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Hey guys,
This was my first bike 16 years ago and I've had bikes come and go, but I'm back to trying to get her back on the road and running perfect.

Now, I've run through most everything on this bike and replaced many, many parts. But I've cleaned and adjusted the carb, replaced float valves, pilot screw seals, new Dyna coils, plugs and wires, new carb holders, all kinds of stuff.

It starts and idles perfect, but I can't get the carbs to sync right. They're close, but no matter how much I turn the screw I can't get the last little bit. One carb won't quite come down to match the other...its within 5 points on my carbtune.

Also when I turn the pilot adjustment screws, nothing changes. I have racked my brain and I just can't think of anything I'm missing. I can turn the sync screw over and over and it doesn't bring the level down to match. And it runs pretty darn good, honestly. Any thoughts?

Float level too high?
Steve

I checked a while ago before I put the bike in storage and the levels were dead on. I filled it up today and had the problem I described...I haven't changed the float level at all. I can check again to be thorough.

Sounds like a vacuum leak somewhere. Are you sure all the vacuum ports are plugged when you try to sync the carbs? And did you do a visual sync before trying the vacuum sync?

I was reading up and everything I saw pointed to vacuum as well...I also forgot to mention that the rpm's hang occasionally at stoplights, then slowly come back down to idle...classic leak symptoms.

I'm not sure what I need to plug up when I do the sync...the vacuum ports have the plugs from the sync tool in them with rubber O-rings, and I've messed with them by slightly screwing and unscrewing them while attempting the sync and I got nothing different.

Could the NOS carb holders I bought be letting outside air in? No I didn't do a bench sync...

NOS carb to head rubbers will be air tight, if they are leaking its more likely to be at the joint to the head or they are not sealing around the carb. With the bike idling spray some carb cleaner around the rubber and see if you get a change in revs. No change will mean no leak. Bogging down will mean a big leak as it sucks in too much cleaner (fuel). Speeding up will mean a small leak as it sucks in enough to correct the mixture. Either way a change in revs will indicate a leak that requires correction.
When you say you cant get them to sync, whats the issue, are you running out of adjustment?

Warren3200gt wrote: NOS carb to head rubbers will be air tight, if they are leaking its more likely to be at the joint to the head or they are not sealing around the carb. With the bike idling spray some carb cleaner around the rubber and see if you get a change in revs. No change will mean no leak. Bogging down will mean a big leak as it sucks in too much cleaner (fuel). Speeding up will mean a small leak as it sucks in enough to correct the mixture. Either way a change in revs will indicate a leak that requires correction.
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This is THE best way to check the carb holders for leaks. One other thing I would add - make sure the idle speed is set to very low rpm when doing the test. This is how I found carb holder leaks on my KZ650. The holders were leaking so badly that spraying carb cleaner around the carb holders actually stopped the engine from running. Replaced the holders and erratic idle problem was fixed. Ed

Are the airbox & air filter properly installed? Also, check that the air filter foam seal is good & the ducts are soft.
The 305 airbox is kind of similar to the 440-Ltd >> the 440 airbox is different but the cap can be installed wrong, causing an air leak.
On the 440 the test is to gently pull up on the back of the cap >> if it moves, it's installed wrong.

Edit: airbox cap >> the air filter fits inside the box-like cap >> see diagrams at Partzilla.

I'll try that today. When I say they won't sync...say the right side is high and the left side is low. I turn the adjustment screw slightly to the left and they get even farther off. So I turn to the right and they start to get a little better, so that's the direction I need to turn. Well I keep turning and turning and they still won't quite even out.

I can crank the crap out of the screw and they won't even out, I mean I can turn it 360 degrees, and then 360 degrees again in the same direction and nothing will happen.

So if there is a leak around the carb holders, what do you recommend?

The air filter is newish. I've got the filter and box installed tightly...what do you mean a cap? Mine is just a filter that drops in a box and the whole box is screwed in place to create a seal.

Depends where the leak is. If its between the head and rubber joint you have no choice but to take them off , ensure the head side is clean and flat, same the rubber side is the same. If there are any scratches, even tiny ones you'll need to use a very thin smear of sealant when re assembling.
If it the carbs not sealing in the rubbers, ensure the clips are TIGHT , even it it means using jubilee clips instead of khi clips. Remember the khi clips are 40 years old and likely are sloppy and stretched.

Seal the carb holders at the head and bench sync the carbs then try to sync them.
Steve