Carb butterfly screws question

[JoBrCo]

I'm cleaning/checking everything on the carbs for my 1984 Yamaha FJ1100LC, (original owner) .  Took everything off/out of carb body including butterflys to check butterfly shaft seals. I had to file the tails of the screws flush with the shaft because they are flared via peening at the factory.  Though in hindsight I almost wish I hadn't.    I realize that the reason they are flared at the factory is to ensure they don't get sucked into the engine if one happens to come loose due to vibration.  So I was thinking that I should use some sort of thread lock material that's fuel proof at the very minimum.  I truly don't even want to think of buying new screws and trying to support their heads so as to peen the tails such that it won't do damage to the carburetor bores in the process, as it seems like it would be a bit tricky. At the factory, I assume they used a special pneumatic or hydraulic tool to ensure a neat clean peen without collateral damage.

The reason I went this far is because these carbs are all original and have been sitting collecting dust along with the bike since 1995, because I started having problems with the float needle valve o-rings leaking fuel, and decided to not get involved in their replacement at that time.  So now I decided to do a really good job, and bought a gallon of Berryman's Chem-Dip Carburetor and Parts Cleaner, and wanted to remove/check all rubber and plastic pieces before submerging as per the directions.    

So far, I've only done this to carb #1.

Does anyone have experience with this, knowing of any good means to secure the screws with a fuel proof adhesive?  Or any other tips to complete this procedure for carb #1 at least. I'm not sure if I should procede with the other carbs in this manner or not.  If not I worry about the butterfly shaft seals, which seem to be made of plastic, or if rubber they have indeed become hardened.  Either way I'm thinking of replacing them on this carb to ensure there's no vacuum leaks at the shaft.  Then it would seem appropriate to continue with the other carbs to ensure equilibrium amongst the 4.

Any experts capable of delivering me from my uncertainty?  

Thanks in advance!

JoBrCo

[simi_ed]

I'd recommend some flavor of Loctite.  Don't use Red, no matter what!  Personally, I'd reassemble what you've done and cut your (potential) loses.  Did you find any significant wear or looseness on the shaft and seals?

[FJ1100mjk]

I've done what you're doing on severals sets of carbs now. Strangely, I've found one set of carbs to have their butterfly screws peened over, and other sets not. The latter, appeared to have their screws held in with some kind of threadlocker. After thoroughly cleaning both screws and their tapped receiving holes with acetone (or lacquer thinner), I used low strength Loctite 222 (purple), to lock them in. This is the type of threadlocker recommended by them for smaller screws like these.

If you halt where you're at, and proceed to soak your carbs in Berrymans, there are (as you've seen already) cup seals on the butterfly shafts hidden by carb synch screw stops, that are on the shafts' ends. These seals may be damaged by the carb soak solution (Berrymans, or other), if soaked long enough.

I'm sure that others will have something to offer up too.

Good luck.

Marty

[JoBrCo]

I'd recommend some flavor of Loctite.  Don't use Red, no matter what!  Personally, I'd reassemble what you've done and cut your (potential) loses.  Did you find any significant wear or looseness on the shaft and seals?

I'm not sure what the wear tolerances are for the shaft to hole clearance, but the hole doesn't seem to be elliptical, if so or out of tolerance it would mean I'd have to get a new carb body, of course.

The seals are hard, so I'm thinking, if they are in fact made of rubber, then they need to be replaced, because they should be pliable so they can seal, or so one would think.

Originally I thought that they may have been o-rings, but in fact they are cupped like camshaft oil seals, requiring that they be put on with the cupped side facing in.

Anyone know for sure if the seals are rubber or plastic?  I'm thinking rubber, but they feel like plastic, (non pliable).

[JoBrCo]

I've done what you're doing on severals sets of carbs now. Strangely, I've found one set of carbs to have their butterfly screws peened over, and other sets not. The latter, appeared to have their screws held in with some kind of threadlocker. After thoroughly cleaning both screws and their tapped receiving holes with acetone (or lacquer thinner), I used low strength Loctite 222 (purple), to lock them in. This is the type of threadlocker recommended by them for smaller screws like these.

If you halt where you're at, and proceed to soak your carbs in Berrymans, there are (as you've seen already) cup seals on the butterfly shafts hidden by carb synch screw stops, that are on the shafts' ends. These seals may be damaged by the carb soak solution (Berrymans, or other), if soaked long enough.

I'm sure that others will have something to offer up too.

Good luck.

Marty

Thanks!  I'm glad someone has gotten away with doing this type of thorough clean.  OK, so the purple loctite is for both small screws and fuel proof?  To my way of thinking the thread lock should be fuel proof in this particular application, right?

Yes the reason I removed the butterfly was so the seals would not be damaged by the carb soak, if still good, but they are hard and non pliable, so I'm thinking they need replaced.  They are rubber, correct?

As long as I can get a hold of some reliable fuel proof thread lock, I think I should proceed as I have thus far with the other three carbs, removing and replacing the butterfly shaft cup seals?

TIA

[pdxfj]

Perhaps Randy will chime in about the seals.

Personally I'd go to Harbor Freight, buy their $80 ultrasonic cleaner and do one carb at a time.  I bought one several years ago and it works great on carbs, master cylinders, etc..

You'll be amazed at how much more stuff comes out of the carbs while they are in the cleaner. 

[JoBrCo]

Perhaps Randy will chime in about the seals.

Personally I'd go to Harbor Freight, buy their $80 ultrasonic cleaner and do one carb at a time.  I bought one several years ago and it works great on carbs, master cylinders, etc..

You'll be amazed at how much more stuff comes out of the carbs while they are in the cleaner. 

I hope Randy does, and with good news too, because I've noticed that in the 84 FJ1100LC IPB there is absolutely no reference to any portion of the butterfly valve assembly, which leads me to believe that those cup seals are unobtainable.   

[racerrad8]

The seals for the throttle shafts have never been a serviceable item from Yamaha or any other vendor I am aware of.

I never, unless someone else has screwed something up, remove the factory staked butterfly screws. if I remove them I usually replace the screws with 3x6mm button head allen screws. I use blue loc-tite because I never want them to come out again. I am not worried about the loc-tite being fuel proof, because once they are setup, the head of the screw will strip out before the screw comes loose.

The seals are rubber and yes they are usually hard as a rock, but since there is nothing you can do with them I never disturb them.

I ultrasonic clean every carb body and never use the old style carb dips.

Randy - RPM

[JoBrCo]

So, for those that use an ultrasonic cleaner, what solution works best.  I noticed that the Harbor Freight model comes with some sort of powder that is mixed with water.  Is Chicago Electric Power Tools cleaner any good, or is there another preferred solution for our precious Mikuni carbs? 

[racerrad8]

...or is there another preferred solution for our precious Mikuni carbs?  

Here is a topic, with another topic within, about the cleaners people use.

http://www.fjowners.com/index.php?topic=11088.0

Randy - RPM

[JoBrCo]

OK, guys thanks for your time and energy, I'm stuck with what I've got for now, but this will be both the first and last time I use the Berrymans, opting for the ultrasonics the next time around, as I truly prefer MSDS's that are closer to being blank.  Hopefully I'll be back soon with some lessons learned to support the forum, but most probably it'll also include more questions. ;-)

Until next time, here's to keeping the FJ's alive! 

[JoBrCo]

The seals for the throttle shafts have never been a serviceable item from Yamaha or any other vendor I am aware of.

I never, unless someone else has screwed something up, remove the factory staked butterfly screws. if I remove them I usually replace the screws with 3x6mm button head allen screws. I use blue loc-tite because I never want them to come out again. I am not worried about the loc-tite being fuel proof, because once they are setup, the head of the screw will strip out before the screw comes loose.

The seals are rubber and yes they are usually hard as a rock, but since there is nothing you can do with them I never disturb them.

I ultrasonic clean every carb body and never use the old style carb dips.

Randy - RPM

Randy, I was wondering why you chose to go with 3x6mm "button" heads instead of the "countersunk flat" (actually "oval," but extremely hard to find) heads for the butterflys/throttle shafts in the Mikuni BS36's.  Also mine are actually M3x8mm not M3x6mm.  Of course they were 6mm long after I filed them down flush with the throttle shaft.  I prefer the longer length because I'm going to try and flatten the threads on the back with some long nosed visegrips.

I'll tell you though, it's truly a bitch, trying to find M3x.5x8mm JIS phillips oval head machine screws that have been zinc (yellow) anodized, WOW!  The closest I've gotten so far are M3x.5x8mm US phillips flat head machine screws with a zinc (silver) anodized coating.  I'd really prefer the OEM yellow though, as they do a better job at corrosion control.

Just curious if there was a logical mechanical fastening reason for your choice, as I would think the countersunk heads would bind more with the countersunk holes, with the increased surface area actually making contact between the two, increasing the probability of them not backing out.

What have you found to be true; a variance between American and Japanese countersink angle, reducing surface area contact, or something else?

I hope this doesn't seem too nitpicky or extreme, but I used to work on aircraft for the US DOD, so I've been spoiled. Everything was milspec and all at my fingertips.  And of course when working on a multimillion dollar aircraft, it's by the book!

Thanks much for the info and parts so far!

JoBrCo

P.S. I purchased purple Loctite made for smaller screws because the blue said it was for larger screws. How do you think the purple will perform? Do you know why they have different formulations for different sized screws?  I thought it might be a surface area issue as well, but I'm not sure.