carb repair

[Red Baron]

While on a recent tour of the northern United States I experienced a problem that made me think it is time for a carb overhaul or re-build.

I have a 1990 VR with 82K miles on it.

The question I have is:

Is there a carburetor rebuild kit available for these carbs ? If so, where ?

This would be a kit containing gaskets, needles, seats, etc.

I see some good data on the tech bulletin board about rebuilding the carbs but no mention of where to get parts or if a kit is available.

Thanks for the help

Red Baron

[mbrood]

I've never heard of a kit for the Yamaha... you can ask Rick (Buckeye Performance) and he can get you anything. Until you get one apart, it's hard to really know if the needles or jets need replaced. The gaskets are sturdy rubber but the diaphragm, enrichment valve (rubber parts) need careful inspection and guys often replace the two rubber "caps" on the Jet block assembly.

 

Another avenue to check... Mikuni made this special for Yamaha and gave the "rights" to Yamaha so you have to go through them as the main "vendor"... BUT... ours is a down draft BDS34 carb and Mikuni makes the similar side draft version... BS34 It might be worth while to check the bike shops to see if there's a kit for THAT carb.

[Cutty]

What is the problem??

[CrazyHorse]

There is no kit specific parts only.

[GeorgeS]

Most of the time a few dose's of Sea-Foam, and a New Set of Diaphrams, drain the bowls, and set the float levels, and resetting the idle mix adjust screws, to 2 1/4 turns open, will fix them up.

 

And a Sync job, Usually does it.

[Red Baron]

Thanks for your responses to my question about the carb repair kits.

The "problem" was noticed after I had an incident with "no fuel ? " for start after a stop at Devils Tower. May have been vapor locked as the temp was 103 and the engine was very warm after the slow climb up the hill to the visitor center. The reason I think vapor lock is because the fuel pump ran for an extraordinary long time after I turned on the key to start engine. Usually I don't hear the fuel pump run at all after the intial start up of the day. Anyway, later, after this occurred, I can occasionaly smell gasoline a few minutes after I shut down the engine. Makes me think I might need needle / seat replacement and float level checked.

Again, thanks for your input.

Red Baron

[mbrood]

Some have experienced a vacuum in the tank and just cracking the cap can get the gas flowing again... plugged vent? If she's running even and strong, I would be real hesitant about ripping into the carbs. The diaphragms need checked just as a routine maintenance but that can be done real quick and easy from the "outside".

 

Although the vast majority of "I smell gas" seems to be a momentarily stuck float needle letting gas flow out the overflow and onto the ground in front of the rear tire... rapping on the top of the offending carb, or draing the bowl and letting the FULL rush of new fuel flush the needle seat area seems to solve most of these.

 

I just helped a guy with a V-Max.. his ALWAYS took the full "charge" at first to fill the bowls and he always could small gas after shut down... tracked it down to a small leak at the back of the number 4 carb (float cover). I took the carb bank off and found the cover screws were loose! All the others were very tight but the number 4 had three of the four just finger tight. He said he had never had the carbs off so no idea what happened but a bit of tightening and it was all tight and nice again. It was actually detected with just a good visual check... the back of three carbs were nice and aluminum colored and the number four had that typical brown "stain" of gas residue near the bottom... Those "stains" are real important in tracking problems down...

[Cutty]

Because you ran your fuel low, i would change gas filter and in a well ventilated area pull the carbs vents off and see if any of the carbs are over flowing. Should you find any leaking, gently tap bowl with a plastic or wooden handle. If that cures the problem, while you're there blow thru each vent line to make sure they are open. If the tapping did not stop your flowing, probaly a little dirt stuck under needle valve. Try to save the original needle and seat, as the replacements aren't as good.

[Guest Popeye]

I had similar problem last May. Fuel near empty & engine quit.

Switched to RES & it died after 40 miles.

 

I drained gas tank into a 'white' bucket [cut off of a 5 gal pail] & saw black silt [rust] in drained gas. My 'white' color bucket was dumb luck.

 

Carbs had to be rebuilt, but no "kits' available.

Any carb part is available through Yamaha at very high cost.

Mine needed sliders & diaphragms & rest of carb parts could be cleaned-up like new, by hand.

Then, tank had to be acid-washed & relined. I saw orange rust in gas tank when removed, but rust was black in pail of gas.

 

Older scooters with low mileage have probably been stored for long intervals. Some don't keep tanks full during storage, or use fuel stabilizer & some idiots even drain the tanks before storing....any of which will promote internal rust.

 

Draining Reserve tank into a white pail is an easy check for a very common problem.

 

One huge reason to know the history &/or owners of an older bike.

Then is the 'honesty' factor of prior owners.

[Guest primerib]

Ah, the ol' rusty tank. I had a similar issue. Rust a plenty in the tank of my '83. Just a sad occurence with storage and moisture if precautions aren't taken.

 

Anyways. I pulled my tank, flushed it out and used Red-Kote on it. Great stuff and easy to use. Google Red-kote, or you can usually find it on ebay. Great stuff.

[loehring]

When I changed the diaphrams in my '89 I had a member tell me to check a marine parts dealer. As it turned out the carbs were the same as Yamaha puts in boat motors and they charged about half what the bike parts places wanted. Check it out before you spend the money on parts.

[tiny84]

When I changed the diaphrams in my '89 I had a member tell me to check a marine parts dealer. As it turned out the carbs were the same as Yamaha puts in boat motors and they charged about half what the bike parts places wanted. Check it out before you spend the money on parts.

 

do you remember/know what yamaha boat engine used the same carbs? as i'd love to check my local marine shop for the parts

[GeorgeS]

Well I would start with Draining the Tank, and all 4 carb bowls.

 

Let the pump run gas thru the bowls with the bown drain screws open, ( outside, with water hose handy )

 

Maby fuel filter ??

 

Run 3 or 4 tanks with Sea-Foam, then Re assess the situation:

[Denden]

I have often read about carb problems coming up, after turning the petcock to reserve, after reserve hasn't been used in a long time. The petcock has 2 inside tubes feeding gas, the "run" tube is slightly longer than the "reserve" tube. So if you leave it on run and never use "reserve", dirt, crud, rust and water will settle into the bottom of the gas tank below the level of the "run" tube. Then when you get into the situation and turn it to "reserve", you get all that old crud going into your carbs, or clogging the fuel filter (or both).

The way to avoid this is to leave the petcock on "reserve" all the time, and pay attention to the gas guage, and also reset the trip odometer each time you fill up, so you have 2 things telling you how much gas is left.

[Gearhead]

"

When I changed the diaphrams in my '89 I had a member tell me to check a marine parts dealer. As it turned out the carbs were the same as Yamaha puts in boat motors and they charged about half what the bike parts places wanted. Check it out before you spend the money on parts."

 

 

 

That's odd. I have an old boat, and I can tell you that marine parts are none too cheap.

 

Jeremy

[Thom]

i know Yamaha has kits for there outboards , we just need to know what motor

thom

[Venturous Randy]

i know Yamaha has kits for there outboards , we just need to know what motor

thom

 

I am courious about this also.

Hey Tom, how are you and have you heard from Ken?

RandyA