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Question Carb top gasket

  • hackman101
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Replied by hackman101 on topic Carb top gasket

@Loner, thanks for checking. I may be asking a real noobie sounding question. Will the rubber be affected by the gas/oil mix degrade the rubber at all? If not, it would be a piece of cake to cut one out of my 40 year old rear wheel inner tube when I change the tire...
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
26 Nov 2021 21:05 #21

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Replied by loner on topic Carb top gasket

Should be fine, more of an air seal rather than being constantly submersed in fuel. The seal on the fuel cap is rubber.
27 Nov 2021 09:11 #22

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Replied by MarkT on topic Carb top gasket

Some inner tubes I've tried to use for gasket material turn to a gooey mess when exposed to petroleum products for a while...  it would be okay for a while.

Butyl rubber (what many tubes are made of?) is rated "unsatisfactory" for exposure to gas and oil...  if it stays dry, fine...  but usually cap gets wet on my bikes.  YMMV.

I had a really old inner tube (early 1960's is my guess) that worked fine...  I think the rubber was different than more modern inner tubes? 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
27 Nov 2021 11:00 #23

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Replied by RT325 on topic Carb top gasket

I my opinion--the washer in the cap doesn't do anything except make the cap less likely to unscrew by itself--on a vibrating old 360 lol. Just gives a slightly rubbery feel to tighten fully, although they're more plastic i think.
27 Nov 2021 15:08 #24

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  • hackman101
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Replied by hackman101 on topic Carb top gasket

My original gas cap gasket for the plastic screw on gas cap (body cap Yamaha curiously calls it) still had some flex to it still, but the screw on cap itself had shrunk so much the threads would no longer engage. It was a bit of a stretch to get the old gasket over the new cap, but it made with out damage.

It looks like to be on the sure side to get a new gasket for the carb cap off ebay. I will check for the gas cap gasket too since the gasket fits the cap so snug, it has "coned" the old gasket. It is even the detent for the gasket, but....
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
27 Nov 2021 18:53 #25

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Replied by Ht1kid on topic Carb top gasket

Go to Napa and get some gasket material and cut one to size
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28 Nov 2021 09:15 #26

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  • hackman101
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Replied by hackman101 on topic Carb top gasket

@Ht1,Thanks for the idea, I don't know why the tightwad in me didn't think of it.....
A little off topic, your username reminds me of WWE or actually WWF with HBK and the 1-2-3 Kid
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
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28 Nov 2021 10:38 #27

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Replied by Ht1kid on topic Carb top gasket

LOL Hackman101 that’s a good one I’m to skinny for WWE of course Ht1 was my first enduro rode that bike to death
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28 Nov 2021 11:20 #28

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Replied by Scootern29 on topic Carb top gasket

I checked my stuff. Fresh out of them.
Question authority, think for yourself!
28 Nov 2021 13:43 #29

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Replied by MarkT on topic Carb top gasket

I found two old gaskets, both pretty crispy. I have a new carb and that one is fine. Very flexible. But keeping the new one. 

Niche cycle is a Mikuni dealer so should be OEM quality. Or make your own as suggested.  
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
28 Nov 2021 13:46 #30

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