Looking for a more fuel efficient carburettor

I seem to remember my local Indy bemoaning a customer bike with a Chinese Mikuni with issues. I think the complication was metric threads...and jet compatability issues. I may have mis-remembered ill check with him, he was warning me to be cautious as I was looking for a cheap Miki for my Evo.
I seem to remember my local Indy bemoaning a customer bike with a Chinese Mikuni with issues. I think the complication was metric threads...and jet compatability issues. I may have mis-remembered ill check with him, he was warning me to be cautious as I was looking for a cheap Miki for my Evo.
I have post on the shovel page ( facebook)
about these knock offs ,, and the consensus is there good ,,thats the CV,,Mikuni and the S&S copies
i have ordered a CV just to evaluate ,,,£42 the parts alone for the slide would be more than that for original
and how would you know if the parts you buy are not knock off
Ther carbs will need a cable setup as i don't think it's easy to convert to '73 wire throttle.
tik-tok, though not 'easy'. it is not difficult to make early internal piano-wire cable work with kehein-CV or otherwise.

i ran piano wire with CV for years and years. now piano-wire with SU.

can show what to do when im home in a few days if i tetested?
Copied from my thread below yours in the Vintage section.

It may be useful :

Also the whole website is full of useful info, have a look.

If the heavy fuel use is a new thing then the float could be getting fuel inside it. I have read that ethanol can attack solder and I think the Bendix has a soldered brass float. If this has happened it may be possible to paint/coat the float with a ethanol resistant product like that used for petrol tank lining.
the cheap knock off CV turned up today ,
opened the box and theres new petrol tube and filter ,plus 3 main jets and 3 pilot , and a spark plug

on looking at the casting it looks good the slide works as it should ,
so next thing is strip it and see what it look like inside ,,
First problem was the screw holding the float bowl were over tightened and two were damaged getting them out .
no real problem as i have plenty of M4 allens .
every thing inside is good s i will fit it and see if it compares the the original ,,cant see why not ,,
i was going to sell on after i have assessed it ,but now i think for £42 its worth keeping
A CV will give you better MPG but so will losing weight or wearing skinny jeans haha only teasing mate, if you want better mpg before changing out the bendix ( which is a great carb ) I’d look at your gearing first. Stock Flh is geared crazy high 22-51 ? I’d switch out to 23-48.
I'm running 25-48 on the Pan/Shovel but it is a relative light weight compared to a Shovel Electra Glide and I don't add a lot to that. It drops the engine revs to about 2700 at just under 70mph and will pull away on tickover until the primary belt starts to bounce/judder.
Im going down the CV road with my bike, not for fuel economy I just want to see
what the bike is like with a standard carb on as my bike came with a mikuni hsr42
smooth bore on when I bought it in 89 (85 softail)

The bike was originally fitted with a keihin butterfly carb from new, I got this with
some other bits off the previous owner when i bought the bike & still have it but I
dont want to put this carb back on the bike, I want to try a CV as they get rave reviews.

Economy wise I dont think the hsr 42 is to bad, me & my brother rode to the 2022
chill out rally at Southam together, he rides a 2008 fatbob, a journey of about 130
miles, when we filled up for the ride home it cost me £2 more for my full tank than
it cost my brother, not bad for a carb V efi.

I managed to pick up a very low millage Genuine CV of a early twin cam dyna last
year on ebay (looks virtually new to me) complete with air box & filter, so thats the
next job before the first rally, will let you know how I go on.

IMG_20240206_180219086_HDR.jpg IMG_20240206_180106184.jpg IMG_20240206_200508485.jpg

The original keihin off the bike had done about 7000 miles on the bike before being changed
for the hsr 42 by the previous owner, its been in a box in my garage since I got the bike in
1989, it is of no use to me as its something I will ever use, if any CLUB MEMBER can find a
use for it let me know & I will post it out to you.

