740 carb review also known as DFT DFTA weber

[Ansimp]

Sounds like you finally have polished the tuning to a bright lustre :good: :salute:

 

[joedrum]

yes tony seems so ... the whole set up is a bit more seasonal than a stock set up ... but the advantages are huge ....did a small run today ...just awesome roll on power from anywhere... even at lower rpm it creeps up on you fast ... motor fools you ..i sounds like it barely operating but its gaining speed always ....who knows whats next ....

going to do this idle circuit mod to jyd also and see what happens with the 32-32

 

[tom foreman]

kool.joe.your the man. :salute: :music:

 

[joedrum]

there may be misinterpretations of what a thread says .... these threads on single carbs are not to say this one right and some other thread wrong ...there about each individual build ...yes we all collaborate some but the threads are not one against the the other deal at all anything but that ....

the info in this thread is about me and my build and also wants ...maybe that should read my wants for my build ...example ...personaly i got rid of the power valve ..why ..well mostly cause i wanted full control over carb as i could get ...that dosnt mean power valve cant work ...it means i didnt want it ....same with with choke set up plates and all ... i didnt take all that off cause i thought it was no good and not needed ...it was flat out ..i wanted all the air the plates block when fully open ...again personal choice and a long ways from where i started ....when i talk and discount something it because it is a discount to me not the carb the engineers or people that choose to use theres as it not a discount to them but a plus.....but if i leave out i chosse a certain path cause it sounds like a discount ...then the thread is lacking info of my thoughts ...stuff like this is not to cause ill feeling at all....

there are certainly many ways to set up carbs for ... for some its not to touch it ...no problem from me ...and it should be the same for them and all the ways in between ...i am the first on to admit i am a aggressive modifier .....absolutely on purpose ..its the parts in me ... my work in other areas sort of proves that ..... i get flack about stocks carbs purest taking issue with me saying that the weber will out do them ...if i left this out of my posts the thread would be lacking my personal opinion ... i dont have any problem with ones saying i lack the ability to make stock work right and this is why i think that way ...they can think what ever they want ...it is totally there right to.....in the same breath it my right to make my post complete with what i think ..

it is my wish we all share what we think and do ... in no way was this thread meant to be ...what has to be done to work for a single carb ...it is a record of what i did nothing more and complete with my thoughts ... :thanks:

 

[joedrum]

pics

these kinda of suck but ..it shows the idle circuit mod ...just below the open primary barrel you can see the three idle feed accesses ..the two outside ones were drilled then plug ...closing off 2 of the 6 six feeds involved to cut gas charge flow some ...the carb gasket itself seals any leaks from this at the carb base ...rather easy mod once i had the guts to go for it ...can't really see the idle circuit feeds in barrel very good but there are 6.... one you can see is the idle mix screw feed that is below plate...the rest are in the throttle plate line where it closes on barrel ....

this pic shows the plug idle feeds better left and right of mix screw feed... :thanks:

 

[slabghost]

I'm still not good at identifying one carb from another. Is this the 32-32 or the 32-36 you are working on?

 

[joedrum]

this is the 32 -32 carb ..its not the 32-34 carb like hooch has on it ...but the hooch carb is modified the same way ...pics are to see what i did ....in the last mod i made to match carb to motor the way i wanted it ..seems hooch is doing quite well but need some ride time to really be sure ...not looking good today lol white snow rock and ice everywhere :cheeky: soon i hope :BigGrin:

 

[joedrum]

ok...been test riding hooch ...though it is running great ...it was still burning lots of gas ....when i checked plugs after a run on hiway ...the pulgs were good looking around the spark ... but was black around out side and idle was erratic ...getting to my house is a lot loww rpm roads ... i could tell by the way the plugs looked is was rich on the low rpm home run ....

so the last mod i did to this carb was to block 2 of the 6 idle circuit feeds ....this actually made the rpm go up at same setting and with hole in throttle plate ....and i was having trouble controlling the idle ....as it was i had mix screw turn all the way off or in seated...also had no idle speed on linkage either .. and it was idling at about 15-1800 rpm sometimes more ...just way to much ...

so to try and get control of idle again ...i decided to plug the throttle plate hole ....so off came the carb ... and i plug it .....after carb was back on i instantly got control of idle ....i could get it to idle off mix screw only but it seemed to load up after a bit ..and take a few twists to clear it so i knew it was rich still ...i could use mix screw and idle speed control together and it would idle and load also ...so as before with hole in plate ...i turn mix screw in all the way ....

this made three of the 6 idle circuit holes plug ... so idle could only be control from idle speed control ...i got good idle even down below 1000 rpm ... but it seem to be not coming off idle very good when revved ....hmmmm like it was loading up even through at idle it didnt seem so ....so i decided to make one more move and lowered the primary gas jet ....

