Montesa Mh349 -Idenification Of Special "o" Rings Located Under Barrel Securing Nuts !

[gellyburn1]

Hello all fellow Trials fans !. I'm from Perthshire and have recently dug out my old Montesa MH349 which has been stored in my Garage for over 20 yrs. I've had the old beast since new ....about 1984 or thereabouts . Back in the 1980s I did several club Trials on it etc. Whilst it was pretty sound mechanically it looked a bit scruffy and being idle for so long resulted in a dire need for a complete overhaul. I'm in the process of implementing a complete refurbishment and will post a pictorial record of the "Project " shortly !!. For the moment I'd appreciate some advice from a fellow Montesa fan on the following subject ..... !.

When I stripped the engine I found rubber "O" Rings located below the Special Barrel Retaining Nuts. I was able to remove the Nuts with TLC but then encountered the mystery "O" Rings . They were made from a very resilient rubber and I had to resort to burning them out with my trusty Blowlamp !. They were a light brown colour but this may have been rust contamination !!.

The Montesa Part No is M3360-162 (Washer Cylinder Special) . I've tried various suppliers for info to identify this elusive part .....has anyone out there encountered them ,and what was the outcome ??. Are they necessary ? What was their purpose and should they be replaced like for like ?.

I can only think that they were a waterproofing measure to protect the assembly during Trials Sections with deep water /mud etc etc .

As I've said nobody so far seems to know anything about the problematic little swines which are now holding up my engine reassembly !!!.

Any help on this will be very gratefully received.

Thanks in advance ,

Regards,

Ally Straker (Gellyburn!)

[bilks]

They were also used on the 247,looking in parts list,so someone must know a source,or if can't find any, try some normal rubber o rings that will fit.

Edited August 15, 2013 by bilks

[gellyburn1]

Hi Bilks !.

Thanks for your prompt response . Were the "O" Rings of a special grade (ie heat resistant etc ) or do you think a standard automotive version would do the job?

Thanks,

Ally Straker.

[bilks]

Don't know about heat resistance,but i'm sure i replaced mine,many many moons ago,on my 349,where there situated,i wouldn't thought they wouldn't be subject to that much heat.where situated,suprised no others have come foreward with info.

Edited August 15, 2013 by bilks

[gellyburn1]

Hi Bilks,

thanks again for your input. There seems to be some confusion on this issue. It would appear that some MH349s did not have the "O" Rings, but a steel washer. Mine definitely had "O" Rings fitted. I must admit I was surprised to find them in that location . I had a hell of a job removing them and burned them out with great difficulty. They seemed to have been made from a very tough and resilient rubber !.

As my engine had never been stripped from new .....they were obviously factory fitted.

Not sure what my best course of action is now ?.

Regards,

Ally Straker.

[pschrauber]

Yoj might search up o-rings made out of Viton (trade mark). These are heat resistant. You get them in every dimension.

[gellyburn1]

Hi pschrauber,

Thanks for the information.

Regards,

Ally Straker.