• 2 Stroke Husqvarna Motorcycles Made In Italy - About 1989 to 2014
     WR = 2st Enduro & CR = 2st Cross

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250-500cc Ripped FMF Silencer

M

mikebru

Husqvarna
AA Class
Has anybody ever seen this happen?

I took off the silencer last night to repack it. Discovered this.

Going to call Rocky Mtn ATV. Bought it from them just under a year ago.

If I can't get it replaced I think I'll just zip tie it together. When on bike it is barely opened up along the crack.

Thanks
Mikeimage.jpg image.jpg
 
I haven't seen that exact problem before. But those black scuff marks... is that the inside (facing the wheel)? Is your tire hitting the exhaust under full compression? If so, that could cause stress and explain why it's cracked.

If the tire is pushing it aside you'll have the same problem again soon. Some spacers/washers on the mount might be enough to give you the clearance you need.

If those aren't tire marks, then ignore me and move on...
 
I would Tig weld it and ride it. Simple fix.

Clean well first with a "new" wire wheel or scotchbrite pad to get the anodizing off in that area and about 1/2" inch back all the way down to the sticker and your knuckles. Just looking at where your thumb is and the former position of the mounting grommet tells me, something may be bend upstream on the forward part of the pipe now, or it has taken a few good hits so loosen it all up and adjust the flange and front hanger mounts after repair and see why its distorted and stressed there at the cracked hanger flange area when remounting.

If "FMF" or "Rocky Mountain" says no way you did this on your own . ( I wouldn't waste my time even contacting them.) If you can't get no one to do it for you there, send it to me and I'll do it for you. You can PM me. I personally would put it in my Bead blast cabinet to clean it, strip the whole thing of the anodizing and polish and buff it or scotchbrite the whole thing and spray again with some high heat clear coat. It really doesn't get that hot, like you need header enamel on it. I even have a few exact same spare FMF stickers. LOL.

Before welding. Close up the gap with a clamp or in a vise (put your inlet end cap back in first to do this) but get the crud out of the groove in the crack, use a carbide burr to bevel it out and open it up ever so slightly and Tig it. Clean it thoroughly first inside and out. Preparation is the name of the game here. I've seen this happen many times on these FMF extruded silencers.

Clean it good and your local welder will be nice to you. ( Maybe not in Jersey, LOL) No really. Other wise you will be paying the welder to do it for you and he just might send you packing. It will take much longer to prep for welding than the actual weld time takes.

Clean and prep properly, 30 minutes tops depending on how you do it. Weld time? 5 to 7 minutes tops, depending how he does it.

Not trying to take in any work here but this is a simple fix and nothing out of the ordinary for these extruded FMF silencer bodies.
 
Good call, they might be scuff marks.

Thought I checked that when I installed it. I have it spaced off with washers but maybe not enough. Thanks.
 
Wow Big Timmy, thanks for the explanation!

I'm going to check with my brother-in-law, he has a really good tool kit! (Which movie is that from?).

He does some welding.

Maybe I'll end up taking you up on your offer, though.
 
i certainly wouldnt install it, thats silencer is in really bad shape..does your brother normally weld aluminum with a tig or at least a spool gun gun mig? im thinking if i were you i would take up timmy on his offer. at that point it would be better than the original piece likely. i like when the mounts are welded on better anyway.
 
No 1)Nothing in life is guaranteed, They had these extrusions made and it saves FMF a shit load in hangers being welded on or having full wrap around separate hanging mounts that would be ideal made of a composite like a Leo Vince' muffler. The thing is it can't lend itself to so many applications as they have produced with that same offset. Without having to use spacers or keeping a certain tire on the bike. These things are nearly disposable and its intended life span has been exceeded.

But it can be fixed.

No 2) Probably crack again? Why? Other than it being just plain manufacturing brittleness and unsupported? Go back to No 1)

Below is three examples of what is a different way of doing the same thing and one is the dealership sold and supplied "FMF" hangers on my FE501 and the stock FE501 muffler with welded mounts that are off set from one another. But parallel to each other which is not possible with a universal flange on an extruded piece like you have.

If you notice these riveted mounts below on the "FMF" muffler are not the same as each other and are not inline with each other and are made with the offset but the rivets are basically lined up in a straight line.

SAM_1071.JPG

SAM_1079.JPG


The other example is the hanger on the full Leo Vince' system on G450X, nothing to fail here very easily. It wraps around and is like a piece of a Kevlar reinforced composite tire material. Tuff as hell.
SAM_1075.JPG
 
the fmf silencers life span is nearly exceded? it certainly doesnt look very old. although you are probably right about their extrusions.
certainly when dealing with huskies many times options are limited. ill always stick with a good company that welds everything beefy-like. ive always been impressed with how dynoports stuff has fit and looked for what it costs. attaching points are usually large tabs fully welded.
 
Yes, JT.

Brand new cars get damaged and cracked up and they have exceeded their life span also.

The muffler, I say that with regard to brittleness not age. The work hardening of that flange flexing back and forth has caused the damage as it's unsupported (thick area next to thin).

Best to weld the mounts to a patch plate to spread the load out over a larger area. The welding also anneals that area in the heat affected zone and makes it more ductile, so it isn't brittle like the extrusion is in that area in the first place.

Mounts spread over a larger area is, I would guess, probably exactly what Dynoport does.

