Hi all

Just picked up a sherpa model 80 with a sammy miller replica frame, needs quite a bit of work and is going to be a long term project I think.

One of the worse bits is the threads on the barrel where the exhaust screws in are gone, can these be repaired?

cheers

Yes. There was a discussion about this recently over in Club Bultaco. Swoosh Dave will advise.

Edited September 2, 200817 yr by TooFastTim

Yes. There was a discussion about this recently over in Club Bultaco. Swoosh Dave will advise.

There was? I will?

I believe the two choices were Sammy Miller in the UK and Hugh's in the US.

Edited September 3, 200817 yr by swooshdave

Hugh's Bultaco shows that for round cylinder engines at $75.00

http://www.bultaco.com/TechTips.htm

I'd think that any major vintage Bultaco shop probably offers a similar service. You could weld it all up and machine a new thread or maybe put in a big thread insert. Or consider converting to spring mounting with a slip fit exhaust.

cheers,

Michael

I was also going to suggest that if the threads aren't too far gone that you may be able to do something with a thread file.

How to use a thread file.

How to use a thread file.

Very carefully.

Im afraid the threads are completly gone

If it were me I would helli coil them. You drill out to suit the next thread size then insert the helli coils and you are left with a new thread that is the same size as original

Sorry Shameless plug I know! I used to do this for Jeff at Mainly Spanish when he was in business, as well as Brake Relining and also manufactured and supplied all the 2mm oversize flanges to Hughs Bultaco. It's Hughs asking me for more that has rekindled my interest, made me get off my a*** and thinking about riding again instead of just admiring my bikes.

I probably could be presuaded!

Wayne.....

If its the same thread size as an OSSA you can buy them (aluminium inserts for welding in place) off the shelf from Keith Lynas in the US. I will go and check the sizes of both.

Yes I just screwed an OSSA header nut into a Bultaco M27 barrell - perfect fit.

Edited December 21, 200817 yr by feetupfun

The Ossa one is a LOT shorter than the Bultaco flange nut, but you are right they are both M56x1.50 thread. I have both types.

Edit: I'll try to insert a picture to show the differences.

MAR is the rusty one just removed from a bike in my unit. The other two are Std and Oversize Bultaco Flange Nuts.

Wayne...

Edited December 21, 200817 yr by wayne_weedon

That looks the part Wayne, ill be posting the barrel over your direction soon if that suits

cheers

No Problem, I'll be glad to be of assistance, that fixture needs to be used rather than sat in the stores. Perhaps I ought to modify it to allow it to do Ossa Cylinders too.

Wayne...

Hi all

Just picked up a sherpa model 80 with a sammy miller replica frame, needs quite a bit of work and is going to be a long term project I think.

One of the worse bits is the threads on the barrel where the exhaust screws in are gone, can these be repaired?

cheers

Hi all

Just picked up a sherpa model 80 with a sammy miller replica frame, needs quite a bit of work and is going to be a long term project I think.

One of the worse bits is the threads on the barrel where the exhaust screws in are gone, can these be repaired?

cheers

Hi , After you have the threads repaired .Use a exhaust nut for a pursang. The one for a slip in pipe with springs to hold the head pipe in.End of problem you never have to remove the nut again..My model 49 #31 has had this mod done around 1970..

Dean