Nursing Ugly Betty.

[Gyrogearloose]

Hello again. Nice day here, I should be outside getting ready for winter.....but, Ugly Betty is like a magnet! Anyway, previously could only get #3&4 to fire. (Feel the header pipes.) Now, after doing the carbs, I can get #2 to fire as well. Hmmm, looking up! No. 1 still stays cold on running. ? Also lot's of loud popping, like pistol shots going off when running? Took off the carbs again, and taking #1 apart, it's obvious that the main nozzle (jet?) is cracked! Would that stop #1 from firing on start up? I plan on cleaning the carbs all over again (second time), checking the float height, and bread-tie sync them again. (messed with them while running). I made new points on the broken idle mixture screws, and their holes/seats got enlarged/warped on extracting the broken points. Q. #1: where would I be most likely to find a replacement for the main nozzle? and...Q#2: Can I set the idle mixture screws by ear now, or will the plugs give me a clue? I think setting them at 1 1/4 turns out from a lightly seated position may not work now. Oh, #1 is firing (plug out and grounded), but no color on it from a trip to the combustion chamber, and it may only be slightly damp on extraction. ?
I'm getting closer, but......Help!
Thanks alot.

[Gyrogearloose]

Sorry, forgot to include: U. B. is a 79SF.

[AlanB]

Hi Gyro,

Try warming it up, then pull the plugs, turn it over a couple of times (to push any unburnt fuel out of the non-firing No1!) then put the plugs back in, BUT!..... put a HOT plug in no1, and stick the cold one in a HOT cylinder.... and see if that will start it.

Theory is, hot plug fires cold cylinder...... hot cylinder fired by cold plug; both should go!

AlanB

[Gyrogearloose]

Thanks AlanB, I will try that as soon as I get her back together. I guess I'll try "surfing" for carb parts. Has anyone tried making a main jet?

[TopCatGr58]

Hey Gyro,

The main nozzle is of course for the main jet, so it shouldn't bother the idle, but could definitely interfere with off idle and running of the bike!

The main nozzle is listed as different part #'s depending on which carb it's in, 1-4 take one type, 2-3 take another, and if you look closer at them you'll find more vent holes in the sides of the ones that are on the outside carbs. More holes=leaner, hotter, better cooling on outer cylinders; less holes=richer, cooler, for inner cylinders that don't get air cooled as well!

They are both available from Yamaha/Zanottimotor.com

2H7-14941-02-00 NOZZLE, MAIN(X-2 EXCLUSIVE FOR CARB 1,4 =$23.36
3H3-14941-02-00 NOZZLE, MAIN(X-2) EXCLUSIVE FOR CARB 2,3 =$14.47

or, you might find them from Andreas, or Ebay, etc.!
T.C.

[Gyrogearloose]

Thank you, T.C., this is much needed information.

[DiverRay]

Gene,
PM me if you need a few parts...

[Gyrogearloose]

Originally posted by DiverRay
Gene,
PM me if you need a few parts...

[Gyrogearloose]

Whooops, something up.
Anyway, thanks guys. It's back to the parts cleaning bench and a new survey. I'll go through all the carbs again, and get back here. I just can't understand the #1 cylinder not firing. If the carb bowl was full, what is not introducing it into the combustion chamber? I thought I had everything clean and blown out the first time. ?...and grounding out the plug shown it to be firing. This is the idle circuit, as I didn't use the throttle on start up. Oh, initially when it started, it ran at about 2500 rpms (guessing). Then it started climbing fast and I had to shut it off to keep from redlining. A few turns of the idle screw brought it down to manageable levels, but still no #1 (pipe cold). Pistol shots from the exhaust. I'll check for vacuum/air leaks too... Stumped.

[TopCatGr58]

Hey Geno,

Pull the intake boot for #1 OFF the head, check the mating surface, and clean/remove any old breaking/flaking rubber from it, then put some sealant on it, a gasket if you want, and reinstall it on the head. THEN pull the vacuum synch port cap, and squeeze it to see if it cracks! If it's hard, replace it with new pliable one from auto store! Those would be the two places for vacuum leaks besides actually THRU the body of the manifold....fairly rare! But a vacuum leak is a possible culprit to cause the idle to rise too much once it gets warming up, even after turning the idle screw down/back!
T.C.

[planedick]

Synch

Gotta synch those carbs, out of synch will cause the idle to run up and also make all those backfireing noises. That breadtie method really don't work very well. Better to set the throttle plate half over the first hole in the top. It's easier to get closer to a good bench synch.

[Gyrogearloose]

Hey! This is all great advice, and I can do it! I tried the bread tie sync. I'll give the throttle plate method a shot. Good advice about the intake boot and vacuum cap too. No doubt all of this comes from much experience. Thanks again for sharing.