Running Rich and Ethanol Fuels
Posted: Fri Jan 11, 2013 11:10 am
Alcohol blend fuels are becoming a fact of life and sooner or later we are going to have to deal with it.
Viton is the best elastomer choice for ethanol blend fuels. If you want to know more about Viton(FKM) then read this excellent document produced by Oak Ridge National Laboratory http://info.ornl.gov/sites/publications ... b27766.pdf The conclusion of that document is that Ethanol blend fuels are worse than pure Ethanol and that NBR, what your carb seals and o-rings are made from. is the worst material to use. Some members on the V4 forum have been considering the fuel lines and other parts that would also need to be replaced.
Now the richness problem with Mikuni BDST carbs. Most carb seals are there to stop the fuel leaking out. However, the BDST carbs have seals that stop fuel leaking into the throat. They have to be in top condition or your bike will run rich and no amount of fiddling with float heights, mixture screws, main jets or needle clips is going to solve your problem. Your NBR carb seals become brittle when exposed to stale fuel. Many compatibility guides state that NBR is fine with gasoline. Yes, but that is only true if it is fresh. NBR has a shelf life of 15 years, and of course a much shorter service life. How old are your carb seals? How old are the seals at your local supplier?
Please read this assembly guide
http://www.litetek.co/Guide_MikuniBDST_ ... gAssy.html
Also check the condition of the needles and emulsion tubes. There are several good guides on the internet that discuss wear of those two parts and Factory Pro http://www.factorypro.com/tech/needle_jet_wear.html is one of them.
cheers
Blair
Viton is the best elastomer choice for ethanol blend fuels. If you want to know more about Viton(FKM) then read this excellent document produced by Oak Ridge National Laboratory http://info.ornl.gov/sites/publications ... b27766.pdf The conclusion of that document is that Ethanol blend fuels are worse than pure Ethanol and that NBR, what your carb seals and o-rings are made from. is the worst material to use. Some members on the V4 forum have been considering the fuel lines and other parts that would also need to be replaced.
Now the richness problem with Mikuni BDST carbs. Most carb seals are there to stop the fuel leaking out. However, the BDST carbs have seals that stop fuel leaking into the throat. They have to be in top condition or your bike will run rich and no amount of fiddling with float heights, mixture screws, main jets or needle clips is going to solve your problem. Your NBR carb seals become brittle when exposed to stale fuel. Many compatibility guides state that NBR is fine with gasoline. Yes, but that is only true if it is fresh. NBR has a shelf life of 15 years, and of course a much shorter service life. How old are your carb seals? How old are the seals at your local supplier?
Please read this assembly guide
http://www.litetek.co/Guide_MikuniBDST_ ... gAssy.html
Also check the condition of the needles and emulsion tubes. There are several good guides on the internet that discuss wear of those two parts and Factory Pro http://www.factorypro.com/tech/needle_jet_wear.html is one of them.
cheers
Blair