2 Strokes Down Under

I have read a number of articles re the problems with the early 4LO exhaust system and the modified version that Yamaha produced to fix the problem with the "0" stamped on the rear hanger.
It seems to me that most of the issues revolves around the flange and the initial part of the engine pipe.
Can anyone advise if the rest of the exhaust were also modified?
many thanks

Just a strong flange added as far as I know

BRG1200 wrote:Just a strong flange added as far as I know

I tend to think the same. It appears that all the other mods such as studs and midrange issues were dealt with in the new barrels withthe "1"marking.
I can get my handson a reasonable set of pipes.....but they are the older (troublesome) ones. I am thinking of maybe replacing the front pipe up to the first weld mark from my original pipe.Iam not sure though if the first part is simply welded into the larger second part or if the flanged pipe links/is welded to the internal canister.
Has anyone ever had a need to opened up a st of pipes to have a look?

Is there a site that would have pictures/diagrams of the internal?
thanks

last option....does anyone one have a mangle pipe that I could cut open to have a look at theinternal fabrication? I am in Sydney...close to Parramatta.

I suppose someone could add a collar of their own to a set of "pre collar" pipes if they were handy enough and had the time ;-)

hi sunset, were the header joins the pipe its only welded, although the header is much thicker material, id say not a job for the learner welder, i recently converted some german 250 pipes back to 350 , we had to remove the restictor from the end of the header and cut the pipe in half and drill an extra 4 holes in the 1st baffle, theres some type of fibre matting inside and it kept catching on fire etc, the pipe wall thickness is surprisingly thin in places, no wonder they dent easy, ken

pretty quiet site isnt it,

jSorry for slow reply. unfortunately having issue with my browser.
Ken, good to hear from you. I am having a dilema with tbese pipes. Definately has 4LO1411 AND 21 stamped on it...has the stronger flange...but no"0".Had a camera go down the pipes and only has two holes punched in it. The removable baffles on the original pipes have this thick fibreglass type insulator around it....the new ones don't. The old pipes seems to have two baffle plates....the new one only seem to have one!!!!! So I am completely baffled" pardon the punn"
Been tied up with a funeral this week....will try to get back to it on monday and report any findings. I am wondering if they may have revised the pipes for the 82 model! sorry for any mistakes....using my phone atm and the writing is very small for my ole eyes
Phil