silencer for optimum performance I would be very greatfull.
If I do complete this mod will I have to richen the jetting? At the moment it is stock.

Thanks -NZFRED

 

[EricGorr]

Modifying a silencer for length on late model dirt bikes can cause more restriction if its not done correctly. I suggest you buy a Pro Circuit silencer and some spare packing kits. Repacking a silencer often (every 5 races and practises) will make your bike less finicky on jetting.

 

[MikeT]

Originally posted by nzfred
How much to shorten RM silencer?

None. You won't gain any noticable HP, but will gain some unwanted attention. I'd leave it alone.

 

[NO HAND]

Originally posted by EricGorr
Modifying a silencer for length on late model dirt bikes can cause more restriction if its not done correctly.

Eric, by correctly do you mean the right amount to remove and also the way the inner tube is cut to fit the end cap? What is your opinion on the CR shorter silencer?

 

[HLT]

When I've shortened silencers, I've always used the length of a high quailty aftermarket silencer as a starting point. Eric is right though. You have to take your time and do it correctly. It can be a good mod on RMs. As for jetting, you won't know until you try it. In my experience, it leaned the mixture out a bit. Do it right and you should feel a little more oomph out of corners.

 

[motometal]

loud bikes are a real bummer. This is how we lose riding areas. it isn't worth any minimal power increase you may see. If you want more power, get a 250!

 

[MikeT]

Originally posted by motometal
loud bikes are a real bummer. This is how we lose riding areas. it isn't worth any minimal power increase you may see. If you want more power, get a 250!

You can say that again. :silly:

 

[nzfred]

Thanks for the replies guys.
The whole point of shortening my silencer is so I can get a bit more power out of corners, as for buying an aftermarket product, I am on a tight budget at the moment so I cant afford. I have been advised to cut anything from 30mm-50mm of my silencer so I will start at 50mm and work my way back.
Noise is not an issue, in New Zealand we dont have such obsesive "greenies" and my bike is used at motocross facilities only.
Motometal- I could get a 250, but there goes the light, flickable triats of my current bike :-(

Thanks alot - NZFRED

 

[marcusgunby]

Measure a aftermarket silencer and then cut yours the same length.

 

[David Trustrum]

Noise is not an issue, in New Zealand we dont have such obsesive "greenies"

Where have you been dude? How many road race tracks have been threatened with closure, or closed, & dirt riding areas have been closed off mainly from complaints from the public primarily for noise?

State your location & I will list them for you.

If you listen to The Rock, you will know the damage one person complaining can do here.

 

[MX-727]

advised to cut anything from 30mm-50mm of my silencer so I will start at 50mm and work my way back

That won't work. Suggest you start at 30mm and work your way back. ;)

 

[nzfred]

Dave - im not saying our tree huggers arent bad, but they dont make traps, set wires in trails etc, (a.ka American tree huggers) all my local tracks I race at are based in the country so the noise isnt an issue. Just so u can get to know me a bit better I live in Palmerston North, and race at Taikorea and Gold Coast.


KX 727- good one