Dellorto PHBN needles and jets
Вставка
- Опубліковано 19 лют 2015
- Dellorto Needle Carb Fuel Mapper™ software - www.paypal.me/ecih/20
fuelmapper.com/
Understanding why the main jet may require changing, when a different needle is used.
Because the needle continues to obstruct the fuel flow at wide open throttle........ by changing the needle to a sharper point, the main jet must be reduced in size.
Warning Note:
Always tune from a rich setting, to safeguard the engine.
A 'wide open throttle run' must be carried out, and the spark plug checked, to confirm that the main jet has been set correctly. - Наука та технологія
Thank you very much for taking the time to make this video. I thought I understood it, and it turns out I did, but confidence comes from 'Knowing' not 'thinking'. I will now go and watch your other videos :)
Thanks Lozz :)
I've done alot of pitbike motor builds and when I got came and porting in play I will some times modify the stock needle and make my own tapers for certain throttle position openings. Have had some really good results
Nice!
Are you using a pedestal drill, and finger & thumb holding wet & dry abrasive paper?
It's a good skill to learn, and might be particularly useful for 'power jet' use, where an additional jet is positioned 3/4 up the front of the throat.
legend👍
Hello
Can you help me? i have a rieju mrx 2002 with a dellorto phva 17.5 carburetor. Main jet size 70.be the right size? cylinder 49.9cc naraku performance. what kind of needle would be ideal? thank you very much!
I know this is an old video, but could you help me out? I have a stock needle in my dellorto phbn 16 and i think that its running lean on mid gas, even when the needle is in the highest position. what needle should i buy first?
Hi Otto :)
It's not possible to provide this kind of tuning advice, on the basis of a carburettor body type.
Consider visiting fuelmapper.com.
Think about the possibility to educate yourself in the skill of engine tuning - the fuel mapper will help, and I'll send you a general tuning guide.
Best wishes...
Hi mate, having problems with my reiju mrt am6 ,phbh 16 identical to the one in this video. Im running a stock barrel and a technigas exhaust with a 105 main jet and the bike runs idles fine and revs fine in neutral but is completely flat and has no power at all when riding. What main jet would you recommend as i think this is the issue. Cheers
It's hard to say Sol.
105 def sounds large ... but you need to get the pot cooking at the outset.
Set your idle circuit correctly, based around a 36.
Try an A20 dropped low into the atomiser - say notch 4 to delay hitting the taper
... hahaha starve her just a bit at low load - you won't melt the piston, but you will get the combustion chamber hot and ready for when the fuel dump comes, when you hit the taper - then it'll fly like a tart after two weeks in a convent :D
Gradually edge down the main jet, keeping a watchful eye on the plug colour (keeping a slight tan - never white).
@@EngineTuning yea okay mate cheers i dropped down to a 80 main today from 106 down to 98 and then intervals of 2 down to 80 and its running better but sill shit
Please help. I have the needle in position 5, that’s how my kart runs best. Should I change the pilot jet to a bigger one and then bring the needle down to position 3? Is my understanding that if the needle is in position 1 or 5, you should change the pilot jet to a smaller or bigger one so the needle ends up in position 3? Is that correct? Thanks 🙏
Hello Silvana.
The problem that you face, is the need to learn how to tune a carburettor.
This is possible, but it will take some dedication.
Each element of the carb deals with a phase of the throttle, and merges with the next phase.
So the pilot jet deals with tickover and launch.
The needle can effect tickover but mainly deals with launch to mid throttle, while also effecting high throttle.
The main jet deals with high throttle, but also effects the full throttle range.
The first step is to understand this interaction.
The next step is to plan your carb changes.
The next step is to test your carb changes on the road or track.
Then make adjustments and test again.
The Needle Carb Fuel Mapper will help you in all these areas, but you must be prepared to learn.
Visit Fuelmapper.com and view some of the videos.
Good luck :)
Engine Tuning thanks for the help.
RDcarbs. Changing from a Bleed type NJ and needle to a primary NJ and needle (fatter). The primary type runs a smaller main than the bleed type. Proving your point. I am working w/ banshee carbs on an RD. The banshee needle is VERY skinny and i think shorter than the RD needle...My belief was that along w/ the pilot circuit adding fuel...that skinny needle may have allowed some fuel to bleed out of the needle jet and richen things up. I switched to a RD stock needle and am having better results especially w/ idle...if i am wrong, than what a needle does sticking in the N.J. is atomizing the fuel more efficiently, if it is not necessariy limiting flow. Maybe a water hose w/ an adj. nozzle and a bucket would solve this argument. have the nozzle set to maximum atomization...then have it set to a lazer beam type of flow....do both in the sam time frame and then measure the amount of water collected both times. Should solve that problem!!
