Peace may be found between a 45 and 48 slow. The 190 main should bring great joy but you must avoid impoundment. Many, many years ago while testing high speed jet on an unopened section of interstate highway the local police found it necessary to impound both me and the sickle. I did not know about dyno tuning but the ticket for 122mph was better than a print out. I still have it . The speeding charge was dropped but the tresspasing charge was not.
There goes peace of mind.
Everything was great with the re-jetting and then I stopped into the dealer and found out Mikuni now makes its 42 and 45 flatslide for HD to sell under the Screaming Eagle banner. Takes the Screaming Eagle air cleaner set-up I already have. No extra parts needed and the price is in line with what the Mikuni sells for in the US. So, aside from three mils, what are the performance gains/differences between the 42 and 45...
With visions of carbs still dancing in my head....
03FXST
Yes the SE flatslide is a Mik. Either can be tuned to work well. I ride with guy with a 45 on an FXDC Evo 1340 and the results have been excellent. He went from a 42 that was on the bike to a 45 SE and seems pleased with the results. Not sure if it was the 3mm or somebody that knew how to tune a Mik.
I have had carb visions and they can be hard to tune. Dual Weber 2bls on my VW. Dual Amal GPs on my Vincent . A DCOE 40 on a Triumph. It is always a case of just because you can does not mean you should.
If the visions do not go away I can send Fuzz over to drink with you until they stop.
Hey Wright
At the risk of having Fuzz drink me under my own work bench I continue to dwell. I think Buzz is setting me up though. Is it a mere coincidence that Tom Johnson compares the S&S to the Mik this month. I think not. I am curious about one comment he makes about the bigger bore carbs though. "....there would probably be a trade off in low speed performance with either."
Why would that be? Is there a severe loss at the bottom end?
Also, my mill is still grumpy on start up at times. Would the Mik improve starting. Their website says it would.
I guess I missed out on who/what Fuzz is,, tsk tsk.. And Wright won't mind my buttin in..
I will dis-agree with the notion that--- "....there would probably be a trade off in low speed performance with either." ----
when talking about a Big Bore S&S compared to a Mik..
I measured my S&S G, the Venturi is 1.755"..
My 45 Mik's throat,, clear thru is 1.775",, .020" Larger than the G Venturi..
The 45 Mik runs perfect on my Deep-breathing 10 - 1 comp 80" (for example) And Better than any other carb I've run on it..
No loss, instead an Improvement in power/snap/mileage/ and over-all perfomance over all other carbs..
You know me 03--- I don't talk it unless I've done, so here's more..
I also ran the Super G on the 80" and it DID lose a tremendous amount of Low-spd,, Low-end power et. al.............
Now, why is that,,,,, the Slide in the 45 acts as a kinda-sorta adjustable Venturii,, as you twist the wick the slide opens more increasing it's own Venturi size at the same time,,,, it's kinda like that,, I'm tooo lazy to look up and quote the exact Carburatorese that you or anyone can find to confirm..
As I've explained before and it can be read about,,, the Venturi in the G is the culprit,, it is wonderful at High Rpm--- High-Velocity runnin but Not worth a crap in Our regular around town jump-it on the Hi-way driving on a smaller motor.. BTW----
I ran the G on the 120" and it was good,,,,, I installed a 48 Mik and Everything improved from much more snap to about 15% better mileage..
Same with the 127"..
And, Ooh yeah---- the 127" buttons easier with the Mik 48 than the S&S G..
Sooooooo, Yes, there will be a Severe Loss of performance at all but High-Velocity runnin with the S&S G,,,,, but NOT with the 45 Mik..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
I haven`t read the article but I will. The reason people think bottom end power will be adversely affected is the loss of port velocity with bigger anything. Bigger carb, bigger ports, bigger valves and low end power goes down until you are moving enough air to get it back. This was true before modern carbs changed the rules. It is still true with mismatched parts and old style carbs. I don`t think their is much to talk about going from a 40 to a 45 in bottom end power loss. My thinking come from working on op bikes and doing installation work. Miks are neat. No I don`t own one.
I rode an 05 RK with a G that had bottom end problems buring Bikeweek. The bike had an expensive set of heads with long duration cams. Was the carb the problem ? Partly but this combination was picked from the catalog fpr max cfm and peak dyno numbers. Retuned the carb and geared down. Happy owner except for highway rpm.
Hey Frisco
How do you get better mileage on a bigger carb with a larger manifold? Doesn't more air flow mean more fuel going in and therefore a drop in mileage. Or do the Mik's run more effeciently at cruising as opposed to racoing speeds?
My only guess is that the Mik's are sooo much more efficient as in metering the correct "needed" amount of fuel at a given Rpm--- off the line, cruising and High-speed..
Remember--- timing must be finalized and perfect Before fuel tuning..
For example,, the 120" got very good perf out of the G but averaged 34 mpg..
Of course I tuned it perfectly but I never fully trusted it especially on our 116* days.. If I fattened up the Intermediate to help dis-courage detonation it was too fat at speed so I would have to lean the Main--- OK, it had more umphf off the line but would occasionally ping if I hammered it at hi-spd..
OR Vice-Versa.. I had tricks that helped alot but did not cure..
It's that large Fixed Venturi..
With the larger 48 Mik I got more power, Not percieved power---- more power, and increased my Mpg to 39 at the moment.. My Mpg changes during the year,,, I think it's because of the Different Mandatory Gas additives that lower the BTU's 6 months outa the year here in AZ ..
The same with the 93" shovel and the 80" going to 45's..
The 127" went from 31 with a G to 36+ with a 48 Mik,, all with more power too..
Like I said,, it's just a guess, but I think it's simply a more efficient unit..
That's my experience..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
Okay. I tried to stop myself. Wright, I even considered having Fuzz drink some sense into me, but its too late. The Mikuni 45 Flatside is here. I just had to do it. I'll install it this weekend. Wish me luck.
Looking for power in all the right places..
03FXST
Re: SE 44 mil carb 
Linear Mode
