CV40 jet sizes

[turboprop]

That adjustable pump looks interesting for sure.. yes, I'll get a new slide and I can play about with the old one... also needles but which way to go there?

Unlike a Mikuni HSR series pump. Your CV carb with this aftermarket float bowl will still lack the tuneability of the HSR in that while this bowl has adjustable volume it still lacks the ability to adjust the start and stopping points for when the accelerator pump operates. Increasing the volume of the accelerator pump like this will have a global affect on gas mileage.

Surprised that nobody has chimed in about disabling the accelerator pump during tuning. The manual for the HSR calls this out. As does the instructions for the S&S Super carbs. The CV is no different. You should really disable the accelerator pump in that CV and make a few steady state pulls at different throttle openings and then activate the accelerator pump and dial it in. I suspect that if you were to obtain all four  of the needles and re tune without the accelerator pump in play that you would probably end up in a better place at the end.

[1340evo]

Tuning (messing about in a controlled manner) to continue this weekend if its dry 

[JW113]

OK Turbo, good point about the effect of the accel pump, but that is why I basically ignore what the AFR has to say right after a throttle change, and focus on what is going on a few seconds afterwards after that shot of fuel has been purged through the motor. I tend to tune more for steady state, as that is how I typically ride. And I'm categorizing WFO as steady state (for passing). Hold it WFO and read the gauge after the accel pump shot has cleared through. That is not to say that disabling it completely is not a better method, and yes thanks for pointing that out.

I also have not messed around with drilling slides or playing with springs. Call me lazy. Or maybe even  that I'm easy to please. The older you get, your focus on what is important tends to shift.
 

But at the end of the day, these AFR gauges totally rock.
 

-JW

[1340evo]

I agree, they do indeed, to the point where you can see everything. So maybe trying to fix every last issue is not realistic.
I've ordered a slide with a new rubber (looks like they all come from China now) because I have a bit of melt on mine so can have a play when its here, and did think pushing the slide up yesterday that the spring was quite heavy so to address my 'quicker responce' issue, that may be worth a try. But as you say, its now 90% better than it was and safe so even if I called it a day today, it would be sorted much better than it was.

I always advise people not to fit a gauge (oil pressure, temp etc) if you don't need to as 10:1 you'll identify a problem and spend hours and $ trying to fix it, however long its lasted this far 

See what my ".060 os shims does this weekend if its dry

[turboprop]

OK Turbo, good point about the effect of the accel pump, but that is why I basically ignore what the AFR has to say right after a throttle change, and focus on what is going on a few seconds afterwards after that shot of fuel has been purged through the motor. I tend to tune more for steady state, as that is how I typically ride. And I'm categorizing WFO as steady state (for passing). Hold it WFO and read the gauge after the accel pump shot has cleared through. That is not to say that disabling it completely is not a better method, and yes thanks for pointing that out.

I also have not messed around with drilling slides or playing with springs. Call me lazy. Or maybe even  that I'm easy to please. The older you get, your focus on what is important tends to shift.
 

But at the end of the day, these AFR gauges totally rock.
 

-JW

JW, I am not a smart person, but I know a few and can identify the smart people in a room. I tend to do what they say or do. Works for me.

The smart people at S&S and Mak say to disable their accelerator pumps during tuning and do them last as they will mask conditions that can be tuned out with jets. Same thing applies to a CV carb regardless of an adjustable accelerator pump being used or not.

I am also pretty dig on people simply repeating what they have read online without any experience doing or seeing whatever they are posting about. IME, not drilling the slide and the spring is one of those things that gets posted by many as a knee jerk reaction whenever a topic like this comes up. I suspect that very few  of the posters in the 'Don't drill the slide' gaggle have never done so themselves. This is like a self licking ice cream cone. This thread is a perfect example of how drilling a slide or altering/changing the spring might be an improvement.

I rarely get involved with this level of detail in threads like this but I like how the OP is going abut this. He is actually doing stuff. So here I am.

So, with the accelerator pump rod disabled the jetting becomes isolated and the tuner will have finer resolution on how the engine is responding to changes to the carb. I hope the OP follows through with ordering the needles, continues his A-B comparisons of them and moves the ball a bit towards tuning nirvana.  Drilling the slide (or sealing the hole and drilling a smaller hole) and trying springs with different spring pressures will be educational and should gain the OP a few more yards. The aftermarket float bowl with an adjustable accelerator pump with increased volume will be the final piece to cross the goal line.

To the OP, I rarely do this, but I have given you a pretty good plan of action. I hope you follow through with most of this stuff as it will provide a really good example of how precise a CV carb can be tuned and dispel a few internet myths.

