New Owner needs Help!

[1948man]

Don't let it idle too long without a fan blowing on it. It is air-cooled and needs air flow. What is the condition of your fuel tank. Old tanks that spew tiny rust particles into the small passageways in your carbs are common.

[brian]

Ok, here's some photos of my first carb tear down. You'll notice that the fittings with o-rings (pretty much all of them) have a calcium type of build up.

The exterior of carbs looks pretty dirty (old dirt), which makes me question how thorough the PO broke them down and cleaned them?

All the passages and jets seemed clean and clear, but who knows, I still have #1 carb dipped in the carb cleaner...24 hours right? (even thou the instructions on the can say 20 minutes?)

O-rings do look brand new once I got the build up rubbed off. No flat spots, cracks, or dry rotting...they look new.

If you notice the bowls and caps had black paint on them...a little aircraft remover took care of that...and they are in the dip too.

All I have to say is WOW...that's a lot of parts!

Any thoughts?

[brian]

John thanks,

the pic is of the #2 carb which I haven't broke down yet, but the #1 carb has all the rubber removed and all the pieces are soaking. I did use the "special tool" to check all the passages and jets...so far so good.

The hot soapy water trick with nylon (tooth) brush is new, I'll do that when I pull it out tomorrow.

...then on to #2.

Thanks again!

[brian]

Next question,

What happens if the float height is incorrect? Doesn't get fuel, or overflows? Or either?

Also, will someone please clarify: pilot screw, air screw, fuel flow screw??? What is the screw on the engine side of the carbs that can be adjusted after the carbs are installed? The rebuild series calls them air screw, but somewhere else I read pilot screw, and somewhere else I think they were called fuel flow screws? I just need to know how many turns to back them out?

And is there any other screws that need to be backed off a certain amount of turns?

1980 GS 850 GLT - Mikuni BS32SS carbs.

Thanks,

[850 Combat]

There is just that one adjustment screw. It is in the pilot circuit, which pulls fuel through the main jet, then through the pilot jet, where it mixes with air from the pilot air jet. This mixture is throttled by the pilot screw. There is a good drawing of how it works on Cliff's site in the factory manual. Air comes in from the pilot air jet in the air horn of the carb, I think it is the one on the lower left. The one on the right is air to the emusion tubes above the main jet. I like to remove the pilot screw and spray carb cleaner through the air jet and make sure it comes out the pilot jet and air screw hole and the openings by the butterfly in the carb throat, then spray in each of the other reachable openings and visually verify that all the internal passages are clear. I recommend wearing safety glasses while performing this work.

My bikes have experienced clogged passageways in the pilot circuit when I thought they were clean.

You have to have the rubber plugs under the pilot jets so that they draw correctly through the main jet.

It is page 301 of the PDF that clearly shows the pilot circuit. Chapter 14-30 of the manual. The first carb section in the manual is 1979 only. You need to go to the next carb section for the '80 and later type.
http://www.mtsac.edu/%7Ecliff/storag...nual_HiRes.pdf

[brian]

So far so good on the first Carb...everything is clean and clear...perfectly now, and I know it for sure.

Problems I may have found:
1. I think the choke hole in the bowl may have been clogged, but it's clear now.
2. the float level on # 1 was too high (if the bowl was upright), so I adjusted it to the prescribed .88in. Perfect now.

I have a attached a picture that I think should get added to Basscliff's carb rebuild instructions. I didn't know there was a screen inside this. I thought this may help out a little...at least for the new guys.

#2 carb is soaking, it was dirty, but it still looked clean and clear in the passage ways...doesn't matter now...it's going to be spotless. Then I'm on to #3 this afternoon.

Thanks for all the help guys!

[brian]

Update

Ok, this is day 4 so the carbs are spotless.

Here's where I'm at:

1. Cleaned/dipped carbs. I rebuilt them perfectly...ie Soaked for 24 hours, blow out all passages, measured and adjusted floats to .88in., backed off air screw (pilot screw or fuel mixture screw depending on who you talk to) 3 rotations, did the bench sync with the paperclip measure....and the seem to work perfectly now

2. Installed them on the bike and after letting her fill up the bowls she started perfectly, and even idles relatively good too. I have her dialed in to about 1100 for now. BUT...

* Now she's idling a little choppy, but steady. (I was going to blame it on the carb sync not being perfect...yet). BUT...

* When I went to install my carb sync get up, I noticed that the #1 and #2 cylinders are hot (probably normal after running for a minute or two), the #3 and #4 cylinders are not.

