mixture screw right in!

spanner · Nov 29, 2008

fs650e,
148 main jet,
Dales needle clip position 1 up from supplied position.
pilot fuel jet 48,
Adjustable pilot air 1 turn out, have tried 1 1/2 turns, same.

Akro exhaust,
carb bored 43mm,
38mm inlet valves,
32mm exhaust valves,
port work done,
LX1 cam.

With motor running I can screw the mixture screw right in without much change to engine speed.
Have checked float height OK.
Float valve seals OK.
Have tried original pilot fuel jet 45, same thing.
Do I need to go to a smaller pilot jet? note Taffy runs 38 I think.
Could there be something else I have missed.
Exhaust is black and sooty.

Thanks for any ideas
spanner.

berger · Nov 30, 2008

Somethings not right. I would check float level. The carb is pulling fuel from somewhere.
I have one of Dales kits and when I adjust the pilot air screw the smallest adjustment makes a very large difference. When I adjusted it was by 1/16th a turn at atime. I dont recall more than about 1/2 turn of usable adjustment. The pilot air screw is there primarily for altitude adjustment so as to always keep the fuel screw in the 1 1/2 turn area at whatever altitude you may be at. At least thats how I understand it. It makes for a very sweet idle when its all set up properly.

I was running a 165 main in my 650 at 1000-2000ft elevation. It seemed to run well from sea level to 6000 ft.

sparks · Nov 30, 2008

spanner said:
fs650e,
148 main jet,
Dales needle clip position 1 up from supplied position.
pilot fuel jet 48,
Adjustable pilot air 1 turn out, have tried 1 1/2 turns, same.

Akro exhaust,
carb bored 43mm,
38mm inlet valves,
32mm exhaust valves,
port work done,
LX1 cam.

With motor running I can screw the mixture screw right in without much change to engine speed.
Have checked float height OK.
Float valve seals OK.
Have tried original pilot fuel jet 45, same thing.
Do I need to go to a smaller pilot jet? note Taffy runs 38 I think.
Could there be something else I have missed.
Exhaust is black and sooty.

Thanks for any ideas
spanner.

Hi Spanner,

Your problem possibly lies with the pilot air circuit somewhere, either leading up to the PJ or from the PJ to the passage way that feeds the FS.

When I fitted Dales needle I found it excessively over rich on the straight of the needle, do a test with your old needle to see if this alters anything.
Your problem could even lie here.

When you fitted the adjustable PAS did you relieve some material from the plastic bell manifold, if not this could be your problem.

Regards

Sparks.

Taffy · Nov 30, 2008

i'd say that a 148MJ in a 43mm carb was wrong.

dales needle is very rich on the straight so that and a 48PJ makes it ridiculous!

i would go back to a 35PJ or even a 38PJ. needle in clip 1 and i suspect a 160MJ. could need smaller. i use a 148MJ so it's possible! i have the cone filter as the only other difference.

regards

Taffy

bushmechanic · Nov 30, 2008

not that it would fix the problem completley but I prefer caltex vortex 98 over BP ultimate.

couldn't get dales needle to work good with the BP. fuel ain't supposed to make much difference ....... but Taffy already Knows I'm a mad bugger

DaleEO · Nov 30, 2008

sparks said:
spanner said:

fs650e,
148 main jet,
Dales needle clip position 1 up from supplied position.
pilot fuel jet 48,
Adjustable pilot air 1 turn out, have tried 1 1/2 turns, same.

Akro exhaust,
carb bored 43mm,
38mm inlet valves,
32mm exhaust valves,
port work done,
LX1 cam.

With motor running I can screw the mixture screw right in without much change to engine speed.
Have checked float height OK.
Float valve seals OK.
Have tried original pilot fuel jet 45, same thing.
Do I need to go to a smaller pilot jet? note Taffy runs 38 I think.
Could there be something else I have missed.
Exhaust is black and sooty.

Thanks for any ideas
spanner.

Click to expand...

Hi Spanner,

Your problem possibly lies with the pilot air circuit somewhere, either leading up to the PJ or from the PJ to the passage way that feeds the FS.

When I fitted Dales needle I found it excessively over rich on the straight of the needle, do a test with your old needle to see if this alters anything.
Your problem could even lie here.

When you fitted the adjustable PAS did you relieve some material from the plastic bell manifold, if not this could be your problem.

Regards

Sparks.

I will second the comment about relieving the air filter bell. I failed to realize that the bell needed to be relieved and one day I happened to notice that the bottom of the bell was not sealing against the carb body, thus, allowing dirt into the paj or pas as it were and the maj. If you find that this is true you will need to remove that carb and give it a good cleaning. Be careful when relieving the carb bell for the pas, there's not a lot of material there to work with before you can punch through.

