gs850 BS carb sliders frozen

[Guest]

I recently acquired a 1980 GS850 (GT?) project. The carbs were not attached normally, the rubber boots were separated from the manifold plates. The carbs do not look terribly corroded, as judged by inspection after pulling a float bowl and a top, but the slides are stuck tight and will not move. I have tried squirting some wd40, PBblaster and carb cleaner, but that has not freed them. I tried a little gentle pressure by twisting a large blade screwdriver underneath the slides, but no dice, and I don't want to damage them. Want to do the rebuild, but can't get anywhere if I can't remove the slides. And yep, all 4 of them. Am I missing something here? Want to rebuild them, obviously. Any suggestions?

[ShadowFocus603]

Heat and/or soaking them in a solvent of some sort. Berrymans carb dip will seep in there and loosen them. I had this same issue on my second 750L and managed to free the slides after a couple hours in my sonic cleaner with vinegar and water at 60 Celsius.

[tom203]

I see the 1980 , but are these VM carbs due to someones's intake creativity ? I had slides seriously stuck on this style carb.

[Steve]

I see the 1980 , but are these VM carbs due to someones's intake creativity ? I had slides seriously stuck on this style carb.

Where are you finding a picture?

.

[JTGS850GL]

Don't use the Berrymans on the slides because the solution will damage the diaphragms. Try spraying some carb cleaner in from the top and down the needle. After a short time you should be able to use a wood stick or something relatively soft to pry them up. Once they break loose they'll come out pretty easy. Heat may help, but be very careful to not cook the diaphragms. Only heat the carb body. Maybe use some aluminum foil to shield the diaphragms.

[chuck hahn]

Sounds like the dried up fuel has bonded the needles to the needle jets. GENTLY heat the main jets with a heat gun or a torch with the flame turned down real low. ( remove the rubber caps over the pilot jets first). Carefully unscrew the mains so you can get some sauce down in there.
Now continue to gently heat the towers the jet needle and the pilot jets are in and apply some more of that PB Blaster. Heat will soften the gunk and help draw the oil in. Let it set about half an hr and heat it again and add more PB. In te interum while allowing it to soak, get an old tooth brush and grid it down to get the handle to fit under the slides opening in the bores. Use that as your pry bar........NOT a screw driver that can scar up the slides.

Get the tutorial here and follow it when you do the rebuild.....

http://www.mtsac.edu/~cliff/storage/gs/mc_maint/GS_CV_Carb_Cleaning_Series.pdf

http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

Orings here..but wait till next week to order because Robert is on vacation...usually a 2 or 3 day turn around once you order orings, so it gives you time to soak all the carb bodies and clean the jets well. One kit does the full rack...

http://cycleorings.com/

[chuck hahn]

PS...I should note that by "heat it" we mean get it good and warm but not hot enough to melt the carb body. Yes you can melt the metal with the torch if you get too long on it. And be sure to use a well fitting screw driver in the main and pilot jet slots.

[redstar]

Thank you all for the suggestions. Tutorial on hand, and o-rings ordered, along with stainless hex screws. I will be working on these over the next week or two.

This is an awesome site! Used it extensively while putting together a '78 gs550 basket case. I found answers to all my questions without even having to post!

[steve murdoch]

Yes this is a great site and it is good to know you got your previous project sorted just using the search feature and not having to post.
BUT, even if you don't have mechanical knowledge to contribute it is still very useful to have feedback [aye or nay] on fixes that you have found here.
Good luck with your new project.

[redstar]

Frozen slide update. I removed carb 1 from the gang so I could troubleshoot the slide problem on a single carb, as I am mentoring someone and I don't want to deprive her of the unbridled joy of a carb rebuild. At any rate, I used the gentle heat/PB Blaster technique on the needle jet, then as per tutorial, gently tapped on the main jet (without the washer) to push the needle jet up into the throat. The needle jet is now free to move, but only goes so far as the slide is still stuck. I have removed everything removable from the carb body except the pilot screw under the aluminum cap, and of course the slide/diaphragm unit.

The tutorial does not address this, as the slides just come out, right? but I notice that looking from top down into the slide there is a snap ring way down there that appears to lock in a plastic shaft or spike. I also notice that the plastic collar attached to the diaphragm can rotate around the slide, but does not seem to come off. Will it help me to work from this end of the problem? My snap ring pliers don't reach that far down. Alternatively I could soak the body by hanging it into a jar of carb cleaner without submerging the diaphragm. What do you think?

[JTGS850GL]

If the needle jet is moving up but the slide is still frozen, then the problem is with the slide itself. Most likely just old gas gluing the slide to the sides of the bore. You don't need to mess with the snap ring or anything inside the slide at this point. You simply need to get those slides unstuck. Spray some carb cleaner down from the diaphragm side and up from the carb venturi side. Use a tooth brush like previously recommended and push the slide up. You don't have to be to gentle with it as long as you use a pry bar that's softer then the aluminum. Just be a little careful you don't damage the needle. If it still wont budge then apply a little heat to the sides of the tower that the slide rides in. Don't get carried away here. Just add some heat and protect the diaphragm with a heat shield made from some aluminum foil. Should have no problem getting it out with that.

[chef1366]

I'd use an ultrasonic cleaner with HOT water for an hour or two.

[850GT_Rider]

Redstar - where are you located? Might be a GSR member near you, willing to help a bit.....

[redstar]

OK, so I purchased and inexpensive ultrasonic cleaner and I'm working with that as we speak. Nothing so far, but haven't had much time in it yet.

Question: Barryman says it's safe for rubber, and from the MSDS it appears to contain only surfactants, so I don't see why I would need to worry about dipping the diaphragm. I see other brands, like Gunk, have benzene and naphthalene and other nasty stuff that I wouldn't put rubber in, but Berryman looks OK.

850GT_Rider: I am in Chicago. I see you are within riding distance. I do have working bikes, but no car at present.

[redstar]

P.S. My can of Berryman says don't dip plastic or rubber, so maybe I am looking at different products.