Couple Questions about Carbs

[Duo Maxwell]

Alright, so I'm still working on my bike and I've come to the carbs. I've already cleaned them but now comes all the tuning. The previous owner installed K&N filters and each filter covers two carbs...not sure if they fall under pod filter definition. The previous owner also installed a Vance&Hines exhaust and when I tore open the carbs I THINK the main jets were 130's. Also, the needles had the washer and the clip that you can move up or down to change the fuel mixture so I'm pretty certain at this point that it has a jet kit.

Now then, I need to tune the bike and while I have been reading a lot the main things I am not sure about are locations.



I don't have my carbs in front of me so I just googled for a picture...is this right?

Also, I see that each carb has a little nub coming off of it and that the vacuum line hooks into carb #4....I keep reading about plugs...are the other 3 holes supposed to have rubber plugs on them?

Essentially, the bike runs great....no dead spots but the only problem is that it will not idle properly...I have to adjust the idle to about 2.5 to 3 thousand RPM...and I'm going by ear because the tach doesn't work. I've already cleaned the crap out of the carbs...so that isn't the problem. I'm wondering what comes next...here's what comes to mind:

• Adjust pilot (air?) screws...I've left them alone for now.
• Adjust fuel screws? I have them at about 2 and a quarter turns out
• Just synch carbs?
• This jetting/filter/exhaust is a bad combo and I should get the stock airbox

Also, the bike idles fine if I bring the idle adjustment up....and with choke it's fine as well...which makes me think that the mixture is too lean? The exhaust smells like gas and my mileage isn't all that great so that makes me think rich.

Thanks all,
-Duo Maxwell

**EDIT**

I'm going to go out and take a video of the symptoms. Also, I reread carbs 101 and I'm going to try re-visually-synching them.

[III]

Also, I see that each carb has a little nub coming off of it and that the vacuum line hooks into carb #4....I keep reading about plugs...are the other 3 holes supposed to have rubber plugs on them?

Nope, no plugs on the others. I believe they're sealed from the inside out. Just the hose on number 4 goes to the nipple on the petcock that points that way. The only other plugs that I'm familiar with on/in the carbs are the ones that go over the pilot jets under the floats. There should be one on each carb.

Not sure what year and size you have, but the air and fuel screw (a/f screw) are one in the same and they should all be at 2.5, but good luck with tuning with that setup. I bought mine the same way, but the PO took off the exhaust. Ended up having to get a Factory Pro jet kit and the factory airbox to get running decent with out the exhaust.

[Black_peter]

I'm down to almost 2 turns on the F/A screws but that is with stock set up.. A synch is in order. Also make sure that the F/A screws are set up right. Screw, spring, washer then O-ring.. Make sure the F/A holes are very clean same with the jets. And be sure the o-rings for the F/A screws are not all flattened out..

[Kreylyn]

You have a jet kit, now the question is ... what size?...

With mains running 130, it sounds to me like a stage 3 possibly.

If the PO put a stage 3 kit in, then the pilot jets were drilled out to tune the bike for it. The effect of that is... needing to run 4-4.5 turns out on the fuel/air screws for the bike to properly idle.

Krey

[DumbLuck]

almost exactly what it took to get a dynojet stage 3 kit to idle and run on a '90 1100 kat. 4.5 turns out. clean and reclean the pilot circuit. if you cant get a good steadly idle there is no way it's gonna sync.

You have a jet kit, now the question is ... what size?...

With mains running 130, it sounds to me like a stage 3 possibly.

If the PO put a stage 3 kit in, then the pilot jets were drilled out to tune the bike for it. The effect of that is... needing to run 4-4.5 turns out on the fuel/air screws for the bike to properly idle.

Krey

[Duo Maxwell]

You have a jet kit, now the question is ... what size?...

With mains running 130, it sounds to me like a stage 3 possibly.

If the PO put a stage 3 kit in, then the pilot jets were drilled out to tune the bike for it. The effect of that is... needing to run 4-4.5 turns out on the fuel/air screws for the bike to properly idle.

Krey

So, I visually synchronized the carbs today and reset the A/F screws and the bike ran amazingly well....incredibly smooth and just omfg cream in your pants good. The only problem was idle. Essentially, idle was in either one of two modes....limping and barely living....or really high (3k or so -- guesstimate). I could get it to idle around 2k but slowly backing down the idle adjustment but after hitting the throttle a couple times it would go back to limping mode.

In limping mode it lives for a couple minutes but eventually just cuts out. Now then, I am more than fairly certain that the bike is running really rich...it seems the idle is crazy high then eventually with less and less air going into the bike it starts flooding and thats when the idle starts to die.....and then finally too much gas and it cuts out.

