82 carb jetting

[hydra10]

Hey guys, wondering about the jetting on the 82 carbs. I got some jets from Lucky to put in after I did some engine work, and he told me to use:
130 FRONT Pilot air
135 REAR Pilot air
127.5 Main Rear
122.5 front main
It does not seem to be running as well as it did before I pulled it apart, and i realize some of that may have to do with idle screw adjustment, valve adjustment, etc. I want to know if I should use different jetting for high altitude. (carbs have seen cleaned -several- times)
Also, the accelerator pump is not working. He also sent a new turret for the front cylinder, and it used to work, but doesn't after the rebuild.
Any input is much appreciated!

[Rick G]

That jetting should be fine to at least 8000 feet. With out a working accelerator pump it will stumble upon acceleration.

[Rikugun]

Do you know what sizes came out before replacing them?

Other than valve adjustments, what other work was done and what are the symptoms now?

[hydra10]

It was at the regular stock jetting before I changed it. I had to pull the front cylinder head apart to get to a fallen accelerator pump nozzle >.>
I actually have yet to do the valve adjustments on it. Have a feeling I may have mixed a couple of the shims up when putting the cylinder back together. No matter what I do with the carbs (syncing and whatnot) it doesn't seem to want to go above 6k rpm.

[Lucky]

do you have the ball check & weight under the turret?

[admin]

as a guess, it sounds like the cam timing chain is off a tooth...

[hydra10]

Lucky, I'm 99% sure I made sure the ball and weight were in there before I put the turret in. Is there anything else that would be preventing it from working? There isn't any fuel going through the tube from the first to second carb. I did check the diaphragm and it doesn't seem to have any holes in it.
And I suppose that it could be off a tooth....will have to check maybe tomorrow. Thinking about checking compression as well.

[The Prophet of Doom]

If your accelerator pump doesn't work then you will get a massive off-idle stumble - best you fix that before worrying about anything else. That won't affect max RPM though.

I've written a lot about jets in the past.  My opinion is that air jets should be even.  135/135 (or possibly 130/135) is stock for USA, but remember that these needed to pass California rules, so not really a performance benchmark.  I switched to 120/120  (Euro / Australasian standard) and got a significant improvement across the board.

But if you have messed your valve clearances, then nothing else will fix it

[Lucky]

Timing off is unlikely...
since you know that you don't have fuel at the rear carb outlet going to the ft carb, work backward from there.

[hydra10]

I did check the valve clearances on the front cylinder, they are off by one, two shim sizes max. Clearance if I can remember is a little low on both intake and exhaust.
Any idea where to go on the accelerator pump issue? Is there maybe a passage that could be blocked that feeds it to check? Maybe there could be a leak from when I put on the new turret.....
Would you guys recommend putting any kind of sealant around the turret? It was a rather tight fit, so I assumed it would be fine.

[Lucky]

no sealer on the turrent. pull the hose that feeds the front pump & operate the throttle. if fuel comes out the hose, then the pump works, the ft nozzle is clogged. if no fuel comes out, does it spray out the rear nozzle? if no, the pump needs investigation. if yes the feed for the ft nozzle is blocked (take the diaphram off again)

[QBS]

roro, my '83 is and always has run factory jetting.  Your comment about going to 120 air jets got my attention.  What does this actually do to the carb? What kind of improvements did you see with the 120s'?

[The Prophet of Doom]

My stumbles vanished and it pulls much better at all RPMs
Of course I had to re-do my idle mixture and sync as well but it was well worth the effort.

[Cdnlouie]

Hydra make sure you look over the check ball in the carb body (different from spray nozzle) to see that the passage is clear, to allow fuel into the diaphragm area or else it will not work.  Also, the check ball in the carb body (directly under the diaphragm) has to be clean to seal (as a check valve) when the diaphragm compresses or again the nozzle will not spray fuel. Encure the passageway from the float bowl is delivering fuel to the nozzles and then you can know that the problem is in a nozzle.

Your best bet is to bench test these items with fuel in the carburetors to isolate any issues, or else you are just doing a crap shoot and wasting a lot of time with things that may not be related at all.  You can do a blow back test if the diaphragm pushes bubbles or fuel back into the float bowl then the check valve is not sealing.  Make sure you can see the little stainless steel ball and that it is rattling around in the carb body. It should seal if you trying blowing back with your mouth over it too (make sure the carb body is clean or you will taste fuel for a few meals) when you are in the cleaning phase as a rough check.

Always put a bit of penetrant in there and blow (compressed air is best) the check ball around as much as possible to work loose any corrosion on it.  Check diaphragm operation (with check ball working well) and then proceed to check the nozzles for clogging (back spray them) with a tightly fitted hose over the end and use a very fine wire (copper if possible as it is softer) to carefully push through them.

Good luck


 

[hydra10]

Will definitely look into the accelerator pump this weekend, thanks louie.
On another note, wasn't so right about the 6k rpm limit. It's very hesitant up until that point (at WOT), but once it hits about 7k rpm, it takes off like you wouldn't believe. So, either I have a clogged jet I'm guessing, or the jetting/sync needs adjusting (just throwing some options out there :) )
What do you guys think? Any input would be great!

[Rick G]

Try syncing the carbs , if that doesn't do it you will need to dip,them.

[Cdnlouie]

Did you remove the jet in the bottom of the carb bowl and clean the passage way there?  It sounds like you have a clog in the low-mid range zone which is covered by this part of the carb circuit. Any rust in the tank will clog this area up faster than you can say " Yamaha Vision." It is usually the first area to be affected with crud.  This jet is a very fine metering circuit and it hates dirt.

[hydra10]

I've cleaned the carbs many times in the year or so I've owned the bike and have made sure to remove the pilot on the lower side. Maybe with any luck, one more will do it. There is (and has been) a small in-line filter on it, but I think I will replace it; does seem pretty old. Might also go back to stock jetting and see if that helps.

[Rick G]

If you have cleaned the carbs many times and still are having problems , perhaps your method of cleaning them is faulty. I dipped my carbs in  2001 and they were fine until 2008. I dip carbs and send them off into the world , so I only get one chance at it .

[hydra10]

They were doing fine until I disassembled the engine. Had a falling out with an accelerator pipe >.>
I figured they could use a cleaning since I had them out. Wondering if I might have loosened something. Last cleaning was in an ultrasonic cleaner with some 409. Have used simple green in the past.