Another clue, this can't be right!

[Dragonslayer]

While reinstalling the diaphrams today I noticed something odd.

 

On carb #3, (right front) the brass round piece that the diaphram needle goes into was protruding about 3/8" out of the carb throat wall. On the other three carbs it was flush with the carb throat walls.

 

Could this be a factor in the poor gas mileage problem and why. See Pics attached.

 

[ATTACH]71678[/ATTACH]

 

[ATTACH]71679[/ATTACH]

 

[ATTACH]71680[/ATTACH]

[kevin5549]

I have the same thing on my bike and was told that is one of the jets and it has come loose on the other side. You have to split the cabs to repair. Mine is in the shop now cause the guy that cleaned my carbs didn't tighten them correctly and 3 of them backed out. Great lose of power and poor gas mileage. Sorry

[Dragonslayer]

I have the same thing on my bike and was told that is one of the jets and it has come loose on the other side. You have to split the cabs to repair. Mine is in the shop now cause the guy that cleaned my carbs didn't tighten them correctly and 3 of them backed out. Great lose of power and poor gas mileage. Sorry

I can't blame anyone but me cause I'm the only one that has been in the carbs. Sure hope this fixes the problem.

[gibvel]

Do you, perchance, have a macro setting on your camera? This is usually a button with a tulip (flower) or something like that on it. If you use that the camera will focus better on things when you take pictures from shorter distances like these.

 

Just an FYI tip.

[Dragonslayer]

Do you, perchance, have a macro setting on your camera? This is usually a button with a tulip (flower) or something like that on it. If you use that the camera will focus better on things when you take pictures from shorter distances like these.

 

Just an FYI tip.

thanks for the info, I did not know that

[pmelah]

i did not know that either good to know now

[Peder_y2k]

That's definately the problem/issue. The main jet has come loose and extra fuel is flowing past the loose jet fastener screw, the jet block o-ring, and around the outside of the jet. No wonder the bike has bad fuel economy. Still doesn't explain the oily crud on the diphragms.

BTW, the o-ring is 10mm i.d x 1mm cross section and are usually found at most bike shops that have a real owner/mechanic.

-Pete, in Tacoma WA USA

'83,88 Venture

[Dragonslayer]

That's definately the problem/issue. The main jet has come loose and extra fuel is flowing past the loose jet fastener screw, the jet block o-ring, and around the outside of the jet. No wonder the bike has bad fuel economy. Still doesn't explain the oily crud on the diphragms.

BTW, the o-ring is 10mm i.d x 1mm cross section and are usually found at most bike shops that have a real owner/mechanic.

-Pete, in Tacoma WA USA

'83,88 Venture

I thought this may have been the issue but I'm unsure about the o-ring of which you speak. the jet block o-ring can you give me more details there is not an o-ring around the the fastener screw. Just a brass washer.

[Peder_y2k]

The jet block o-ring is located between the jet block (the cast piece held in place with 4 screws that contains all the jets) and the wall of the carb casting. It seals around the brass needle jet tube by compression. These o-rings can shrink over time, and cause engine vacuum to draw fuel right past it. Best to replace all 4, one in each carb.

The service manual briefly mentions the o-ring, and one of the carb parts diagrams poorly shows it. When you remove the jet block, you'll see it sitting there waiting to jump out and dissapear. Not to worry, a bike shop has more. I think I paid $1.00 for all four.

-Pete, in Tacoma WA USA

'83,88 Venture

[Dragonslayer]

The jet block o-ring is located between the jet block (the cast piece held in place with 4 (2 screws and the screw that holds the brass needle tube in place) screws that contains all the jets and the wall of the carb casting. It seals around the brass needle jet tube by compression. These o-rings can shrink over time, and cause engine vacuum to draw fuel right past it. Best to replace all 4, one in each carb.

The service manual briefly mentions the o-ring, and one of the carb parts diagrams poorly shows it. When you remove the jet block, you'll see it sitting there waiting to jump out and dissapear. Not to worry, a bike shop has more. I think I paid $1.00 for all four.

-Pete, in Tacoma WA USA

'83,88 Venture

Ok I found the o-ring. It did kinda look a little dry and crusty so I guess I'm gonna have to go on a hunting trip for them.

 

Thanks for the info.

[frankd]

Bob,

 

In view of the fact that 1 cylinder has been flooded with a lot of gasoline, I'd also change the oil after you get the carb. fixed.

 

Frank D.

[Dragonslayer]

Bob,

 

In view of the fact that 1 cylinder has been flooded with a lot of gasoline, I'd also change the oil after you get the carb. fixed.

 

Frank D.

Good point, Planning to change the oil anyway

[icebrrg3rd]

Ok, how do I thank this whole thread?

 

Bob, I was searching thru threads since I too was having fuel economy issues and a poorly running bike (a 2nd genner coulda beat me!) and I found yours. I looked into my carbs last night and saw that same seat sticking out on cyl. #4. I pulled the carbs, screwed it back in, re-synced my carbs, and WOW!!!! I took a test ride down the alley and I nearly pulled the wheel up! Plus there is no more backfiring from that side, and it runs so smooth. I am soooooo happy. Now to see if my mileage improves too.

 

I really love my bike now!

 

-Andrew

[Dragonslayer]

Ok, how do I thank this whole thread?

