Dead bike

[rosso75]

I did not.  I looked around locally for various O-rings, and the only ones I could find in the proper size were the 6mm fuel transfer tube rings.  I took a chance on the rest.  I'll order some, replace them, and see how that works.  Kinda makes sense now....each carb seems to be leaking from somewhere.  When I pulled the set off, the butterfly valves were all coated with fuel.  I just don't know enough about carburetors to know what I should be looking for as the cause, so thank you. 

On the plus side, it did run, and fairly well.  I used the 4 carbs from the non-running bike.  I figured if I screwed them up completely, I still had my set that came off a bike that was running last week.  Anyway, they were pretty nasty inside, so I'm rather thrilled that the bike started at all.

Thanks for everybody's input.  I really do appreciate it. 

[movenon]

Randy at RPM has an O ring kit. http://www.rpmracingca.com/proddetail.asp?prod=carbkit&cat=24

Also these will work for your needle and seats   http://www.oringsandmore.com/viton-oring-7-1-x-1-6mm-price-for-25-pcs/
George

[breeze48552000]

FTHY

Clean the carbs on the maroon bike...clean them correctly.

Read the Carb Files.......Study the Carb Files. Roll up your sleeves and do it...

We have documented all the information you need to do the job correctly. We worked hard on this. We did this for a reason. We get the same questions over and over. How do I clean my carbs?
We tend to get VERY cranky when people don't read it... if you figure what parts or parts you need I have them , just let me know

Remember...Carb cleaning 101: Half measures will avail you nothing. Do it right.
Any parts you need for the carbs are available from RPM.

I've not seen a vacuum petcock like that. No clue were it came from. The '84/85 petcocks are a less expensive alternative to the pricey '86-87 reserve petcocks...also available from RPM. See the vendor file section.

You are going about it wrong....instead of swapping old parts from a running bike to a old non running bike, fix the parts on the non running bike (like the carbs)

Pick one bike and work on it...step by step....failure to do so will send you and US into vapor lock.

[rosso75]

Been a while...work got in the way of toys.

I bought all new O-rings, replaced all of them in two sets of carburetors, and cleaned everything spotless.

Reinstalled one set on the red bike, it ran great, and I sold it.

Reinstalled the other set on the maroon bike, and I'm back to where I started.  Bike starts at full choke, and dies instantly when I twist the throttle.

Haven't sync'd the carbs yet.  Probably tomorrow.  I tried the mixture screws in multiple positions from one turn out to two and a half.  No setting was better than any other.  Plugs are not wet, or fouled.

Any thoughts on what to chase now would be appreciated.

[yamaha fj rider]

My 2 cents. Order this http://www.rpmracingca.com/proddetail.asp?prod=carbkit&cat=24  Money well spent.

It started with the choke on. This tells us, it is a carb problem. Did you use a ultrasonic cleaner? Clean carbs again.

Three owners have not gotten this right yet. Keep working at it. Starting with the choke on, will it stay running with the choke on? Not twisting the throttle.

There are very small passages that are probably still blocked.

Kurt

[simi_ed]

Kurt has hit it.  Pilot circuit is clogged. 

Try spray carb cleaner into the mixture adjusting screw hole. JAM the tube in so it lodges in place.  Spray until cleaner comes out the front air jet.   Cover air jet, spray again until cleaner comes out of pilot jet.  Now cover pilot jet, air jet & spray again.  Cleaner will come out of small passage down-bore of the throttle plate.  This WILL clear a plugged pilot circuit.  Reassemble and repeat until all 4 carbs are done. 

[rosso75]

Initially it started with the choke on, and I could rev it a bit but it would stumble like it was misfiring, and pop out of the exhaust.  I rode it about 100 feet, with the choke still on, and it died.  After that, it will only run with the choke on, and any throttle kills it.

I replaced every O-ring in the carbs, so I probably won't get the kit just to get new bolts.  If I still needed the O-rings though, that's a good deal. 

So, as long as I'm pulling the carbs apart again, I suppose I should re-jet it.  It's got a K&N filter and a big no-name single can exhaust on it.  Otherwise, it's stock mechanically.  Any advice on jetting, or should I leave it as is?

Thanks for the advice and suggestions.  I appreciate it.

[Arnie]

One thing at a time.  This is a GOLDEN rule of mechanics.

Fix your problem first, and then if needed go back and change ONE other thing.
If you clean the carbs, and change the jetting, and adjust the needles, and change the air filters, etc, and it runs like crap...... What is the cause?  In fact, even if it runs like a brand new scalded cat, what is the cause?

Yes, I know how tempting it is to be "efficient" with your time, but think how much more efficient you'll be at R&R carbs after a few more goes. :-)

[movenon]

Sorry you are still having problems. Take nothing for granted.  I would start with a fresh look at the problem.  Apparently this problem was inherited from the PO and you don't know what he (and others) did in trying to fix it.  Anything is possable.

Just because it is the way I am. I would pull the valve cover,  check the cam timing marks and valve clearances.  
Check the plugs for any clues.

In the fuel system:
Start at the petcock.  Make sure you have fuel flow..... Don't assume it, double check it
Fuel line routed exactly as Yamaha spec's.
If you pull the carbs out take your time, completely tear them down, clean and inspect... Its an old bike anything is possable.  Are the needle and seats the correct ones (there are 2 sizes)?  At a minimum clean with lots of cleaner and compressed air.  Check the intake manifolds for cracks. Change out the intake "O" rings. Make sure the floats are not binding, are even and adjusted correctly.  Check every bloody detail.  Take your time.  Post some pictures and ask questions if you need help or advise.

If you are inclined to have someone else rebuild them then I would strongly recommend Randy at RPM.  He knows those carbs inside out.  He is the only one I would recommend.

Best advice,  assume nothing, something is "dicked" up. It is just a machine and in the end you will probably find out out it was something real simple. Have faith you can fix it.  For me in an unknown situation putting it back into factory spec's is a good start.  Base line....
George

[yamaha fj rider]

First, you say the carbs are clean. If the carbs were clean then the bike would be running. This is not a put down but to put you on the right track.

Second, disassemble all four carbs. Keeping the parts separate. Then blow all the small passages with carb cleaner. Doing it this way, if one or two have have the cleaner coming out of a passage and the others don't. You have found a problem, this may not be the only problem. Blow one passage at a time and move to the next carb. Unsure if you got it, let it sit for a couple of minutes and spray that passage again. If it was me, I think that I would do all carbs twice in this manner.

Third, o rings. Getting the o rings from where ever is fine, as long as you got the correct sizes. This is the main reason we recommended the RPM kit. You and we know that you have the right parts. Also, some buy pluming o rings, that the gas will destroy.

Fourth, worrying about the jetting, on a bike that wont run is like putting the cart before the horse to me. When you have the carbs apart write down all the jet sizes to refer back to once the bike is running. Check sizes on all four carbs, assume nothing.

Last, buy EXPENSIVE CARB CLEANER!!!! Don't buy the cheap stuff!!!!! If the bike had been, being ridden last year you could get away with it but it has been sitting and you NEED GOOD CLEANER. Stay with it, you are close. Just a few small details and it will be running and you will be ridding it.

Hope this helps.

Kurt   

[rosso75]

I figured it had to be a problem with some little passageway somewhere, but my knowledge of carbs is limited.  Thanks for pointing me in the right direction.  They're off, and apart, and I'm in the process of blowing out the pilot circuit, and everything else just for kicks.

The "One thing at a time" theory...have to say, I'm not a fan. 

The O-rings are all viton, in the exact sizes specified somewhere here on this site but I don't remember where.  One of the carb tutorials maybe, I don't recall.

As for the fuel, I pulled the tank off my lawn mower and I've got that hooked up with fresh fuel.  No petcock, just straight flow.  At some point I'll drain the tank when I put it on, but for now I doubt it's a fuel problem, or a flow problem.

If the carbs were clean then the bike would be running.

Well, assuming it's not running due to a carburetor problem.  That's the assumption, but as was pointed out, I'm chasing some unknown problem that two previous owners couldn't fix.  Point taken though.

As for the cart and the horse, knowing myself as I do, once it's running I won't pull the carbs again the jet it.  If it needs it, I figured I should do it while it's apart (for the 3rd time).  I'll let it go though.  This is one I just want running so I can get rid of it.  I've got bigger fish to fry.

Anyway, in the process, I heard some little metal piece hit the floor.  This is what I found. 





So, I've got a set of carbs from my '90 that's in permanent project status.  They're the same, right?  I can use one of them?

Really appreciate the help 

[movenon]

There is a minor change between the 86 and a 1990 carb. The 86 being gravity feed has different needle and seat. The 1990 has a smaller inlet orifice because it is fuel pump driven.   Just use you 86 needle and seat.  I am told those post's can be micro welded.  But that's about the extent of my knowledge.
George

[racerrad8]

So, I've got a set of carbs from my '90 that's in permanent project status.  They're the same, right?  I can use one of them?

Really appreciate the help 

It depends on which carb body that is to determine if you can use the 90 on the 86 bank. You can only use the two end carbs from the 90 on the 86 bank.

Randy - RPM

[rosso75]

It's not an end carb, unfortunately. 

[rosso75]

This is where I admit to stupidity...

So a friend comes by, and I'm telling him how I can't get it running, and he asks me if I did a compression test.  I tell him I'd love to, but I don't have the 10mm adapter.  He had one.  End result...zero compression in #3.  I put oil in it, and still nothing.  I'm assuming a burned valve or two.

Obvious moral to this story...check compression.

So, I've got a '90 that I plan to keep.  If I'm going to put money into a valve job, or whatever this needs, I'd rather be putting that money into a keeper, not a bike I'm going to sell.  My thought was to swap the whole motor from my '90 into the '86, and rebuild the '86 motor to use in the '90.  If that'll work, I can have it running much quicker and cheaper.

Any thoughts on the viability of that option would be appreciated