Carb leaks

So, I got my carbs rebuilt. Got them back on, and everything hooked up. Primed them, and then..... There are "t"s in between all the carbs, the fuel goes into the middle t, the outside t's had hoses hooked on them running down under the bike. Once primed, gas runs out of these two hoses. I plugged them, and can get the bike to run, but only on the middle two cylinders. The outside cylinders are cold. Questions are, are those hoses overflows, or do they hook to something, and does this sound like the cause of the no fire on the outside cylinders (carbs not getting gas) or do you think that's a separate issue? There's fuel in all the bowls, as in the bowl drains allow fuel out when screws are turned. I'm thinking after some digging that the outside cylinders may be the coil not firing, I'll have to do some testing of that, but the leaking is my biggest concern at the moment. It's part number 3 in the diagram.

 

yes the hoses are overflow and it is the problem with bike not running outer cylinders. you need to do a wet set of your floats or your float needle valves are not working properly

 

Who did the carbs?

 

A guy nearby. He does carbs and dyno tuning, but he mainly does Harley. Apparently he didn't get the floats set correctly, but that's fixable. There is fuel in the bowls on all four carbs, and the outside plugs are getting wet, so I think that may be a coil issue. I'll have to test them this weekend. Considering where this bike started, I'm not upset, these are minor issues. How difficult is it to adjust float levels on the bike?

 

there should only be one T and two straight pipes but plugging the two extra hoses should work. that's probably not your problem.
give 1 and 4 a smack, those floats might just be stuck

 

That's what my carb guy said, but that's what was on it from before, and that's what the Yamaha diagram shows as well. I'm going to try adjusting the floats and go from there.

 

I'm not an expert on the electrical/ignition side of these bikes, but...

Since 1 and 4, and 2 and 3 cylinders fire together from the same coils, perhaps you do have bad coil on 1/4? Or perhaps a TCI issue (hope not)?

http://xjbikes.com/forums/threads/how-to-ignition-troubleshooting.21932/

 

That's why I was thinking that. Once I can get a meter on it I'll know. When I got this bike it had been sitting and wasn't running, so there are many little issues I'm sure I'm going to run into. Just gonna tackle them one at a time.

 

this was very nice to hear after the work that I've done. Not bad for two cylinders.

 

Yes one "T" and 2 straight for fuel delivery but 2 t's and 2 hoses are overflow and 4 upper vent lines. the 2 t's and hoses between 1/2and 3/4 should not be plugged.

 

Ok, I just spoke to my carb guy, and I think we've figured it out! Apparently someone has taken these apart before, and when they reassembled they switched the feed tubes and the overflow t's. He put them back where they were because he only had the carbs, no bike and assumed that there were multiple attachments for those hoses. He's going to swap those out to the correct location and adjust the floats if needed free of charge. This explains why it wasn't dumping fuel into the engine or air box while I had them plugged. This is why I love this forum, you guys are so willing to help. Even when people throw out stupid suggestions it helps getting us closer to the right answer.

 

Ok, with the carb problem figured out, I'm on to the spark. Tested the coils and got 2.8 ohms on the primary and 13k ohms on the secondary on both coils. That's close to spec, and one coil was definitely firing. Getting good voltage (within spec) to the primary of the coils. What should I check next, and how. Voltage on the signal wire while cranking perhaps?

 

did you also ohm out the spark plug caps and pickup coils?


XJ700 air-cooled models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range


Spark plug caps:
1985 N/NC models: 5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range
1986 S/SC models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range


Spark plugs:
1985 N/NC models: 0 ohms per plug
1986 S/SC models: 5K ohms per plug

 

117 on the pickup
About 8.5 on the caps of the non working cylinders, 4.9 on the working cylinders. So bad caps?

 

did you ohm out both pickups?

trim back the spark plug wire 1/4 inch may be corroded I would replace the caps

 

Yes, I did both pickups and all 4 caps. Both pickups were 116.8 117.3
I ordered some new caps and plugs. If that doesn't do it, then I'll try new coils and wires.

 

Got the new caps in, and I'm now firing on all 4. Runs like crap as the new plugs haven't arrived yet, but it starts easier and does run. As a sidenote, I actually ride the bike around the back yard, at a whopping 10mph, but this is the first time it's been under it's own power in years. It will do a burnout, thanks to my clutch cable for showing me that. As I have changed the geometry of the bars it's left me with a bad bend in it so it's very tight. Is there anyone that can suggest a good how-to on measuring for a new one? Everything I find online is for longer, or for Harleys. As always any help is appreciated.

 

Is it at all possible to reroute the cable to reduce the bend? I'm guessing you gave probably tried this but just thought I'd throw it out there

 

Definitely been tried. Is going to need a shorter one.

 

I know motion pro makes a bunch of cables, as far as properly measuring one to know what you need to get...I'd like to know myself haha.

 

someone posted a link to motionpro web site recently where you tell them the bike and what handle bars you put on and make you a set of cables.

https://www.motionpro.com/motorcycle/custom/

 

I've built cables for mowers and go carts and such, so I know I can do it and hate to pay a "professional".