 

Bob, I was searching thru threads since I too was having fuel economy issues and a poorly running bike (a 2nd genner coulda beat me!) and I found yours. I looked into my carbs last night and saw that same seat sticking out on cyl. #4. I pulled the carbs, screwed it back in, re-synced my carbs, and WOW!!!! I took a test ride down the alley and I nearly pulled the wheel up! Plus there is no more backfiring from that side, and it runs so smooth. I am soooooo happy. Now to see if my mileage improves too.

 

I really love my bike now!

 

-Andrew

my pleasure

I do try to leave a positive footprint in the universe as much as possible.

Just a shame about those times when it's not possible:95:

Hoping this fixes my problem as well:thumbsup:

[Dragonslayer]

The jet block o-ring is located between the jet block (the cast piece held in place with 4 screws that contains all the jets) and the wall of the carb casting. It seals around the brass needle jet tube by compression. These o-rings can shrink over time, and cause engine vacuum to draw fuel right past it. Best to replace all 4, one in each carb.

The service manual briefly mentions the o-ring, and one of the carb parts diagrams poorly shows it. When you remove the jet block, you'll see it sitting there waiting to jump out and dissapear. Not to worry, a bike shop has more. I think I paid $1.00 for all four.

-Pete, in Tacoma WA USA

'83,88 Venture

I found the o-ring alright, Yamaha part # 22U-14147-00, but the price was $4.17 each plus tax. But, I had to have them so :mo money:That's just obscene for a tiny o-ring 10mm X 1mm , this big O

[Peder_y2k]

I stand corrected on the number of screws holding the jet block, just going from memory from some time ago, being 65 y.o. has a way of screwing with recall.

Regarding o-ring availabilty, is there no generic bike shop in your area? I'm lucky to have such a shop nearby, and it has 3 Suzuki dragsters on the showroom floor built by the owner/mechanic, so this shop has generic parts and real knowhow. I go there for anything not proprietary and save big bucks, but I get my Rotella T3 oil at the Walyworld.

-Pete, in Tacoma WA USA

'83,88 Venture

[Dragonslayer]

I stand corrected on the number of screws holding the jet block, just going from memory from some time ago, being 65 y.o. has a way of screwing with recall.

Regarding o-ring availabilty, is there no generic bike shop in your area? I'm lucky to have such a shop nearby, and it has 3 Suzuki dragsters on the showroom floor built by the owner/mechanic, so this shop has generic parts and real knowhow. I go there for anything not proprietary and save big bucks, but I get my Rotella T3 oil at the Walyworld.

-Pete, in Tacoma WA USA

'83,88 Venture

You know, this was a generic bike shop that used to be a Yamaha dealer. He must have a gigantic old yamaha parts inventory cause he always has the old stuff that yamaha dealers can't get anymore. He never has not had what I needed yet.

 

Doraville Motorcycles used to be Yamaha of Doraville

Buford Hwy

Doraville, Ga.

 

But he aint cheap.

 

I just figured it was probably cheaper and easier to pay the price that spend the time and gas hunting them down.

 

$17. and change won't ruint me yet.

[Flyinfool]

You can get the o-rings from McMaster-Carr P/N 9263K286

You want the Viton ones, $4.59 for a pack of 25.

[Dragonslayer]

You can get the o-rings from McMaster-Carr P/N 9263K286

You want the Viton ones, $4.59 for a pack of 25.

Had I only known.. Where were you when I needed you to tell me that.

[RandyR]

anything else you might need to know?

 

[dingy]

1st picture is of the bowl side of a carb. Main nozzle is part sticking through into venturi in original post.

 

The part just to the right of the float is the main nozzle, it comes through the body from the venturi, goes through the jet block, then is fastened with a brass screw from the bowl side. Screw is in main nozzle in picture.

 

Main jet is below main nozzle.

 

Under jet block to left side is 37.5 pilot jet (problem child for a lot of idling issues)

 

Under jet block on right side is Main Bleed Pipe.

 

Float needle valve is lower left of picture.

 

2nd picture is parts oriented more similar to position in body.

 

3rd picture is parts assembled in body. Screw holding the main nozzle is just above half moon shape at top of float.

 

Gary

[Dragonslayer]

anything else you might need to know?

 

Yea, How you doing ? Have you got us a hunting spot picked out yet? Call me.

When I get the carbs back on and the bike on the road I'm gonna need to run up to your place and do a carb sync. That OK?

Edited September 20, 2012 by Dragonslayer

[Dragonslayer]

1st picture is of the bowl side of a carb. Main nozzle is part sticking through into venturi in original post.

 

The part just to the right of the float is the main nozzle, it comes through the body from the venturi, goes through the jet block, then is fastened with a brass screw from the bowl side. Screw is in main nozzle in picture.

 

Main jet is below main nozzle.

 

Under jet block to left side is 37.5 pilot jet (problem child for a lot of idling issues)

 

Under jet block on right side is Main Bleed Pipe.

 

Float needle valve is lower left of picture.

 

2nd picture is parts oriented more similar to position in body.

 

3rd picture is parts assembled in body. Screw holding the main nozzle is just above half moon shape at top of float.

 

Gary

Gary,

Thanks for the info, I'm good with all of that.

My question is: Could this condition have caused or contributed to the stumble then pick up of acceration at 4200 rpm we talked about?

[frankd]

My name's not Gary but I did stay at a Holiday Express....

 

 

Yes, it probably would make the bike stumble. You had a cylinder that was very rich, and when you would floor it, it probably would clean out somewhat. Between the diaphragms and the jet, it'll run WAY different now.

 

Frank D.