T350R Fuel tap

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saab9002
On the street
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Joined: Mon Mar 05, 2012 9:44 am
Country: uk
Suzuki 2-Strokes: GSX250,GT750.GS850G,2XGT250 GT550M, T350R
Location: Hampshire UK

T350R Fuel tap

Post by saab9002 »

Good afternoon All,
Just had the carbs and fuel tap ultrasonically cleaned after a bit of a lay up, put it all together, started 4th kick and ran up well, then fuel started pouring out of the bottom of the diaphragm. Stripped the tap and lapped in both the faces of the diagram body and cap with 800 wet/dry, no tears in the diaphragm so put it back together and it's doing the same, I've got a spare diaphragm and changed that but still the same.
Can anyone point me in the right direction, either blanking off the diaphragm part of the tap or any other suggestions. A new tap is as I'm sure you all know, is a bit pricey, if you can get one.
regards Chris
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jabcb
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
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Re: T350R Fuel tap

Post by jabcb »

Gas is probably pouring out the vent hole in the petcock base.

The vent holes in the diaphragm & the pentagon-shaped plate have to line up with the vent hole in the petcock base.
See:
Image

You may be missing the tiny gasket that goes between the petcock base & diaphragm — it seals the vent hole.
See tiny gasket it this pic:
Image

Those pics are for parts that this website sells:
https://hard-to-find-parts.de/epages/af ... hn_Auspuff



Alternatively, you could use a manual petcock. I’ve had good luck with the manual petcock that Paul Miller sells on eBay.
See:
https://www.ebay.com/itm/172308959807

When using the manual petcock, you will have to seal off the carb’s petcock vacuum tap. You can use a vacuum line cap from an auto parts store.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
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karl pa
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Re: T350R Fuel tap

Post by karl pa »

jabcb wrote: Wed Jun 09, 2021 4:02 pm Alternatively, you could use a manual petcock. I’ve had good luck with the manual petcock that Paul Miller sells on eBay.
See:
https://www.ebay.com/itm/172308959807
I have done the same with no problems.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
saab9002
On the street
Posts: 11
Joined: Mon Mar 05, 2012 9:44 am
Country: uk
Suzuki 2-Strokes: GSX250,GT750.GS850G,2XGT250 GT550M, T350R
Location: Hampshire UK

Re: T350R Fuel tap

Post by saab9002 »

Thanks jabcb and karlpa
Do you mean the very small one above the spring and below the filter, if so on uk models it is moulded into the diaphragm not
separate.
I think you are right it is coming out of the small hole in the diaphragm body and I can't get a replacement diaphragm anywhere.
I've had a look at the manual taps that Paul Miller sells and that looks the I'll have to go, but I still can't get my head round why it's
leaking, everything is cleaned up and aligned ?
Thanks again for the reply.
regards Chris
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jabcb
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: T350R Fuel tap

Post by jabcb »

Yes, the very small one.
I don’t think it was molded into the diaphragm, but sticks to it because of age.

Suzuki didn’t sell diaphragm repair parts. Perhaps because there is a “trick” to getting it to work correctly.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
saab9002
On the street
Posts: 11
Joined: Mon Mar 05, 2012 9:44 am
Country: uk
Suzuki 2-Strokes: GSX250,GT750.GS850G,2XGT250 GT550M, T350R
Location: Hampshire UK

Re: T350R Fuel tap

Post by saab9002 »

Hi jabcb,
Thanks for the tip, I'll have another look at it, just had a thought, the O ring on the end of the diaphragm that goes into the body is worn and it could have been letting fuel through all the time so I tried to remove it, needless to say, it split so I've had a measure up and found some in the UK and ordered, the size I've ordered is 3.5mm I/D with a 2mm cross section, whether it works or not I'll post the results, it might help others in the same boat.
regards
Chris
karl pa
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Re: T350R Fuel tap

Post by karl pa »

saab9002 wrote: Thu Jun 10, 2021 9:02 am just had a thought, the O ring on the end of the diaphragm that goes into the body is worn and it could have been letting fuel through all the time
Unfortunately that o ring only controls fuel flow to the carbs, which can be a problem with flooding carbs and engine, but shouldn't have any connection with fuel coming out diaphragm vent hole. The normal cause for fuel leaking out vent hole while running is a tear in the diaphragm. I know you said there is no tear in them, but I would have another close look, especially around the valve peg.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
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