It's interesting that you're experiencing this.
I can only say for certain that this is the case with Dellorto PHBN (and PHVA) carbs..... because that's what I've tested.
I think the conclusion is: Be very careful when swapping needles.... particularly when going from a skinny to a fat needle, as it could create a dangerously lean mix.
In such a situation, I would up the main jet size, and test with caution ;)
Hello, dear Engine Tuning! 7:12 what a needle? A02 or A12? Thank you!
At 7:12 it is the A02
I am thankful! dellorto phva 12 What kind of needle do you recommend?(original, long minarelli 50ccm)
That's a big question
The PHVA 12 is a tiny carb.
It is generally associated with 'performance restriction'.
For this reason, I have no experience in tuning with a 12mm carb.
However... you can still tune it.
The PHVA is a good design.
Most tuners prefer the PHBN, because it is NOT auto choke,
PHVA is the auto choke variant.
(Non-auto choke means that you know 100% that the choke is off)
Other than that the PHVA and the PHBN are exactly the same.
If you wish to begin to learn how to tune a carburettor
... you really need to gain a big advantage and use what modern technology offers.
Download the Needle Carb Fuel Mapper™ from fuelmapper.com/
This has the PHBN/PHVA already setup, with all the needles available.
You only need to change a couple of measurements (I'll advise you).
You can experiment with the PHVA 12.
The good news is that you can then acquire a PHBN/VA 17.5 and all the needles and jets will fit.
You lose nothing!
Ultimately, if you want to find performance.... you must find a PHBN/VA 17.5.
This will give your bike a major performance boost.
At the moment, your engine is struggling to breathe.
That's okay while you are learning, but to advance.....
Here is a video on how to use the fuel mapper:
ua-cam.com/video/9JxZKboE5cI/v-deo.html
When you get it, I'll help you set it up.
Also, I'll point you to where you can buy a selection of needles and jets very cheaply.
(you'll need those).
Like I said... anything that you buy for the 12, will fit the 17.5.
The 17.5 is a serious racing carb with around 1000 fuel maps.
I used the 17.5 to do the 70mph run:
ua-cam.com/video/VzAxxfhsPeU/v-deo.html
:)
Thank you! :DDD
:)
I own a Yamaha tzr50, recently I bought a new Reed valve for it but the bike will not idle - only run with the throttle cracked. However if I place the old original (incredibly worn) minerelli Reed valve in the slot, the bike will idle but not go above 7000 rpm
Any ideas of how to fix this?
It could be any number of problems
... but most likely it will be cumulative issues.
The idle circuit is probably not set correctly.
The reed valve might be a touch too thick.
The piston rings may be worn, or clogged with carbon, and the cylinder bore glazed.
It could need a new spark plug, and plug cap.
It may be time to remove the barrel, break the glaze (or rebore), and change the rings and maybe the piston.
... normal fun work :)
@@EngineTuning So ive resorted to using the original read valve, just so the bike will at least idle, but it will not get above around 7k revs. The barrel and piston is new, the entire engine has recently been rebuilt and the ignition system is new. It smokes alot and will not rev high. Any advise on what to do here, thanks.
@@daveontherocks3111 If it smokes a lot, then it is running rich.
If the engine has been rebuilt, then this could be the problem area also.
Hey, it could be simply that your choke is stuck on :D
Have you checked the plug colour?
You need to work your way through the engine and carburettor, eliminating problems, until you find the problem.
Only you can do this ;)
hi Engine Tuning, I'm having a nightmare with my pbhn 16 on a Reiju mrt 50 am6 motor, I replaced the top end with a cast iron 50cc after market one. I have a feeling the old one may have been a 70cc kit, as the main jet was a 112. I've replaced it with a 82 main. the problem is total lack of power. the cable choke doesn't do anything, although the cable does move the choke freely, also the idle adjustment screw does nothing to alter the revs, even when fully in. the bike was left outside for 6 months, so I stripped the carb completely, including the atomiser tube, and cleaned everything thoroughly, and blew it all through with an air line. the reeds are good and there are no air leaks on the rubber manifold. I've replaced the magneto side crank seal, as the plug isn't getting oily, I didn't bother with the clutch side. please help! many thanks, rob.
