Author Topic: Pilot Jet (Read 4810 times)

23hp · **on:** May 17, 2009, 07:00:28 pm

Hi all!

Been playing with the jetting of my CV Carb. I managed to work out that the carb is a: BS29 and that the Main Jets are model: 102.221. So I bought a 117.5, 120 ad 122 main jet.

Adjusting the mixture screw does nothing at all and I have cleaned her out so upon reading more about this here and bearing in mind that we are at sea level here (thanks ace) I am thinking of upgrading to the 17.5 Pilot Jet which should solve this mixture screw problem. Anyone know the Mikuni model number (VM28.213 etc) so I can order one? I would order from our hosts but the mail quote for Spain being almost 30usd standard is a no-go...

As for the main jets all of them seem to work more or less well with a bit more gurgling at the 122 coming off full throttle. I really need to do a real plug chop as instructed here, but time is really tight just now so I did a quick ride around using full throttle before cutting her off. I was really surprised that the Iridium plug was as follows - sorry for the crap quality but the plug is black round the rims but quite white under the spark initiation point and really hot to touch:
http://niederle.googlepages.com/Plug.jpg/Plug-full;init:.jpg

This makes me think that she is still lean as the plug looks ok and the block is Very HOT. The bike has slowly made its way back to standard apart from the exhaust. Any opinions would bee appreciated on the plug colour.

23hp · **Reply #1 on:** May 18, 2009, 05:46:06 pm

Well think I went too far on the jets. With the 122 main jet coming off the throttle at any mid to full range causes the engine to die. Time to try the 120 or go back to the 117.5. Thing is that she is still darned hot. Maybee its just the way she is suppost to be. Leanburn=hot. Air cooled=hot. Spain=hot.

PhilJ · **Reply #2 on:** May 19, 2009, 12:16:38 am

23 HP, my plug check looked pretty much like yours on a new plug with a low mileage check. I think you need to run it in a normal manner for a few miles/kilometers then find the time and space to run it out properly. Changing jet sizes randomly can get confusing without having a definitive reading.

Joe28 · **Reply #3 on:** May 19, 2009, 01:42:35 pm

Take it from someone who has jetted 2 smokes off road bikes for decades.
You gotta remember the needle when jetting. This controls the mixture from 1/8 throttle to 3/4.
On a lot of older KTM, they ALWAYS had a burble at 1/8 throttle, where the pilot ended and the needle/slide took over.
The cure for this was to install a bigger cutaway slide, (stock was 6.5 you tossed that in favor of a 7).
This is my 3rd R.E. and I never had to replace the slide

, just set the needle position.
I like to have my mixture screw at @ 1 1/2 turns out, this way I have a little mixing room for temp., fuel, etc.
You can go CRAZY

and broke dropping in brass.
I got a set of brass from our host here that should cover all your mixing needs.
But, if'n you need brass, take a jet to a bike shop and they should be able to match it up.
Do one step, run it, then another.
Always make a record of what you did. I write on the bowl the jet sizes, so I know where I'm at.
Make sure you filter is clean, and if you oiled it, all the excess oil is pulled off it.
Good luck and let us know the final settings.
I'm running a free-er flowing exhaust, (A slip on that was a Harley 1200, opened the bottom of the air box, (I have a military model), so I think I'm breathing easier.
I ended up 2 steps richer on the pilot, (I can't remember the #)

, a 120 main, 1 step richer on the needle.
It starts nice, pulls strong, and my plug is a good tan.
Just this old guys thoughts!

Joe
If it's running great, I didn't fix it!

23hp · **Reply #4 on:** May 19, 2009, 05:34:13 pm

Thanks for the info and advice.

I started with the 110 with upgraded exaust but she was way lean, white plug and topped out at about 55mph. In a temporary measure, until I found out what serial number type of jet to use I raised the needle a bit (tricky on the CV) and she ran much better but still topped out at 55-60. Now with the 117.5 she accelerates well and tops out at about 65 but you are both right and I should go back to basics and put the needle back and start with the standard plug chop procedure. before trying out the other jets. Or just leave the main jet and needle like that cos she runs good!

