Cold #1 exhaust

[Bartman]

I need advice.
I have been working on a 78 standard most of last year and thought I was close to riding. But, as it warmed up it would run poorly and smell very rich. I hadn't checked compression yet since the valves hadn't been checked. So I checked and swapped shims and after putting back together thought the carbs were correct. As the motor was running it started sputtering and smoking out the left exhaust.
I turned off and borrowed my brothers compression checker. 110,115, 112,110. A few days later it finally cranked and i thought was doing ok. I was warming up to get another reading and I noticed that the #1 carb was sweating and cold. I then checked and could touch the #1 exhaust but not the other three. There was a fan blowing on the motor while running.
I pulled the #1 plug wire and it was sparking but there was no change in the idle.
Could I have gotten the valves too tight or do I need to rebuild?

Thanks for input.

[oldyam80sg]

I think that gas is not getting to that carb.Does it get warm at all?

[Bartman]

Yes, it was warm, but I wonder if it was heat transfer. The motor running about 10 minutes before I realized.

[oldyam80sg]

I been chasing the same issue myself.Going to do a thorough cleaning of the carbs and go from there.Now need fuel line that actually fits.

[Bartman]

My carbs have been cleaned three times as recommended x two! The last time I put filters clipped onto the bottom of the needle seats. New filters in line and new ones in the tank. At this time the tank is not on the bike, I am using a pint sized weedeater gas tank hung on a ladder next to the bike. I do wonder if the carb could be hung up so how and not be getting gas.....I might go and unscrew the bowl bolt and see if gas comes out! But it is almost bed time, tomorrow after work.

[oldyam80sg]

Same here! Remove screw on bottom of float bowl.I started out with a teaspoon-now i get a lot more!

[tarzan]

Did you pull the spark plug on #1 when you realized it was cold? It would have told you if it was wet or dry.And if it was flooding and fouled, or was getting no gas. If it was running rich, fouling would be normal. Are the carb's correct for that year? If so, float height should be set at 25.7mm . If you have earlier carb's, then 23mm.
ALso, your compression looks a little low. Did you check it with the throttle wide open?

[DGXSER]

Tarzan, your close. You got it right on what his floats should be set at, but that IS the earlier carbs. The 80 and up carbs are set at 23mm.

I would agree it is carb related, and fuel related. Let it idle with the miss for a minute or two, then look at the plug for that cylinder. That will tell you if you have to much fuel or not enough.

Now, depending on the spark your seeing, you may want to remove the plug cap and cut a 1/4" or so off the plug wire and re-install the plug cap.

[tarzan]

Oops sorry, I meant later carbs at 23mm.But as I stated, the 79 carbs should be at 25.7mm.

[fredintoon]

Hi Bart,
swap #1 & #4 plugs & wires. If #1 runs & #4 don't it's ignition.
If #1 still acts up, it's fuel related.
Betcha it's the carb.
I fought with my XS11SG ignition for a week trying to get #4 running.
It took just a half-hour to clean #4 carb & get all 4 working.

[Bartman]

These are the correct carbs for a 78. The carb floats were set to 25.7mm and I verified them by putting in my vise and clear tubes out the bowls. I worked the floats several times and then let them sit for over an hour to make sure that the seats weren’t leaking. I feel good about the carbs, but there is that possibility that something is hung up or….I will check bowl.

I pulled the spark plug and changed with a spare but I didn’t really look at it. Sunday when the problem of smoking exhaust occurred, all of the plugs were very black and smutty.

When I changed the tight and very tight valve shims last week I didn’t like the stiff coil wires because one had a noticeable break in the sleeving. I used the coils from my #2 (next project) bike and so they are “New” to this equation. Yes they are the correct coils.

Last night I cleaned the plugs and finally got it started. I thought that it was running good and was letting it just run with a fan on the motor when I saw the sweating carb. I pulled the #1 spark plug wire and no idle change so I first thought of the “New” coils. I had rubber gloves on and used a small screwdriver and it was sparking good. I don’t think coils are the problem. I can swap #1 with #4 but haven’t yet.

I did NOT check compression with WOT. I will need to retry.

I am at work and I won’t get a chance tonight to try much so hopefully tomorrow night I can get back on it.

Thanks for input.

Bart

[Bartman]

Update, I swapped #1 and #4 wires, cleaned plugs, opened #1 bowl and gas dumped out, plenty of gas.
It took a little while to crank but finally did and after a few minutes able to get choke off to idle. As it was warming up all 4 exhaust were hot. After a few minutes it started to have a hard time running and I would have to bump idle to keep alive. The #1 exhaust got cool and I unplugged the #4 wire and it didn't make a differance.
I took off the air box so that I could see if the diaphram was moving up and down as I reved the bike and it did. After a few more minutes it wouldn't keep running so I turned it off and pulled the plugs.
#1 was black suety, the other 3 were all light tan. This time I checked compression with WOT and the numbers are now: 1=166, 2=163, 3=164 and 4=170. Very close together even though very high????
I can change the coil out but I don't think that is the problem. I could change the carbs out, I have another set on the table from #2 bike, it would have smaller jets but I could try, or do you guys know something that might be getting hot and killing #1?

[IanDMacDonald]

Compression looks good. Obviously your #1 cylinder is running rich. Have you synced your carbs since messing with the valve clearances? Get your carb synchronizer on those carbs first. Then, work on the fuel mixture. I cannot remember off hand if you turn left or right on the mixture screw to lean out the mix, but, that's your intended goal.

[Schming]

Compression looks good. Obviously your #1 cylinder is running rich. Have you synced your carbs since messing with the valve clearances? Get your carb synchronizer on those carbs first. Then, work on the fuel mixture. I cannot remember off hand if you turn left or right on the mixture screw to lean out the mix, but, that's your intended goal.

Clockwise to lean it out and of course CC for to richen the mixture.
2 to 3 turns out (CC) is a usual starting position

Bartman, you may want to try a new or a known good plug in #1 as the current one may be fouled.

[Bartman]

I didn't sync tonight but tomorrow night I will try another plug and see if I can lean it out a little. I am borrowing an old four gage sync from someone and I wonder if it is accurate enough.
I read that it might have carbon build up to have such high compression. Once it runs good I can deal with that.
It's bed time so I'll try again tomorrow night.