Hi Rob.
I'm busy on something at the moment ... I'll get back to you later.
no worries, not that familiar with UA-cam posting, sorry! I appreciate your time, thanks
1) Youu have replaced the 68cc or 74cc barrel with a 50cc barrel.
- 40mm D - 47mm D - 49mm D
Measure the previous cylinder diameter to learn the previous capacity.
Obviously the performance will plummet - at least by a third (33%), which is huge, when riding a small capacity bike.
2) The barrel contains the inlet and exhaust ports to the cylinder.
The barrel casting (containing these inlet and exhaust ports) can be crap.
They can be good, but they can be crap.
I'm going to do a video about this, but for the moment...
I tried a TNT 50cc replacement for the original Minarelli (which was shagged) - yet the new TNT barrel was far worse than the shagged original - it offered no zip whatsoever.
... it was (and is) good for a doorstop.
I put the original barrel back, before upgrading to 74cc.
In effect; if your cylinder ports are crap ... no matter how well you tune the carburation, it will always be crap.
3) Next ... you don't understand how fuel is delivered to the combustion chamber, from tick-over through to WOT (wide open throttle).
This is entirely normal.
There is a multitude of carb options, to adjust the fuel delivery throughout the throttle range.
Basically low, mid, high throttle ... all based upon airspeed through the bore of the carb.
However, these adjustments can effect the low and mid, the mid and high, or the low mid high.
This is a nightmare until you relax, and begin to see the whole fuel delivery as a progression from 0% throttle to 100% throttle.
Once you see the whole throttle range, it gets much easier.
To see the throttle range ... consider viewing this video : ua-cam.com/video/GeaEaIdfeco/v-deo.html
You will begin to think about low throttle settings AND feeding the powerband with fuel.
4) Low throttle settings
If your idle jet is too large, you will find that adjustment via the screw is very difficult.
Check the idle jet size ... it should be around 36 / 38.
The engine tick-over only needs to spin the crankshaft.
Set your tick-over rpm using the standard method, to gain maximum efficiency of the fuel burn.
This will create a hot combustion chamber, that will allow you to dump fuel into it, that will be immediately burned.
This is what gives you immediate acceleration (and a fun bike).
5) Just remember that you can spend hours, days, and weeks, pissing around with your carb ... and be more confused than when you started (the normal route for most people).
Consider downloading the Needle Carb Fuel Mapper to assist with your education, and the perfect tuning of your engines (now and for the rest of your life) @ fuelmapper.com/.
6) If the bike has no zip, after tuning ... the ports are crap. (and you can do nothing about that)
You've not wasted your time, if you are actually advancing your knowledge (rare) ... but you will not have the performance that you desire.
Hard luck ... that's life ... you've bought a doorstop (just like I did).
In such a case, the only solution is to buy a 74cc cylinder, and then you can enjoy remarkable performance.
The PHBN 16 will provide excellent power, from low to high throttle.
You will probably be limited to around 66mph (thereabouts) ... but that will get you faster than 100 kph lorries (your worst enemies).
AND... the low end response out of corners should be amazing.
PHBN 17.5 is probably the ideal all-round carb for 74cc (can hit 70 mph ua-cam.com/video/VzAxxfhsPeU/v-deo.html ).
19 PHBG has potential for a bit more top speed, at the expense of lower throttle power.
However, my advice would be to tune the 16 to the max, before changing to 17.5 (because it will be fine).
For 50cc the PHBN 16 will be perfectly fine, if the bike has been fully de-restricted.,
Good luck!
@@EngineTuning thanks very much for the information. I think that's what I get for paying £25 for a barrel, a bloody door stop! It seems you get what you pay for. Unfortunately, I chucked the other barrel and piston away, as they were knackered. But the bike was apparently very quick, before the piston packed in. Its time to put my hand in my pocket, thanks again, you're a gentleman
Ah yes Rob ... at least the door stop was cheap.
Don't throw it away, because it will be a useful reference, and perhaps good for practicing on.
ua-cam.com/video/lRD7_V14lPs/v-deo.html
I'm sorry that I can't offer you a good barrel.
I have a good source, but it needs a manufacturing order.
You can easily get money to piss up a wall ... but independent engineers soon discover that the money supply doesn't exist for them.
Apparently we are dangerous.
