Dipping VM carb bodies?

[Guss77]

Hi... I have a '77 GS750 with VM Carbs. Page 4 in VM Carb rebuild guide says to dip the carb bodies after removing all obvious rubber and plastic. This is actually in a section before you go about removing all the jets etc... but the suggestion is to dip the whole body eventually.

http://gsarchive.bwringer.com/bikecliff/images/vm_carb_rebuild.pdf

question... there is a plastic part that fits into the groove of the slide assembly. it's transparent and looks like a sight hole of sorts from the outside. Can this part be dipped? or removed? I'm just being cautious as I don't want to wreck anything.

[Big T]

Dip away
That piece is not an issue

[Guss77]

Thank you!! 😀

[Nessism]

I recommend dipping the minimum time required to clean any varnish from the bodies. I'm doing some KZ VM's right now and noticed fizzy bubbles coming from the dip after two carb bodies sat in the sauce for a few hours. Quickly pulled them out and they were covered in a dark gray smut. The dip seemed to be reacting with the zinc material, and I'm using the crappy low VOC formula Berryman's that's sold in California.

[Steve]

I have noticed that gray stuff, too, but usually only on the VM carbs. The BS carbs don't seem to be affected.

Using a toothbrush will brush it off quite nicely.

.

[Guss77]

Cool. Thanks for the advice guys!
I have to buy some dip still, it ain’t cheap, but I took them apart to have a look. The bike runs rich, very black sooty plugs.. hesitates at mid throttle, air box is old and likely leaks air like mad, missing idle screw device, slides 1 and 4 are 1 mm higher at full close position than 2 and 3. Maybe that’s to compensate for lack of idle screw? Dunno. Air jet (on the side) - all 4 were the same: 1.5 turns out. Fuel screw (bottom) 2,3,4 = 1 turn out, carb 1 is 4 turns out. Lol. The needles are set to the second to last notch to the bottom - putting the needle quite high up. There are no little springs in the needle mechanism. I’m pretty sure my bs carbs had a little spring in there because I remember fighting them to during assembly. Hmm. Yup. Looking at the VM guide pictures there is little spring supposed to be there, somewhere. Hmm. Dang.

this bike came with a parts bike, so I think I’ll take the carbs off the parts bike and see if it has little needle springs I can scavenge.

I had similar mid throttle issue with my yamaha xs. The fix was to literally move the needle down 1 notch (by raising the clip that is). Or maybe it was the other direction. I’m wondering if I should lower my gs needles as well when I clean them?? Any thoughts if that would help the rich issue?

Going to check the valves and point clearance before I clean the carbs of course. Oh, the valve cover looks like the PO used some sort of goo to seal it up instead of a gasket. Hmm. That might take a while to clean up. I have gasket paper and instructions from Bike Cliff to make a new gasket. Lots to do!!

oh, and I have those plastic main jets. Lol. I’m going to do as the guide says and clean like crazy and only replace the o rings and carb gaskets - even though I purchased re build kits. I went through this with my xs - used all new carb jets and made it all worse. Cleaned the carbs 3 times and put all the original jets back it and it finally ran nice. Hoping the same will happen with my gs.

[Guss77]

Update... decided to order an ultrasonic machine. Gunk, Berryman's etc.... are very hard to find and, based on posts I've been reading, they take a long time to work. Waiting for that to arrive to start the cleaning. In the meantime, I pulled the second carb set from the parts bike and tried it on my '77. it actually works better, aside from a leaky carb #2 (only leaks when running). Idle is better, mid range is better... did not ride it though as I started to see gas leaking from #2 after about 1 min. running. Doesn't leak on prime with engine not running, so I'm thinking needle jet stuck maybe. Again, I still need to clean them all up real good, I was just testing to see if carb set #2 was at all viable.

Something else interesting though, carb set 1 from '77 bike has the vent vent hoses linked together! Needles set at one notch from bottom and missing spring, washer and spacer. Carb set #2 from parts bike has hoses dangling off carbs 2 and 4 as they should be, slide components are all there: needles are set at second notch from top and has all internals as well (spring, clip, spacer and washer)... and is in a much cleaner condition compared to carb set #1 from the '77 bike. I think I might focus on carb set #2 from the parts bike. Picture of carb set #1 with vents joined

[Big T]

Yeah, go for the #2 set, being complete and less molested

No reason that one couldn't connect the vents, but, why do it?

I'd carefully check every system on the bike, based on the prior owner hacking the carbs.

[hannibal]

What ultrasonic cleaner did you get? Curious to hear your thoughts on how well it works.

[Guss77]

I agree Big T!!
Has not arrived yet. Amazon special pretty good reviews, we will see.

5B2C0B9A-3790-4C25-9198-B86725820FBE.jpg
The carb body measures just a bit smaller than the dimensions, so it should fit!!

Ultrasonic Cleaner 200W Heated Parts Cleaner 2L (1.5L liquid capacity) for Carburetors Injectors Guns Bullets Brass and Jewelry Professional Ultrasonic Bath DAREFLOW Gifts for Men 2020 Upgrade https://www.amazon.ca/dp/B07H5NNR97/..._M09FFbGWE69EE


on my phone. Sorry for the crap picture.

[Guss77]

Hi... quick update. the ultrasonic works pretty good on dirt and caked on stuff. Didn't do much for grease though. I'm pretty sure it loosened up a lot of crap in the carb bodies, so I'm happy I got it. I sprayed carb cleaner in all the passages etc after wards as well.
not the greatest picture, but this is after only 10 min. in the ultrasonic. Not bad. Before/after

[Big T]

Give it more time in the ultrasonic

What are you using for cleaning solution?

[Guss77]

I tried a few different things: just water, then water and a bit of dish soap, and water and a splash of vinegar. The dish soap worked the best I think 🤔

[metalfab]

I have used a lot of different cleaners, I've been building carbs for over 40 years. Right now I use a 10 liter ultrasonic cleaner. I have noticed that common cleaners can remove metal on some carbs. I like to dip for the minimum time possible. Berrymans Chem dip carb cleaner is my go to cleaner. It is light years ahead of any detergent type cleaner. There is a consumer grade chem dip I believe it is part# 0996 that is popular and it works well. The version I am talking about is a professional formula, it is part# 0901, this type product is pretty much in a class of it's own. There are clones of it from some other company's. One big caution is don't heat it, and I mean not at all. If you do heat it the fumes are different but are reminiscent of taking a smell of ammonia. I don't like to put it directly into the ultrasonic cleaner because I don't know how good the Chinese ball drain valve is. If you fill the ultrasonic cleaner with water and set a metal pan in it or a large juice can with carb cleaner in it down into the water, the ultrasonic waves pass through a thin pan or can as if it wasn't even there. This allows you to keep strong cleaners and filth out of your ultrasonic machine. The 0901 chem dip comes in a rectangular metal can like lacquer thinner comes in. You absolutely want to keep in in the can when not using it. To describe the 0901 cleaner briefly. It cleans amazingly good, and it puts off a strong smell much more so in hot weather.

[roeme]

Do note that the bowls of VM's (among other aluminium parts on the bike) may have some factory varnish/coating on them, in order to preserve the aluminium's shine by preventing oxidation.
30-40 years later, that varnish/coating is still there, but the passage of time has them yellowed (and one might confuse it for old caked-on gasoline that just won't go away easily).
From what I can recognize on your picture, that might be the case for yours as well.

Ultrasonic can break through it, but it needs a *lot* of time. Some preparation by dipping or sanding (but then you absolutely need to polish them up after the ultrasonic) may be appropriate.

That is, of course, if you want them to shine. Functionally, it makes no difference.