Cold #1 exhaust

[Schming]

If it runs well enough to take it for a 15 - 20 min. ride to really warm the whole engine up you'll get a better synch

You could synch it and then move the hoses to different carbs to see if the gauge holds steady.

GL

[Bartman]

I have ridden this bike for a total of three miles and it also didn't make it home. But I am letting it run with a fan blowing on it for 10~20 minutes at a time.
I did swap the hoses back a few months ago. The Gage's work, just once they are equal it is only reading about 7 on them. I did read the other night to turn the idle screw for each carb to get the highest reading first. I need to redo again tonight.

[Schming]

Sounds like you're on the right track. Let us know how the synch goes.
Also as long as the carbs are evenly synched that's what's important.
I does pay to get the best reading IF the gauges are good.

[Bartman]

I put another plug in #1 and cranked it up. It doesn't want to crank with the choke all the way out. Backfires. I end up in the first choke position until it warms up. I am watching the sync Gage's and filling my little pint gas tank for about ten minutes. The exhaust is hot but without a true reading the back of my hand says that it is not as hot as 2~4. There is a fan blowing on the motor and after 15 minutes some light smoke is coming out the left pipes and it is starting to sputter and not long after it dies.
I wonder if the valves are leaking or is there a crack some where or is it still carb related. 35 year old carbs have poorly tapered needles and wallowed out holes that I am working around.
Does anyone in Georgia want to loan me a color tune?

[Bartman]

Also, since I now know that the compressions are high and I must have carbon build up, could that be causing some of my problems? Do I try and fix that next or wait until the bike is running correctly?

[oldyam80sg]

If the carbs are worn out as you say they are if that is the problem-either Andreas Weiss i would contact on here or they show up on E-Bay all the time or some on here have gone to ZRX 1200 carbs.Just a suggestion.

[TopCatGr58]

Hey Bart,

Crazy Steve has found high compression on several engines that he's worked on, and they did not have carbon buildup, and has postulated that Yamaha provided underrated comp. values. After my little big bore (1179cc) I ended up with 180's , but mine is the later model year, and that kit doesn't provide the full compression kick/boost that it does for the earlier engines. So...I wouldn't worry about that for now, they are similar(within the 10% tolerance spec).

I will say that many members chased what they thought were carb issues that turned out to be ignition issues. I know you have verified spark on all 4 cylinders. However, you have 30+ y/o coils...and they are the 1.5 ohm style that runs with a 1.5 ohm ballast resistor inline so that after starting at full 12 volts via a temporary starting circuit, they get only ~9 volts while running to keep from burning them up! But they are also not very strong coils....~15 KV at best...and then when running on only 9 volts...possibly even less!

Then....the charging system doesn't adequately charge the battery at IDLE speed....1100 rpm....it can actually DRAIN it at that rpm!! It doesn't reach full charging rate/potential until 2500 rpm or above! So...you might want to put a jumper from a car battery or jump starter booster battery to help keep the system voltage up while idling!

You've got a fan blowing across the engine, so it's probably NOT getting overheated....the smoke from the exhaust is probably just burning off previous unburnt fuel/oil in the pipe.

The wallowed out vac. slide needles/jets shouldn't be causing you any problems while you're running on the idle/pilot circuit anyways. Sputtering after it warms up could be carbs...could be vacuum leaks, could be dropping voltages to the TCI/coils due to battery drain....lots of things to check and rule out! Keep at it!

T.C.

[crazy steve]

....Crazy Steve has found high compression on several engines that he's worked on, and they did not have carbon buildup, and has postulated that Yamaha provided underrated comp. values. After my little big bore (1179cc) I ended up with 180's , but mine is the later...

Compression numbers between 160-170 are fine. As TC said, I've ran into numbers as high as 200 and the motor ran with zero issues. And more than a few have seen 180-190 numbers after cleaning everything with new rings installed and a short break-in. I think Yamaha listed low numbers so as to reduce warranty claims...

[Bartman]

Thanks T.C., for now I can put my charger on while running. If that improves the problem then new coils will be in my near future!

[Bartman]

I forgot to mention that I sprayed carb cleaner all over the carbs and boots last time it was running and no change so no carb leaks.
I think you are on the right track with voltage checks.

[Bartman]

Ok, I checked my battery charger and it puts out 13.4 volts. I fashioned a board to fit inside of the battery well that would extend out to make a shelf to put the battery onto while having the charger connected.
It took a while to get the motor running but once it was and warmed up it didn't stumble and I was able to do a better tune....so I thought. The #1 was still cool enough for me to hold the exhaust. I thought that maybe with it hot and better tuned that it just needed the spark plug cleaned again. So I stopped and cleaned and got running again. I revved it good and it idled well, still not hot. I pulled the plug again = black. I did swap #1&4 wires one more time to see if the higher voltage was fixing anything. It did run better and #2, 3&4 were good looking plugs. So now I guess that the #1 carb must have a sticking float or something so I will pull them off and look 1 more time. The resistor measured 2.6 ohms when hot.
I may go ahead and put the other carbs on and try them. They have smaller jets.
For information, the bike that I am working on didn't have carbs and Yamahansolo gave me his with the bike since he has the 1200s on his. My bike has two into one exhaust pipes that go back and turn out. Chris's carbs have 140s, 210 and 45 pilots. The other carb set up has 137.5, 180 and 42.5 pilots.
Anyone with these pipes can give me their set up would be appreciated.
I have the stock air box on and taped up the drilled holes that a PO had done.

[TopCatGr58]

Hey Bart,

Well, 2.6 ohms on the ballast resistor is too high!!! It should be 1.5 ohms...the coils also have 1.5 ohms, for total of ~3.0 ohms for the TCI to see. With that higher resistance the coils are seeing even LESS voltage and generating less KV for the sparks! You don't want to run without the B.R. for very long because it can/will burn up the coils as well as the TCI because of too little resistance drawing too much current thru it. SO...you may want to look into getting another B.R. to install. They do get hot when they are working, but shouldn't go up much in resistance....so it is probably going bad.

Black sooty plug is too rich! UNTAPE the OEM airbox holes...., 140 isn't too much higher than the stock 137.5, the 45 pilot "may" be too much?? ALSO have to bring up the question of what "TYPE" of pilot jet does it have...the wrong type with too few vent holes also tend to run rich! ALSO...are you sure the #1 float is FLOATING....if it has a small pinhole, will sink and cause overly rich!

T.C.

[crazy steve]

Well, 2.6 ohms on the ballast resistor is too high!!!

That may be a good number if tested hot. The 1.5 ohms number is cold, and in a wire-wound resistor you'll get a big change when in use.

[Bartman]

I wonder if the float is sticking also, or worn out parts.
I work with Chris (Yamahansolo) and he told me today that back when he had the carbs that it would load up and stumble and die at lights. He has Kerkers and air pods and it was trying to be rich with him.
Pulled the carbs off and dumped gas out tonight. Didn't start the tear down yet.
I think that I will double check the second carbs and try putting them on next.
There is a 81 XJ three miles from my house at the scrap yard. I pulled the coils from it a few weeks ago. I don't remember seeing a resistor on it. Chris told me that I could use them without the ballast resistor if needed....
At this time I was trying to use the stock air box, but if needed I can open the holes back up.

[Bartman]

I reread and have more info.
I checked the floats by putting in hot water the last time that they were apart.....three months ago. But, I try to keep an open mind and could me wrong.
I am trying to remember the pilot jets. I think that they had rows of four holes and two holes.
Work on again tomorrow night.