Author Topic: yamaha labyrinth seal, for 100cc 125 cc twins  (Read 1732 times)

0 Members and 1 Guest are viewing this topic.

Offline GTDWH

  • Newcomer
  • Posts: 40
Re: yamaha labyrinth seal, for 100cc 125 cc twins
« Reply #45 on: September 24, 2022, 02:11:16 PM »
10 differant people could measure them and all come up with differant size all be close.

You could ask a machinist with expertise and the right gear to measure for you?
While s/he's at it, ask for a quote to reproduce it?
And no, CNC is not a requirement.

When someone needs a lab seal that cannot be found (or too expensive?), having one made could be the only other option.
Last comment first, That was the reason I started this thread...
My point about measurements is because it's irrelevant to the likes of you an me, is only important to the machinist..
It does not end there, getting the correct material to make it, is a huge factor.
Seems you don't read my posts fully, I already found a machinist who said he could make them, but he didn't know
what material could be used.

For me it's just a labour of love, I don't really have the spare time to pursue this full time.
Its unlikely i'll need anymore, have 2 new in bags, and 2 cranks to be rebuilt, so I have enough and could even end up with a spare.

I have 7 small yams that i'm trying to restore, these days it takes me a week to do what I used to do in a day for reasons I won't go into other than age and health related.


Offline Bluehaze

  • Back Lane Scratcher
  • Posts: 423
  • Location: Australia
Re: yamaha labyrinth seal, for 100cc 125 cc twins
« Reply #46 on: September 24, 2022, 11:49:11 PM »
I thought you were hungry for knowledge. :)

At a wild guess, I think the material for the lab seal should have the same heat/expansion character as the crankcase material.
The crankcase would be made of an alloy with a low so-called coefficient of thermal expansion.
The seal material could also be selected of a low-ex type, so as to be in the ball park at least.
While important, it may not be catastrophic if you got it slightly wrong.
Maybe your machinist could measure the diameter of a sample seal at different temperatures to see how much it expands.
« Last Edit: September 25, 2022, 12:24:21 AM by Bluehaze »

Offline GTDWH

  • Newcomer
  • Posts: 40
Re: yamaha labyrinth seal, for 100cc 125 cc twins
« Reply #47 on: September 25, 2022, 09:39:50 AM »
I agree crankcase type material may/should be suitable, but may not be easy to find an area with enough material.
I no longer have the contacts I used to have when I was in the trade and racing yams.
Back in the day this would have been much easier, I knew guys that are sadly no longer with us
that would have been more than able to make these lab seals and would have made 1 just for the Hell of it

There may be another avenue to explore, it maybe possible to use the 180cc-200cc Lab seal.
There are still a few about, at a more realistic price at this time...
It may be possible to modify that seal, it looks to have the same id and od, and more than likely be made from same material.
It is just thicker, by about 5mm, it may be easier to modify, rather than start from scratch with a chunk of crankcase.




Offline Bluehaze

  • Back Lane Scratcher
  • Posts: 423
  • Location: Australia
Re: yamaha labyrinth seal, for 100cc 125 cc twins
« Reply #48 on: September 25, 2022, 01:16:57 PM »
Without going to the expense of a piece of new alloy rod, I'm thinking the top of an alloy piston from a large diesel engine might supply a big enough piece of easy to machine low-ex material. Truck wreckers could be a source?
Alloy containers for compressed oxygen, as for oxy-acetylene welding, have thick bottoms. Some have made motorcycle hubs from them.
There's always the chance of failure when trying this sort of thing, so early success might not happen!