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I have this set of VM33 Mikuni's I bought new back in the 80's I put them on an 81 GS1100E, and only put about 3,000 miles on them. I pulled them off when I broke the crank on the bike, and they sat on the shelf bagged up in a box for 25 years. I rediscovered them, and decided I would use them on a 82 GS1100E with a big bore kit that is in the works (75mm) I broke them totally down, I mean all the way, and soaked them in berrymans chemdip for 48 hours and meticulously cleaned them blew out all the passages and jets, reassembled them, with new bowl gaskets. The needles and seats looked great. I replaced all the O rings I saw. Now these beautiful clean pieces of s*#t leak like a sieve. It is like the needles and seats are bad. I popped them open and checked out the float level, and the needles, and even the round gaskets for the seat where it screws into the body of the carb. Every thing looks 100%, but they still leak. Has anyone here dealt with the VM33's enough to tell me what the problem might be. I started to buy new needles and seats, but if there is an O ring out of sight I didn't see that can do this, I would like to find it before I spend a lot of bucks on the new needles and seats. They cost about $100. I cant help think that there is something I am missing here. Possibly something the Berrymans ate into and dissolved. It might just be needle and seat time, but they look pristine. My next step is to take them and run some mineral spirits into the gas inlets with my motorcycle IV gas bottle and manually push the floats up to see if they still flood. I have literally rebuilt hundreds of carbs, bikes, cars, and aircraft, but this one has me scratching my head. If someone knows some trick for these I am all ears.
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Last edited by Guest; 07-10-2010, 04:33 AM. -
You need to check out http://members.dslextreme.com/users/bikecliff/ Bikecliff's site for the unbelievable gold mine of pdfs like these ones that you should have a read of to make sure that you have fully stripped it (and not left a o ring in which has dissolved in the carb bath)
and my personal favourite....
All courtesy of the 'How To Host With The Most' our very own Basscliff -
did you check the floats to see if they took on any fluid? those brass floats can sometimes get pin holes then fill with fluid.
how does the surface of the fuel valves look? are they grooved up? Whats your float level?
new or old float bowl gaskets?
I assume you used vitron type orings on your rebuild?78 GS1000 Yosh replica racer project
82 Kat 1000 Project
05 CRF450x
10 990 ADV-R The big dirt bike
P.S I don't check PM to often, email me if you need me.Comment
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The bowl gaskets are new, and one float had a pinhole, I always soak the brass floats overnight submerged in gas, then weigh them the next day. A micro dot of solder fixed the hole. The solder only made it weigh .0014 ounces more. So the floats are not the problem. I will look at the links in the other post. I hope they are VM33 specific. Thanks for the help.
Originally posted by first timer View PostComment
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Good stuff, it looks like it is the needles and seats, because there are no hiden parts. It is weird they all 4 went bad from sitting. Now it is time for the chrome plated shaft if I want to use these carbs LOL. I have been looking for the original Mikuni 002-699 part number it is a rebuild kit for the VM33's, no one seems to have them. It is hard to believe I can buy carb kit for a 29 Dodge, but I cant find one for an 80"s performance carb. I guess it is part of the motorcycle parts shaft that we see to often.
Originally posted by Colin Green View PostYou need to check out http://members.dslextreme.com/users/bikecliff/ Bikecliff's site for the unbelievable gold mine of pdfs like these ones that you should have a read of to make sure that you have fully stripped it (and not left a o ring in which has dissolved in the carb bath)
and my personal favourite....
All courtesy of the 'How To Host With The Most' our very own BasscliffComment
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Order # Size
002-503 2.5
002-504 2.8
About $24 for each needle & seat assembly.
Don't forget the sealing washer. 002-187The Three Horsemen
'85 GS1150ES (Current Income Eater)
'83 GS1100ES
‘77 XLCR
"Never ride faster than you can see. Besides, it's all in the reflexes."
Porkchop ExpressComment
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Searching for Carb kits for a set Smoothebore 33's , this is the only thread I was able to resurrect. Its looking like I can only purchase individual parts??Comment
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Only individual parts! Sudco is where I got all my parts.1978 Gs1085 compliments of Popy Yosh, Bandit 1200 wheels and front end, VM33 Smoothbores, Yosh exhaust, braced frame, ported polished head
1983 Gs1100ESD, rebuild finished! Body paintwork happening winter 2017
I would rather trust my bike to a technician that reads the service manual than some backyardigan that THINKS HE KNOWS how to fix things.Comment
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Did you disassemble the rack prior to soaking? The fuel rails have rubber (Buna) orings and I doubt Berrymans would add to their life span. Also, with the brass floats, shake them and see if you can hear gas inside... if leaking, best buy new floats. Z1Enterprises.com carries the floats plus the float needle/seat assembly.Comment
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I hope not..... you need to use Nitrile O rings for the carb internals, the Viton O rings are suitable for the intake manifolds as they will withstand the heat that nitrile wont, but the viton are no good for the internalsOriginally posted by first timer View Post1978 GS1085.
Just remember, an opinion without 3.14 is just an onion!Comment
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Curious... which orings are internal to VM33s? The only orings I can think of is on the air screw and fuel pipes. I think buna would work well as there is little to no direct fuel exposure.Comment
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Any O rings that have direct contact with fuel should be Nitrile.Originally posted by geol View Post
have a read through this website, Robert supplies a lot of members here with O ring kits for their GS carbs, he knows his stuff ....
1978 GS1085.
Just remember, an opinion without 3.14 is just an onion!Comment
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