We have changed all of our float bowl seals to Fluorosilicone (basically a blend of FKM and silicone). Also jet housing seals and some float seat seals will also be changed. The reason is that Fluorosilicone (FVMQ) suffers very little from swell when fully immersed in ethanol blend fuels and returns to exact original size within a few minutes. I am not going to rant on about how good this stuff is. You can read about it yourself on the internet rather than listen to my biased opinion. Anyway I have been running all sorts of tests over the last year. Here are some. Here is one of our FVMQ seals that had been fully immersed (assembled in a carb) for 90 days. When removed it showed a minor amount of swell but within 5 minutes looked like this. Now what happens if the seal were fully immersed by itself and not fitted into the carb? This seal I threw into a bottle of rotting fuel on the 1st May. It is now the 27th May. Still fits perfectly. Now you are thinking, 'so what I can buy OEM parts or good Chinese stuff'. I threw a genuine Kawasaki float bowl seal into the bottle at the same time. This seal was used as the pattern for our FB-024 part (the blue one in the image). Good luck trying to get that back into the bowl. For your Chinese junk, if it has not dissolved then you should be happy with that. Furthermore, the OEM part has lost a lot of strength. It has turned limp. Now I know that this is an extreme case. Your float bowl seal is not completely submerged, but it demonstrates the point. In the past, we were using FKM (Viton) which also suffers from swell about the same as the NBR that the OEM parts are made from. It does not rot away like the OEM part but the swell is not acceptable as far as we are concerned. Fluorosilicone is not cheap, it costs more than FKM (Viton), in fact more than just about everything else. However, it is a superior elastomer for purpose. Sorry, it took me so long to get to this point. Originally I relied on scientific research to choose FKM, but unfortunately all of that research is not done with the tiny section gaskets that we use. I had to conduct my own tests over time with different elastomers to get the results I wanted. Cheers Blair
For all the troubles that the carbs on the little (and not so little) four cylinder bikes give us I am so thankful that someone like @maelstrom has taken the time to research and invest in finding and producing these great fitting and lasting seals. Thank you Blair.
Thanks Mr Jet. I just want to do a good job. Got lots of new stuff in the pipeline that should be coming soon and help owners with various issues. Sorry, ZXR owners, the hoses are still in limbo at the moment.