Reddit mentions of ATVATP 4X 494768 Shut Off Valve for 1/4" Fuel Line for 698183 Cut Off Valve 697947 493960 5091 5091H 5091K & 493629 691035 Fuel Filter

I HAVE THE SAME BIKE!
Mine is a GS450TX


TL;DR = fix bike fairly quickly and just ride :)


I hope this helps.

(INCOMING WALL OF TEXT!)

2 years ago I cut my mufflers off and mounted Emgo Shorty's. I also replaced my air box with Uni foam pods. I re-jetted the pilot from 17.5 to 20. I moved the main jet up from 115 to 122.5. I briefly cleaned the carbs with the spray parts cleaner, set the air mixture screws to 3 turns, and reassembled the bike. It ran like crap because I took so many shortcuts. I spent a couple weeks riding and fighting with the bike then I parked it for winter. 2 years went by and I didn't even want to deal with the crappy state my bike was in so I left it parked until we moved (better school zone for kids).

Once we got settled I brought my bike home and started tearing it down.
I spent a couple weeks doing the following:

• Downloaded manual = https://skydrive.live.com/redir?resid=2370B62DDF9F0C6B%211334&authkey=%21APM7hx6Q2ynLu-A
  
  
  
• Properly cleaned the carbs (soaking them for 12 hours in original Pine Sol (50/50 mix with water) cleaned them better than any other parts cleaner I've used in the past). All of the rubber on the carbs were in excellent shape, so I lucked out there. Rinse with mild soapy water then hit each part for 1 minute with toothbrush. Rinse with water and reassemble. Adjust air mixture screws to 2 turns out.
  
  Bench-sync slide/butterfly valves PDF Guide = http://members.dslextreme.com/users/cbsaunders/gs/gs450_carb_cleaning_guide.pdf
  
  Parts = https://www.partzilla.com/catalog/suzuki/motorcycle/1982/gs450t/carburetor
  
  Rebuild = https://youtu.be/w16in05ANN4
  
  Soak = https://youtu.be/zDkOgnPidPs
  
  Bench-sync = https://youtu.be/AS77T2CUsjI
  
  
  
• Changed Jets to: pilot = 22.5 / main = 130
  http://www.jetsrus.com/a_jet_kit_street/suzuki_450_GS450S.html
  
  
  
• Carb boots + o-ring were still in good shape so I left them alone.
  Test boots for leaks = https://youtu.be/XzjSEYB9RDU
  
  
  *Modified Uni foam pods: 1) removed half of the inside lip with an knife so the air intake circuit wouldn't be partially obstructed 2) Temporarily restricted Uni pods by taping a ziplock bag around the sides and cutting the bag away from the back end so air intake would be smooth.
  
  
  
• Removed gas tank and filled it with a 50/50 mixture of distilled white vinegar & water for 24 hours (be sure to remove gas cap and petcock and tape closed). Drain mixture from petcock hole, take a picture of 1lb of rust chunks and post on Reddit for easy karma :) Fill tank 25% with water from garden hose and shake for 1 minute solid. Drain and repeat x10. Ok, last time add 1/2 cup of baking soda/powder to neutralize vinegar. Rinse clean.
  Clean tank = https://youtu.be/UpaGo_nq5Rk
  
  
  
• Test petcock vacuum before reinstalling. Suck in vacuum tube and plug with finger. Test Reserve, Fuel, and Prime settings. The latter should be the only one that allows air to flow without sucking on the vacuum tube. My petcock's diaphragm was ruptured so I replaced it. Pro Tip: don't by the cheap $20 replacement from Amazon. It is crap and constantly leaks fuel on all settings once fuel begins to flow... even when no hoses are attached. Find the OEM replacement for $45 and move on.
  
  
  
• Install new fuel/vacuum/vent hoses on carb. Also get a cheap kit from Amazon that has an inline fuel filter and cutoff valve. (This will make draining and carb maintenance easy) https://www.amazon.com/dp/B07MXH6Z7S/ref=cm_sw_r_cp_apa_i_tse1CbD0V0DY3
  
  
  
• Test battery charging system = https://youtu.be/njky7cNEdYU
  
  
  
• Change engine oil = https://youtu.be/Opqbbqfxmsk (use Lucas semi synthetic 10w-40 to aid with shifting due to wet clutch)
  
  https://www.amazon.com/dp/B001KWGA10?ref=ppx_pop_mob_ap_share
  
  
  
• Buy a Seal Mate (or make from plastic container) to fix fork seals if dirty = https://youtu.be/8wlzfoVroSY
  
  
  
• Change fork oil = https://youtu.be/81hWzXOAvww (use Lucas semi synthetic 10w if under 200lbs, and 15w if over 200lbs. Also, when you refill fork oil compress forks completely, with springs removed, and fill to 6 inches from top)
  https://www.amazon.com/dp/B0041CDW7G/ref=cm_sw_r_cp_apa_i_Pye1CbGHFE87B (buy locally at O'Reilly's cheaper)
  
  
  
• Change tires = https://youtu.be/D8MFXZr36hs
  (I found a great deal on Kenda Dual Sport K761's at http:/denniskirk.com Front = 100/90-19. Rear = 120/90-17.
  Tools needed = Spoons with 2 Rim Protectors https://www.amazon.com/dp/B079JZN5BC/ref=cm_sw_r_cp_apa_i_QEe1CbCMX9JBM
  Balance tires easy = E-Z Tire Beads Motorcycle Kit, Ceramic Balancing 2 oz Front + 2 oz Rear. https://www.amazon.com/dp/B00VOAOSDA/ref=cm_sw_r_cp_apa_i_hDe1Cb8QTNKYF
  
  
  Other notable links:
  
  The GS Resources = https://www.thegsresources.com/
  
  GS Forum = http://www.thegsresources.com/_forum/index.php
  
  Bike Cliff's site = http://members.dslextreme.com/users/bikecliff/
  
  Parts = https://www.babbittsonline.com/oemparts/l/suz/50d3f2caf8700230d8b4bf8c/1982-gs450tx-parts
  
  
  *** After all this maintenance, my bike starts easily, sounds incredible, shifts wonderfully, is very reliable, and a hell-of-a-lot of fun!
  
  
  ~Best of luck friend~