mikuni carb question

On the 550 Seca is there a pilot jet? If so according to clymer you can remove it - but the picture in clymer is completely misleading? There are 2 tubes in the float chamber sticking into the fuel, the main jet and then another with what appears to be a brass fitting inside, that looks nothing like what is in the clymer, applying masses of force on it on my scrap carbs with a screwdriver, none of the 4 so called pilot jets would budge and I stripped all 4 I tried blowing through the tube by stuffing a piece of clear pipe through but all 4 are totally sealed? no air gets through even with my blowing till purple - which makes me think they serve no purpose..... so the question i have is - where is the fuel drawn through for idle? is it the brass pipe that I thought was for the choke circuit? - or does it serve both, or is it drawn through the main jet and skirts round the butterfly valve - which means that syncing the carbs is absolutely vital for good idle.. I have a 550 that absolutely refuses to idle, despite adjusting all 4 pilot scres in and out on about 10 different settings, it will idle for 20 seconds then just dies, no amount of fiddling main idle screw or cleaning of the carbs have worked - i have cleaned them 5 times now and sick of doing it

 

That brass fitting inside the tube next to the main jet is your pilot jet. Its longer and thinner than the main jet, and for cleaning I find its best to remove them and let them soak in carb cleaner ( I leave them in overnight). As I understand it (and I'm sure someone will correct me if I'm wrong) that jet meters the fuel at idle rpm's, the pilot screw meters the air. If your bike is not idling and you can adjust the screws, then its a good indicator that maybe your jet is plugged.

 

This is a picture of the offending hole, thanks for the explanation darthbob but I just cant believe that this is the pilot jet, since if I blow into this hole through all four of these jets with all my might nothing flows through its totally sealed -

 

I can see that there is a slot in the top of it, which you would think would mean that you can unscrew it anti clockwise, but all four of these on my scrap carbs were also blocked off totally and I stripped that slot off the top on all four, by trying with all my might to unscrew just one of them, either these are welded and sealed shut with years of crud building up or I dont have enough puff in my lungs to blow any thing out of the holes.

 

You have 2 racks of plugged carbs, and 3 550 ' s How's the third rack?
I don't have any 550's , but I'd say you need a deep cleaning.

 

As you say time2ride I am making myself really popular with the mrs. with boxes and boxes of bits from 550's all over the garage, 3 bikes, all the same, and I think I have 3 spare sets of carbs, ( I have a mate who scraps bikes here in TO) . OK so I admit I am a teapot. This could be a lesson to all others suffering the same fate. I managed to get one of the blasted jets out and the thing has a teeny weeny hole in the end that was blocked on two of the carbs. The 3rd would not budge but there was some flow through, so rather than continuing to strip what was left of the slot I let it be. So this is the most stupid flipping design I have ever seen , a teeny weeny hole just begging to be blocked up with years of crap, the end result being that your bike will simply not idle, and you will be mucking around with syncing and cleaning and adjusting pilot screws forever. and never get it right. And while they were at it - make the jet deep inside a tube that you cant get into, or see into, and make it out of soft brass so that when heat and emulsion sealed in there you cannot ever get it out without drilling and replacing the thing.... Do I sound frustrated ? I have stopped short of remounting the carbs on the bike, something to look forward to tomorrow, my guess is that this will be like a new bike experience ! My question now is - is there a way to clean out that teeny orifice without having to extract the jet?? I thought about a wire off a wire brush wiggled in the end of the jet? Any suggestions

 

Hate to burst your bubble, but I'm afraid it is.

...and you would be correct. Either yours are severely gummed up or you didn't have the right size blade -- in order to try and prevent this from happening, one should take a cheap screwdriver and grind it down so that there is NO free play when putting it in the slot. None. Mine came out with little diffculty; maybe because of this, or perhaps because of something else...

Spock: "Random chance appears to have operated in our favor."

McCoy: In plain, non-Vulcan english... we were lucky."

Spock: "I believe I said that, Doctor."


So, what to do next? Short of breaking the rack and soaking each individual body in carb dip for a day or two, I can't think of anything... and doing that would likely require replacing the throttle shaft seals, which on Mikunis is an adventure in itself, or so I'm told. I checked Chacal's last known parts list, and he didn't have any Mikuni pilot jets listed; ergo, I don't know that drilling and extracting them would be a good idea.

Rick? Chacal? Please pick up the white courtesy telephone.

 

Simona, I have mikuni carbs on my bike.
I just took a wire brush and tried on my 37.5 pilot jet, it went through easy.
Fill the hole with carb cleaner and let it soak over night. Then tomorow try to wiggle it around to open it up.

 

Simona, when fighting with seized pilot jets, you want a perfect fitting screw driver.

I've managed to get a few stubborn jet out by dousing them with penetrating oil, applying some heat--making sure that I'm not roasting any rubber and plastic parts--and a little impact (I have a screw driver with the shaft exposed on the handle. I place the driver in the slot of the jet and GENTLY tap the jet, making sure that I'm not destroying the top of the jet. I do this after I heat up the aluminum surrounding the jet.) With the aluminum still warm, try turning the jet out.

good luck