As for the Pilot Jet I think.. I should change it for the larger size as the mixture screw has no effect at all untill she cuts out. I have a few bike shops around but none specialise in older stuff and really don´t want to help so I really dont want to waste my time with them and try and do my research here and buy online. Problem is that you really need to know what model numbers you are looking for first. I worked out the main jet type but the Pilot jet type still eludes me...

23hp · **Reply #5 on:** June 03, 2009, 01:54:16 pm

Just to close of this thread and provide the info for anyone else hunting, I found the model # for the Jets:

Main Jets: N102.221 (I bought 117.5, 120, 122.5, currentlu 117.5)
Pilot Jets: VM22/210 ( I bought 17.5 & 20, currently running 20)

Recomended removing Pilot Jet when blowing out with carb cleaner. Idle screw now seems to work again.

Rick Sperko · **Reply #6 on:** June 03, 2009, 03:29:01 pm

When you get it dialed in, if you want to post your settings to this thread:
http://www.enfieldmotorcycles.com/forum/index.php/topic,3955.0.html
I will add it, I am hoping for one stop shopping for people to find good jet settings.

-Rick

23hp · **Reply #7 on:** June 03, 2009, 03:54:19 pm

Hi Rick,

Will do and excellent thread. I just want do do some testing on the idle when I leave the office first. When I am really happy (if ever!) I will post.

UncleErnie · **Reply #8 on:** June 03, 2009, 04:29:47 pm

All that info and AVL's are left out in the cold?

Rick Sperko · **Reply #9 on:** June 03, 2009, 05:00:51 pm

Quote from: UncleErnie on June 03, 2009, 04:29:47 pm

All that info and AVL's are left out in the cold?

I am glad to post your settings. I thought AVL owners did not like to work on their bikes, that is why they didn't buy iron.

Ok, I will stop before I anger the AVL and UCE owners (all three of them).

-Rick

plane95302 · **Reply #10 on:** June 03, 2009, 07:50:36 pm

Hey, knock it off. There's four of us!

faltnerc · **Reply #11 on:** June 03, 2009, 08:34:14 pm

That´s not true!
Electra-owners like to work on their bikes as well!

The truth is that it is very difficult to give this bike better performance.
It is a modern construction and air filter, carb, inlet manifold, valves, combustion chamber, exhaust pipe and muffler work together very well and every change in this components must be done very carefully!

AVL in Austria is a really good company and I am very sorry that the new EFI-Engine was not built in company with them.

Greetings from Austria!
Chris

P.S.: Today I drove 400 km, mostly at speeds around 100 km/h with max speed 120 km/h, the engine runs like a clock!!

23hp · **Reply #12 on:** June 03, 2009, 09:48:55 pm

Quote

I am glad to post your settings. I thought AVL owners did not like to work on their bikes, that is why they didn't buy iron. Wink Ok, I will stop before I anger the AVL and UCE owners (all three of them).

-Rick

Trust me, my AVL has given me me lots & lots of work... and still not tuned in...

PaulF · **Reply #13 on:** June 04, 2009, 01:25:28 am

Quote from: 23hp on June 03, 2009, 09:48:55 pm

Trust me, my AVL has given me me lots & lots of work... and still not tuned in...

I can't understand why? I too consulted Ace on this matter. I currently have a 20 pilot, 125 main, one click down on the needle and K&N filter and aftermarket silencer. Voila! Ace, (and I), think I can actually go a little bigger on jetting. But it starts one kick, runs good with no flat spots. I'm happy with where it is.

The big question is, how fast do you wanna go? Its a 25HP motor. It's not a GSXR. If it ran perfect for you, it will still only be a perfectly running 25HP motor. Unless of course you want the world's fastest Bullet.

23hp · **Reply #14 on:** June 04, 2009, 09:16:22 am

Quote

The big question is, how fast do you wanna go? Its a 25HP motor. It's not a GSXR. If it ran perfect for you, it will still only be a perfectly running 25HP motor. Unless of course you want the world's fastest Bullet. Grin

Its not about speed. My tinkering with this carb is due to problems that I have been having with the Idle mixture screw not doing anything and the bikes refusal to start when hot. I just want her to work properly and not have to look for a hill to run down before turning her off. I also posted this in the Lonley Bobs forums in the UK also as they have a lot of AVL owners over there: http://tinytim.forumcircle.com/viewtopic.php?t=1489

longstrokeclassic · **Reply #15 on:** June 04, 2009, 10:06:23 am

23HP,

If the idle mixture screw is unresponsive, the cause will be incorrect fuel height in the float bowl (assuming all passageways are clear) .

