Boiling carbs - temp range of rubber

I'm still having issues with some carbs and am going to disassemble and reassemble the carb bank. It was suggested that boiling the carb bodies for 1/2 hour may free up any possible material in the various internal conduits. I was thinking boiling in lemon juice or vinegar would also be more effective for removing any remaining residue, especially and mineral build-up.

I have just replaced all the throttle shaft seals and do not want to remove the butterflies to remove them prior to boiling. What I'm wondering is, are the Shaft seals going to be OK at boiling temps? I know neoprene & O-Rings are fine at that temp but anyone have experience with throttle shaft seals at that temp?

Thanks!

 

If you can't "Blow" Carb Cleaner through the Passages, ... Boiling is in order.

If the Carbs have been Cleaned.
Passages flushed.
The Passages not clogged and allowing for flushing; Boiling is unnecessary.

You probably wont hurt the seals boiling them in Citrus of Vinegar.
They can handle the temperature.

 

I think I did a really decent job of cleaning them but I'm going to separate all the carbs and re-seat them on the rails. I just bought two 2" x 1" x 13" pieces of aluminum stock and have hogged out a channel for the throttle attachment to fit in and will re-assemble them with those pieces clamped together to keep the bodies linear while tightening the rail screws.

While I have them apart to do this, I might as well go the extra mile and boil the carbs to remove any crud which may remain after all my efforts to do a good job of carb rebuild. if I can do so without disassembling to the bone then I will. I just don't want to undo the butterfly screws again if I don't have to.

Good to know the seals won't be damaged by boiling temps.

 

Keep an eye on how much Lemmon juice you use. To high of acid will turn the aluminum black. Dont learn the hard way like I did.

MN

 

Thanks for the heads up!

My engine & bike is all black except for the chrome so maybe the black carbs would look good?

 

Don't think you would like that kind of black. But let us know how it turns out.
Dried gas clogging passages blows big time.

I'm never going to let gas sit in my carbs ever again. I got those really nice stainless Allen head drain screws from Len and they are great. I have a tee handle Allen wrench and a set of tubes to fit the drains. I can drain those carbs in less than two minutes start to finish.

MN

 

I too bought those same Allen screws from Len & for the same reasons. For that matter, all the screws were also replaced by SS Allen heads. I don't know what is wrong with the carbs, I'm pretty anal when I work on mechanical things and I check & double check my plans before starting out.

I checked the compression and it's excellent. With that, my poor gas mileage comes back to the carbs as the most likely culprit. Sometimes the carbs hang keeping the RPMs higher than they should be before returning to idle, I can feel bogging when WOT at 3K and even though the sync is beautiful, it sputters at idle. Yet at upper RPMs the bike screams. So it seems prudent to re-address the carbs in a way that hasn't been done before.

So I've separated the carbs and am going to strip them down, removing the idle adjust needle & jets/emulsion tubes (leaving the throttle shafts in place as the seals are new) and will do this boiling extravaganza on all the parts. I figure 30-40 minutes in this bath will surely get whatever the carb cleaner I immersed them in last month, didn't get.

Amazing how exacting the carbs are. Gotta be done right...

 

Sputtering at idle? I assume you went over everthing with propane to see if you were leaking vacuum. Also you should unhook the vacuum line to the vacuum operated fuel valve and cap the port off. My fuel valve was leaking and it was sucking fuel into that fitting.

MN

 

I have read a few posts lately where members have had had hanging idle and went through the carbs several times. What they found was a vacuum leak at the car boot to intake gaskets. If it still hangs after the carb rebuild, might try that. If it were me though, I would go ahead and replace them anyway if they haven't already been replaced. I needed a new boot on my #1 carb, so I just bought a whole new set of boots and gaskets for mine.

 

Getting the carbs back-together "Plumb & Square" does not take Jigs or Special Tooling.