WOW this did it ....for the first time i can get idle below 1000 and it will run for long time never load up ..and revv good instantly off idle ...i think it ready for prime time ... im really hoping this is the mpg buster ...it seems to idle like a stock rack now and run like a weber from there ......

my point is ... im anouncing right now that my carb has no hole in the throttle plate now .....and the blocking of idle feeds seems to be the thing to do for my motor ....not saying it for all oldwings ....

im really hoping for 40mpg now maybe ... i will have to check the jetting size as most of my jets have been drill ....so not sure what it is yet ....seems passed here everything is perfect......

yesterday roll on throttle only would break loose the rear tire in first gear ...and second will spin tire on hard gear change ..and swiggle smoothly ....

the reality is just as i thought hooch is all over the 1100 final drive ...it is certainly the fastest gearing of all the set ups i have done . :builder: :thanks:

the idle feed block pics are just a few posts above this one this

 

[dan filipi]

So if I'm understanding.... You find the throttle plate hole not needed after plugging 3 of the idle feed holes?

 

[joedrum]

yes .... it not only floods at idle but just off idle too ..witch involves a lot of riding time ....seems the hole in throttle plate only helps it burn the excess fuel and is not a fix ... to much gas is just to much gas ... 50% in feed is quite huge ....i have to say this seems to be the best mod ive done to the carb ...this project has been a heck of a carb school ...

 

[dan filipi]

I guess that makes sense, but I have to wonder why doesn't making the jet size smaller have the same effect as plugging those holes.
Are these holes being fed gas from more than one jet?

 

[joedrum]

no but i am already at 45 gas jet thats smaller than stock the carb comes with....we will see how it plays out ...i just want to post any changes i do to keep thread up to date with me ....i feel like a huge thing happen today

 

[esturdivant]

i like what Dan said - why not go even smaller idle gas jet size and not plug holes?

 

[joedrum]

well after test rides today ...im rather convinced i dont want the hole ...it is filled now and rejetted to get through entire rpm zone and the idle is great now ...and stays that way ...there was some rejetting done ...got the primary main gas jet a bit smaller as all testing was done under load and bike in use ....

as far as the hole filling goes ...i used soder as it is soft and if it ever came out and also through the screen below 1 to 2 transition piece ..it is to soft to really hurt motor ....i cut a short piece and used it like a rivet smashing it with pliers ...makes a very tight fit and takes up almost no room ...very kool plug i think ...i like coming up with it ...

 

[joedrum]

pic

this is pic of hole plug ....it is just solder .. fashion by hand to make to make rivet ....and smash to make fit tight ...it is also very soft and if it did come loose witch i highly doubt ..im gambling on it ...it for sure is not to much danger to the motor in my opinion ... the carb has screen below transition piece also to stop drop ins from getting to motor .... :builder: :thanks:

 

[Trak]

:rocks:

 

[joedrum]

major development...ive always had a problem getting to secondary barrel with jetting on stock emulsion tube ...well after knowing idle feed mod had gotten me right there ....any time i raise the jetting to get to secondary without lean popping the idle would slow down some ...this is from to rich condition ..so even at idle the main jetting can have an effect on it .... so today i looked at tubes ...seems the secondary tube the holes are less and further apart and tube was skinnier ...it look like enough difference to try ...and jet this tube in the primary barrel ....so i did end result from test riding was i could get to secondary ...with 120 gas jet with the secondary tube and 220 air bleed ....this is 4 steps lower again from yesterday and 8 steps lower from 2 days ago ....test ride went great ...idle stayed great ...this is huge to me and now i am in the emulsion tube school ...tube making a 4 step change is big happening to me ...man it sure did take a while to get here ..i have been hard at it for days now ..staying right on it ... i am 8 steps leaner than before ...i also have on hooch the 220 air bleed and was mandatory over the 160 stock air bleed.... i could not get good charge with it for hooch ...it is a rainy humid day here today and bike is running great ... :builder: :thanks: .

 

[slabghost]

excellent! This should whiten the plugs nicely.

 

[joedrum]

vid
[video]https://www.youtube.com/watch?v=pOVurp3lbhc&feature=youtu.be[/video]

 

[Ansimp]

Nice sounding video Joe :good: