Carb identification?

[Paul1965]

I ran across what I think is a good deal on a set of used FJ1200 carbs. Guy had them on a Baby Grand until he blew the motor. The trouble is, he doesn't know what year the FJ was. Is there any way to properly identify the carbs or does it even matter? For $140 shipped I'm willing to take a chance on whether they'll work or not. More than anything I would just like to have a spare set on hand.

I did have a look around the file section, found plenty of info on jet size, etc but nothing about the carbs themselves (or I just wasn't in the right spot).

[Pat Conlon]

Randy can chime in but from my experience the first thing that easy to spot is if the carb's are off a fuel pump model FJ (USA '89-'93) they will have a single center fuel inlet (between #2 and 3)
The '84-'87 gravity flow carb's have dual fuel inlets (between #1 and 2 between #3 and 4)
The early '84/85 gravity flow carb's had flat bottom slides, the later '86+ carb's have curved bottom slides.

That's about all I know.

[Paul1965]

Randy can chime in but from my experience the first thing that easy to spot is if the carb's are off a fuel pump model FJ (USA '89-'93) they will have a single center fuel inlet (between #2 and 3)
The '84-'87 gravity flow carb's have dual fuel inlets (between #1 and 2 between #3 and 4)
The early '84/85 gravity flow carb's had flat bottom slides, the later '86+ carb's have curved bottom slides.

That's about all I know.

Thanks Pat. I had a line about "as long as they're from a FP" but deleted it before I made my post. They do have the center fuel inlet and curved slides.

[Pat Conlon]

OK You should be fine with using these on your (beautiful) '91 I think you got them for a great price.

If they came off a race car, no telling what jets are in there, so figure on new air/pilots/mains as well as new emulsion tubes (aka needle jet or jet nozzles) Chances are with the rigors of racing, the tips of those slide needles have elongated the holes in the emulsion tubes.

Cheers

[Paul1965]

OK You should be fine with using these on your (beautiful) '91 I think you got them for a great price.

If they came off a race car, no telling what jets are in there, so figure on new air/pilots/mains as well as new emulsion tubes (aka needle jet or jet nozzles) Chances are with the rigors of racing, the tips of those slide needles have elongated the holes in the emulsion tubes.

Cheers

Yeah, I jumped on them as soon as I exchanged a few texts with the guy to get more info. I haven't opened them up yet and he couldn't remember what jets are in it, but strangely enough said they were leaner than stock. Being they were in a race car I would think they'd be richer than stock. At any rate I'll just add building them to my list of things to do this winter. Thanks for the help Pat...

[racerrad8]

Pat covered it.

84-87: gravity feed - dual inlets
88+:    F/P - single center inlet.

Flat bottom slides only available on the 84 through some mid point of 85 1100's.

Paul, if the jetting is leaner than stock, that is flat out scary and might be why the engine blew up...

The carbs for the race cars, just like all of the US 1200 bikes, came with 110 mains, 37.5 pilots & 155 air bleed.

Randy - RPM

[Paul1965]

Paul, if the jetting is leaner than stock, that is flat out scary and might be why the engine blew up...


Randy - RPM

That was exactly what I was thinking.

Thanks for the info on the jets too. I've got some extras out in the garage, just need to see what sizes before I order anything.

[Paul1965]

Pat covered it.

84-87: gravity feed - dual inlets
88+:    F/P - single center inlet.

Flat bottom slides only available on the 84 through some mid point of 85 1100's.

Paul, if the jetting is leaner than stock, that is flat out scary and might be why the engine blew up...

The carbs for the race cars, just like all of the US 1200 bikes, came with 110 mains, 37.5 pilots & 155 air bleed.

Randy - RPM

Well I don't know where that guy got his info from. I took the first carb apart and the main is a 125 and the pilot a 42.5. Maybe he just doesn't know the difference between rich and lean lol.

[racerrad8]

Well I don't know where that guy got his info from. I took the first carb apart and the main is a 125 and the pilot a 42.5. Maybe he just doesn't know the difference between rich and lean lol.

Well it is all relevant...

a 125 Keihin jets is the equivalent to a 110 Mikuni...

Plus, it is going to depend on what needle is in the carbs to ensure the proper main jetting.

Randy - RPM

[Paul1965]

Well I don't know where that guy got his info from. I took the first carb apart and the main is a 125 and the pilot a 42.5. Maybe he just doesn't know the difference between rich and lean lol.

Wellmit is all relevant...

a 125 Keihin jets is the equivalent to a 110 Mikuni...

Plus, it is going to depend on what needle is in the carbs to ensure the proper main jetting.

Randy - RPM

I did actually talk to the guy, and he said these were professionally built early this year but I really wonder. The bowl gasket is as hard as a rock, the jets aren't shiny new and I had one hell of a time prying the seat out of the housing. As far as the jets go, I see no other markings other than 125 so I don't know how to tell it from a Keihin or Mikuni. The needle does have 6 adjustment slots though. In the end, since my FJ is stock except for the Uni pods, my goal is to just rebuild the carbs with stock jets and go from there.

[Pat Conlon]

Start fresh with new jets. No guessing. They cost next to nothing, chump change really.

We know the USA bikes were set on the lean side from the factory (EPA) so personally, I would not use stock jet sizes.

Randy's the guy to talk to....

[Paul1965]

Start fresh with new jets. No guessing. They cost next to nothing, chump change really.

We know the USA bikes were set on the lean side from the factory (EPA) so personally, I would not use stock jet sizes.

Randy's the guy to talk to....

Yeah, I've already got 4 rebuild kits sitting in my RPM shopping cart, just waiting to pull the trigger. Good thing that Christmas bonus is right around the corner