specifically for 26mm TK carbs used on 82/83 GPZ 550, but I imagine if there is a way it would be good for any
I have two sets of carbs and one set of them the diaphragms are stiff, as in rigid.
I'm not sure what happened except they have sat around for a long time.
kind of shoots down my idea of using one set to mount pod air filters, which may be a good thing in that it might be more trouble than it is worth
A good test would be to attach a shop vac to a carb with stiff diaphragms and then to an identical carb with soft diaphragms. How much difference is there in slide movement.
A soaking in ArmorAll or other vinyl treatment may help.
I have read about guys trying desperately to soften up the air box to carburetor boots by soaking them in a wild variety of concoctions. The best result I have seen made them softer for a bit, but they soon became hard again. So far as I can tell, once rubber gets hard, it stays that way.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
I have heard about softening rubber by soaking in a mixture of wintergreen oil and water. Most discussions online of people trying this seem to result in success.
But keep in mind that this is not restoring rubber, it's just softening it. It might prevent it from cracking and might restore movement, but I would still put it on the 'experimental' list of things to try.
The way I see it, if you have time then it's probably worth giving a go if you can get some wintergreen oil cheap.. If it's already rigid, it's useless. The wintergreen oil will either restore it (yay!), do nothing, or ruin it - but it doesn't really matter if you ruin a part that's already stuffed.
Have you tried JBM industries to see if they have new diaphragm for your carbs? I just did mine on my 6 BS34's(2 on my XS650 and 4 on my '82 750GPz carbs).Took almost no time at all to do them. Rode the XS650 with the new diaphragms and life is good!
I don't have a plan and I'm sticken' to it! '77 KZ 650 / 750 GPz custom project in progress
Having never worked on tk diaphragm carbs, when they say fitted what exactly does that mean? I doubt the original assembly process is something that couldn't be replecated by a reasonably competent enthusiast or am I wrong?
So far, I haven't located any reliable source for new diaphragms on the TK26/27 carbs. I have already converted one set of intakes to use the much simpler Tk22 carbs. They work pretty well on the motors that came with 26's.
JBM doesn't seem to sell TK diaphragm's and that place in the UK is expensive and requires sending the slides to them, which may be buzz kill if living far away.
There are a few decent looking sets of carbs on ebay. That may be the path of least resistance. I'd contact the seller and have them verify the diaphragm's before buying though.
As I mentioned, I already bought a set of carbs ($150!) and yes, inspected to make sure the diaphragms were good. Since that's the only reason I was buying them.
so if I can find some diaphragms, I would have two set of carbs
I cannot believe the prices people are asking for crappy sets of carbs, the ones I got were a steal apparently