XR50R Exhaust

I'm sure there have been plenty of thread on this, BUT...

My 7 year old son is saving his pennies for an exhaust. He really wants an FMF, but it will be quite a while before he can save up that much money (~$180). Also, we wanna keep it kinda quiet. Don't wanna piss off the neighbors to bad.

Is there another exhaust out there that is just as good for the less money?

Any FMF owners out there not happy with it?

Is there another exhaust out there that is just as good for the less money?

just as good? i think everything is pretty much better than FMF when it comes to a 50 pipe, they arent known for there 50 pipes and i think everyone pretty much sais stay away from them

I know he mainly wants the sound right? FMF is prob. the worst exhaust performance wise but price wise you cant beat it. I just gave my fmf to my nephew b.c. i got a two brothes and the fmf is on his stock 50 and its still kinda quiet but a little deeper than the stocker. He should like it. :D

At rockymountainmc.com they sell it for $125.

I would just modify they stock one real nicely like this.


Just take the S/A out and leave the baffle in and you'll get a little performance increase and alot better sound (still quiet) and paint it with some 1200' exhaust paint.

Yeah, he mainly wants the sound and name. I'm sure he'd like a little performance too. Anybody run a big gun? They have a quite version for about the same price. Just wondering about performance and sound on it. Thanks.

how come pipes for these bike dont have an expation chamber like big motocross do?

just wondering!

how come pipes for these bike dont have an expation chamber like big motocross do?

just wondering!

Two Smokes have expansion chambers.

The expansion chamber is designed to control the exhaust gas pulses so that they help in scavenging the exhaust out of the cylinder after combustion and then keeping the incoming fuel/air charge in the cylinder as the piston closes the exhaust port. That's why they have such fat bodies.

The first part of the body diverges (gets bigger) - helps pull the gasses out of the cylinder. Then they converge (taper) so they reflect the exhaust pulse in time with the incoming charge (in they jug) stuffing the cylinder with fuel/air.

This is why you hear people talk about the bike coming "on the pipe" (getting in the power band) - the pipes are tuned for specific rpm ranges. Power valves also help control this pulsing, hence widening the power band. In general, the longer expansion chambers are low end/torque pipes, while shorter are more rev oriented.

Four strokes, on the other hand, have valves that shut off the cylinder during the upstroke in prep for combustion. The pipes do make a difference on the way the system works, though - once again, (in general) a longer header pipe will make more torque/low end while shorter is more top end.

No matter if it's two or four stroke, the pipe is tuned to control the pulses of the exhaust as it flows out of the engine.

thanks alot, i just wondered y on big motocross bikes ive seen they have an expansion pipe at the front of the engine!


not all motocross bikes do, look at a crf450 or 250, they are 4 stroke race bikes, although i did see a knock off with an expansion chamber and it was 4 stroke and looked like a toy from a happy meal

On a stock bore or even a 72 kit the modded stock pipe is the best.Otherwise check out Thunder Alley.They are one of THE BEST performing pipes.Also they are fairly cheap.

the expansion chamber you see is on a two-stroke....

just keep the stock exhaust

if you want a little more performance and a lot better sound just take the end cap and spark arrester out of the stock pipe. it sounds pretty good, its alot louder though. thats what i did to mine and i ike the way it sounds, its got a more deep sound like a big bike.

if u have a stock engine i heard that u will loose power by taking the end cap out because u need the back pressure

i dont care what you think five0, i like the way it sounds and you do lose a little torque but not alot. i think it goes faster w/o the end cap

I have a 2 bro's pipe I'll hook ya up with for $165.00 shipped (lower 48 states). Its in perfect condition, no dents or anything, just needs a bath,lol.



removing the endacp isnt going to change shit tho. its all in your head if you really think its that much faster :D

removing the endacp isnt going to change shit tho. its all in your head if you really think its that much faster :D

remember, its all about how fast you SOUND! :D

I love TT :D A very generous person donated their old (used twice) FMF they didn't like, and made one VERY VERY happy 7 year old :D He loves it, I don't think it made any perfomance gains on the stock bike, but will probably help a little with the UNI filter we'll get someday. Sounds good though, not too loud, but with the FMF sound he was wanting (and stickers) :D

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