IMG_20240206_200758513.jpg IMG_20240206_200905450_HDR.jpgIMG_20240206_200854651.jpg
if that cv is bone stock, some neat upgrades is to replace the plastic fuel inlet for a brass one.
the obligatory N65C needle and drill out the mixture plug to access the screw and fit a thumb-screw one to aid easy tuning.
cv-performance ones are definitely machined better (thread/tip/thumb-wheel), but i found no difference in operation comparing to cheap chinese ebay ones.
also consider ditching the cable-chole for one that screw directly into the carb. i think kawasaki ones fit, as they use the same carb.
someone will confirm this?
i have a nice brass one made by some guy i got off ebay years ago after my cable failed and repro ones were just unfit for purpose.
jetting; 48 slow and 190 main is a good starter and likely all you'll need.
cv's operate on the slow-jet for like upto 3/4 throttle, main jet only comes in at almost wot?
riding around i find i'm mostly on 1/4 to half throttle, not much more?
food for thought.
your cv will not dissapoint.
to add to this from Jayzedkay
the choke from a Kawasaki is available off a KL650 that screws to the CV carb ...
this is new to me but just found them on Ebay and ordered one , £8,
Watch when you fit that choke, you will need to alter the fuel inlet angle, otherwise the fuel pipe blocks the choke knob or at the very least makes it hard to find on the move with gloved hands --
Don't ditch the old cable, I ended up fitting it to the filter back plate with a rubber covered "P" clip, much easier to use --
be interesting how you get on with that choke john?
is this what you have ordered, little over eight clams?


very similiar to what i have, but the main body on the one above looks longer to what i have, and that is an advantage.

agree with the fuel-inlet angle, i tweaked mine to suit fuel-hose better.
aided with some slighty thinner-walled quality fi-rated fuel hose.
most of it has stupidly thick wall which makes working with short pieces a pita.

operation wise, i guess it horses for courses and setup regarding access; tanks, cleaner-housing, support brackets etc?
after breaking my oem cable, i couldn't get junk cable to work properly. tried all sorts of orientations, brackets and placements. main issue it wouldn't stay out. having too tight a bend radius seemed to introduce other hassles?
considered tracking down an oem cable or making my won. but then came across the hard-assemblies, unaware of the kl650 compatability at the time, but considered them a better option?

i never ride on choke, even colder/winter months; start bike and dick about getting ready to ride. by the time i'm done or so, it's off choke and will idle.
i always found an advantage to run an extended idle-speed screw too. basically an M4 is it, piece of 'thread' screwed into an appropriate outer-cable. i had a lambretta throttle-outer kicking about. i used an M4 tap to put some thread inside the outer-cable. all loctited up for integrity. other end a M4 thumbscrew with same prodcedure. whole assembly just long enough to give access.
you can see the thumbscrew poking from behind the cleaner, about 12 o'clock pos'n.
i still run the same, but an su-cv.


i found that off choke, but not properly hot, it would benefit a turn or so on the idle-speed. but then once proper hot, back off to normal.

also i don't like those twangy-straps of metal from carb to centre bolt on the case to support the carb.
i considered a betterer option; neater and robuster carb mount to be utilising an evo-cv support plate and brackets.
it requires tweaking for alignment, but nothing a hacksaw, welder and bit of creativity can't resolve.
support hangs off the two lower-mounts on the rocker-covers. but only later rocker-covers have these mounts.
a spacer between hangers' and carb-plate provide alignment.
below is on my su during fabrication/install, but it shows the support-mounting clearly and simply imagine a kehein-cv instead of the su. capice?


anyway, opologies if thread somewhat side-tracked/hacked.
but it's all good 'cv' info/experience someone might benefit from?
Thanks jayzedkay, some good ideas there, im going to fit the CV as it is for now (standard) & see
how it goes, Can look at upgrades at a later date. The choke mod looks interesting but looks a bit
awkward to get at as Oldguy has said & being on the right side of the bike would have to let go of
the twist grip while trying to find it.

There's certainly plenty of kits & bits about to upgrade the CV & as you say the N65C needle is a
popular mod but will look at all that at a later date.
Thank you everyone for the various suggestions and advice. Very much appreciated!

I’m going to read up a bit more on this, before taking things to pieces.