Expansion chamber stuffed. Advice needed please

[cr125nz]

my expansion chamber on my cr125 is poked just wondering if i change to a normal pipe will i lose any horsepower etc cheers.

my crf 250 is sweet and good., but enjoy the 125 for trial rides so want to keep it for trail rides. as still getting use to the 250

[cs363]

my expansion chamber on my cr125 is poked just wondering if i change to a normal pipe will i lose any horsepower etc cheers.

my crf 250 is sweet and good., but enjoy the 125 for trial rides so want to keep it for trail rides. as still getting use to the 250

Normal pipe? Do you mean the stock chamber?
If it's had an aftermarket chamber then yes, you will most likely lose some horsepower somewhere in the rev range, depending on what brand/model of pipe you had - however some of the later model CR125's actually went better with the stock chamber and an aftermarket silencer.

More info required for a more definitive answer :)

[theblacksmith]

Stuffed ? In what way? I can fix them relatively cheaply-and clean them out the same time.What material is it - Stainless or steel or Ali?Got a pic?
Cheers.

[cr125nz]

just have the stock standard chamber on it but it has 2 major dings so was wondering whats the best way to go about it either repair or replace with small pipe like the modern cr thanks for your help guys

[cs363]

Pictures of the dings would probably be a good idea, but unless they are REALLY major it should be repairable. Not sure what you mean about the small pipe on the modern CR - what year is your 125?

[cr125nz]

mine is 2001 and on my crf i have a small thin pipe to exhaust

[Buddy L]

cr's and crf's have competly different types of exuashts.
I got mine repaired by custom chambers (in Auckland) and the guy their did a great job.
Mine was off my old 02 cr125 and had a real massive dent.
send some pic's to "the blacksmith" and see what he says.

Custom chambers needed the bike as well though. (for smoke-O runs i think)
to make sure everything lined back up and fitted, as he had to cut the pipe open to get dent out.

[cs363]

cr's and crf's have competly different types of exuashts.
I got mine repaired by custom chambers (in Auckland) and the guy their did a great job.
Mine was off my old 02 cr125 and had a real massive dent.
send some pic's to "the blacksmith" and see what he says.

Custom chambers needed the bike as well though. (for smoke-O runs i think)
to make sure everything lined back up and fitted, as he had to cut the pipe open to get dent out.



What he said, lol :)

[cr125nz]

thanks guys have contacted blacksmith cheers :shifty:

[Pierce]

Glad to hear your keeping it bro. She's a minter. Just stop dropping her and keep the pipe dent free ;-)

[B0000M]

anyone ever had a pipe that just wont stop cracking? i had one on my CR250r, FMF Fatty - on the tight bend (the one that does the u-turn on the left side of the bike) it had a repair when i bought the bike which lasted ages, then it got a crack on the other side of the pipe.
so i got it welded up

then the first side cracked again

welded up

crack

weld

crack

weld

crack

weld

give up and buy a new one.

was there a way of fixing it in a way that it wouldnt keep cracking?

btw it was made from stainless

[cave weta]

crack

weld

crack

weld

crack

weld

give up and buy a new one.

was there a way of fixing it in a way that it wouldnt keep cracking?

btw it was made from stainless[/QUOTE]

weld it with the correct filler rod- ie: 366 314 or 304 a welder should know top check first

[cs363]

btw it was made from stainless

Umm...no it wasn't (unless it was a one off.... :laugh:) FMF Fatty's are made from 19 gauge mild steel which is nickel plated.
Whilst the plating process may make the steel somewhat more prone to cracking, in most cases this is caused by fatigue due to incorrect mounting/alignment or just plain old vibes/old age.
So I would surmise that either as cave weta implied the incorrect welding rod was used or it's just plain knackered and should be binned and get a fresh one. :)

[B0000M]

hmm, well stainless was my presumption.

whatever the case 4 different people had goes at it, none of which worked, 2 of them were fabrication engineering guys who work with a range of materials, one was a bit of a home / work handy guy, and the other was a mechanic - surely one of them got it right!

anyway i think probably its had a hit at some stage so theres a stres point there.

[theblacksmith]

Ive repaired lots of them over the years
- make sure no carbon is near the weld area as this will precipitate into the weld and cause it to become too hard/brittle - hence the cracking.
-

[Danger]

Ive repaired lots of them over the years
- make sure no carbon is near the weld area as this will precipitate into the weld and cause it to become too hard/brittle - hence the cracking.
-

Whats the best way to ensure carbon is not present in the area blacksmith? Heat it to glowing red with oxy acetelene to burn of the carbon in the welded area before tig welding?

[theblacksmith]

Whats the best way to ensure carbon is not present in the area blacksmith? Heat it to glowing red with oxy acetelene to burn of the carbon in the welded area before tig welding?
I usually clean it mechanically-die grinder or grinder depending on access(usually I split chamber by hacksawing through weld after marking ref marks all around).With stainless I clean with pickling paste and scotchbrite prior and after welding(with TIG and 316L filler rods) With mild steel I usually mig weld and apply post heat to stress relieve around the weld.We all hate cracks( on exhaust pipes anyway lol):laugh: