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Old 05-21-2013, 09:35 AM   #1
Dang! OP
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R90/6 Maint Jet stuck

Hi folks, greetings from a new member here. I've previously been a Honda owner but I recently picked up a '76 R90/6. I love the bike, I've put about 1k miles on it since purchase last month with no real issues until this past weekend. Not too long into my ride I lost a cylinder. Things seemed fine at idle but pulling on the throttle cable to my right carb produced just a sad flat sound, with occasional brief, jarring moments when it would kick in. I limped back home and the plug on that side seemed good so I started to pull the carb apart hoping the whole thing just needed a good cleaning. I got as far as the main jet when things went south. Basically, it's stuck in there good. I've tried WD-40, heat, PB blaster, and it's not budging. Even after applying all of those things a good socket wrench still stripped it cleanly. I filed it down to the next size (9mm) with similar results. At this point I definitely need a new main jet but there's still the extraction problem. Anyone ever have this issue, and know of a way to get it out with minimal damage to the carb body? Any help would be appreciated, thanks.

-D
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Old 05-21-2013, 09:41 AM   #2
chollo9
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I assume you're talking about the jet holder, not the jet itself?

I'd let it soak in some carb cleaner, the HD kind you buy from NAPA or others that comes in a gallon paint can, for a day or two and then try it again. There are probably varnish-like solids that have glued the holder to the carb body.

If you're not talking about the holder, then pull that, and replace both if you can't separate them.
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Old 05-21-2013, 09:52 AM   #3
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Yeah, it's the holder, what the fiche calls the venturi. Thanks for the tip!
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Old 05-21-2013, 10:38 AM   #4
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Tough one.You may have to mount the carb firmly (carefully) in a vise and drill out the metering hole to a suitable size to tap in an easy out.Continue tapping to maintain your bite on the venturi and turn it out.Firmly and carefully.
A bit of heat here might not hurt.When drilling be careful not to damage the threads of the body.
I find the square easy outs with the flutes being the best.
Good luck !
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Old 05-21-2013, 10:56 AM   #5
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I try to avoid easy-outs as a policy. Historically they've gotten me into more trouble than they've gotten me out of. I'd just drill the whole thing out... carefully.
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Old 05-21-2013, 11:02 AM   #6
190e
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Main Jet Stuck

Did the jet holder have the O ring by the /6's ?

You may have already thought of this but bear in mind that any penetrating fluid won't get past the O ring so you have to attack it from the top side of the threads by squirt fluid down the emulsion tube air inlet or down through the needle jet.

I had stuck jet holder when I first got my airhead. It took several days of heating/cooling cycles and penetrating oil to shift it. Nice feeling when it finally broke free.

As a last resort Bing will remove it for you at a price.
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Old 05-21-2013, 11:12 AM   #7
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AW's advice is good, assuming soaking won't work. The threads are coarse enough that if you drill one size at a time, and remain centered, that you will reach a point where you will be able to pick the remains out with a scribe or some-such.
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Old 05-21-2013, 11:14 AM   #8
_cy_
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Quote:
Originally Posted by Dang! View Post
Hi folks, greetings from a new member here. I've previously been a Honda owner but I recently picked up a '76 R90/6. I love the bike, I've put about 1k miles on it since purchase last month with no real issues until this past weekend. Not too long into my ride I lost a cylinder. Things seemed fine at idle but pulling on the throttle cable to my right carb produced just a sad flat sound, with occasional brief, jarring moments when it would kick in. I limped back home and the plug on that side seemed good so I started to pull the carb apart hoping the whole thing just needed a good cleaning. I got as far as the main jet when things went south. Basically, it's stuck in there good. I've tried WD-40, heat, PB blaster, and it's not budging. Even after applying all of those things a good socket wrench still stripped it cleanly. I filed it down to the next size (9mm) with similar results. At this point I definitely need a new main jet but there's still the extraction problem. Anyone ever have this issue, and know of a way to get it out with minimal damage to the carb body? Any help would be appreciated, thanks.

-D
soak the offending part in Beeryman Chemtool .. the spray type carb cleaner. not a fan of the soak type carb cleaner. which probably will destroy O-rings that's not evident until you tear into carb further.

spray carb cleaners are designed specifically to desolve dried crud from gasoline. as you've already discovered, it's best not to force any frozen part. soft brass strips pretty easy.

this bing from a R80RT is plugged solid from sitting 20 years ... a cotton swab soaked in carb cleaner is used to clean float seat very tenderly


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Old 05-21-2013, 11:17 AM   #9
disston
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The /6es do have the O-ring.

Use heat first. It may be Locktighted. Heat to break the chemical. Will also help with removal.

Next use a well fitting box end wrench or a six sided socket on you longest ratchet. Use a pipe if you have to on the wrench.

Yes you may ruin your carburetor but the best way to do this is to use enough force to begin with and not pussy foot around with it. You may need soft jaws on your big vise for this job but I have always gotten them out by holding in my knees.

It is not as stuck as you think. You are using too small a wrench.

I also avoid Easy Outs if I can. I have a special set of left turning drill bits that sometimes work.
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Old 05-21-2013, 11:33 AM   #10
Bill Harris
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Whoa. Put the tools down, back off. Slowly...

It's not a/the venturi, that is the restriction in the carb throat that causes the pressure drop that makes everything work. Hush this talk about drilling and easy-outs. Used carbs can be a crap-shot, new carbs sing to the tune of FIVE Big Bills.

Prolly you're talking about the "Jet holder", AKA "Mix Tube" (59 in the attached schematic). It is threaded in, as you've found. On top is an "Emulsifier" (57) and the replaceable "Needle jet" (58).


http://bmwhucky.com/7513S.html

What has likely happened is that at one time a little water got in the float bowl, wicked up into the threads of the mix tube. Then the bike got put up and not run. The water oxidized ("rusted") the aluminum-zinc alloy of the pot metal, thereby corroding the mix tube in. Heat and solvent is your best friend. The Al-Zn laughs at PB Blaster, but is slightly water-soluble. Pop the sucka into a pot of boiling water and cook it. Put Ove-Gloves on, take the HOT carb body out and clamp the hex-end of the mix tube in a vise, and firmly turn the body counterclockwise. If it moves a little, work it back-and-forth to work the mix tube loose. And pop it back in the boiler. Repeat. The mix tube is thin brass and if it snaps, the carb becomes a paperweight.

Failing that, ship it to the Carb Doctor at Bing. They know incantations.


Used to be in Antioch, dunno where they is now...


Good luck...

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Old 05-21-2013, 01:36 PM   #11
190e
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When removing a stuck jet holder I think there is as much risk of breaking off the carb boss as shearing the jet holder. Don't fancy scrapping a carb body so all I can say is I use as much force as I feel is safe and no more. Keep heat/cool cycling and if it doesn't eventually move then think about drilling. At least you have a ready made pilot hole dead centre which is half the battle and brass drills very easily provided the drill bit is new or very sharp.
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Old 05-21-2013, 01:50 PM   #12
Plaka
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Quote:
Originally Posted by Dang! View Post
Hi folks, greetings from a new member here. I've previously been a Honda owner but I recently picked up a '76 R90/6. I love the bike, I've put about 1k miles on it since purchase last month with no real issues until this past weekend. Not too long into my ride I lost a cylinder. Things seemed fine at idle but pulling on the throttle cable to my right carb produced just a sad flat sound, with occasional brief, jarring moments when it would kick in. I limped back home and the plug on that side seemed good so I started to pull the carb apart hoping the whole thing just needed a good cleaning. I got as far as the main jet when things went south. Basically, it's stuck in there good. I've tried WD-40, heat, PB blaster, and it's not budging. Even after applying all of those things a good socket wrench still stripped it cleanly. I filed it down to the next size (9mm) with similar results. At this point I definitely need a new main jet but there's still the extraction problem. Anyone ever have this issue, and know of a way to get it out with minimal damage to the carb body? Any help would be appreciated, thanks.

-D
I'd do any of the soak techniques and take you sweet time. While you're at it, work on the screws that hold the top on. Chances are great you have a bad diaphram. Gives the symptoms you describe. Buy a set of reuild kits and the new main jet(s). and just keep soaking while you wait for the parts. You are going nowhere without them anyway.

If you soak in solvent, as opposed to the boiling water, you will have to pull the butterflies to replace the trashed o-ring. Real pain. Make sure new screws and o-rings are in your kit. Also spend the big bread on stainless carb top screws. Thank me later.
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Old 05-21-2013, 03:23 PM   #13
Dang! OP
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Thanks for all the useful info folks, much appreciated.

Quote:
Originally Posted by Plaka View Post
I'd do any of the soak techniques and take you sweet time. While you're at it, work on the screws that hold the top on. Chances are great you have a bad diaphram. Gives the symptoms you describe. Buy a set of reuild kits and the new main jet(s). and just keep soaking while you wait for the parts. You are going nowhere without them anyway.

If you soak in solvent, as opposed to the boiling water, you will have to pull the butterflies to replace the trashed o-ring. Real pain. Make sure new screws and o-rings are in your kit. Also spend the big bread on stainless carb top screws. Thank me later.
Thanks for the tip on the diaphragm, I still need to open up the other carb while this one continues to soak to clean/compare them and make sure I don't need anything else before placing an order.

I've also got a Lufty fairing on it I've been wanting to remove some rainy day, looks like this is my opportunity to do that too. Thanks again,

-d
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Old 05-21-2013, 03:48 PM   #14
Plaka
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Quote:
Originally Posted by Dang! View Post
Thanks for all the useful info folks, much appreciated.



Thanks for the tip on the diaphragm, I still need to open up the other carb while this one continues to soak to clean/compare them and make sure I don't need anything else before placing an order.

I've also got a Lufty fairing on it I've been wanting to remove some rainy day, looks like this is my opportunity to do that too. Thanks again,

-d
The kits are basically a bunch of o-rings. If you have one bad diaphram, replace both and keep the still usable one as a spare, or leave the good one in place and carry a good one under the seat. But make sure the screws are free. It's a simple roadside replacement. (so is changing jets usually).

I use a 1/4" drive 6 point (never 12 point) socket on that main jet, usually with the carb on the bike (supports it nicely).

Replace the needles and needle jets depending on mileage. older needles are steel and I haven't seen them wear with less than 100+k miles. Newer are alloy and apparently don't last as long. Needle jets are brass and wear. I'd replace @ 60k or so.

Examine the float bowls for sediment. If there is much, fit little fuel filters. Also clean petcock screens in tank.

There are jets for the cold start system in the bowl. Clean them.

never wear boots with eyelets that stand up. Can catch on wire bail and you lose a bowl and it gets run over by car behind you. (ask me how I know)

Replace float needles always. Floats only if totally fuel logged. Discolored don't count.

Examine the rubber sleeve between carb and head. Replace if stiff or cracked. This one is important. If it's halfway flexy and lively it's good, leave it.

All stainless clamps from the plumbing place (must say "all stainless" on them) look great and work well too. They are wider and one can replace double stock clamps above the carb.

Condition of rubber above carb (airbox side) not critical.

Gaskets between bowl and carb body not critical. As long as there is something there. A set of the stock cork ones last about forever.

Fill the rusty spot on top of carb with gloss black enamel. Gluing in some coin has gotten cliche.

Don't remove the cover over the "choke" assembly unless you gotta. When replacing, there is a narrow spot in the gasket. it gets sucked in here so glue the crap out f it. A smear of clear silicone on the outside won't hurt either. They face in, doesn't show.

Take a pic of fairing on bike before removal, then a pic of the installed brackets w/o fairing. Be ready to sell that sucker. Might get enough to buy a happy meal minus the fries and coke.
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Old 05-21-2013, 03:54 PM   #15
_cy_
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to clarify ... when I stated soak with spray on chemtool carb cleaner. I mean spray on, then let it soak, then spray again. repeat ..

if you dip entire carb into any type of carb cleaner .. odds are Orings on butterfly shaft will be destroyed. removing and replacing split screws securing butterfly is a major PITA. that should be avoided if possible. especially if oring involved would be good for many miles yet.

if you don't stake split screw properly and it backs out. that screw will be sucked into engine. possibly resulting in major damage to your engine.

this is why I'm not a fan of carb dips .. orings like on butterfly getting destroyed will not be obvious until too late.

Bing carb initially opened after sitting for 20 years ... if there's enough interest, will post a step by step tutorial on rebuilding a Bing.

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