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Exhaust springs keep braking CR125R 04

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I have this problem with my sons CR the exhaust springs keep braking.

I had these inexpensive ones that kept braking so I went for heavy duty ones but that one is missing now.

The exhaust is new FMF Fatty.

Any idea what what the problem is and what brand of springs to use ?

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I've had an eye on this thread...14 hours and still no replies...seems that I'm not the only one who's baffled by your exhaust quandry...no pun intended...

Until last Memorial Day Weekend, I've never owned a dirt bike that wasn't a 2 stroker, and have never had any problems with the exhaust springs.

My only reasonable suggestion would be to call or email FMF directly and see if they could help resolve your problem.

Wish I could tell you more...

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That's very strange. The only thing I can think of is you're not getting the pipe on cylinder enough so the added distance is putting too much strain on the springs, causing them to break.

In order to get the expansion chamber on fully, you need to take a rubber mallet and tap it on.

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Nothing unusual or rare about it. Not real common, but it does happen, Harmoincs. Two cheap easy ways to fix it. ONe, take some safety wire and run it around the pipe, thru about the middle of the springs. Don't need to reef it down, just snug it up. Or you can take a lg hose clamp and go over the springs and do the same thing. Its the harmonics, the vibration that weakens the spring and causes them to break at the base end of one of the hooks, usually the pipe end of the spring. THe safety wire, hose clamp simply helps cut down on the vibration adn eliminates the problem. An old endurance road racer trick!

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Nothing unusual or rare about it. Not real common, but it does happen, Harmoincs. Two cheap easy ways to fix it. ONe, take some safety wire and run it around the pipe, thru about the middle of the springs. Don't need to reef it down, just snug it up. Or you can take a lg hose clamp and go over the springs and do the same thing. Its the harmonics, the vibration that weakens the spring and causes them to break at the base end of one of the hooks, usually the pipe end of the spring. THe safety wire, hose clamp simply helps cut down on the vibration adn eliminates the problem. An old endurance road racer trick!

There's some good knowlege to gain...I can feel my brain growing again...

I've always wrapped the end of the pipe with teflon tape to help ensure a good seal...would that provide a little isolation that might be eliminating or reducing the transfer of the resonant frequencies or harmonics?

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you can also push rubber tubing over the springs.this will help harmonics as well as keep rattling down.a couple other things to ponder - did you put o-rings in the new pipe? did they give you the right pipe.it wouldn't be the 1st time they sent one out for the wrong year.The flange on the cylinder may be worn out causing a lot of vibration too.

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There's some good knowlege to gain...I can feel my brain growing again...

I'm with you sonobob, that's the first time I've heard of this in 40 years of riding 2 strokes; but it makes sense. Guess I've been lucky so far.

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Lot of things seem to affect it. How tight the pipe fits into th cylinder, worn out O-rings. Different pipes/pipe construction. Also, how the other pipe mounting is accomplished.....fairly rigid mount , well cushioned rubber mounts, etc. The more rigid the other pipe mounts, the more likely you are to have a problem. Of course, just like valve springs, the sring construction itself. The srpings that taper down to a beehive like cone on the end with the attachment hook actually being a separate piece of metal....never seen one of them break! Besides safety wiring the pipe, the other thing we always do is double the number fo springs. Most typically have a top and bottom spring, or close to it. What we also do is add two other springs....one from the top engine attachement point around to the bottom pipe attachment point, then the other from the bottom engine point to the top of the pipe mount. Helps stablize the pipe.

The other little advantage....got to do a quick between heats top end? With the springs wired or clammped to the pipe, all you do is loosen the spring at the cylinder adn they stay right there on the pipe....don't go flying off into the dirt somewhere or happen to fall off when you are moving/wiggling the pipe around. Just a littl side benefit.

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Oh, and another little save teh spring trick. If you are having trouble with them poping off and loosing them, what you do is take your good ol' safety wire, run it up thru the center of the spring, thru the hole the spinrg hooks in on the engine, and then back down the outside of the spring thru the pipe mount back to the other end. Don't tighten this wire down real tight, otherwise it will likely break if the spring snaps off, instead leave it a little bit on the loose side. If the spring pops off, it'll stay there instead of getting left somewhere in the dirt out on the track/trail and you can just re-attach it. However, wrapping it around the pipe/springs will also keep it there, too.

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Hey Charlie

Thanks for the advice, sounds logic.

The O ring is new, the flange is new, the pipe is a snug fit. The other mounts are very rigid.

First I had these inexpensive "10 in a bag" and they broke within 30 minutes riding slow endurance slope. Then to my real surprise one of those real heavy conical springs (both ends narrower than the middle) with the hook separate from the spring part was missing.

I will try the safety wire trick and see how it works.

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On my WR´s kickstand was a rubber hose through the spring when I got it new.

Probably to solve the same problem, but on the kickstand spring.

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I dont even use springs just because one snapped! I have no problems without any. You dont need them, they dont really hold the pipe on anyways. Thats what screwes are for :thumbsup: .

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I dont even use springs just because one snapped! I have no problems without any. You dont need them, they dont really hold the pipe on anyways. Thats what screwes are for :thumbsup: .

I'll keep using my springs, thanks.

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I dont even use springs just because one snapped! I have no problems without any. You dont need them, they dont really hold the pipe on anyways. Thats what screwes are for :thumbsup: .

What screws???

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The screw connected to the frameand pipe near the swingarm pivot axel and near the waterpump on the frame twards the front.

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The screw connected to the frameand pipe near the swingarm pivot axel and near the waterpump on the frame twards the front.

Ohhhhh, the mounting bolts...o.k.

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