Taffy's suggestion of going to your stock needle, a T straight (?), at the stock setting for a quick check is a great idea and is easy to do.

And Berger is right as well, a 1/4 turn on the PAS makes a pretty big difference in the PS adjustment.

spanner · Dec 1, 2008

RE: Re: mixture screw right in!

thanks guys. I have relieved the bell to clear the adjustable air screw so that is not the problem.
Will not get a chance to look at it again until Friday.
I have had the carb on and of at least 6 times, so I am going to the shop to get a smaller 35or 38PJ as Taffy suggests as I can get that in with out pulling the carb again!
Will let you know how it goes.

Cheers spanner

Neil_E. · Dec 1, 2008

RE: Re: mixture screw right in!

Remove the starter motor to get better access to the bottom of the carb. Remove the main jet cap. You may need to grind a screwdriver to fit correctly for the pilot jet. Not too hard to get out, but a major pain to put back in. A small inspection mirror helps. I take a length of heat shrink tubing and shrink it on the body of the pilot jet. This lets me get the jet up in place and start the thread. The well that the jet goes into is so snug that a regular piece of tubing won't work. So yes, it is possible to change a pilot jet without dismounting the carb.

bushmechanic · Dec 1, 2008

RE: Re: mixture screw right in!

I take a length of heat shrink tubing and shrink it on the body of the pilot jet. This lets me get the jet up in place and start the thread. The well that the jet goes into is so snug that a regular piece of tubing won't work. So yes, it is possible to change a pilot jet without dismounting the carb.

can use masking tape too.

on the 650 can do all jets with the carb in the bike,can change the needle and air jets too, I made a sort of a gutter to stick under the carb so the fuel doesn't piss all over the starter motor, I leave it in. would be simpler to turn off the fuel and run it dry but thats too complicated

Regards
Bushie

spanner · Dec 2, 2008

RE: Re: mixture screw right in!

Might just take it off again am getting good at it now.
Am thinking there may be an internal leak somewhere, If it is still rich with a 35 or 38PJ I will know there is a leak internal.
I think.

Cheers spanner.

spanner · Dec 7, 2008

Well put the #38 pilot jet in on Sunday now I have adjustment.
Awesome to ride now.
Think I my go up to a # 40 as if I snap the throttle while parked it wonts to die, although wasn`t a problem while riding,
Forgot to mention not running acc pump.
How come I have had to lean it off so much? Perhaps the cam is causing reverberation and picking up extra fuel from the carb?
Now all I need is another 1000 rpm feels a bit limited at the top. CDI?

Cheers
spanner

bushmechanic · Dec 7, 2008

MAJ?

drill and tap it to take one if there is no MAJ

maybe try a 160 or a 155 with the 148 main just for giggles

the secrets is in dem air jets 8O 8O

regards
Bushie

Taffy · Dec 7, 2008

spanner

if i could i'd kick your arse from here to adelaide....

do as your told or i'll come down there and slap ya!

you did half of what i said and i was right, now do the second half.

regards

Taffy

spanner · Dec 7, 2008

Taffy don`t you always say only one adjustment at a time?
Bushie, It has a MAJ #200, I think I will look into changing that.
Thanks everyone for the surgestions.

Cheers,
spanner.

spanner · Jan 15, 2009

I am very close now.
Tried a 40 pilot and lost adjustment so back to a 38
7/16 of a turn on adjustable air screw,
1/4 turns pilot screw,
148 main jet,
180 MAJ
Dales needle 3 slots from the bottom,

Some more time on the bike is needed to be sure.

Cheers spanner.

Taffy · Jan 15, 2009

always count from the top spanner if you could and never say what you do to the clip - only what happened to the needle: "i raised the needle one clip" etc etc

regards

Taffy

arkley123 · Jan 22, 2009

Just about to fit a new needle & atomiser plus another jet Taffy sent me to my Dellorto. What is the best click on the needle to use counting from the top of the needle - ie click 1 raises the needle relative to the slide - click 2 raises it further etc.. and what does this actually do. I know raising the needle will let more fuel in but how does this manifest relative to generl running conditions.

Taffy · Jan 22, 2009

the needle on a dell orto is 90% about midrange.

if you have a 4 clips stick it in C2 it'll be that orC3 that will do the job. should really try and blow the carb out while you're there james. find imagintive ways to reverse blow through the carb by blocking other ways out.

regards

Taffy

arkley123 · Jan 22, 2009

Cheers for that. I did give it a good clean just last week though. water in the boot / **** in the filter - thought that would have cured it, but fingers crossed for this weekend.

arkley123 · Jan 22, 2009

How do you post a pic as viewed rather than is a text box as above??

mixture screw right in!

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