I will also share with you that JW was initially very reluctant to get or use an AFR gauge. He was chasing his tail tuning something. I knew the answer but instead of serving it up on a silver platter I encouraged him to get an AFR gauge and learn for himself. He got an AFR, tuned that bike very well and is now a big advocate of using an AFR gauge to tune carb'd bikes. I suspect that after this thread JW (and others) may re-look their tunes and their reluctance to altering the slide and/or spring.

Final thought. The float bowl with the adjustable pump has come up on this forum a few times. Search, it is here. You will see a bunch of negative responses from posters that have said they have not used it. This thread really highlights why Boyesen went IRAD to develop it. They are smart people and they saw a need/requirement for it. This is it. I am anxiously following this thread.

-TP

[JW113]

Naaaah..

 

LOL. Not to say that you are not correct, because obviously you are. However, there is tuning to make the AFR gauge happy, and there is tuning to make ME happy. If I achieve the second one, then I don't spend much more time on the first one. Hey, I said I'm lazy, right?

On that note, my impression is that the slider hole and spring have more transitional fuel metering than it does with steady state metering. And perhaps rate of change of air flow as well I suppose. I do know that one of the 'complaints' about CV cab is their lack of "responsiveness" meaning they don't snap to action the way a butterfly carb (ala S&S) does, which gives the perception of more power. The hole/spring function to dampen the rate at which air flows changes through the carb after throttle plate changes, especially rapid changes. Like a shock absorber. I actually embrace that. The thing I hate most about S&S carbs is how twitch they are. I suppose on the race track, nobody cares and is probably an advantage, but on the totally worn out crap roads here in San Jose, every little bump you ride over gets transmitted to the right side handlebar grip, and you end up with a bike that wants to jerk and surge. No thanks, but thank you CV for damping out that crap.

Yes, yes, yes. You absolutely sold me on the value of an AFR gauge, and to that I owe you a big THANK YOU. I drank the cool aid, and now am a firm believer, and preach the AFR gospel every chance I get.
Was one of those life changing deals, actually.

Great info Turbo, and always appreciated when we can lure you out of your lair and share some of your knowledge.

-JW

[1340evo]

Thanks for all your input guys, its an education doing this as I thought I was quite close before. But the AFR gauge has been a revalation for sure. As you say, how many others out there think they are close and maybe this is why so many bikes do "Potty mouth" pistons and valves because they are just set up wrong.

I for one would never think a 45 and a 195 jet would run together to give the best results... I used to think go up on one so the other must follow and the other way for coming down.

Okay, I do have V&H exhausts which we know are not the best, but out of the threads I have looked at, those who were saying 45 / 195 or even 200 with drag pipes where not that far out, but I'd dismissed them before as not knowing what they were doing...

I've disconnected the pump earlier today as you said and will see what that tells me.
Also reading many posts and trying to stear a way through the dross out there, it does sound like drilling the slide is worth a try.
The 1/8 hole is too big and will bog down on acceleration, but the hole I have now is spot on 2.5mm so what people have done for lighter bikes (which mine is) they have drilled 7/64" or 2.75mm which sounds to work well and may solve the problem I have.

Also using a spring from a CV44 27728=99 appear to be a thing as its shorter and has a reduced rate. If thats not available by cutting 3 coils from the existing spring, you get the same end result.

At least I have options to play with now and see how things alter. I think before my time a cheap re-furb kit had been put on the carb so I also need to check everything out but I know the spring rate it should be now, so I can measure it...

''You can either install a DynoJet spring which is shorter and a lighter spring rate, (8.8 onces for 3" compression and 5" long VS stock which is 12.5 onces for 3" compression and 5.5" long) a stock spring, or take a stock spring, cut off 3 rings from it, and your slide will react faster, giving similar results as the DynoJet spring.''

All good fun, but at this rate it's going to take all summer to get it set up 100%.. but whats the rush.
And then you start thinking 'injection' and doing the maps for that ??.. maybe / maybe not. Got to say I do like the carbs for their simplicity once set...

I will play with needles but in the UK they are not that easy to find so will have to order from the US and await their arrival. I know measuring between the two I have here on the shadowgraph at work they differ greatly so will make a hell of a differance when in the carb.

Onwards and upwards. It's raining again so don't want to get the gauge wet.. see how it looks tomorrow 

[Finn]

...I will play with needles but in the UK they are not that easy to find...

You should be able to get HD needles with part number from every Harley dealer in UK. It may be that they have no stock but nevertheless.

Aftermarket companies such as Motorcycle Storehouse (and others) also have needles etc. available. They have many dealers in UK.

