TOPIC:

Once I knew the Y manifold was ordered, I removed the old one. Out of curiosity (of course) I looked at the carb slides, turned the twistgrip a bit, and watched the nearside slide lift up. i had worked out that the offside slide had a diaphagm (obvious from looking on top), so I poked my finger in and lifted the slide. And it stayed up when I released it. Hmm. Not good.
Today I dismantled it carefully. The diaphagm feels stiff but is otherwise undamaged.
Are replacements available, and if so, at what cost?
I continued dismantling various parts such a float chamber etc. The float valve seemed OK so I left it alone, but gave the float bowl a good clean out.
I saw what appeared to be an adjustable needle located underneath the nearside body, and "eyed things up" to see where it was in respect of the main choke -- On the engine side, and looking in, not much to see, but my probing finger felt something sharp poking up.
I carefully screwed in in to record its position, (1-1/8 turn), then removed it completely. A screw with a reduced parallel end, but no tapered needle as I might have expected.
Probing with my finger again, the sharp projection is still there. It looks as if the needle end has dropped off, probably overtightened by a previous owner, the one who ruined the thread in the front forks no doubt.
So, where can I get a replacement?
Further searching on the www found these two sites:--
www.offmoto.com/viewtopic.php?id=6686
ttr250.com/Carb/TTR250_carburettor_strip_and_rebuild_guide.htm
The first link suggests the needle adjuster is item 42. In the second link, a 30mm Teikei for a Yamaha is dismantled and rebuilt, so maybe a Yamaha dealer.
I have NEVER ordered a Yamaha part from a Yamaha dealer. something I may need to learn.
Unless somebody here has a spare needle and decent diaphagm to part with.
Cheers, Les.

you may hav a look at the carb sheets from the old GeN for all those numbers on the needles and jets

For the slider oft he secondary carb with the diaphragm you may search for a Yamaha 600 part
The Yamaha dealer might be rather expensive so search for a Keyster spare part wich is also not really cheap.
There is also a gasket set available for those XT600. Keyster or Tourmax
Hope those parts are also available in GB

ciao Joachim

Joachim, any chance of a link please?
I have downloaded all the original GEN issues, but too many to quickly search. The summaries do not indicate "Look here" to me.
Cheers, Les.
I think I have a source for the mixture adjuster. Has anybody softened hardened diaphagms? Perhaps a soak in alcohol and glycerine mixture or something similar?
Les.

Les,
I'm sure there was a firm in the UK that fitted new diaphragms to carb slides, from when I was interested in and owned Suzuki VX800s. I think all my paperwork is long gone to the next owner though. Perhaps do a search?
Nick

the gasket kit should be

KEYSTER K-840YK

The diaphragm should be this one

TourMax VCC-238

ciao Joachim

Thanks Joachim, I see them now. Frightening prices though. The diaphagm unit with postage just under £70, and they MAY want more at this end.
There seems to be a diaphagm only available from China for just £10, I may well go for that. That was easy to find using the XT500 details from your link.
The mixture screw IS broken. I tapped out the jammed needle end from the body, and now have a drawing of it.
Plenty of other mix screws on line, but different threads and the only ones with measurements are too small diameter in the needle. Not something I feel comfortable about trying to produce on my lathe, but we shall see.
Les.