What do you think

[funky]

Hi all an update on the state of play with my re jetting process
well to any one who has not done this its definatley is a process and you get very proficiant at taking your carbs on and of and taking them apart.
I just received the new air pilot jets i ordered.
I got three in a progressive size going up in increments of 2.5 they are 135 137.5 and 140
stock was a 130.
My plugs prior to fitting a new air pilot was still running rich after reducing the main jet to 127.5 there was an improvement from stock 132.5 but not enough,
I fitted the new air pilot 137.5 decided this may be better result than the 135 and re fitted the air filters as air pilot jets can be changed without having to take the carbs off the engine.
I attempted to start the bike after a few goes, i increased the idle screw and it started but ran lumpy, I then had to dial out the mixture screws about 1/4 turn to get a good idle which was about 1500rpm i reduced the idle screw to about an idle speed of 1100 which means the mixture had been weakend by changing the airpilot. I bliped the throttle and took the revs up no pops or back fire test run tomorrow
All the best Funky

 

[peanut]

excellent ...sounds like definite progress.
I'm switching my main jets back to the 145's that were in the carbs when I got them. It definitely didn't like the 140's I put in from 3/4 to WOT

Lets hope the rain stops for an hour or two tomorrow

 

[funky]

Hi all this is the pic of my plugs when i started the jetting process
left side Plug

Right side Plug

This is now

The Jetting is as follows 117.5 main jet,,, 140 Air pilot jet 42.5 pilot,,, needle at postion 2 from top.
The bike runs well no back fire hold 50mph at 3500 rpm, with lots of power.It feals allot better smoother too.
What do you think. I have pilot jets coming soon to lean off that circuit a little i have oredered 30,35,37.5,and new rubbers
Do i need to continue and try and get a better plug reading it still seems a little rich but much better. your wisom will be greatly appriciated .
All the best Funky

 

[funky]

Hi All as far as i am aware, the pilot jet plays a part in the first instance I.E when starting the bike and up to 2000 RPM, so logic suggest, that the air pilot feeds the pilot circuit with air ??? is that correct.

The reason I ask, is that i am going to reduce the size of the pilot jet to lean the mixture further on that circuit.
When looking at the schematic of the BS34 carbs it looks as if the air pilot feeds the emultion tube, so it must have a role to play in the mixture on the main jet circiut also Is this correct ..or am i confused again
All the best Funky

 

[TwoManyXS1Bs]

Hey, Funky. Here's some more to digest.

On these bikes, like many other vintage bikes, the idle fuel is metered thru the pilot jet, and intermix air is metered thru a bleed-air jet. The two are mixed (emulsified) within either the brass pilot jet body (early models) or above the pilot jet within the idle fuel passage (later model EPA carbs), and this foamy/frothy mix travels to the transition/bypass/off-idle and idle ports.

So, the idle mix screw actually meters an emulsified/frothy fuel/air mix to just the idle discharge port.

Other bikes, like Honda, elected to make this screw meter the amount of bleed air when the EPA regs came out, different system.

This fuel emulsification actually serves multiple purposes.

First, it takes on a property that is similar to your kitchen sink faucet water. Your faucet head has an aerator that intermixes air with water. This aerated water stream doesn't splash, and flows smoothly, even at high flow rates. Try your faucet without the aerator, and your high-flow water splashes everywhere.

Second, the frothy fuel atomizes more quickly, and is less prone to puddling.

Third, this frothy fuel has a lower density, and responds more quickly to changes in demand, known as fuel delivery delays.

The density and nature of this frothy mix also influences the total fuel delivery through orifices.


Enough of that. For more fun, do the forum's google search on "plug chop", to see how's that done.
However, you may want to wait for after break-in before doing those...

 

[funky]

Thanks Twomany That is really intresting i will research this more Thanks for you help.
All the best Funky

 

[funky]

I think im there

 

[peanut]

still look a little lean to me but its difficult to tell .
They are old plugs well worn and wire brushed . They would certainly benefit from having the ground electrodes filed square so there is a nice sharp edge for the HT spark to jump to

 

[funky]

Hi all i think i have done it i checked with the NKG web site and the result is good to perfect heat range nice grey brown earth strap and centre insulator.

I went to a 137.5 Air Pilot... 117.5 Main .... 42.5 Pilot ....Notch from top 3 on the needle.
All the best funky

 

[TwoManyXS1Bs]

Hey, Funky! Those look pretty good.

'ave a cuppa tea on me...

 

[funky]

Thanks Twomany got up to 95mph in 4th gear so i know its going too break 100 I am happy with the engine sounds and feels real mean, time to tweek the suspension. thanks to everyone who posted here.. If anyone in the uk wants to know how to jet the BS34s for the uk this is the thread.
All the best Funky

 

[funky]

Hi just to say i got the bike down to my friends workshop he repairs cars amd does MOT tests... got it on a gas anyliiser and balnced the fuel mix have done over 200 miles faultlessy loving the bike... As we say over here Sweet as a nut
All the best Funky