After you have removed the sharp edges ... don't forget to add some extra oil to the fuel tank.
Best drain it, to find out the quantity.
Here's a fuel mix calculator: www.upnor.net/tools/fuelmixcalc.html
The engine will have an oil pump.
Always fit a clear tube from the pump to the carb, so that you can see that it has oil.
(you have to get creative to fill the tube with oil ... toothpaste helps after the event, if taking the direct route)
If it has oil at the carb ... an extra 10ml per litre of fuel will do it.
Good for running in, but also good to cover the increase in capacity, if going for a 74cc barrel.
A decent fully synthetic oil will be much thinner than a semi or mineral oil.
Castrol Power 1 Racing is expensive, but it's like water and lasts for ever.
The pump will pass more oil, and you can drop the extra mix to around 5ml once run in.
Personally, from a safety perspective, I'd go for the 74cc, so that your lad (or lass) can keep up with the traffic.
Get a couple of spark plugs B9ES and a new plug cap.
They are free with cornflakes www.carsparkplugs.com/1x-ngk-copper-core-spark-plug-b9es-2611.html
:)
Does it make for an overlap effect then
Everything overlaps everything else, so yes.
But you'd have to be more specific regarding your question.
does anyone know the main jet size of phbn 12
You need to discover this by testing.
It depends upon the engine and exhaust setup.
Hi engine tuning do you know the thread size of the main jet on a phbn 12?
Hello Mark, could you be so kind to help me with PHBN 16NS on my Rieju MRT 50. I asked you a question on apriliaforum.com. Thanks a lot for helping.
Your problem is primarily with the A39.
It has a 10mm 'land'.
This means that even at notch 5, at tick-over, the needle is already on it's taper.
At tick-over, the throttle slider is likely to be open by around 8% to 10%.
(throttle twist grip at zero)
IE. you may think that the throttle is closed at tick-over, but it isn't ... it's open.
Therefore, at all notch positions, the needle is dumping fuel into the carb, while the engine is idling.
(BTW it is a myth, that the needle has no effect at low throttle ... it does, and you are experiencing the effect).
-----
Tuning the idle circuit is very difficult with this needle, because any change, also changes the taper opening.
You need to experiment with needles with a longer land.
This will push the taper, way past tick-over.
-----
This is why I developed the Needle Carb Fuel Mapper™ software.
Without it, you cannot understand what each needle is doing.
It allows you to examine the fuel flow, using 'at a glance' fuel maps.
If you can afford the €20 you will have it for life, and all carbs can be mapped.
... and by good fortune, it defaults to the PHBN carb, with all the available needles loaded.
So it is very easy for you.
Sorry it is charged for, but I gave up some months of my life to develop it, and I think it is a very fair contribution to make.
(There is a download link in the description above)
-----
It will be best is you measure the carb bore height ... the 16 may be different to the 17.5
However, you can immediately see all the fuel maps for your carb as a graph.
You can also overlay different needle maps, to compare needles and atomisers.
Go to fuelmapper.com/
On the menu - click news - the tutorial videos are listed.
I'm going to make another tutorial over the next few days.
All the instructions and help files, are available on the web site - hopefully they translate well enough.
(they are in English within the program).
-----
It is easy enough.
In the fuel mapping module ... you choose the needle(s) that you wish to examine, and the notch position.
In the drop box, select the atomiser.
Start with your current setup (your current map).
Then make different maps, from the needles that you have (or needles that you might wish to buy).
You can test everything virtually, before ordering any needles.
You will also begin to understand, what the carb is doing, at different throttle phases.
-----
Without this software, you are 'in the dark' (which is why I developed it).
To help you...
Using the fuel mapper, I've mapped your current needle and atomiser on notch 5.
I've then overlaid the A35 on notch 2 and also on notch 3.
fuelmapper.com/images/A39n5-vA35n2.png
fuelmapper.com/images/A39n5-vA35n3.png
(if you have difficulty displaying the images - copy the links, and paste into Firefox)
You can see, that the:
A35 on notch 2 - does not hit the taper until around 15% throttle.
Also it remains leaner until 36% throttle.
A35 on notch 3 - does not hit the taper until around 20% throttle.
Also it remains leaner until 63% throttle.
-----
These are simple comparisons, so that you can see how the carburettor works, and how you can experiment virtually, with the needles that you have (or might wish to order).
Then test the setup on the road.
If it is better, then you know you are heading in the right direction.