Refit the standard pilot jet and adjust the float height to the richer (smaller) float height setting in the manual.
From memory (which isn't that brilliant even on a good day) the measurement is taken from the centre of the inlet to the bottom of the float with the carb inverted.
If your unable to do that try altering the float height by 1mm, run the bike and then go for another 1mm . You shouldn't want to raise the float height ( or lower it when measuring it upside down) any more than 2mm.

ric

23hp · **Reply #16 on:** June 04, 2009, 10:14:19 am

Ric

Thanks! I had adjusted the float on the Amal but not touched the CV carb yet. Will add to my list for the weekend!

Cheers

23hp · **Reply #17 on:** June 11, 2009, 10:08:45 am

Well, I didn't get round to the float as I have been cleaning the carb out with the little time I had to ensure that the Jets were clean but alas to no avail.

Well I sat down to the float bowl today with the Electra Service Manual. I have read and reread but cannot work out how to measure this properly Please see below:

https://sites.google.com/site/23hpre/_/rsrc/1244710368681/Home/Float.jpg

I think I have a problem with the float as when inverted the float point Y is resting on the base of the carb below. I think that this would mean that the carb float is at its highest point and possibly causing overlyrich situation.

Where I am really confused is with how to measure the float height. As the Service Manual states the carb should be inverted and the measurement should be from the mixing chamber body face to the top of the float and this should measure 17.1mm

Elsewhere in the manual it coincides with rick stating the centre of the mixing chamber to the top of the float.

Now the more I look the more confused I am getting and starting to question what is the top and the bottom of the float (when inverted) and what is the centre of the mixing chamber and what is the mixing chamber body face!!! Really driving me mad now.

Anyone care to assist before I toss this out of the window...

Any suggestions on how to bend the tongue without breaking it would be appreciated (I'm a bit of a disaster)

-Edit-

Well stuff the Measurements. After a week of not starting, trying everything all I had to do was to bend the float tongue a bit. I say a bit as that's how I measured it... As it was resting against the base it could only bend one way (less fuel - leaner) so about 4-5mm to give her some clearance. Fitted her. Primed her. First kick a slight backfire. Not good. Choke out. Primed. Second kick - WHAM grrrrrrrrrrrr thump thump yepeeeeee

Drove her around the garage a bit then turned her off. Kick grrrrrrrr - excellent she started again. The great thing is I took her to work this afternoon and turned her off. Tried to kick her and she started again! When HOT!!!

Now I know I'm jumping to conclusions here as I have yet to test her on the open road, see if she overheats, check if she starts when hot always, but she started so I am one step better than I was last week.

Jerry · **Reply #18 on:** June 12, 2009, 12:22:17 pm

Congratulations!! It sounds like you're making progress. I always find carbs, especially the float settings, a bit mysterious. I haven't done anything with the carb on my avl Military yet but plan on opening up the exhaust and air filter system and rejetting at some point. So....I have no advice for you but wanted to offer moral support and an attaboy for all your work and progress so far. Good Job!!

Jerry

23hp · **Reply #19 on:** June 15, 2009, 10:22:35 am

Thanks Jerry

After the weekends rides I am confident that with this forums help I have managed to fix a problem that has had me baffled for the last good while. She starts cold with the choke and a firm kick and warm without choke and a nice soft kick. Runs perfectly and idles great.

I think that this problem has caused both of my Sprag failures (now removed) due to the spiting and backfiring when starting her so I am happy to have found the root of the problem. This is how the bike should have been for a long time and now I can now spend more time enjoying her and looking for other things to break!

With regards to your bike the BS29 CV carb is actually quite nice to work with with the jets being really easy to change even though some of the manuals tell you otherwise. So enjoy getting your hands dirty!