For those thinking of retrofitting a CV40

[jbexeter]

Mine, '02 FXSTB, later SE Stage IV'd to 103 with the holley carb, which was IMHO a POS... all this done by the original owner who bought it as a stock 88 and started throwing money at it.

The holley *allegedly* did 98 BHP / 108 ft /lbs, the original owner no longer had the dyno sheet and couldn't remember where the dyno work was done, but that is what he was told... and that is what he told me.

Opinions are like assholes and everyone has one, but never trusted S&S for carburation since my Shovel days when we just went with SU, so for the twinkie the Mik HSR 4xx is the usual touted alternative, and a great carb, but it ain't a CV carb, and I *like* a CV carb, for many reasons.

So we finally got her on the dyno, initially it was built as an "internet tune" that saw a refurb HD CV40 with 220 084 main, 52 019 pilot and needle clip down 4, medium strength spring.

So CV40 with old style bugye filter and V&H big shots with baffles in.

Bike started and ran great but was obviously too rich at cruising revs (better than to lean so we loaded everything that way) but it was all seat of the pants stuff. Seat of my pants I reckoned 20-30% too rich... turned out I lowballed it..lol

BTW tip for new players in europe the main jet in the harley cv40 is a 6 mm thread, (and a 6.1 pitch at that, not the 6.08 like the dellorto) the euro kelhin cv40 main jet is a 5 mm thread.... also the harley Cv40 doesn't have an adjustable accelerator pump, gotta change the rod.... also watch out for jets rated in flow vs rated in diameter, the numbers are close-ish around the 1.9-2.0 mark

Throughout the aim has been a cruise / riding tune, not max power or anything.

Dyno was an AFR tune only.

On the dyno the original set up wasn't bad until the main jet opened, and AFR went as low as 8's, bike started and ran well and pulled cleanly from "slogging" rpm up to 5,700 but was clearly getting strangled as soon as the main opened up, to around 4,000 / 4,500 when you could see the effects of the 40 mm throat holding everything back.

Swap the 220 main for a 200 and and drop the needle one and AFR stayed between 13 and 12 (at 8 there was danger of washing the bores down with unburnt fuel) with a little bit of "sine wave" which we are going to put down to the pipes / reversion and so on, so good to go.

dyno itself was a dynojet and not a "happy" one either, HP curve was a nice smooth convex curve that still tailed off at around 4,000 RPM and was fairly flat (still slightly convex) from there to 5,700, so the numbers are 72 RWHP at 4,700 RPM.

100 ft lbs comes in at 3,000 rpm for those interested, so *very* tractable and rideable bike.

These are obviously low low low numbers in an absolute sense, unless you were comparing them to the stock off the showroom floor new 02 88 lump. (85 ft/lb - 49 bhp @ 3,000 from memory?)

Obviously a CV44 is going to give "better" numbers (maybe 80 / 85 BHP in my build??) and an HSR 4xx better still, but the CV44 is (here in europe) rocking horse "Potty mouth", and the mikuni ain't a CV, and that is what *this* bike is all about, simplicity and rideability, while liking some things that are bad for power and performance like V&H duals etc

So I thought I'd put this out there (as AFAIK this info was not available to me when I was researching this, or at least I couldn't find it...) for those thinking of taking a twinkie back to carb in general and CV40 in particular, and the numbers are a CV40 on 103" gives you 70 BHP at the rear wheel more or less, mebbe not enough for the bagger boys who ride 2 up, but 15 ft/lbs more than the 88 motor at 3,000 RPM and only really holding the 103 back from 4,000 rpm, so for the FX range probably "enough" carb to run the 103, so I certainly would not reject the CV40 outright as being way too small a carb for the 103 twinkie.

For *this* rider and this bike it is "enough", I *might* go to CV44 if one landed in my hands for free, but that's a big maybe.

Again, the numbers are "low" for a 103, but they are *honest*

If you're in europe and looking at the "complete" Mik HSR42 HD kit for 560 quid (xe says that is US$733 at today's rates) or a refurb ready CV40 for 50 quid and money is tight, don't discount the humble cv40 out of hand...

So for *this* rider and *this* bike (and euro 4% ethanol fuel) OK on a 110 motor the CV40 isn't going to be big enough but CV44 should do ya, 103 or less, the CV40 is a *practical* solution, *if* you're not chasing big power.

Obviously will be a million different opinions on this, but I can only report what I found on this particular bike / dyno / day etc, it is what it is, and what it is works for me.

[PC_Hater]

I borrowed the CV40 off my Sportster for the EFI to carb conversion on my now FLTR not I. (still not finished, waiting for an aftermarket petrol tap that fits to arrive.)
Sooo, where's all the 50 quid take-off CV40s then? All I can find on ebay is carbs from the USA at £160 plus £20 postage!
I would quite like 2 - The WLA45 could do with something better than a Linkert though I do have an SU carb available.

[jbexeter]

PM sent

[Don D]

Holley takes some dialing in. They are actually a nice carb. I have a new Holley in the box. Reminds me of dual throat S&S. Like a CV44 and 51 neither was perfect even with rejecting out of the box.

[jbexeter]

Holley takes some dialing in. They are actually a nice carb. I have a new Holley in the box. Reminds me of dual throat S&S. Like a CV44 and 51 neither was perfect even with rejecting out of the box.

yup, I'd have to agree, even dialled out *my* bike was *much* faster accelerating in any gear from 3k on up than it is on the CV40, the downside is the dialling in, and the "bulk and awkwardness" compared to the cv40

know a guy in germany who is running what he calls his "hsr eliminator" in a sort of homage to the old SU eliminator, dual HSR42 on individual tract but joined manifolds that are a work of art.... he says it no longer really runs or sounds like a harley

contrary to *many* on this board I'm not seeking high HP/CUID, if I was I'd probably be looking at a diavel not HD, but a diavel is everything I *don't* want in a bike.. lol.. if the new for 2017 HD lump was a 120 sidevalve with magneto I'd buy one... dribbles... 

[PC_Hater]

I replied to you PM.

Meanwhile, Joe Hunt does a magneto conversion for Twin Cams at $1500 or so, and it shouldn't be beyond the wit of man to do unspeakable things to a pair of cylinders to covert them to sidevalve operation then cast or machine billet heads based on the WLDR go-faster mods