Then you can continue fine tuning if you wish.
-----
If you can't afford a copy of the fuel mapper, you can do some rough maths calculations that might help you get closer to the needles that you need.
Basically ... push the taper further into the throttle ;)
Good luck
Report back on how it all went :)
Oh thank you for you quick answer. It is really helpful. You confirmed my thoughts. Now i already have A12 A13 and A20 needles. I wish to start from A20 because it has 20 mm land instead of 22 mm on A39. Its 3 notch is the same like notch 5 of A39 needle.
I know that needle and main jet affects on all operational modes. In dellorto tuning guides there are a lot of simplifications. In fact even main jet affects on idle circuit.
Sorry but 20 euros is expensive for me and i need only to setting up only one moped. Aprilia SR50R sold out.
Anyway thanks a lot. Any words about Aprilia SR50R carburetor? :-) Its my own discovery no one knew about this before. it was interesting for me to know is this restriction was on earlier manufactured carburetors or not. But nobody answered me. :-(
Re: Having spare money ... it is understood by all, when it is not available.
That's why I did a bit of freebie analysis for you.
It's not lost.
Anybody checking out your question, will get a view of the needle comparison graphs.
... the knowledge spreads.
BTW the A20 'land' is 12mm from notch 1.
The A39 land is 10mm from notch 1.
You measure from notch 1 because it is the notch that determines the distance.
(no need to measure, because for the A series, Dellorto provide the dimensions)
Regardless... the extra 2mm makes all the difference.
For a 20mm bore height, it is an additional 10% of throttle movement.
Once the taper is past the idle tick-over ... you can then set the idle circuit easily.
Thereafter, you might determine the effective WOT.
With the idle circuit correct, and WOT correct ... you can concentrate on the transitions.
Re: Restrictions
Sharing localised restrictions is always worthwhile.
You share the knowledge that you can ... usually it is a personal voyage of discovery ;)
Anyway, it is good to hear that you can now move forward :)
Sorry, its my fault, i meaned that a39 taper part is 22 mm long but a20 is only 20. And its land part is 12. I have no a35 now, but have a20 and it is easy to try it. Its strange because this carburetor is in stock configuration. Default main jet was 78 and needle was in the lowest position.
The A20 might give you the result that you are looking for ;)
Work from notch 3 upwards.
Set your idle circuit @ N3.
Testing on N4 & N5 won't change the idle circuit, because the needle will be on its parallel land.
Having increased the cylinder swept volume by 50% ... you will likely need to increase airflow, at the airbox.
On the forum, I did document this mod (somewhere).
Suddenly ... you will have power at your fingertips, and the bike will surge forward :D
I will say that this is a good quality video but your explanation was foggy at best.
+AVI inc
Yes...... I accept all criticism.
My videos are done on the fly and unscripted.
They are usually way too long, but the info is there.
I've just watched through it again... obviously It could be improved, but it does prove that certain carbs have the needle in the atomiser at all times.
Bear in mind that you will find very few tuning docs (if any - I've never seen one) that explain this mission critical information.
On tuning forums time and time again, you will see people misled, through the regurgitation of 1950's carb tuning advice.
Even the official Dellorto guide misleads in this area..... old info just copied and pasted.
In fact this video was created to counter just such misinformation on a tuning forum.
Ie. Primarily, if you change the needle on a carb of this type, you may need to change the main jet.
I think, if the initial few statements are not absorbed, the objective of the video might be missed.
Perhaps I should have opened with a text statement first.... or better prepared the opening statements.
Anyway.... too late now..... hopefully what I've just said, clarifies where clarity was missing.
Thanks for the feedback :)
septic, cut your frigging nails
Hahaha ...I'm always doing things ... I need my nails.
I'll leave the nail beauty to the fairer sex :)
this guy shouting into the mic just waffle and fiddling with focus his video asking stupid questions and stating the obvious. He thinks padding this video will get over his point! waving around a Dell'orto carb It doesn't so don't bother He guesses needle sizes perhaps if he invests in a good micrometre he can kid himself even with more pointless drivel
*Hahaha!* That was a beautifully hilarious comment Andrew ... thanks for posting and putting a smile on everyone's faces (hopefully they will appreciate your humour).
Also ... thanks for taking me back to this video, and topic ( _it has been sometime_ ).
Thankfully, the conclusions arrived at _(all those years ago)_ have been verified, and now represent current thinking and awareness.
Nice one Andrew!
😀