Motorcycle Storehouse CV Performance parts

[JW113]

I'm not sure I'd go with stock HD needles. They were developed for street (aka EPA) engines and are tuned accordingly, i.e. "lean". You can attempt to compensate by using shims under the needle head, and I have indeed done that myself. You can also 'maybe' find one of those SE race tuner kit, but it's been so long since HD sold a bike with a carburetor on it, not sure if you can still find them. Next time I think I'd try those aftermarket needles as Turbo suggested. If for no other reason that to see how they do. But here is some stock info for you if interested.

You cannot see attachments on this board.

-JW

[turboprop]

I will play with needles but in the UK they are not that easy to find so will have to order from the US and await their arrival.

Why order from the US a needle that is made in Japan? Seriously. No need to pay the Harley overhead. Buy the oem manufacture pins. Certainly someone in your country has a source for the needles that I linked to that does not include Harley.

[1340evo]

I will play with needles but in the UK they are not that easy to find so will have to order from the US and await their arrival.

Why order from the US a needle that is made in Japan? Seriously. No need to pay the Harley overhead. Buy the oem manufacture pins. Certainly someone in your country has a source for the needles that I linked to that does not include Harley.

yes, you are right... I even have a mate in Japan

[1340evo]

This is getting a bit strange now :- normal running it bobs about 12.5 to 13.5.. open it up a bit it will just go over 14, open it up more its 12.4 and it goes well,
as it revs the ARF climbes...
Ive now got :-
45 idle
195 main
0.060 shims,
2.5 turns
N65C

Tickover 12.7, 5th at 70 13.3, 3rd at 40 12.8, 4th 40 to 80.. too low rpm at 40, think this may be my cam as it likes to rev a bit ...anyway, bogged down a bit then climed up to 14 at 80.
If I run it real top end to the rev limiter im seeing 15.5 up there but loves it??

I now have a linear line kind of from 12.5 at the lower rev rang all the way up to 15.5 at the top end??

Switch it off and back on but without starting, the AFR reads 17 and slowley over a period of time counts up to ---- so does this suggest unburnt fuel in the exhaust I guess.

But plugs look good for the hours running about I've done



 

[turboprop]

Obviously the N65C needle is not working in this application. I bet if you spent less than 10 minutes looking at the chart that JW posted a solution will present itself. You have good data. Pin selection will not be a one and done process if you truly want to achieve tuning nirvana. Your next needle change will get it closer. Keep chasing it.

[JW113]

If I am understanding your measurements correctly, you are too rich at cruise/part throttle, and too lean at top end WFO. I would interpret that as the needle is too high, and the main jet is too small. Try a larger main jet and see what it does to the WFO and RPMs above 3500. 15:1+ is too lean, and though it might seem to run great, it will run a hell of a lot better if you get it below 13:1.

As I said before, I did not have great luck with the N65C. It is a SPORTSTER needle. Smaller motor. It's claim to fame is it is rich in the low end, as you are finding. '88 XL was a one year only CV that had no accelerator pump (why???), and that needle was their "solution". That's all. It is not in any way a performance needle.

Last thing, you mentioned "unburnt fuel in the exhaust". That AFR meter has no idea how much fuel is in the exhaust. It measures how much unused oxygen is in the exhaust. If there is unused oxygen, then there is not enough fuel being supplied to consume it during combustion. Try not to get confused by what that gauge is telling you, focus on what it is actually measuring.

-JW

[1340evo]

Away for a week now so will get a few bits in ready for when I return.

The gauge was strange, I've never seen it do that before as its always heated up and come on at ----

But it was sat there at 17 and over I guess 5 mins, slowly counted from 17 to 21 where it went ----
so from what you say, its measuring unused oxygen which with the engine stopped I'd of thought would go to ---- more or less straight away as I only have minimal baffles??

I'll go back to my old pin first and see what that does (standard), then as you say, with a couple of sets of data, i'll be able to apply this to the pin chart

[JW113]

Can you clarify, are you monitoring the AFR with the bike running, then shut it off, turn the key back on but not start the engine and watching the AFR gauge? If yes, not sure why you're doing that. The reading is meaningless. What's in the exhaust pipe is spent exhaust gases (H20, C02) until the atmosphere starts working it's way back up into the pipe.

-JW

[1340evo]

yes. went for a ride to look at what changes I'd made, came back and switched the bike off.
Then went to put it away, switched it on but didn't start it straight away. After the heat cycle the sensor goes through I was suprised to see it reading 17 on the gauge.
I'm sure when I've done this before its gone to ---- more or less straight away?
I'm not trying to measure anything obviously, just wondering if its working right?
It must of taken 5 mins before it went to ---- even blowing a bit of air up the exhaust??

