Ethanol/Methanol/E85 Carb Conversion

[ggl205]

Ross, have you given any more thought to dry sumping the float bowl? No more needle & seat or float.

John

[wobblywalrus]

Is there only one carb?

[Stainless1]

And only one turbo, but there is a thought Ross... twin turbo twin carb twin... 

[mc2032]

Happy Fourth of July (credit to Joe Dirt).  I think this is the same outfit I bought my turbo from.

[wobblywalrus]

The force that closes the float valve is caused by buoyancy of the floats.  Any aeration of the fuel in the float bowl due to heat or vibration reduces fuel density and lessens the upward buoyant force from the floats.  Also, leaky or soaked floats have less buoyancy.  It is a good idea to make sure the floats are in good shape.

Pressure is force divided by area.  The upward force from the floats causes more pressure on a small diameter float valve seat due to its lesser area.  Sometimes we install big valves to pass large amounts of fuel and this reduces the float seat pressure too far.  The fuel pressure overcomes the forces from float buoyancy and the float valve does not cut off fuel flow.

All of this can be calculated.  Fuel demand can be estimated using formulae in John Baechtel's "Performane Automotive Engine Math."  The carb manufacturer can give the correct size of float valve needed and help with the rest of the calculations.

The two 45mm Mikuni flat slide carbs on my bike have enough float fuel flow capacity to feed oxygenated gas to a 120 horsepower natural aspirated 1000cc twin cylinder engine.  This is a puny engine by Harley standards and both of the carbs have larger than standard float valves.         

[mc2032]

Bo, vibration/aeration might be part of the problem as this motor is not much more then two paint shakers joined at the hip.  I am using the race (6AN inlet with the larger needle).  the stock needle/seat is at Stainless's so I can't get a measurement to compare to the race sized inlet/seat.  The overflowing fuel has been an annoyance more than a performance issue.  the facet/purolator pump is there just to assure the bowl stays full.  I have confidence that gravity would supply the carb but I had the parts and used them.  Aero improvements next, after I put all the nuts and bolts back on the bike that shook off during tuning.

[wobblywalrus]

Mikuni makes carb kits for Harleys.  They are the HSR series flat slides.  Those carbs are what I use on my bike.  They hake a special needle valve assembly for use with a fuel pump.  It is size "2.3" (part # 007-478).  The ones I use with a gravity flow system are size "4.5" (part # 007-708).  Smaller valves are used with a pump so the valve will have adequate seating pressure.  These carbs mount to a rubber spigot on the manifold.  This provides some insulation from heat and isolation from vibration.  The counterbalances are removed from the engine and it runs for miles at 8,900 rpm.  There is some vibration, for sure.  This does not seem to affect the mixture. 

[mc2032]

Spent a few evening at Bob "Stainless" Steeles putting a little aero on the race bike.  Yes it is barely a polished turd, but it is entered in Speed Week.  I think there is a saying that goes something like pretty is pretty and fast is fast.  I just hope this thing goes pretty fast, relatively smoke free.  There are a few things left to button up before next week but I think we will get there, fingers crossed.  Did add some shade to the trailer, 8x10 should make a few friends.

[Sporty Dan]

Glad you are getting all ready to go. I've got just a few more things to do on the bike and then another shakedown run tomorrow. Then it's time to start organizing everything to load on the trailer.

[mc2032]

Sorry about the delay reporting an update, my bad.  Speed week was good and not so good. Track was less than desirable, the SCTA did their best with what they had, 'nuff said about that and beating that dead horse doesn't do anyone any good.  So, I did learn bunches from everyone I met/talked to. And what I learned was aero, something I did not have.  So, let me introduce the Powers/Steele or Steele/Powers bike for 2020 and beyond.  This mint '95 1200 is going to become the next dyno mule to test the limits of our Jackson swingarm dyno adapter.  Best described as a 600 pound magnet drug through the chrome spare parts bin.  Plan is to get this jewel started, first.  Then keep it running long enough to run through the gears at least once.  If it doesn't turn itself inside out by then, strip it to bare metal, add some cc's to get closer to the class size limit, EFI and turbo then wrap it in something slippery. More to follow.

[Sporty Dan]

Ross, sounds like you have quite the project to  keep you busy over the winter. It was great meeting you and Stainless in person. Thanks for all of the information and beer you gave me. I definitely learned a lot as a rookie and also realized exactly what you guys meant when you said that running on the salt was different. Looking forward to seeing the progress on the new bike.

[generatorshovel]

John Trease (rip) had a misfire all week , eventually he tracked it down to carb bowl vibration, it sounded like,,,
https://youtu.be/y0ULiYk8zf0