What to adjust?

[Guest]

Working on the electrical on the bike and saw that the carbs were easily accessible. Ah ha I thought, after reading about painting the carbs. Its about time I started to invest a little bling to the bike and I needed to wait for the electrical anyway, so I pulled the carbs.

They were dipped 3 years ago and the bike ran fine last fall. I opted for the ultrasonic cleaning and while I was at it, sprung for new boots all around (the old ones worked, but hey, I thought, let's eliminate any problems) and new o-rings from Mr. Barr.

Made sure the openings were taped and painted the carbs. Tops and bottom black, the bodies silver using caliper paint. Reassembled the carbs (CV), turned the mixture screws at 2-1/2 turns out and bench synched using a small paperclip as the clearance standard.

Have everything reassembled now (shame that the carbs are next to a dingy engine, but a little more polishing next year) and finally got it to start.

Boy, does it run rough with some backfire coming from the exhaust pipes and I cannot adjust the idle. I just now remembered that I had the carb/tank vacuum port open. I'm trying to get the engine warm to begin the standard synching.

What am I missing on adjusting to get me to the "golden purr"?

[chuck hahn]

Be sure the air filter is clean or better yet, new. Best to be sure she is breathing properly when your doing AIR to fuel adjustments.

[Riding Again]

Thanks for the advice Chuck, but yes, I did clean the air filter (it seemed as if I'd never cleaned it-used some K&N filter cleaner on the foam filter) and reoiled it, this time with filter oil.

However, I finally have had time to go back and pull the carbs and this is what I found.

1) Gas in the air box
2) The carb tops (diaphragm covers) weren't completely tightened
3) A split #2 Bowl gasket
4) Float valve stuck on #4

However, I did have fuel in the #4 bowl so whatever caused it was intermittent and I cleaned out the passages just to make sure.

I'm not going to make excuses for any of this as it was my work and it appears to have been shoddily done. Though I do know I checked the float valve operation before closing up the bowls as well as the bowl gaskets. Still--no excuse.

I'm rechecking the float valve operation as that would be the only way I could see how gas got into the air box. (No, no gas in the oil either)

[Riding Again]

Went through the offending carb, with sprays to make sure there was nothing blocking gas flow and to clean the float valve. Then I double checked the float levels and they were all good.

I made new bowl gaskets from gasket stock, inserted them and double checked my work (tightening the screws).

And then.......It started!!!

[tom203]

Riding again said....

"I'm rechecking the float valve operation as that would be the only way I could see how gas got into the air box. (No, no gas in the oil either"

Now would be good time to check petcock- they've been known to fail !

[Riding Again]

Riding again said....

"I'm rechecking the float valve operation as that would be the only way I could see how gas got into the air box. (No, no gas in the oil either"

Now would be good time to check petcock- they've been known to fail !

I suspect it had more to do with me trying to empty the fuel tube a time or two by blowing back through the overflow tubes to remove any air pockets [insert doh! smiley] The petcock is good, still need to apply a vacuum to release the fuel.

[Steve]

I suspect it had more to do with me trying to empty the fuel tube a time or two by blowing back through the overflow tubes to remove any air pockets [insert doh! smiley]

Neat trick. What "overflow tubes"? Your bike does not have any.

What you were probably blowing on were the VENT tubes. There are two of them, they are connected to the tees between carbs 1&2 and 3&4. There are no "air pockets" that will be removed by blowing on them. The only thing accomplished by blowing on them is pressurizing the float bowls, which will force a bit of gas into the throat of the carbs, kind of acting like a "choke", because it will put more gas available to be burned.

The petcock is good, still need to apply a vacuum to release the fuel.

Yep, you have "the dreaded '80 petcock" on that bike. It takes steady vacuum (running engine) to keep the fuel flowing in the ON position, but it also takes vacuum (briefly) to get the fuel flowing in the PRIme position.

If you feel that you need to prime your carbs, there is no need to disassemble anything. Just move the petcock to the PRIme position with a screwdriver, crank the engine for a couple of seconds, turn the key off. The few vacuum pulses from the cranking engine will be enough to start the fuel flow.

Don't forget to turn the petcock back to the ON position when you are done.

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