Exhaust thread fix idea..

[daxman]

Left hand exhaust thread on teh 'A' is nadgered. I bought a nice replacement 54.0mm barrel off ebay only to later discover its a K, L,M version. So unless anyone has one to swap I might try fixing the old one.. Options

1) try the aluminium tape idea - not sure how well this might work but a cheap try-out.. Any brand preferred?

2) file down the current threads using the bottom of the thread valley as guide to get it roughly round. Buy soem 48mm x 1.5 mm steel tube and get it threaded by mate with lathe or machine shop trya for interference fit on old spigot plus countersunk grub screws, metal putty jollop etc.. to keep secure..

Thoughts..

[johnakay]

this what you need,brilliant stuff wouldn't be with out it now..
I use it for allsorts of alloy repairs inc steel.
one of the fins on the engine casing was missing on my old T500.
so made my own using jb weld and in the 2 years I've owned it never came off.
and the 500 does vib a bit.lol
also I've used it for thread repairs to and one was on my piaggio exhaust stud worked fine.

https://www.ebay.co.uk/itm/JB-Weld-Orig ... OSwp3Jau0d~" onclick="window.open(this.href);return false;

[dollydog]

ali tape? waste of time. the exhaust threads need machining off and a threaded ali tube slipped over the top and grub screwed to the stub. anything else such as metal putty is a waste of time [and money]. the threaded sleeve method is the best way to go by far. i have got a l/h barrel i'd be willing to swap, but i'll check it out first and see what size it is. i'm sure the threads are good on it though. give me an hour, i'm busy typing atm
cheers, dd.
ps, sorry john, didn't mean to tread on your toes

[johnakay]

you can't of done it right. I've no problems at all.
leave the old damage thread in just give it wash out with thinners a fill it up with jb weld re drill/tap.
thread insert would be better if theres enough meat to do so.
in the past I've made my own for the heads and they worked ,using thread lock. never came out in the time I had it.
these alloy heads have a very low torque 10 nm? threads are easily stripped by ham fisted fellas.lol

[daxman]

... i have got a l/h barrel i'd be willing to swap, but i'll check it out first and see what size it is. i'm sure the threads are good on it though. give me an hour, i'm busy typing atm
cheers, dd.

so dd, what did you find? (before I stick mine back on ebay.. )

[dorT500]

Are those threaded sleeves just held in/kept from turning in with the casting process of the cylinder? With or without some type of stops or stubs?



Anyway, this way would probably take some of the the aluminum with it just creating more damage and it would be a steel tube in this case but it might be fun to try it on a cylinder that is about to get thrown away anyway....just a thought.... same way you get engine mount bushings out.


starting around 1:35.....https://www.youtube.com/watch?v=pSPGLJXypK0" onclick="window.open(this.href);return false;"

[Vintageman]

I got the correct die and just rethreaded the crossed up threads, Sure the thread peaks were not as high anymore, but did screw on and straight and all the way (some good threeds near the end?) and I lightly torqued, or probably would have stripped. Now you really rely on the locking doohickey to keep it from unscrewing. Depends how bad it is I suppose to start.

If it goes on and holds but crossed threaded (not straight) sand down the exhaust doughnut on and angle so it seals 360. When I got one of my t350, it was put on crossed, leaked oil (now that would suck yes). If could have took the exhaust gasket sanded on angle of glued it in place it would have worked/seal well. But as said above I took a chance and rethread.

If someone was good at welding they could add material in spots so when you rethread there is some material. I don't think you need to fully replace all lost metal on threads. I was going to do this with my TIG if the rethread above does not hold... got lazy

[johnakay]

oh I was under the impression that it was a t500.

[dollydog]

sorry dax, after checking the last pair of gt250a barrels i've got - the left hand barrel has very worn threads on one side, which is a shame because it's on standard bore right hander is fine - typical the top quarter is deep thread, but the rest is yuk sorry chuck.
cheers, dd.

[daxman]

Hi Thanks for looking, maybe a pic to see if it's better than mine?

I haven't yet examined the nut which might be packed with shards of ally that need picking out. Then I also thought about using a thread file like this.. https://www.youtube.com/watch?v=dYu_fl59Ztw" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Although I realize this is not ideal..

[dollydog]

i've just seen your auction post and THAT IS A RIGHT HAND BARREL what it isn't is a left hander. let me check if my 250a barrel - the right hand one - is ok and i'll get back to you. ps, where did you get that price from?
cheers, dd.

[daxman]

Well you know something when I bought it I had doubts - I was going to questiom teh seller but it had LHS marked on it and I presumed he knew better. It is the left hand I need though so I must now change my listing.. I do feel somewhat stoopid I must say. i was wrong on two counts.

[Indy650]

I never liked the screw down exhaust flanges. Get one lazy or novice owner that doesn't notice they are loose and there goes the threads. Seeing I make my own expansion chambers for sleds and recently decided to try bikes I had the idea of milling of the threads, making two o-ring grooves where the threads were and having a slip fit flange on the header pipe held on by springs. I think this would be better than the screw on flange. I have had many bikes/sleds that use this method or similar where the flange fits inside a bolted on exhaust manifold.