If you remember that I just replaced the coils with new Dyna's, but I don't think it's those because 1 coil controls 1st and 4th plug, and the other controls the 2nd and 3rd plugs.

* I also noticed that while she was idling, I would give the throttle a small twist or two and she was very sluggish to throttle up and slow to recover...I'm thinking this is a combination problem with the #3 and #4 cylinders not hot, but not sure so I thought I would mention it.

I'm letting her cool now, I'll check the plugs in a while.

I'm not sure where to start to diagnose this?

BTW - Thanks guys for getting her this far, I never would have been able to do this without you...thanks!

[David_510]

When you re-assembled the carb (im not sure if your are like mine) but my inner cyclinders (2&3) have larger jets and the outers have smaller jets... Maybe you mixed them up?

[brian]

Nope, but thanks for the reply.

All of my carbs are the same, and I disassembled/cleaned them one at a time so I wouldn't swap parts on them.

I'm going to get a compression tester now. I needed to check the compression anyway. This may answer some more questions.

Any other ideas?

[Octain]

Make sure you dont have the plug wires crossed and make sure they're in good shape with good ends. I hate to sound so repetitive but the plugs should be in new unused condition at initial fire-up. At least you'll know(99.9%) its not the plugs.

When I put a 650(cv 32's) back together it had one cylinder that was not firing(no. 2 if my memory serves). Loosened the drain plug on that carb and there was no fuel in the bowl.
I did everything I could to keep from pulling the carbs back off but in the end it couldnt be avoided.
Took that carb apart and found nothing wrong. I hooked up a fuel source sitting on the bench and it was getting fuel.
Reinstalled the carbs and it started right up and ran perfect.
To this day I have yet to figure out why only that cab wasnt getting fuel.


Perhaps those two carbs on your bike arent getting fuel for one reason or another.
Check the bowls for fuel.
Also be sure the airbox and all of it contents are correctly assembled and there no leaks.

Keep us posted

[brian]

Check the bowls, got it!

As far as the plugs. Everything is brand new, but I'll check connections
(new Dyna ignition coils, new wires, new connectors, new plugs)

I pulled the plugs a little while ago, the #1 + #2 look like they have been running, but the #3 + #4 plugs look cleaner (like they haven't been running much).

I have my compression tester now, I'll check compression first thing in the morning.

[Octain]

Sounds like those two carbs arent getting fuel.
Do they smell of fresh fuel, are they wet?

[brian]

I agree.

I have the airbox on (it doesn't like to run without it?), so I can't really smell or check them visually for being wet.

I just check the drain plugs and they do have fuel in the bowls. I didn't let them drain completely, just broke torque and let them drip a little.

Should I pull the airbox and try to get it to run without it? That way I could check the intakes for fuel.

[waterman]

I agree.

I have the airbox on (it doesn't like to run without it?), so I can't really smell or check them visually for being wet.

I just check the drain plugs and they do have fuel in the bowls. I didn't let them drain completely, just broke torque and let them drip a little.

Should I pull the airbox and try to get it to run without it? That way I could check the intakes for fuel.

I believe Octain was referring to the spark plugs being wet or smelling of gas, especially on cylinders 3 and 4. If they aren't firing and you are getting gas to cylinders, then they will be wet with gas or at least smell of gasoline. If they are dry and clean with no carbon, like new, then they are not getting gas. Obviously, a little carbon indicates they are burning gasoline and hence running a least some of the time.

Try changing spark plugs from running cylinders to non running cylinders. If it is bad plugs, it will follow plugs. Do this right after engine has been running with plugs warm. Take care not to burn self, but after only running short time engine shouldn't be extremely hot.

Leave airbox on, these bikes will not run well without some sort of intake restriction.

[brian]

Waterman,

thanks for the advice I changed the plugs from 1+2 to 3+4 and it seemed to be the problem. 3+4 started getting warm.

I say warm because it didn't run for very long (maybe 30 seconds). The 3+4 exhaust headers were warm and 1+2 were cold.

Then I changed the 1+2 plugs out with new ones out of the box. Gapped properly to .31 (formerly the old 3+4 plugs before the swap)

I tried to start and it turns over strongly but won't start.

Being the engine was warm from running earlier, I did the compression test here's what came back: #1 = 130, #2 = 122, #3 = 135, #4 = 145

During the recent starting attempts, I'm now getting some popping noises coming from the carb area.

I pulled the airbox and the intakes of the carbs have a little oily deposit (maybe mixed with fuel too) on them.

I'm really getting confused? Help, please...

P.S. Oh yea, now all the plugs are dry??? the working plugs before were a little wet.