Even if it is welded it will likely break again right next to the weld. Again thick against thin = a weak spot.
 
ah, i see what you mean now...the silencer is likely hosed at this point. would be interesting to see what fmf says.
heres a pic of how the front mount is on my dynoport sparky silencer, being italian it has two of these. fairly large tabs spread out on both sides with a large hole for a big rubber bushing.Photo678.jpg
heres an old answer sparky from my 84 250, a very long mount but its just butted to the top.
Photo679.jpg
 
JT, The second silencer picture is a good example of spreading it out over a large area. If it was steel like your pipes probably are the best thing to do is form a doubler patch square or rectangular in the shape that fits the contour of the area you want the mount to be and then weld the mount to the patch piece, then weld that to the pipe.

If the mount breaks it has to pull the whole patch plate off with it. Also brazing is best for any thick to thin sections like the flange or mounts attached directly to any of the cones. This stops undercutting on the all important thinner cones material and again making weak spots. Or use a Tig welder using silicon bronze filler rod as that's not really welding (it's brazing) to the parent metal and will help it from cracking at that point. Thick mount against the thin sheet metal, not good.

One look at this example of a Scalvini pipe shows exactly what I'm talking about, the stinger, the end of the stinger, all the mounts, the cylinder head flange, the spring loops, etc. are all brazed and this companies pipes compare to no elses ones craftsmanship. They have the best workmanship in the world in my opinion and they are only about $100.00 more for this piece of art compared to a hammered out piece of "shite" like most stamped cone pipes from any other company. Period.

The ones that are stamped out, stretched and then welded and plated are even worse for cracks to happen to them as the plating process itself makes them even more brittle as embrittlement is a result of the plating and from the plating itself. Look it up! Chrome, Nickel. etc. Not good for any stressed components on race car parts that are fabricated from 4130 chromoly. Or any alloy steels for that matter.

I'll bet you Scalvini won't even plate one of there pipes even if you paid them extra.

Even painting one of these Scalvini pipes is sacrilege in my opinion.

All the pipes I've made over the last 35 years only got coated with cooking or salad oil at first and then again they got glazed with a good wiping of salad or cooking oil during its first warm up. That's it.

Any kind of Paint gets sticky when curing and then everything in sight sticks to it and causes a set up for future hidden corrosion. Plus it can't be easily inspected for failure or cracks either.

Suzuki%20RM250%20Scalvini%20FP.jpg
 
sadly there is nothing lke like the scalvini available for any of my swedes or my older italian. its either run stock or a fmf for the italian. thankfully dynoport makes pipes for all the 80s liquid huskies and the 90s italians. they are a tad thicker gauge than a gnarly and arent the craftmanship of a scalvini but at least arent stamped crap that wont fit. stock pipe is out of the question for my 360 as its a bizarre double wall 10 pound choker. Photo383.jpg
 
Yep, my 300 did the same exact thing. Twice! After having it welded, i found to only use the rear mount by itself. So far so good. Mostly do MX and hare scrambles. I thought for sure the one mount would not hold but its been ovet 6mths and lots of moto-ing
 
Looks like 5 sections are stamped at that head pipe on that picture of your Dynoport pipe but that's no big deal and very common.

Scalvini does this too, to at least the first 2 pieces in many of there pipes and in the one in the picture. The rest are hand rolled cones. But what they use is an exhaust donut if it has to be a real tight turn with a closer radius than is possible with a mandrel bender or they just use a mandrel U bend to make the first 1 or 2 pieces as there is hardly any taper.
 
damn my q stealth on my wr300 did the exact same thing a couple of years ago(started a thread i think)! obviously somethings not right with those long silencers. got mine from mx giant who contacted fmf & sent a new one out(although i had to pay postage to AUS). still not bad as i got to keep the busted one which i shortened(chopped 100mm off & ditched the SA) & had rewelded. has cracked again there though but not much & seems ok. imho i reckon the silencers are too long & put too much stress on the mount areas causing the cracks. mine only cracked about 2-3" nowhere near as bad as yours!:eek:
 
husqracer probably right to just use the rear most mount. wish you lived near me big timmy id keep you busy fixing pipes & making new ones for me!!!:cheers:
 
Probably agree with you on the rear hanger only after welding.

The heat affected zone from the welding will spread out and anneal this welded area and it won't be so brittle in that area in the future.

Send it back to the vendor with your proof of purchase and wipe off those scrub marks with something first what ever they are. a rag with some brake cleaner, goof off, goo gone. Whatever caused the scrub mark wasn't enough to even mess up the sticker so, I would think that had minimal impact on causing any of the damage but it doesn't help either . It is rubber mounted and the tire would flex the mount rubbers first and would have scrubbed the sticker clean off. If it was really scrubbing.

Give it a try and see what they have to say and maybe they would replace it according to these guys posting who have had similar issues and solutions. Sometimes a single simple mount is better as long as it has a rubber isolator bushing or grommet. It has to move a little as it's subjected to a tremendous amount of vibration like a tuning fork out there on the end.
 
duggoey said:
Could flex in the sub frame cause the space between the two mounting points to change causing failure??
Click to expand...
Thats my consensus. I even went out to check it was still good after i posted. I agree with bigtimmy, weld it up, pack it, and use the rear mount only.
 
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