Strange

[1340evo]

I'm kind of not getting this.. its like the carb or the gauge works backwards?
cruse at 50 and close throttle slightly it goes rich, cruse at 50 acceletate a bit and it goes lean. I guess this is how a CV carb works.
Down hill its ritch, up hill it leans out
Are you guy's tuning CV's or something with a more dirrect link?
I've got it now where it cruses at 14's mid range, down at lower RPM's its crusing at 13.2 area... but anything over 90 MPH its still going lean  .. how can that be I've got a 200 in there now and it should dround it! but does come down a bit if you hold it up there lets say 5.5K area.
It will do for now I guess, picks up real nice and is quite fast on acceleration. I'll see what MPG I'm getting also.
Next thing to try may be more restriction in the pipes??
Done maybe 20 miles tonight, not sure what you make of the plugs...

[Hossamania]

Are you still running V&H Shotguns? Do they have any baffles?
I just looked up Shotgun pipes, nothing with that name came up immediately. Are the called something else? Short shots? Long shots? Staggered? What diameter?
Might help to post a picture of them.

[kd]

I'm kind of not getting this.. its like the carb or the gauge works backwards?
cruse at 50 and close throttle slightly it goes rich, cruse at 50 acceletate a bit and it goes lean. I guess this is how a CV carb works.
Down hill its ritch, up hill it leans out

Remember when you close the throttle blade when rolling it off, the drive train is maintaining the rpm.  That is simple physics at work.  Closing the throttle increases manifold vacuum and with a stronger negative manifold pressure you will draw raw fuel from the lower speed circuits behind the throttle plate. (idle and mid)  That changes the AFR because you have reduced the air flow and increased the fuel introduced.  That also turns out to be a good thing as a richer mixture will reduce exhaust popping on decel.

IMO, the plugs look OK and are nice and even (as in balanced).

[Ohio HD]

Remember when you close the throttle blade when rolling it off, the drive train is maintaining the rpm.  That is simple physics at work.  Closing the throttle increases manifold vacuum and with a stronger negative manifold pressure you will draw raw fuel from the lower speed circuits behind the throttle plate. (idle and mid)  That changes the AFR because you have reduced the air flow and increased the fuel introduced.  That also turns out to be a good thing as a richer mixture will reduce exhaust popping on decel.

IMO, the plugs look OK and are nice and even (as in balanced).

Agree, you have to jet for idle, cruise and wide open throttle. Not for deceleration.

[JW113]

And one more agree. The plugs look fine, but I'm guessing that you've been on the throttle a bit. I'm getting the impression that you're paying way too much attention to that gauge during transient states. Don't! It doesn't matter. As Ohio said:

Idle: so it don't load up and foul the plugs but also starts/runs at cooler temps OK.
Cruise: for good mileage. 14.4 or higher. Even 15 is OK as long as it's steady state. Try locking the throttle and let it stabilize, then read the gauge.
WFO: For power. 12.5-ish is ideal, or something close to that.

It sounds like you're happy with the power, and that's good. Time to do a mileage test. Try a 100 mile highway ride and see how much MPG you are getting. 45 is good, mine gets close to 50.

-JW

[1340evo]

Hi All, been banned for a few days as I put a picture up on the V&H Straight Shots I have fitted... (OOps, keep forgeting that rule as its not a thing in the UK... Will try my best to remember!!).. so not Shotguns at all, no idea where that came from ...

So been to a rally this weekend with my Slave friends, a good 100 mile round trip and the bike is running the best it ever has. Just looked at the plugs and they have not changed much from the picture about so for now I'm saying it's good to ride.
I may get a CVP Velocity Needle at some point as I'm told its shorter so does not restrict as much top end (anyone got the dim's for this?) and / or try a bit more restriction in the pipes (the have the std V&H baffles right now, so quite open....
So with this okay for now, I'm going to move on to my timing again as its set stock now, maybe try a bit more advance and see how that goes.

My settings now are :-
45 pilot
2.5 turns air screw
200 main
N65c needle
0.030" shim

I also made a small brass washer to put under that main jet as the one I have appear to have 2 head sizes, so this made a shorter head into a longer head version.. not sure if it helped anything but makes it less likeley to come out of the fuel.
Suns out in the UK so its riding time so here we go.. Again, great help guy's and thanks for all the support.

To admin.. sorry for posting pics that are not mine, as I say, its not an issue in the UK but you are always quick off the block to spot and remove them 

[capn]

That afr gauge WILL drive you crazy.

[1340evo]

It already has, and on a CV its probably a lot worst as the carb does what it wants depending on the vac in the manifold, where as a Mikuni I guess just delivers what you ask it to.
But having got used to it's bouncing about, it does give you a good idea for sure where you are and where you need to be...
I've gone from 180 main to 200 main and lifted the N65c by .030"... think it could still do with a bit more but thats all its getting for now.
If I'd not of fit it I'd be well in damger on the top end / freeway...