I've got a FCR41 on my Sparks parts 465EX. This weekend I tried to tune the carb in for alky. I wanted to make sure I was good and fat so I installed .113 main jet, .043 pilot jet, 1.5 out on the fuel screw, 3 turns out on the air screw (behind the bell, air filter side), OCFBK needle on bottom clip as directed by FTZ. I wanted to be very rich and figured that this might do it to start. First off it would die the moment I let off the gas and when I ran some wide open runs it felt sluggish...not as much power when I was running gas, and occasionally it would back fire on deceleration. Is this a sign of lean or rich? I wanted to get it where it would bog then come down from there. I could not get it to bog even with a .125 main jet installed. What jetting set ups are you guys/gals running in your ex's on alky. I need a good starting point on a FCR.

Thanks
Jay

 

I know ABSOLUTELY NOTHING about alcohol but a backfire normally means a lean condition. I am going through the same growing pains with my 250X. I have been backfiring and the plug is grey (a little lean). Wish I could help you out.

 

Jay, what does your plug look like? Sounds like you are still lean. My 352 ended up with a #30 drilled hole (.1285") with my 39. Are you running a top end lube? What mix?

 

My plug is good and dry. I did not run the machine long enough to get a good plug reading. As I mentioned I went all the way up to a .125 drilled out mj and backfiring did not stop and power was way down compared to gas. I'm running Uplon, 1/2 oz. per gallon as specified on label. I'm thinking I might have to go in and drill out the emulsion or dump tube to get more alky through it. I did a search and found a thread authored by WideLoad that is pretty detailed. Wide Load said that the emulsion tube had to be .022 larger than the needle. I think I'm way fat on the idle circuit for the motor dies as soon as I let off the throttle.

Thanks
Jay

 

The dump tube on the FCR should be large enough to flow the alky. Both of mine were setup by a guy that worked at FTZ, and as far as I know, he didn't drill them out. Like I said, I was running a .1285. My tube supported it, so yours should flow for the .125. Is the 125 the largest jet you have?

 

Alky...125 is the largest that I have at this time. I'm going to drill somemore mains larger and see what happens. I will try the #30 and a #29 (.1360). What needle are you using Alky? I'm using the OCFBK, they make a OCFBH that is richer.

Thanks
Jay

 

I sanded down a needle to match what I wanted. I can't remember which needle I started with but it was one for a gas 39. Your 41 might be a longer needle. I know the length is different between my 35 and 39. I never seemed to be able to richen my midrange without making my low too rich with the needles that FTZ supplied me with. So, figuring I had nothing to lose I started sanding. Put the needle in a drill press on low speed and went to work with a fine paper. This is probably not the best way to do it, but it worked.