Suzuki 2 Strokes

Does anyone have any idea where I can find a diaphragm for a '73 Gt250k petcock. The one that's shaped like a pentagon. I can't even find a part number. I'd appreciate it if anyone can point me to one.

Suzuki never sold replacement diaphragms.

A company in Germany sells new replacement diaphragms.
https://hard-to-find-parts.de/epages/af ... hn_Auspuff

Alternatively, you could switch to a manual petcock

I’ve had good luck doing manual conversions of stock GT-series petcocks. Conversion of your GT250 petcock should be similar. Use a flashlight to make sure you correctly mapped out the flow passages before doing the conversion. (i.e. measure twice & cut once.)
See: viewtopic.php?f=9&t=14743&hilit=manual+petcock

Pingel sells new vacuum & manual petcocks. I’ve had good luck with them but they are pricey.
Some forum members have had good luck with other cheaper new aftermarket manual petcocks.

Thanks for the help!

That ebay listing has the wrong size gasket for the bowl and selector knob. The four hole gasket on mine is 21mm and the one in the listing is 24mm. Is the diaphragm the right one for a petcock? I'm worried that won't be the right size either.

The diaphragm pictured on Ebay is 55mm measuring though the centre from the flat edge to the point.

I took the old diaphragm out but didn't pay attention to which way the divot in the plastic divider piece faces. Does anyone know if the divot faces inward, towards the petcock, or outwards?

I just got the order in from that ebay listing and it doesn't fit. Is my only other option to do the exchange with the place in Germany? I'm not really interested in doing the manual conversion.

The plastic divider has a vent hole that lines up with the vent hole in the diaphragm.
The plunger/diaphragm has the o-ring on one side & a metal disk on the other side. The depression in the plastic divider is on the metal disk side.

Some forum members have had good results with diaphragms from the German company.
Not sure, but I think he has you mail him your diaphragm. Something about some variations in the part.

Just wanted to give an update. I was able to get a new diaphragm from the gentleman in Germany. His name is Volker Shulz and his email is transportschulz@aol.com. The part was about $75 USD, but the real killer is shipping your part to him. Took a little over a month from purchase to getting the part in the mail. I'm satisfied with the end result. May have been more than what I was expecting to spend but I'm not complaining since this is a sentimental project and I think we all know how cost can take a back seat in these situations. Anyway, I just wanted to recommend Volker to the community from experience. Having a brand new part, in my opinion, is miles better than shoving JB Weld into the petcock. Only thing is, the bike isn't running yet, so I can't give a review of operational ability, but I plan on revealing my bike in the forum soon after the carbs are rebuilt and the bike is fully operational.

Bmurphybcr wrote: ↑Thu Feb 17, 2022 11:22 am Having a brand new part, in my opinion, is miles better than shoving JB Weld into the petcock.

To each their own, I have been using set screw and JB Weld in some of my bikes petcocks for 10 years now with no issues. Some brand new petcocks leak right out of the box, but like I said ,to each their own, I am glad your happy with yours, but I am just as happy with mine.

I hear you, Karl. I'm sure I could have done that with success, but I've spent so much money on this bike and paid attention to so many details that to not return it back to factory was just not an option for me. I've already come so far, why stop now? It was my grandpa's bike, so I haven't been sparing any expense within reason. The main thing was for me to know what my options were, and the advice is appreciated.

Basically I am saying to be careful about "opinion"
On these bikes some people make modifications to make these bikes run better or more dependable.
You will find the new regulator/rectifier mod is a much better charging system on the twins than "Factory" With factory system you can get 16-17 volts on the system, obsolete headlights going for $100-150 or more, I won't depend on a system and replace lights just so it's "Factory"
There is the ignition relay mod, to give more voltage to the coils so you get a hotter spark. The "Factory" wire harness is to small gauge wire to carry full voltage to the coils.
I have seen my share of leaking petcocks,even replacement ones, that is why I went the set screw and JB Weld mod.
But my bikes are riders not just show, so I want dependability out of them, But I have no issue with someone restoring to "Factory"
So all I am saying is to be careful about opinions because others will have differing opinions and reasons.