1200cc engine, VM29 carbs, Pods, what jetting?
- Nessism
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Re: 1200cc engine, VM29 carbs, Pods, what jetting?
04 Feb 2026 09:41Some people think Viton O-rings are better than nitrile, but in truth, it depends on application.FYI : The labyrinth O ring gaskets on RS/TM/CVK are 2mm OD, the groove they sit in is about 1.6mm deep X 2.2mm wide. Shown is a float bowl from a 1985 Canadian version GSXR750R which were early TM series 29mm flat slides.
The only downside of the rubber gaskets is when the are wet with gas they swell and will not go into the groove unless you heat the rubber to remove the gasoline. A few minutes with a heat gun usually shrinks them down enough to go back into the groove. Its a pain to do but if you don't the gasket will pinch somewhere and you will have a substantial fuel leak.
Nitrile swells slightly with gas contact. So in applications where the O-ring is trapped in a space, they affect a good seal. Fuel Tee's and transfer tubes are an ideal application. Those float bowls are another. Funny, on my old Nissan Sentra car, when pulling the fuel pump, the O-ring was swollen up just as you mention. I baked it in the oven at 175F, for half an hour, and it shrunk down to size, so I could reinstall it.
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- Wookie58
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Re: 1200cc engine, VM29 carbs, Pods, what jetting?
04 Feb 2026 10:44 - 04 Feb 2026 10:56
From what I have read, Nitrile is OK in gasoline but not so good in Ethanol. The Viton I ordered swells less than 10% in 90/10 gas ethanol mix (having an issue there as I have 2 pieces 1.5mm thick and 2 that are 2.00mm thick. I ordered all 1.5mm but they ran out so just sent 2.00mm instead !!!!)
Every day is a school day for me right now
EDIT: having re-checked I see that whilst Nitrile is not good for E85 fuels, in the UK the common is E10 so as you say Nitrile will be fine (which is good as I have a sheet of that which will do all four carbs
Every day is a school day for me right now
EDIT: having re-checked I see that whilst Nitrile is not good for E85 fuels, in the UK the common is E10 so as you say Nitrile will be fine (which is good as I have a sheet of that which will do all four carbs
Last edit: 04 Feb 2026 10:56 by Wookie58.
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