From what I've read...turning the screws out adds air (right?)...currently I'm at 2.25 turns out or so (which most likely means I'm running extra rich)...I'll go back down tomorrow and turn them out even more.

One last thing....I've noticed that the carb 4 (or 1...can't remember which end) A/F screw has a small brass thing on the outside...almost like a cap. Also, this carb is the only one where I can feel a spring while tightening/loosening.

I'm going to go set the screws to 4.5 tomorrow and see what happens. If I still have problems I'm going to take them apart and check out the screws themselves. Worse comes to worse I'm going to just jet it stock and get the air cleaner.

Thanks all,
-Gabriel

[Kreylyn]

So, I visually synchronized the carbs today and reset the A/F screws and the bike ran amazingly well....incredibly smooth and just omfg cream in your pants good. The only problem was idle. Essentially, idle was in either one of two modes....limping and barely living....or really high (3k or so -- guesstimate). I could get it to idle around 2k but slowly backing down the idle adjustment but after hitting the throttle a couple times it would go back to limping mode.

In limping mode it lives for a couple minutes but eventually just cuts out. Now then, I am more than fairly certain that the bike is running really rich...it seems the idle is crazy high then eventually with less and less air going into the bike it starts flooding and thats when the idle starts to die.....and then finally too much gas and it cuts out.

From what I've read...turning the screws out adds air (right?)...currently I'm at 2.25 turns out or so (which most likely means I'm running extra rich)...I'll go back down tomorrow and turn them out even more.

One last thing....I've noticed that the carb 4 (or 1...can't remember which end) A/F screw has a small brass thing on the outside...almost like a cap. Also, this carb is the only one where I can feel a spring while tightening/loosening.

I'm going to go set the screws to 4.5 tomorrow and see what happens. If I still have problems I'm going to take them apart and check out the screws themselves. Worse comes to worse I'm going to just jet it stock and get the air cleaner.

Thanks all,
-Gabriel

Turning the screws out adds fuel.

The issue with the idle revs being high is actually a LEAN issue. Trying the setting at 4.5 is a good start.

Krey

[Duo Maxwell]

Alright so I set the air-fuel screws at 4.5 turns out...now it runs a lot better still. Idle is still a little funky...after riding it around for a block or just giving it gas for awhile it will stay at idle...a bit high, but still idle. If I just start it up it will idle but then drop down to the really slow barely alive idle...basically the same problem as before only not as bad.

Also forgot to hook up my vacuum line which made it fun to ride once my bowls ran out of gas =P.

Was gonna ask about hoses, but it turned out to be really damn long so I'll wait and post another thread later on.

I'm assuming I should turn out the A/F screws a little more (another 1 or .5 turns) right?

Pulling the choke very slightly (like half an inch) makes it run pretty well.

Thanks again everyone,
-Duo Maxwell

Thanks,
-Duo Maxwell

[wepainters]

I guess you have already checked all of your boots to make sure you dont have a leak somewhere as sometimes a boot leak will mess with things

food for thought

[Duo Maxwell]

I guess you have already checked all of your boots to make sure you dont have a leak somewhere as sometimes a boot leak will mess with things

food for thought

Yeah I have...everything was in pretty good condition.

Thanks,
-Duo Maxwell

[Kreylyn]

I'm assuming I should turn out the A/F screws a little more (another 1 or .5 turns) right?

Pulling the choke very slightly (like half an inch) makes it run pretty well.

Unfortunately, 4.5 is about the max turn out you want, any further and you risk them being able to vibrate out due to the length of the spring inside used to keep them "tight".

If it's still having a little bit of issue, I would consider cleaning them agian (one cleaning is never enough, trust me... ), checking float heights again (I have to run mine at 14mm), and making sure all rubber is in good shape (gaskets, hoses, boots) with no cracks at all.

Have you check for vacuum leaks while it's running by spraying rubbing alchohol from a spray/spritzer bottle around the carb bodies? If the revs pic up any when you do that, you have a vacuum leak there.

Nother option would be for you to swap out the pilot jets with new factory setting ones, instal a stage 1 jet kit (better road rideability anyways) and then be able to go back to the 2.5 setting on the air/fuel screws.

I just ordered a full set of the pilot jets for around $20.

Krey

[DumbLuck]

grubby pilot circuit. especially if you're running pods. they let all sorts of crap thru and it doesnt take much more than a spec to clog a pilot jet

[Duo Maxwell]

I backed the A/F screws down to about 3 turns and its running better....basically a midpoint between the two. I'll run it for a few more days and see how it does and I'll post back with results.

Really appreciate everyone's help, and a special thanks to you krey.

-Duo Maxwell