Sigh, carbs again

[Rocinante]

OK, noe I´m getting tired of this and know I better leave the bike to someone who knows what he´s (or she´s) doing. After installment of engine and rear suspension linkage everything is fine, except, as always when reinstalling them, the carbs. Here´s the facts:

Runs on two cylinders on low revs, when I gas it all three runs fine.
Starts easily.
Seems to be the centre cylinder, since disconnecting the middle coil does not affect the idle, while disconnecting any of the other two makes the engine stall.
I have tried swapping the coils but problem persists on the centre cylinder (water on pipes test).
All carbs cleaned and confirmed that the pilot screw(when taking it out and blowing through), pilot jet and the main jet has got passage.
Pilot screws where at 3 to 3,5 turns
The middle pilot jet is stuck. It gets loose from the threads, but want fall out of the tube like the others. Tried knocking lightly on the housing.

Any ideas?

Dag

[Rocinante]

No one?

Anyone heard of or experienced a stuck pilot jet? It swivels out the right number of turns before being loose(same as the other two jets), but it simply will not fall out of the pipe. I have even tried to hook it with a long thin thingy with a tiny hook at the end, to no avail.

The other two pilot jets drops right out.

Dag

[CoolHandLuke]

The Mikuni pilot jets are renown for becoming one with the carb body.  You can get them sorted, but it costs as much as getting a second hand set of carbs.

[pegleg]

I would imagine the jet has a slight burr from the wrong or a bad screwdriver.
Try hammering a needlework pin into it and pulling it out.
Will probably ruin the jet but cheaper than replacement carbs.

[Rocinante]

Thanks guys. It seems to me there´s a burr or similar, yes. It screws almost all the way out and then it drops back a tiny little bit. The other pilot jets does not.

I tried again tonight to withdraw it, but to no avail. Now it´s opened up and soaked in carb cleaner. I´ll put it back in tomorrow and fire up. If it´s still bad, I´ll call my dealer and leave it to him. Nuff hours spent in busy times.

[rybes]

find a small self tappin screw and very gently screw it in till it bites. that should give you enough to pull it out.

[Rocinante]

Puh, got it!

I used a tool that inelegantly translates to pigs dick. It´s a screw release tool with left rotating threads, and it worked like a charm. Problem solved. Bike runs. I´m happy. Thanks folks.

[BruKen]

Pigs dick .....   :P perfect metaphor for it.

[Rocinante]

Well, it wash´t ok after all. Had to let it sit for a while and now it´s back to square one again.

Problem is simple enough, it won´t run on the centre cylinder on idle. Give a little gas and it runs like a champ, although it sputters and coughs when I let go of the gas, especially when cold, less so but still when warm. At normal speed it runs rough at low throttle.

Done so far:
Rejetting (done independently, but believed a damaged pilot jet to be the cause, hence replaced all); mains set to 110, pilots to 45, two turns on the fuel screw, plus shimmed up the needle by 0.03" as suggested in the sticky. Runs smoother and better, but problem persists.

I haved removed all jets and the fuel screws and cleaned and blown and cleaned and cleaned, also used carefully a copper wire and have confirmed that the centre carb has the same passage as the other two.

O-rings on the fuel screw seemed worn (one was broken, not the centre though), and has been replaced.

Pistons and diaphram cleaned and checked for movement, which is fine.

WOrth mentioning is that it ran fine before I took off the carbs when I took off the engine earlier this spring. When I removed it I forgot to blow  the exterior of the carbs clean, and  as a result lots of grains of sand from having fun last year I guess, came down into the venturi. So my suspicion has been a grain of sand in the pilot system. Can it still be?

[Mustang]

do the pilot screws have all the bits on em

ie :
screw
spring
washer
and last oring

in that order ..........cuz if they don't it'll never run right

are you still using stock airbox ?
got a good seal on the air boots from filter especially #2 ?

when was the last time carbs were synched .

#2 is the master cylinder  and number 1 and 3 have adjusting screws to match #2  ....#2 has no adjustment other than the master idle knob which controls the linkage for all three .

but yeah it does sound like the pilot circuit is still plugged on #2

have you tried blowing compessed air thru the little bitty hole in the carb body when it is COMPLETELY STRIPPED OF PARTS
and has that body been soaked in a carb cleaner solution overnight at a minimum .
and have you checked the rubber intake boots between carbs and head if they are cracked and sucking air it will run like shit .

[Rocinante]

do the pilot screws have all the bits on em

ie :
screw
spring
washer
and last oring

in that order ..........cuz if they don't it'll never run right

Yes they do.

are you still using stock airbox ?
got a good seal on the air boots from filter especially #2 ?

I think so. The boots are new and Ive never been better at mounting the carbs... :roll:

when was the last time carbs were synched .

#2 is the master cylinder  and number 1 and 3 have adjusting screws to match #2  ....#2 has no adjustment other than the master idle knob which controls the linkage for all three .

Never, me thinks.

but yeah it does sound like the pilot circuit is still plugged on #2

have you tried blowing compessed air thru the little bitty hole in the carb body when it is COMPLETELY STRIPPED OF PARTS
and has that body been soaked in a carb cleaner solution overnight at a minimum .

Blown through yes, not soaked it overnight. Might be my next  step.

and have you checked the rubber intake boots between carbs and head if they are cracked and sucking air it will run like shit .

Visually while sitting on the head yes, not taken it off to check.

Thanks, Mustang, a few more things to look at here.

[Bixxer Bob]

At the risk of repeating Mustang but using different words, I had exactly that problem recently on a friend's bike. It turned out to be a blockage in the little brass pipe that sticks up in the float area and goes inside the float assy tube when you fit the assy to the carb. It goes down the outside of the carb and into the venturi.  It was a b°°°°°d to clear. Twice I thought I had it because it would let a little air through then block again. I ended up putting plastic tube over it and filling that with brake cleaner. It soaked in and freed it in about 15 mins. Eventually I could blow through it no problem. Even then he had to take it for a good thrash with fresh petrol before it behaved.

I'm not familiar with these carbs but I'm guessing that tube is some sort of device for putting a shot of fuel into the intake if the throttle is snatched so as to stop it bogging down.  My old Volvo Pierburg carb had a pump that did much the same thing.

[Mustang]

I'm not familiar with these carbs but I'm guessing that tube is some sort of device for putting a shot of fuel into the intake if the throttle is snatched so as to stop it bogging down.  My old Volvo Pierburg carb had a pump that did much the same thing.

only the mikunis have that silly tube
the keihins are a normal cv carb

[Rocinante]

and have you checked the rubber intake boots between carbs and head if they are cracked and sucking air it will run like shit .

Visually while sitting on the head yes, not taken it off to check.
[/quote]

 :roll: To my weak defense the crack was below the steel band and out of sight while on the bike. Weak, I know...

But thanks Mustang. If you want to move to Norway, there´s a house available just down the road...

[Mustang]