Just mount the Carbs to the two rails.
Leave the Fasteners loose enough to position the Carbs with a gentle tap.
Use the edge of a level.
Straighten the TOPS without the Hats.
Tap the line-up "True"
Next, ... straighten the Intake Necks.
Tighten all the fasteners enough to require a STIFF RAP to move the Body.
Sight any offending Carb.
Smack it into position with a rubber mallet.
Work the linkage.

The stock braces are practically self adjusting.
Place the Level in a Vice.
Lay the Carbs on the level.
Bump into position with a rubber mallet.
Lock 'em up.

 

While you're waiting for you solution to boil..........

take the intakes off and check the o-rings and their mounting surfaces. The X has no gasket, just a thin o-ring. Take a look at the attached pictures that show how badly corroded the ones were on my 750X. New ones aren't cheap, but you will have eliminated a potential source of vacuum leaks.

Tony

 

Good replies.

I've checked for intake leaks with both propane and starting fluid & no change in idle from either. I rebuilt the petcock and it seems to be intact with no gas leaking. No question the O-rings on the X bikes intake get mangled. I'm not sure what kind of O-ring is necessary but probably those vitol rings are OK? My intakes look really good & on this bike they are the best looking of any of my 3 bikes. No doubt though & without looking, I know the O-rings on the boots are compressed...

 

IF you boil those carbs in anything you can plan on new throttle shaft seals.

Boiling in lemon juice, lime juice or even CLR is for RAW parts. Not subassemblies with stuff still inside.

A standard service manual "bench strip and clean" (which ignores throttle shaft seals and pilot mixture screws) is effective about 50% of the time, based on raw experience. Do the pilots, and the success rate increases.

My personal opinion in regard to throttle shaft seals:

-DO NO HARM. They might still be fine, especially in Mikunis.

-even with Mikunis, they're inevitable.

-"Inevitable" can be a good long time, as long as you don' f* them up cleaning the carbs and they still work.

-when they finally need replacing, then just dive in and do it right.

 

The Manifolds may have what I call an "Occult Leak"

The Manifold's Rubber O-ring may be deteriorated and aged having no resiliency left in it.
The Seal is OK until Vacuum forms and air seeps through.
Tightening the Cap Screws is an exercise in futility.
They seem tight.
Actually, ... they're seized.

Dealing with the seized Fasteners is dangerous.
Breaking-off a Cap Screw can cause serious complications requiring the Head to be removed for outsourced machine shop repairs to excise seized bolt fragments.

The best course of action is too run a bead of sealant all-around the seam at the mating surface.

 

I already have put in new shaft seals, about a month ago. The pilots looked fine but I replaced their O rings. I don't want to have to go through the hassle of removing these new ones just to soak the bodies in a hot solution that will hopefully dissolve anything the carb cleaner didn't get. Heat speeds up the molecular activity of the solution so heating makes sense. I've already put about $200 in rebuild parts into these and two full days of soaking/cleaning /spraying/ cleaning all metal parts. If they're not working right, I need to deal with what that is. Seeing as I replaced everything but the diaphragms (and they all checked good), there's not much left to replace. A different cleaning approach and a precision reassembly is about all that's left.

 

That makes sense and a good trick to remember but in this case, I can't detect a leak with either propane or starting fluid sprayed at every carb junction. I don't think I have a leak.

 

You don't need to Boil carbs that are clean and flowing.

You boil Carbs that look like a dirt road the Prison Farm Road Gang tarred in "COOL HAND LUKE".
Nasty.
The ones that Carb Cleaner cant penetrate the Varnish and you can't believe how stupid you feel because the Ebay description said they came off a runnin' bike.
Those.
Ones that are disgusting.

Not one's really off a runnin' bike.

 

You mentioned poor gas mileage. The float levels are critical to mpg. Thought mine were correct using clear tube method and was getting 33mpg and sooty plugs. Checked the floats with a float gauge and adjusted them to factory specs. Rechecked the clear tube method and they were still within specs. MPG went to 40. I'm going to tweak them one more time since one of the plugs is still a little sooty.