3 carbs not working

[Audioslave784]

I have never gotten my 850 firing on all cylinders. Before I rebuilt the top end, I was getting 1 and 2 firing all the time, 3 firing some of the time, and 4 rarely firing.

After new rings, a hone, valve clearance checked, and a CV carb dip/rebuild (using the CycleOrings.com kit), I figured that whatever was plaguing the engine should be fixed. Unfortunately, now only 2 fires all the time, with 1, 3, and 4 kicking in intermittently when given throttle.

I tried shifting the carbs over 2 spaces to the right (so the 1&2 carbs fed cylinders 3&4) and found that cylinder 4 was now firing all the time. I then shifted the carbs over 2 spaces to the left (so the 3&4 carbs fed cylinders 1&2), and couldn't get it to start. Basically, whatever cylinder was fed by carb 2 would work great. The other cylinders would only fire when given throttle, and only intermittantly.

So I'm fairly certain that that carbs 1, 3, and 4 are not working properly, but I can't figure out when. Pilot screws were all set 3 turns out, and bringing them out further while on the bike didn't change anything. I blasted some carb spray through the pilot jets, and that didn't seem to help either.

I set the float heights during the rebuild. The last thing I did today after messing around with the pilot screws to no avail, was to lower the float height to make sure the bowls were filling enough. This had no effect either.

I have no idea how to proceed. What do you guys think?

[BassCliff]

Hi,

Just a thought....

Did you replace the float bowl gaskets? There are places to punch out holes in the gaskets according to where they are in the rack. Did you match the punch outs on the new gaskets with the old gaskets?


Thank you for your indulgence,

BassCliff

[Don-lo]

Before you did anything you should have checked compression. Did you check compression after the top end work? What is it now?

Did you put in new spark plugs? Cleaning them correctly is difficult.

Did you check/test your carb diaphrams?

With 3 carbs not working, it may be time to either question your carb cleaning, or suspect the coils/ignitor/pickups.

[Fenixgoon]

I had some problems with my cylinders not firing and part of it simply was they weren't getting fuel.

Check the vacuum and fuel lines from the carburetors. My vacuum line was too short and replacing it made a huuuuuuge difference.

Sometimes it's just the little things. Hopefully it's something simple and easily fixed

[chef1366]

Sounds like you did the hard way in finding out your ignition is stuffed.

[Audioslave784]

Interesting... I did replace the gaskets, and I don't think I punched out any holes. I believe I still have the old gaskets so I will compared them first thing tomorrow. Got my fingers crossed that that's the problem.

The reason I don't think it is the ignition is that both cylinder #2 and #4 fired using the #2 carb, but cylinders #2 and #4 both didn't fire using the #4 carb. Also, all the plugs and plug caps are new, and the resistance in both coils is in spec for both coil packs.

Fenix - That's a good call, as I did just get a new petcock and put on new fuel and vacuum lines. I will check out whether I'm getting a good fuel flow.

[Steve]

I am going to have to go along with faulty/incomplete carb cleaning.

Since the operating cylinder moved along with the carbs, I agree, the ignition is not the problem.

When you dipped the carbs, how long were they in the dip? Recommended time will vary based on how long it has been since the bike ran well, but I usually go a full day for each carb. After rinsing the carb with hot water, I then spray all the passages with carb cleaner and follow with compressed air. Don't forget to poke a strand of copper wire through ALL the holes in ALL the jets, just to make sure there's nothing caught there, either.

You have set the float levels. Have you verified fuel level? Or at least pulled the drain plug to verify that there is fuel in the bowl? Maybe even compare the amount of gas in each bowl to see if they are close to the same? It would seem unlikely that fuel would not be getting into three float bowls, but I can certainly understand three pilot passages blocked.

.

[Audioslave784]

The problem has been (along with a couple of other lingering ones) and the bike is finally running like a champ. Don't think there's any better feeling than the first ride after all the hard work.

The problem was that the jets had a bunch of green corrosion on them, to the point where at least a couple of the holes were completely blocked. When I dipped the carb bodies I dropped the jets in there too, and when they came out the surfaces were kind of splotchy and white. My theory is that the Berryman's stripped off whatever surface treatment the jets had, allowing them to become badly corroded over the next couple of weeks. Is this possible? And if so, am I going to need new jets to avoid having to clean them all the time?

[chef1366]

The jets are made of brass. Clean them up and run them. They'll be ok.