GS550 with Mikuni Dual Throat Carb, No Info

[Nessism]

I had a tip stick like you describe once. Drilled out the bulk of the screw, but the tip was stuck fast.

I used PB Blaster down the passage, and several cycles of heat, using a torch. Not stupid hot, but enough to boil the oil. I also put a punch down the hole, trying to kick the tip sideways, breaking it free. I was almost ready to give up, when all of a sudden, the broken tip just fell out.

BTW, the best way I've found to remove stripped pilot screws is to drill a small hole in the top, and then pound a torx bit into the hole. That usually affords enough leverage to get it out. Of course, use plenty of penetrating oil and heat first. That's a given.

[dgates1]

Those videos are horrible.

Lol.. agreed. Not much out there. I wouldn't want to have to deal with this problem.

[Witehorse Motors]

Well needless to say I got burnt out on this project and still am. I finally got a 14K gold testing bottle of Nitric acid (said to dissolve brass and leave aluminum pretty untouched) and have been trying rounds of that today. Not really reacting to the screw much and so far no results. A few folks on forums and short vids claim success but I am not seeing it.

[Witehorse Motors]

UPDATE:

Nothing I did helped the stuck screw.
I located another set of carbs though!!!!!
Mated them together after a good cleaning, by hand then ultrasonic... I got the bike running with the enrichening cable pulled out some but seems like there was a air leak around the intake boot. racing idle. then a better idle but no response. Some spray also affected it ..
Gonna try and get it sealed better later.
This thing is chopped out with flowing 4 into 2 exhaust and some CRUDE homemade pod filters made from airbox boots, but even still
it should get to a decent idle and some ability to ride (with lousy mid range im sure, but I just want to send it home running and never think about it again, HA!!)

[Witehorse Motors]

Ignition

[Witehorse Motors]

Cleaning

[Witehorse Motors]

[Witehorse Motors]

[Nessism]

You should remove those Jet Needles, and clean everything...if you haven't already do so. Also, replace O-rings. Most of the O-rings are common with the other BS carbs, and I have a kit for those.

[Witehorse Motors]

I put o ring on the crossover fuel tube, the float valve seats and drain plugs.. only ones I didn't appear to be the ones for the choke (enrichener?) plunger..
Got up today to try to get the intake to seal up, but no luck.

The right side carb has a slight bit of gas weeping from the tiny air jets that face the air filter. Gotta find a spec for float height or check the needle valve is working, they are the metal type.

I tried to leverage the carbs fully into the intake boots with no luck. Even got them really warm with my hair dryer but they just dont want to seat.

This chopper has been a real pain to work on. I just drained the tank again and I am removing the carbs (again).. Might have to remove the intake boots to see WTF is up with the fit.
Trying not to despair at the constant set backs. I hope I can look back on this some day soon and laugh (or puke). Ha.

[Cipher]

I put o ring on the crossover fuel tube, the float valve seats and drain plugs.. only ones I didn't appear to be the ones for the choke (enrichener?) plunger..
Got up today to try to get the intake to seal up, but no luck.

The right side carb has a slight bit of gas weeping from the tiny air jets that face the air filter. Gotta find a spec for float height or check the needle valve is working, they are the metal type.

I tried to leverage the carbs fully into the intake boots with no luck. Even got them really warm with my hair dryer but they just dont want to seat.

This chopper has been a real pain to work on. I just drained the tank again and I am removing the carbs (again).. Might have to remove the intake boots to see WTF is up with the fit.
Trying not to despair at the constant set backs. I hope I can look back on this some day soon and laugh (or puke). Ha.

They are hard to get on.
my method required both hands and a length of 2x4

[Witehorse Motors]

Yes indeed, I did that a lot back in the day with my SOHC Honda 750's

I went to the owners parts engine and retrieved a decent right side intake boot.
Online searching I put in an order for
Intake boot o-rings 4
bowl drain seals 2
new float valve seats and needles w/ o-rings 2
exhaust seals 4
new spark plugs 4

My second go round I will be using an auxiliary fuel tank for easier testing, The bike ran and even idled poorly with the intake leaking so I think we are getting close to a working chopper again.

I drilled out the plugs covering the air screws on the replacement carb, and since there is no air box (just stock boots with air filter foam tightly taped in) (I know proper tuning is unlikely)
I set all 4 air screws at 2.5 turns from seated.

The choke plungers seem to seal well with their o-rings

After all this effort I hope to have a functional chopper next week

Now about that rear brake return spring....... ha

[Witehorse Motors]

UPDATE:

Carbs are sealed up, intake sealed and tight and a nice bath and blow dry heat (and a touch of lithium grease) the carbs seated really well.
Bike fires up just like a jap bike should, even with non-compliant exhaust and intake.. It is running like it used to again.
Gonna leave it to the owner to decide about increasing jetting and new tires, chain, etc...
What a struggle but Im calling that a win.
Thanks to all the forum members that offered advice.

Now for that Shovelhead crank seal leak..